contract no: 15-069 wastewater review and options …
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CONTRACT NO: 15-069
Wastewater Review and Options Study for Edgecumbe and Matatā Incorporating a High Level Review of Tāneatua and Te Teko
Contract 15-069 - Work Streams 2a and 2b
Prepared for Whakātane District Council
22 September 2015
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final Project No.: 805 08148 22 September 2015 Our ref: \\NZAKL1S01\Projects\2012 Onwards\Whakatane District Council\805 08148 WDC Edgecumbe WW Options\4.0 Technical\2a-2b Report\WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15.docx
QUALITY STATEMENT
PROJECT MANAGER PROJECT TECHNICAL LEAD
Garrett Hall Jim Bradley
PREPARED BY
Jim Bradley/Garrett Hall/Rainer Hoffman/Darren Wilson
CHECKED BY
Rainer Hoffman/Darren Wilson
REVIEWED BY
Jim Bradley
APPROVED FOR ISSUE BY
Garrett Hall
AUCKLAND MWH House Level 3, 111 Carlton Gore Road, Newmarket, Auckland 1023 PO Box 9176, Newmarket, Auckland 1149 TEL +64 9 580 4500, FAX +64 9 580 7600
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Executive Summary Introduction
Whakatāne District Council (WDC) has a number of urgent and pending wastewater infrastructure and associated consenting matters that require addressing in a comprehensive and efficient manner.
MWH has been engaged by WDC to assist in these matters. This Report includes the following five Tasks:
Task 1: Consideration of the future treatment and disposal/discharge options for Edgecumbe (referred to as Edgecumbe standalone) given the existing resource consent for the discharge from the Edgecumbe Wastewater Treatment Plant (WWTP) expires in 2026;
Task 2: Consideration of combined Matatā and Edgecumbe treatment and disposal/discharge options. A joint scheme will allow comparison with the Matatā standalone shortlist options being separately developed by WDC and AECOM Consultants (formerly URS) following the Matatā Environment Court decision in May 2015;
Task 3: High level consideration for the future treatment and disposal/discharge from the existing sewerage scheme in Tāneatua (this consent also expires in 2026);
Task 4 High level considerations of a possible future reticulated sewerage scheme for Te Teko; and
Task 5: Review WDC’s Infrastructure Strategy 2015-45 as it relates to Council’s wastewater services. This part of MWH’s engagement is separately reported on as Work Stream 1 of this Contract 15-069.
Methodology
In developing and assessing the various options available to WDC, Tasks 1 and 2 follow the same broad methodology and staged approach being:
Stage 1: Identification and development of long list options;
Stage 2: Refinement and assessment of the long list to the confirmed long list;
Stage 3: Refinement and assessment of the confirmed long list to the short list;
Stage 4: Compilation of information to enable the short list to be assessed; and
Stage 5: Assessment and ranking of the short-list.
This draft Report has been prepared to Stage 4 and will be used to inform the further assessment and ranking of the short listed options for Stage 5. It is proposed by WDC that Stage 5 will also include the Matatā standalone options being developed by WDC and AECOM Consultants.
Edgecumbe Standalone Options
The following long list options for the standalone Edgecumbe scheme were developed and identified under the following subheadings:
Conveyance Options
Option 1 - Conveyance of Edgecumbe raw sewage to Kawerau WWTP;
Option 2 - Conveyance of Edgecumbe oxidation pond treated wastewater to new ocean outfall around Matatā;
Option 3 - Conveyance of Edgecumbe from a new WWTP at Edgecumbe to new ocean outfall around Matatā;
Option 4 - Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne existing ocean outfall;
Option 5 - Conveyance of Edgecumbe raw sewage to Whakatāne WWTP oxidation pond .
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Treatment at Edgecumbe Options and Land Application at Edgecumbe
Option 6 - Upgrade of existing Edgecumbe oxidation ponds and Land Application at Edgecumbe;
Option 7 - New WWTP at Edgecumbe and Land Application at Edgecumbe.
Treatment at Edgecumbe Options and Land Application at Thornton
Option 8 - Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes;
Option 9 - New WWTP at Edgecumbe and Land Application at Thornton Dunes.
Treatment at Edgecumbe Options and Discharge to Tarawera River Catchment
Option 10 - New WWTP at Edgecumbe and Tarawera River Discharge.
Treatment at Edgecumbe Options and Discharge to Rangitaiki River Catchment
Option 11 - New WWTP at Edgecumbe and Rangitaiki River discharge; and
Option 12 - Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki River discharge.
These options were then refined and assessed to the following short list after an assessment based on qualitative environmental, social, economic, key advantages and disadvantages and risk factors. Maori cultural considerations have not been included in the assessment to date although some information made available to WDC has been recorded in this Report.
Option 1 - Conveyance of Edgecumbe raw sewage (LPS) to Kawerau WWTP;
Option 4 - Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne ocean outfall;
Option 5 - Conveyance of Edgecumbe raw sewage to Whakatāne WWTP oxidation pond ;
Option 8 - Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thorn ton Dunes;
Option 12 - Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki River discharge.
For Option 8 an alternative land application area was also considered by WDC is part of the expansive Whakatāne Airport land. This option was subsequently identified as Option 8A.
A more detailed risk assessment was then compiled alongside the high level cost estimating of these options to assist the further WDC decision making process.
The summarised cost breakdown for these short list options for the Edgecumbe standalone scheme is shown below.
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
CAPEX ($M) OPEX – Year 1 ($M)
OPEX - Year 20
($M)
(for Comparison)
NPV ($M)
Option Conveyanc
e Treatment Total Capital
Maintenance/ Replacement includes KDC Bulk Charge
for EDG1
Power Dosing Total Year 1 - OPEX
Total Year 20 - OPEX
TOTAL COST
EDG1 $10.520 $0.300 $10.820 $0.315 $0.020 $ - $0.335 $0.590 $15.705
EDG4 +Actiflo + UV
$10.080 $0.520 $10.600 $0.040 $0.010 $ - $0.050 $0.125 $11.470
EDG5 + Actiflo + UV
$10.400 $0.440 $10.840 $0.040 $0.035 $0.045 $0.120 $0.290 $12.890
EDG8 $6.150 $5.550 $11.700 $0.085 $0.185 $0.030 $0.295 $1.425 $18.355
EDG8A $7.670 $5.550 $13.220 $0.090 $0.185 $0.03 $0.305 $1.425 $19.895
EDG12 $1.625 $4.315 $5.940 $0.080 $0.185 $0.025 $0.295 $1.410 $12.515
Taking into account a range of considerations through a Multi-Criteria Analysis (MCA) including cost, the ranking of the top three options were:
1. Option 4 – Oxidation Pond Wastewater to Whakatāne WWTP Ocean Outfall;
2. Option 5 – Raw Sewage to Whakatāne WWTP; and
3. Option 8A – Upgraded Oxidation Ponds and Land Application at Whakatāne Airport.
Options 4 and 5 propose the conveyance of either wastewater treated in the oxidation ponds at Edgecumbe or raw sewage to Whakatāne WWTP. Both options utilise the existing infrastructure at the Edgecumbe and Whakatāne WWTP’s, and would require a condition change to the existing resource consent for the discharge of treated wastewater from the Whakatāne WWTP, or a new consent to be applied for.
Land application at the Whakatāne Airport also ranks highly, and may be possible to combine with a future treatment option at the Whakatāne WWTP, where land application of treated wastewater from the Whakatāne ponds may be possible in the future.
Combined Matatā and Edgecumbe Options
The following long list options for a combined Matatā and Edgecumbe scheme were developed and identified under the following subheadings:
At Kawerau
Option KL1 - Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP and Rapid Infiltration Bed (RIB) Land Disposal.
At Edgecumbe
Option EL1 - Conveyance of Matatā raw sewage to Edgecumbe Oxidation Ponds - Land Application at Edgecumbe
Option EL2 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe – Land Application at Edgecumbe;
Option ER1 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe and Omeheu Channel Discharge;
Option ER2 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe and discharge to Rangitaiki River; and
Option ER3 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds upgraded as necessary and discharge to Rangitaiki River.
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
At Matatā
Option ML1 - Conveyance of Edgecumbe raw sewage to new WWTP at Matatā - Land Application at Matatā;
Option ML2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā Land Application. Matatā standalone treatment and joint land application with Edgecumbe at Matatā;
Option MR1 - Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to Lower Tarawera River;
Option MR2 - Conveyance of Edgecumbe upgraded oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint discharge to Tarawera River;
Option MO1 - Conveyance of Edgecumbe raw sewage to Matatā, joint treatment and discharge to ocean at Matatā; and
Option MO2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint ocean discharge at Matatā;
At Thornton
Option TL1 - Conveyance of Edgecumbe raw sewage to Matatā. Joint treatment at Matatā, land application at Thornton;
Option TL2 - Conveyance of Edgecumbe upgraded oxidation pond treated wastewater to Matatā. Matatā standalone treatment and joint land application at Thornton; and
Option TL3 - Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe upgraded oxidation ponds and conveyance to land application at Thornton.
At Whakatāne
Option WO1 - Conveyance of Matatā to Thornton and Edgecumbe to Thornton – then combined conveyance to Whakatāne WWTP upgraded and Ocean Outfall Discharge;
Option WO2 - Conveyance of Matatā to Whakatāne WWTP and Edgecumbe to Whakatāne WWTP upgraded (via Awakeri) and Ocean Outfall Discharge;
Option WO3 - Conveyance of Matatā to Thornton and Edgecumbe Oxidation Pond treated wastewater to Thornton to the Whakatāne ocean outfall;
Option WO4 - Conveyance of Matatā raw sewage to Whakatāne WWTP and Edgecumbe Oxidation Pond treated wastewater to Whakatāne (via Awakeri) for joint Whakatāne ocean outfall;
Option WO5 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option A – via Thornton; and
Option WO6 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option B – via Awakeri.
These options were then refined and assessed to the following short list after an assessment based on qualitative environmental, social, economic, key advantages and disadvantages and risk factors. As per the Edgecumbe standalone option, Maori cultural considerations have not been included in the assessment to date although some information made available to WDC has been recorded in this Report.
Option KL1 - Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP and Rapid Infiltration Bed (RIB) Land Disposal.
Option ER3 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds upgraded as necessary and discharge to Rangitaiki River.
Option TL2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment and joint land application at Thornton; and
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Option TL3 - Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe oxidation ponds and conveyance to land application at Thornton.
Option WO1 - Conveyance of Matatā raw sewage to Thornton and Edgecumbe to Thornton – then combined conveyance to Whakatāne WWTP and Ocean Outfall Discharge .
Option WO5 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option A – via Thornton.
For Option TL2 and TL3 an alternative land application area currently also being considered by WDC is part of the expansive Whakatāne Airport land. These were subsequently labelled Options TL2A and TL3A.
A more detailed risk assessment including identification of further mitigation measures was then compiled alongside the high level cost estimating of these options to assist the further WDC decision making process.
The summarised cost breakdown for these short list options for the combined Matatā and Edgecumbe scheme options is shown below.
CAPEX ($M) OPEX – Year 1 ($M)
OPEX - Year 20 ($M) (for
Comparison)
NPV ($M)
Option Matatā
Reticulation Conveyance Treatment Total Capital
Maintenance/ Replacement includes KDC Bulk Charge
for KL1
Power Dosing Total Year 1
- OPEX Total Year 20 - OPEX
TOTAL COST
KL1 $6.000 $18.955 $0.300 $25.255 $0.365 $0.030 $0.065 $0.460 $0.855 $32.085
ER3 $6.000 $9.765 $5.155 $20.920 $0.115 $0.200 $0.045 $0.360 $1.540 $28.495
TL2 $6.000 $10.490 $8.985 $25.475 $0.115 $0.255 $0.040 $0.410 $1.625 $33.810
TL2A $6.000 $13.585 $8.985 $28.570 $0.120 $0.255 $0.040 $0.415 $1.630 $36.945
TL3 $6.000 $13.310 $6.540 $25.850 $0.120 $0.200 $0.045 $0.365 $1.555 $33.515
TL3A $6.000 $14.835 $6.540 $27.375 $0.120 $0.200 $0.045 $0.365 $1.555 $35.045
WO1 + Actiflo + UV
$6.000 $16.240 $0.625 $22.865 $0.090 $0.020 $0.065 $0.175 $0.410 $25.705
WO5 + Actiflo + UV
$6.000 $17.125 $0.700 $23.825 $0.075 $0.025 $0.015 $0.115 $0.280 $25.760
MW1 + Actiflo + UV
$6.000 $9.410 $0.180 $15.590 $0.060 $0.010 $0.015 $0.085 $0.185 $16.915
Taking into account a range of considerations through a Multi-Criteria Analysis (MCA) including cost, the ranking of the top three options were:
1. Option WO5 – Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe
oxidation ponds treated wastewater for joint Whakatāne Ocean Outfall discharge
2. Option WO1 – Conveyance of Matatā raw sewage to Thornton and Edgecumbe raw sewage to
Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge; and
3. Option TL3A - Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at
Edgecumbe oxidation ponds and conveyance to land application at the Whakatāne Airport.
Similar to the Edgecumbe standalone options, the conveyance of treated wastewater to Whakatāne in option WO5 has a number of advantages over the conveyance of raw sewage in WO1. Land application at Whakatāne airport also ranks highly and should be included in further considerations.
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project No.: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Whakatāne District Council
Wastewater Review and Options Study for Edgecumbe and Matatā
Contract 15-069 - Work Streams 2a and 2b
CONTENTS
Executive Summary ................................................................................................................................... i
1 Project Context ................................................................................................................................... 1
1.1 Background .................................................................................................................................... 1
1.2 Project Scope and Overall Approach ............................................................................................. 1
1.3 Inter-related Projects and Decision Making ................................................................................... 3
1.4 Existing Investigations and Documentation ................................................................................... 3
1.5 Whakatāne District Council – Key Project Drivers ......................................................................... 4
1.6 Community and Tāngata Whenua Consultation – Key Considerations ......................................... 4
1.7 Work Stream 1 Output and Relationship to this Project ................................................................ 5
2 Project Inputs, Assumptions and Methodology ................................................................................... 7
2.1 Project Inputs and Assumptions .................................................................................................... 7
2.2 Study Area ..................................................................................................................................... 7
2.3 Wastewater Volumes and Flows .................................................................................................... 7
2.3.1 Matatā Design Flows .............................................................................................................. 8
2.4 Technical Approach ..................................................................................................................... 10
2.5 Building up a Complete Scheme.................................................................................................. 11
2.6 Concept Design Assumptions - Conveyance ............................................................................... 12
2.6.1 Managing Septicity and Odourous Gases in Conveyance Systems ..................................... 14
2.6.1.1 Chemical Dosing (Liquid Phase Odour Control) ........................................................... 15
2.6.1.2 Odour Treatment (Gas Phase Odour Control) .............................................................. 15
2.6.2 Balancing of Raw Wastewater .............................................................................................. 16
2.6.3 Balancing of Treated Wastewater ......................................................................................... 16
2.7 Concept Design Assumptions - Odour Management of Conveyance Systems ........................... 17
2.8 Concept Design Assumptions – Treatment ................................................................................. 17
2.9 Natural Hazards and Climate Change ......................................................................................... 18
2.10 Environmental Effects Assessment ............................................................................................. 18
2.11 Land Application Options ............................................................................................................. 18
2.12 Existing Resource Consents ........................................................................................................ 23
2.13 Risk Considerations ..................................................................................................................... 24
2.14 Discharge / Disposal Options – Land, Freshwater, Marine.......................................................... 24
3 Legislation and Planning Instruments ............................................................................................... 26
3.1 Overview ...................................................................................................................................... 26
3.2 National Policy Statement for Freshwater Management 2014 ..................................................... 26
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project No.: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
3.3 New Zealand Coastal Policy Statement 2010 .............................................................................. 26
3.4 Regional Policy Statement and Regional Plans .......................................................................... 27
3.4.1 Operative and Proposed Regional Policy Statement ............................................................ 27
3.4.2 Regional Air Plan .................................................................................................................. 28
3.4.3 Regional Water and Land Plan ............................................................................................. 28
3.4.4 Regional Plan for the Tarawera River Catchment ................................................................. 29
3.5 Matatā Wastewater Consents and Designation: Environment Court Decision 2015 ................... 32
4 Cost Estimates ................................................................................................................................. 33
4.1 Basis of Cost Estimates ............................................................................................................... 33
5 Edgecumbe Standalone Options ...................................................................................................... 35
5.1 Methodology ................................................................................................................................ 35
5.2 Identification of Long List Options ............................................................................................... 35
5.3 Evaluation of Long List Options ................................................................................................... 39
5.4 Assessment of Confirmed Long List Options ............................................................................... 41
5.4.1 Option 1 (EDG1) - Conveyance of Edgecumbe to Kawerau WWTP ..................................... 42
5.4.2 Option 2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to New Ocean Outfall around Matatā ....................................................................................................................... 43
5.4.3 Option 4 (EDG 4) - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Whakatāne Ocean Outfall ................................................................................................................. 44
5.4.4 Option 5 - Conveyance of Edgecumbe Raw Sewage to Whakatāne WWTP ........................ 45
5.4.5 Option 8 (EDG 8) - Upgrade of Existing Edgecumbe Oxidation Ponds and Land Application at Thornton Dunes ............................................................................................................................ 46
5.4.6 Option 9 – New WWTP at Edgecumbe and Land Application at Thornton Dunes ................ 47
5.4.7 Option 10 - New WWTP at Edgecumbe and Tarawera River Discharge .............................. 48
5.4.8 Option 11 - New WWTP at Edgecumbe and Rangitaiki River Discharge ............................. 49
5.4.9 Option 12 (EDG 12) - Upgrade of existing Edgecumbe Oxidation Ponds and Rangitaiki River discharge .......................................................................................................................................... 50
5.5 Confirmed Long List Assessment Summary ................................................................................ 51
5.6 Comparison of Short Listed Options ............................................................................................ 53
5.6.1 Estimated Costs .................................................................................................................... 54
5.6.2 Short List Options: Information Summary ............................................................................. 55
5.6.3 Ranking of Short Listed Option ............................................................................................. 55
5.7 Discussions and Findings ............................................................................................................ 62
6 Combined Matatā and Edgecumbe Options ..................................................................................... 63
6.1 Matatā Stand Alone Scheme Option............................................................................................ 63
6.2 Methodology ................................................................................................................................ 63
6.3 Identification of Long List Options ............................................................................................... 63
6.4 Evaluation of Long List Options ................................................................................................... 70
6.5 Assessment of Confirmed Long List Options ............................................................................... 74
6.5.1 Option KL1 - Conveyance of Matatā and Edgecumbe to Kawerau WWTP ........................... 75
6.5.2 Option ER2 - Conveyance of Matatā to new WWTP at Edgecumbe and Discharge to Rangitaiki River ................................................................................................................................. 76
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project No.: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
6.5.3 Option ER3 - Conveyance of Matatā to Edgecumbe Oxidation Ponds Upgraded as Necessary and Discharge to Rangitaiki River ................................................................................... 77
6.5.4 Option MO2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Matatā. Matatā Standalone Treatment – Joint Ocean Discharge at Matatā .................................................. 78
6.5.5 Option TL1 - Conveyance of Edgecumbe Raw Sewage to Matatā. Joint Treatment at Matatā, Land Application at Thornton ............................................................................................................ 79
6.5.6 Option TL2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Thornton. Matatā Standalone Treatment and Joint Land Applica tion at Thornton ............................................ 80
6.5.7 Option TL3 - Conveyance of Matatā Raw Sewage to Edgecumbe. Joint Treatment at Edgecumbe Oxidation Ponds and Conveyance to Land Application at Thornton ............................. 81
6.5.8 Option WO1 - Conveyance of Matatā to Thornton and Edgecumbe to Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge ........................................................ 82
6.5.9 Option WO5 - Conveyance of Matatā Raw Sewage to Edgecumbe Oxidation Ponds. Edgecumbe Oxidation Ponds Treated Wastewater for Joint Whakatāne Ocean Outfall Discharge Route Option A – via Thornton.......................................................................................................... 83
6.5.10 Option WO6 - Conveyance of Matatā Raw Sewage to Edgecumbe Oxida tion Ponds. Edgecumbe Oxidation Ponds Treated Wastewater for Joint Whakatāne Ocean Outfall Discharge Route Option B – via Awakeri ........................................................................................................... 84
6.6 Confirmed Long List Assessment Summary ................................................................................ 85
6.7 Assessment of Short-Listed Options ........................................................................................... 89
6.7.1 Estimated Costs .................................................................................................................... 90
6.7.2 Short List Options: Information Summary ............................................................................. 91
6.7.3 Ranking of Short Listed Option ............................................................................................. 91
6.8 Discussions and Findings ............................................................................................................ 99
7 Conveyance Issues and Considerations for Short Listed Options .................................................. 100
7.1 Vertical Alignment ...................................................................................................................... 100
7.1.1 Individual Short-List Route Option Long-sections ............................................................... 101
7.2 Start-up Flows ........................................................................................................................... 104
7.3 Other Considerations ................................................................................................................. 104
8 Risk Assessment, Management and Mitigation .............................................................................. 106
8.1 Risk Management Background and Approach .......................................................................... 106
8.2 Evaluation of Risk ...................................................................................................................... 107
9 Tāneatua and Te Teko Options ...................................................................................................... 119
9.1 Tāneatua.................................................................................................................................... 119
9.2 Te Teko Options ........................................................................................................................ 119
10 Conclusions and Next Steps .......................................................................................................... 121
10.1 Conclusions ............................................................................................................................... 121
10.1.1 Edgecumbe Standalone Options ........................................................................................ 121
10.1.2 Matatā/Edgecumbe Combined Options .............................................................................. 121
10.1.3 Taneatua and Te Teko ........................................................................................................ 121
10.2 Next Steps ................................................................................................................................. 122
11 Acknowledgements......................................................................................................................... 123
12 References ..................................................................................................................................... 124
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project No.: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
13 Glossary of Terms and Abbreviations............................................................................................. 127
LIST OF TABLES
Table 1-1: Long Term Plan Key Principles................................................................................................. 4
Table 2-1: Matata and Edgecumbe Wastewater Volumes and Flows ...................................................... 8
Table 2-2: Matata Concept Design Flows for Low Pressure Reticulated Network .................................... 9
Table 2-3: Existing Resource Consents ................................................................................................. 23
Table 3-1: Regional Plan for the Tarawera River Catchment –Limits for Edgecumbe WWTP ............... 30
Table 5-1: Long list Options for Edgecumbe Schemes ............................................................................ 36
Table 5-2: Evaluation Criteria for Long List Options .............................................................................. 39
Table 5-3: Long List Option Assessment Summary ................................................................................. 40
Table 5-4: Confirmed Long List Option Assessment Summary ............................................................... 51
Table 5-5: Edgecumbe Standalone Shortlisted Options .......................................................................... 53
Table 5-6: Estimated Costs for Edgecumbe Standalone Options ............................................................ 54
Table 5-7: Edgecumbe Standalone Shortlisted Options – MCA Analysis Criteria (Independent of Cost) 57
Table 5-8: Edgecumbe Standalone Shortlisted Options – MCA Analysis Weighting ............................... 58
Table 5-9: Edgecumbe Standalone Shortlisted Options – MCA Scoring Results (Independent of Cost) . 59
Table 5-10: Edgecumbe Standalone Shortlisted Options – MCA Results Scoring Rationale (Independent of Cost) 60
Table 5-11: Edgecumbe Standalone Shortlisted Options – MCA Summary Results ............................... 61
Table 6-1: Long list Options for Combined Matatā and Edgecumbe Schemes ........................................ 65
Table 6-2: Evaluation Criteria for Long List Options .............................................................................. 70
Table 6-3: Long List Option Assessment Summary ................................................................................. 71
Table 6-4: Confirmed Long List Option Assessment Summary ............................................................... 85
Table 6-5: Matatā and Edgecumbe Standalone Shortlisted Options ....................................................... 89
Table 6-6: Estimated Costs for Combined Matatā and Edgecumbe Options ........................................... 91
Table 6-7: Combined Matatā/Edgecumbe Shortlisted Options – MCA Analysis Criteria (Independent of Cost) 94
Table 6-8: Combined Matatā/Edgecumbe Shortlisted Options – MCA Analysis Weighting ..................... 95
Table 6-9: Combined Matatā/Edgecumbe Shortlisted Options – MCA Scoring Results (Independent of Cost) 96
Table 6-10: Combined Matatā/Edgecumbe Shortlisted Options – MCA Results Scoring Rationale (Independent of Cost) .............................................................................................................................. 97
Table 6-11: Combined Matatā/Edgecumbe Shortlisted Options – MCA Summary Results ..................... 98
Table 7-1: Summary of Main Conveyance Routes for Shortlisted Options ............................................ 104
Table 8-1: Likelihood Scale .................................................................................................................... 107
Table 8-2: Consequence Scale .............................................................................................................. 108
Table 8-3: Risk Matrix Definitions .......................................................................................................... 109
LIST OF FIGURES
Figure 1-1: Inter-relationship of Projects .................................................................................................... 2
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project No.: 805 08148 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Figure 1-2: Decision Making Flow Chart .................................................................................................... 3
Figure 2-1: Treated Wastewater Land Application Option within 7.5 km of Edgecumbe Wastewater Treatment Plant ....................................................................................................................................... 20
Figure 2-2: Treated Wastewater Land Application Option at Thornton Dunes ......................................... 21
Figure 2-3: Treated Wastewater Land Application Option at Whakatāne Airport ..................................... 22
Figure 3-1: Regional Plan for the Tarawera River Catchment Map ......................................................... 31
Figure 5-1: Schematic for Option 1 .......................................................................................................... 42
Figure 5-2: Schematic for Option 2 .......................................................................................................... 43
Figure 5-3: Schematic for Option 4 .......................................................................................................... 44
Figure 5-4: Schematic for Option 5 .......................................................................................................... 45
Figure 5-5: Schematic for Option 8 .......................................................................................................... 46
Figure 5-6: Schematic for Option 9 .......................................................................................................... 47
Figure 5-7: Schematic for Option 10 ........................................................................................................ 48
Figure 5-8: Schematic for Option 11 ........................................................................................................ 49
Figure 5-9: Schematic for Option 12 ........................................................................................................ 50
Figure 5-10: Schematic for Option 8A ...................................................................................................... 54
Figure 6-1: Schematic for Option KL1 ...................................................................................................... 75
Figure 6-2: Schematic for Option ER2 ..................................................................................................... 76
Figure 6-3: Schematic for Option ER3 ..................................................................................................... 77
Figure 6-4: Schematic for Option MO2 .................................................................................................... 78
Figure 6-5: Schematic for Option TL1 ...................................................................................................... 79
Figure 6-6: Schematic for Option TL2 ...................................................................................................... 80
Figure 6-7: Schematic for Option TL3 ...................................................................................................... 81
Figure 6-8: Schematic for Option WO1 .................................................................................................... 82
Figure 6-9: Schematic for Option WO5 .................................................................................................... 83
Figure 6-10: Schematic for Option WO6 .................................................................................................. 84
Figure 6-11: Schematic for Option TL2A .................................................................................................. 90
Figure 6-12: Schematic for Option TL3A .................................................................................................. 90
APPENDICES
Edgecumbe Oxidation Ponds Flow Balancing Technical Memorandum
Whakatāne Oxidation Ponds – Capacity Assessment Technical Memorandum
Legal Advice on Regional Plan for the Tarawera River Catchment
Edgecumbe Standalone Options – Long List Assessment
Edgecumbe Standalone Options – Short List Route Alignments
Matatā and Edgecumbe Combined Options – Long List Assessment
Matatā and Edgecumbe Combined Options – Short List Route Alignments
Conveyance Capital and Annual Operating and Maintenance Costs
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Treatment and Disposal / Discharge Capital and Annual Operating and Maintenance Costs
Net Present Value Estimated Costs
Actiflo® and MBBR Treatment Processes Supplier Information
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1 Project Context
1.1 Background
Whakatāne District Council (WDC) has a number of both urgent and pending wastewater infrastructure
and associated consenting matters that need addressing in a comprehensive and efficient manner.
WDC has engaged MWH Consultants to work with WDC Officers and prepare this Report
In summary, these matters as addressed in this Report include the following five Tasks:
Task 1: Consideration of the future treatment and disposal/discharge options for Edgecumbe (referred to as Edgecumbe standalone);
Task 2: Consideration of combined Matatā and Edgecumbe treatment and disposal/discharge options. A joint scheme will allow comparison with the Matatā standalone shortlist options being separately developed by WDC and AECOM Consultants (formerly URS);
Task 3: High level consideration for the future treatment and disposal/discharge from the existing sewerage scheme in Tāneatua;
Task 4 High level considerations of a possible future reticulated sewerage scheme for Te Teko; and
Task 5: Review WDC’s Infrastructure Strategy 2015-45 as it relates to Council’s wastewater services. This part of MWH’s engagement is separately reported on as discussed in Section 1.6 below. This is referred to as Work Stream 1 in the Contract 15-069.
1.2 Project Scope and Overall Approach
The scope of Tasks 1 and 5 are set out in Appendix 3 of WDC’s “Professional Services for Wastewater
Review and Options Study for Edgecumbe Wastewater Treatment and Disposal” document 15 -069
issued on 19 May 2015.
Soon after award of the 15-069 contract to MWH, WDC expanded the brief by adding Task 2 above to
include consideration of joint options for Matatā and Edgecumbe. This was done as it was both prudent
and necessary in terms of further assessing alternatives for Matatā (following the 2015 Matatā
Wastewater Scheme Environment Court decision). Following that Tasks 3 and 4 were also added.
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Figure 1.1 (prepared by WDC) diagrammatically shows the inter linkages between Tasks 1, 2, 5 and the
WDC/AECOM Matatā standalone further options assessment.
Figure 1-1: Inter-relationship of Projects
In summary the approach to Tasks 1, 2, 3 and 4 of this Project has involved the following:
Further definition of the Project Tasks with WDC;
Confirmation of key background information from WDC (question and answer emails from Inka Krawcyzk (16 July 2015) and Santha Agas (17 July 2015) and Tom McDowell of Kawerau District Council (refer references to this Report) for Kawerau District Council correspondence;
Site drive over and walkover survey with WDC Officers;
Workshops with WDC Officers on 8 July 2015 and 27 July 2015, the later also attended by Terry Long of the Bay of Plenty Regional Council (BOPRC);
Review and use of previous investigations and reports (refer Section 1.4 below and Project reference list in this Report);
Formulation of “Long List” and “Short List” options for both Edgecumbe stand alone and Edgecumbe and Matatā combined options and comparison of these using a wide range of criteria and identification of advantages, disadvantages and key risks for the options, part icularly for the short listed options;
Further assessment of the evaluation criteria for comparison of short listed joint Matatā and Edgecumbe options with Matatā standalone shortlisted options separately being compiled by WDC and AECOM; and
Compilation of this Report.
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1.3 Inter-related Projects and Decision Making
The key inter-related project in terms of securing various subsidy monies, is the Matatā Wastewater
(standalone) Scheme. This inter-relationship is introduced in Sections 1.1 and 1.2 above.
The output of this Report as it relates to the shortlisted options for a Joint Matatā/Edgecumbe Scheme is
to be used along with the output from the Matatā standalone shortlisted options. Figure 1.2 shows how
WDC propose to bring these two projects together in terms of assessing the Best Practicable Option
(BPO) for the Matatā community.
Figure 1-2: Decision Making Flow Chart
Other interrelated projects include:
Task 5 the review of WDC’s “Infrastructure Strategy 2015-45”. This is Work Stream 1 of Contract
15-069 and is commented on in Section 1.7 below; and
Future consideration of the Whakatāne Wastewater treatment and Ocean Outfall Discharge
Consent which expires in 2026 as it relates to these options for both Matatā standalone and
Matatā and Edgecumbe. Also briefly addressed is the question of the possibility of a future
abattoir discharging to the Whakatāne wastewater system.
1.4 Existing Investigations and Documentation
As listed in the references to this Report, there are many WDC reports on former wastewater
investigations along with the Matatā Wastewater Scheme Assessment of Effects on the Environment
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(AEE) document (December 2013) and associated 10 Support Documents, and related National and
Regional Planning Instruments that all provide some relevant background information for this Report.
Those issues of greater importance and relevance to this Project include:
Matatā Wastewater Scheme Support Document 2: Natural Hazards, Constraints and Risk Assessment; and
Matatā Wastewater Scheme Support Document 4: Alternatives Assessment Information.
1.5 Whakatāne District Council – Key Project Drivers
Council’s Vision as set out in their Long Term Plan (LTP) 2015-2025 sets the high level key driver for all
its activities, being:
“To be known as the place of choice for people to live, work and play. In achieving our vision, our community will be safe and surrounded by people who are friendly and caring, businesses will be thriving, there will be respect for, and pride in our history and we will be successful guardians of our natural environment”.
Underpinning this vision there are a number of other strategies and policies that all are in effect key
drivers for these Projects. These include WDC’s Sustainability Strategy (2012-2015) the objective of
which is to integrate sustainable decision-making and actions into the way the Council does business.
In terms of infrastructure development in the LTP, Council has identified for key principles as shown in
Table 1-1.Table 1-1: Long Term Plan Key Principles
Table 1-1: Long Term Plan Key Principles
Responsible We will work with the community to prioritise core services and prudent infrastructure management which will meet their needs
Sustainable We will undertake good stewardship of our assets and services, managing these in a way that does not compromise our ability to provide quality, affordable services to the community in the future
Affordable We will be responsive and sensitive to the issue of rates affordability across the District, in particular when making decisions about infrastructure investments and funding mechanisms
Enabling We will provide the infrastructure required to support and enable growth and prosperity in our district and work with others towards this goal
These principles are particularly relevant in terms of determining the most appropriate wastewater
infrastructure options for Matatā, Edgecumbe and other communities.
1.6 Community and Tāngata Whenua Consultation – Key Considerations
It is outside MWH’s brief for this Project to undertake or consider in detail community and tāngata
whenua consultation output.
It is however, most appropriate that this Report does take into account community, key stakeholders and
tāngata whenua’s key considerations that are apparent at the present time as have been mentioned by
WDC Officers, Terry Long of the BOPRC, AECOM in relation to a Matatā standalone scheme including
these matters raised in the earlier Matatā Wastewater Scheme Stakeholder consultation.
These key considerations include:
Need to protect and if possible enhance water environments into which treated wastewater disposal/discharge would/could be made for the options considered;
Appropriate protection of ground and surface water for land application options;
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Well sited and sufficiently off shore discharges for new (offshore) ocean outfall options;
Selection of conveyance routes that minimise disturbance of road carriage ways and other services as these will have less construction related adverse effects (e.g. traffic disturbance) than alternative conveyance route options;
Options that minimise and mitigate as far as reasonable and economically possible construction
impacts (e.g. traffic control, noise dust etc.);
Options that as far as practicable and practical use, even if upgraded or expanded existing key
wastewater infrastructure. This for example includes the Edgecumbe Oxidation Ponds, the
Whakatāne Oxidation ponds and the Whakatāne ocean outfall;
Use of treatment technologies compatible with WDC’s existing schemes and operator abilities;
If possible use of low energy treatment and conveyance pumping options; and
Adoption of a scheme or schemes for which long term resource consents can be secured at
reasonable costs within a reasonable timeframe and which have community and other
stakeholder and tāngata whenua acceptance.
In terms of tāngata whenua consultation undertaken by WDC Officers, and the range of the options
under consideration the following views have been offered.
A new ocean outfall in the vicinity of Matatā would not be supported; and
Conveyance of raw wastewater from Matatā to Edgecumbe, or to Kawerau or Whakatāne would
be supported (if proceeded with). This implies that conveyance of treated wastewater would also
be supported and probably to a greater extent than conveyance of raw sewage.
As set out later in this Report for the shortlisted options, while an initial comment is made in respect to
tāngata whenua considerations, it is most appropriately recorded that tāngata whenua input is required
in terms of further consideration of shortlisted and preferred options.
1.7 Work Stream 1 Output and Relationship to this Project
As indicated in Section 1.1, Task 5, the MWH review of the wastewater sections of the LTP and
Infrastructure Strategy 2015-45 is being separately reported on. Notwithstanding this will be reported
separately, there are some important key considerations that are relevant to the assessment and
comparison of options and output of this Project. These include:
Core Outcomes
Delivery quality core services;
Encouraging communities and businesses to thrive;
Working together to meet community needs; and
Rates affordability.
Key issues to be addressed
Gaining infrastructure and in Edgecumbe’s case earthquake damaged wastewater collection (reticulation) system;
New legislation leading to stricter environmental controls e.g. National Policy Statement on Freshwater Management 2014 (NPS-FM) (refer section 3 following);
The District being prone to natural hazards; and
Ageing and fairly static population e.g. in Edgecumbe and by contrast reasonable growth is project in Matatā.
Planning Assumptions
Natural hazards risks (earthquake, flooding, tsunami, debris flows, slips and volcanic activity) ;
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Environment processes susceptibility (soil erosion, sediment build-up beach erosion etc.); and
Climate change and predicted sea level rise.
Service Delivery
Consent conditions;
Disaster preparedness; and
Infrastructure needs for growth related development.
Land Use
Assumptions on present residential zoning based on Proposed District Plan.
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2 Project Inputs, Assumptions and Methodology
2.1 Project Inputs and Assumptions
A wide range of Project inputs has been used in developing this Report. In summary these include:
Information contained in the extensive references as set out in the reference list and further recorded in Section 1.4 above;
The Questions and Answers (Q&A) received from WDC Officers (refer Section 1.3) and from Kawerau District Council;
LIDAR (as provided by WDC) and other GIS data publically available and received from BOPRC;
Existing WDC and Kawerau District Council Resource Consents;
MWH wastewater infrastructure databases;
WDC workshops on the Project; and
Local knowledge from WDC Officers and Terry Long from BOPRC.
Three following are the key assumptions made for this Project. Additional topic specific assumptions are
set out in the conveyance and treatment and discharge sections of this Report.
Conveyance pipelines have been sized and costed to cater for long-term flow projections (50
year horizon – 2064/65);
Treatment processes have been sized and costed for medium-term flow projections (20 year
horizon – 2044/45);
Chemical dosing facilities at pump stations for the conveyance of raw wastewater has been
allowed for; and
Bio-filtration beds/carbon cartridge units have not been allowed for at air valves. Further
investigation is required into the needs and details of this through a septicity and odour study.
2.2 Study Area
The study area comprises of:
The community areas of Matatā and Edgecumbe for the options assessment;
The conveyance routes between communities and treatment and disposal/discharge facilities;
Areas considered for land application (disposal);
The existing wastewater treatment and discharge facilities at Kawerau (Kawerau District
Council) and Whakatāne; and
The communities of Tāneatua (which has a community sewage scheme) and Te Teko (which
does not have a community scheme).
2.3 Wastewater Volumes and Flows
The projected wastewater volumes and flows are a key consideration for the assessment of both the
combined Matatā and Edgecumbe options and the standalone Edgecumbe treatment and conveyance
options.
Table 2-1 provides a summary of the wastewater volumes and flows used in this Report. In determining
these volumes and flows the following reports have been reviewed (refer reference list).
1. Wastewater Scheme for the Towns of Edgecumbe, Matatā and Te Teko (Harrison Grierson,
2009);
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2. Wastewater Treatment and Management Options for Edgecumbe and Matatā (Opus, 2013);
3. Matatā WWTP – Flow Rate and Mass Load Assessment for Determination of Land Disposal Area Requirements Reference 42790250-R004 (URS, 2013);
4. Matatā WWTP – Final Design Flows for Employer Requirements – Part 402 (URS, 2014);
5. First Time Sewerage for the Community of Matatā – Preliminary Design Report (Harrison Grierson, 2009); and
6. Matatā Sewerage Scheme – Review of Projected Hydraulic Flow Rates to WWTP (MWH, 2014).
Table 2-1: Matata and Edgecumbe Wastewater Volumes and Flows
Header Matatā1 (assumed population growth)2
Edgecumbe (assume static growth)3
Combined Matatā and Edgecumbe
ADF (existing) (m3/day)
204 7644
ADWF (existing)
(m3/day)
5605
PWWF (existing)
(m3/day)
270 5,600 (peak flows to be balanced within Edgecumbe pond)
Peak flows from Edgecumbe pond assumed to be 1,680 m3/day
1,950
ADF (20 yr)
(m3/day)
375 560 935
PWWF (20 yr)
(m3/day)
415 1,680 2,095
ADF (50 yr)
(m3/day)
423 560 983
PWWF (50 yr)
(m3/day)
555 1,680 2,235
Design Flow (L/s) 156 30 45
2.3.1 Matatā Design Flows
A number of studies have been undertaken for a Matatā scheme in terms of flow estimates. The two
main sources for these figures have been provided below in Table 2-2, are as follows:
1 Matatā Township is currently not serviced by a reticulated sewerage system. Flows are based on population equivalents. 2 Matatā flows sourced from Matatā WWTP Flow Rate and Mass Load Assessment (URS, June 2013) and Matatā Wastewater
Scheme Employer Requirements – Connected Population and Flow Rates (URS, 2014) 3 The actual population of Edgecumbe is 1,700 and static or declining – flows are sourced from Wastewater Treatment and
Management Options for Edgecumbe and Matatā (Opus, 2013). 4 Calculated by adding Matatā ADF and Edgecumbe ADWF. 5 Peak flows based on flow data supplied by WDC. WDC’s proposal is to replace the damaged Edgecumbe collection system with
a lower pressure system (LPS) grinder pump system as included in the Long Term Plan (LTP 2015-25) for 2026-28 at a cost of $17.7M. The current assumption is that the reticulation will be replaced as per the LTP, however this decision is being revisited. Peak flows are assumed to be balanced within the Edgecumbe oxidation pond system both before and after the LPS is installed. 6 Refer Section 2.3.1 for assessment of Design Flow Rate for Matatā for a low pressure grinder pump scheme (LPS).
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1. Contract 14-026 Matatā Wastewater Scheme: Design/Build/Operate for Wastewater Treatment
Plant and Land Application Employer’s Requirements – Part 402 (URS, 2014) – These figures
were developed for the design of a local WWTP at Matatā.
2. Matatā Pressure Wastewater Collection System – Detailed Design Report (Feb 2014, Harrison
Grierson). These figures have been developed in support of the detailed design of the Matatā
low pressure wastewater collection system (LPS). No 2064 figures were developed as the
project was focussed on the design of the collection system to the 2034 planning horizon.
3. 2064 figures have been developed based upon a mix of the URS (now AECOM) and Harrison
Grierson data sources.
4. It is noted there are some gaps in Table 2-2. These are because the information was not
included in the Reports referenced.
5. PE – Population Equivalent and other abbreviations are included in the Glossary of Terms and
Abbreviations in Section 13 of this Report.
Table 2-2: Matata Concept Design Flows for Low Pressure Reticulated Network
Flow Estimate REF1 REF2
Flow Forecast Source
Contract 14-026 Matatā Wastewater Scheme: Design/Build/Operate for Wastewater Treatment Plant and Land Application Employer’s Requirements – Part 402 (URS, 2014)
Matatā Pressure Wastewater Collection System – Detailed Design Report (Feb 2014, H&G)
Time Frame 2014 2034 2064 2014 2034 2064*
Residential (Dwellings) (nr) 250 350 500 250 350 500
Residential (Occupancy) (rate) 2.75 2.75 2.75 2.75 2.75 2.75
Residential (Population) (nr) 687.5 962.5 1375 687.5 962.5 1375
Camping Sites (nr) 40 70 100 40 100 100
Camping Sites (Occupancy) (rate) 2.64 2.64 2.64 2.64 2.64 2.64
Camping Sites (Population) (nr) 105.6 184.8 264 105.6 264 264
Primary School (School Roll nr) 92 130 190 115 160 190
Commercial Sites (nr) 7 7 7
Total PE (nr) 1015.62 1567.06 2109.3 785.82 1119.05 1536.05
Residential PCF (L/hd/d) 200 200 200 200 200 200
School PCF (L/hd/d) 30 30 30 30 30 30
Camp Site PCF (L/hd/d) 65 65 65 65 65 65
Residential Daily Volume (m3/d) 137.5 192.5 275 137.5 192.5 275
School Daily Volume (m3/d) 2.76 3.9 5.7 3.45 4.8 5.7
Camping Daily Volume (m3/d) 6.864 12.012 17.16 6.864 17.16 17.16
Commercial Daily Volume (m3/d) 56 105 124 9.35 9.35 9.35
Nr Lots 290 420 600 288 372 522
Total DDWF Volume (m3/d) 203.124 313.412 421.86 157.164 223.81 307.21
Growth 1.54 2.08 1.42 1.37
Total AWWF Volume (m3/d) (10%) 223.4364 344.7532 464.046
Design Daily Volume (m3/d) 245 375 555 157.164 223.81 307.21
Design Peak Flow (l/s) 28 8.1 9.25
Max Flow (l/s) Power Out 15-20 15-20
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Average DWF (l/s) 2.59 3.99 5.37 1.82 2.59 3.56
3 x ADWF (l/s) 7.76 11.97 16.11 5.46 7.77
4 x ADWF (l/s) 10.34 15.96 21.48 7.28 10.36
5 x ADWF (l/s) WDC CoP 12.93 19.95 26.85 9.10 12.95
US EPA Design PF (1991) 4.09 3.69 3.82 5.78 5.10
Peaking Factor (Walski 2002) 4.26 3.44 2.97 4.84 4.06 3.47
Single Pump Flow (L/s) 0.58 0.58 0.58 0.58 0.58 0.58
Single Pump Flow (L/min) 34.8 34.8 34.8 34.8 34.8 34.8
Probable Max Pumps (E/one 2001) 14 18 23 14 16 21
Peaking Factor 3.14 2.62 2.48 4.46 3.58 3.43
US EPA Design Flow (1991) 10.58 14.74 20.50 10.52 13.20 18.00
Design Flow (Walski 2002) 11.02 13.71 15.94 8.81 10.51 12.33 Peak Design Flow Pumps running (e/one ,2001) 8.12 10.44 13.34 8.12 9.28 12.18
The above references developed detailed flows for the Matatā7. This assessment was largely focused
on delivering local reticulation or assets for the 2034 planning horizon. The conveyance network would
be sized to cater for the ultimate 2064 planning horizon. As such the daily peak flows provided range
between 8 – 16 L/s. An initial check on peak flows of 10 L/s indicated that as the flows were so low this
required the use of pipe internal diameters below 150mm (which increases the risk of blockages) and
higher friction losses per km length of main requiring additional pumping stations.
Given the potential range of flows from the above sources this concept option assessment has been
based on the assumption that the conveyance capacity should be 15 L/s with the potential to upsize the
scheme to cater for larger flows without the need to replace the rising main. This also allows more future
flexibility/capacity for growth over that projected at this time.
This can be achieved by the provision of the future additional pumping station, if and when required,
mid-way along the rising main. This ‘booster’ pumping station would allow the capacity of the rising main
to be increased between 25-50% but requires a more detailed assessment on the effect of the rising
main pressure rating and potential surge issues. A detailed design of this conveyance system should
revisit these issues.
2.4 Technical Approach
In developing options and in assessing these against each other MWH have used the following technical approaches:
Relied on LIDAR information obtained from WDC;
Utilised wastewater generation dates derived by AECOM (formerly URS) for Matatā (as set out
in Section 2.3 above) and Opus for Edgecumbe (based on a future grinder pump/low pressure
system (LPS)) along with existing Edgecumbe pumping records for the flows to the oxidation
ponds;
Undertake conveyance (pumping and pipelines) assessment using industry accepted design
basis and pumping station concepts as agreed with WDC (refer Section 2.5) below and also
where relevant included for in WDC’s technical specifications;
Developed treatment requirements from a “bottom up” approach building up components of the
total treatment need from the components parts;
7 Note that e/one is a proprietary of grinder pump.
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Used typical industry cost figures for cost estimating;
Used data supplied by Kawerau District Council for the options conveying to the Kawerau
WWTP, as they relate to treatment and disposal/discharge at Kawerau;
Used the current Resource Consents (rights to discharge) for Edgecumbe, Whakatāne and
Kawerau where these (may) have relevance to options under consideration (refer Section 2.10);
Been guided by Regional and National Planning Documents for the quality needed for the
disposal discharge to land and water environments, e.g. Regional Plan for the Tarawera River
Catchment, National Policy Statement for Freshwater Management 2014 (NPS-FM); and
Used published soil drainage flooding, natural hazard, biodiversity and other maps and
information for land applications and conveyance.
2.5 Building up a Complete Scheme
A typical small community wastewater system requires up to four components, or “building blocks”,
namely:
1. Collection System: to collect wastewater from groups of properties and transport it to a
decentralised wastewater treatment plant or to a common point for connection to a conveyance
system.
2. Conveyance: to transport raw wastewater from local collection systems to an existing treatment
plant or conveyance from a treatment plant to disposal/discharge and/or reuse.
3. Treatment: to change the wastewater characteristics to meet the standards required for eco-
system re-entry, reuse or conveyance to another treatment facility. The disposal of sludge
arising from the treatment process is also required, although in oxidation pond systems this is
stored and periodically removed.
4. Disposal, discharge and/or Re-Use of Treated Wastewater: discharge pipework is required to
return fully treated wastewater to the environment and/or to a re-use point.
For a new Matatā Wastewater Scheme a low pressure grinder pump collection scheme is proposed. The
design of this is well advanced and output from this is well advanced and output from that in terms of
wastewater flows and volumes and the nature of the raw ground up sewage.
For Edgecumbe, the existing collection system is subject to high wet weather flows that MWH
understand has to a large part resulted from the earthquake damage of the collection network.
WDC’s LTP and AMP have provision to completely replace this system with a new low pressure grinder
pump collection system. A financial allowance of $17.7M is included for this in the 2026-2028 period. A
condition assessment of the existing gravity system has shown that system in uneconomical to repair
and may be deteriorating fast. Considering the high groundwater table and flat nature of the area,
replacing the existing system with a low pressure grinder pump system is currently understood to be
more feasible and economical than a conventional gravity system. Generally, the ground deformation in
Edgecumbe is about 10mm to 20mm per year. However, the timing of this project will depend on further
studies on the pipe deterioration rate to be undertaken in the next three years. After these studies are
completed, the final form and timing of the replacement of the existing reticulation system will be
determined.
As discussed in Section 2.6.3 this may not be necessary for some of the Options considered.
This Report does not include further consideration of estimated costs for collection systems.
For a number of Options it is proposed to continue use of the Edgecumbe oxidation ponds for cost
effective treatment.
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For combined Matatā and Edgecumbe Schemes, these oxidation ponds would either be upgraded to
provide additional treatment capacity and/or expanded with additional treatment units where a higher
degree of treatment is needed. Such proposals are separately shown for each option.
Continued use of existing wastewater infrastructure assets is considered a sound and prudent financial
approach where they have an effective remaining useful economic life, and well fit into the concept of
the option being developed. In this Project a number of options, many of which have been shortlisted
for the more detailed evaluation, include use of the following existing wastewater infrastructure. For
shortlisted options these include:
Edgecumbe Oxidation Ponds for treatment – Combined Matatā and Edgecumbe Options ER3, TL2, TL3, WO5,and Edgecumbe Options 4, 5, 8 and 12.
Whakatāne Oxidation Ponds (in addition for Whakatāne) – Option WO1
Whakatāne Ocean Outfall – Option WO5
In terms of the future of the Edgecumbe existing damaged collection system, note above, the
AMP/Infrastructure Strategy includes $17.7million in the 2026-28 for complete replacement of this
system. Some other options, namely KL1 and WO1, include part or all the oxidation pond structures for
flow balancing.
A number of the options shortlisted which involve continued use of the Edgecumbe oxidation pond for
treatment may/could mean that this full expenditure is not needed providing the higher wet weather
flows can continue to be accommodated in that particular option. Notwithstanding this, it is noted that
the existing gravity collection system is deteriorating and further studies will be completed within the
next three years to determine the final form and timing of the replacement of the existing reticulation
system.
This matter is further discussed in MWH’s separate Contract 15-069 Work Stream 1 Report.
2.6 Concept Design Assumptions - Conveyance
The technical assumptions used in the concept design to size the various conveyance schemes options
are as follows:
Rising Main – The acceptable absolute minimum velocity for raw sewage is 0.60 m/s, this
achieves transport and re-entrainment of the solids contained within raw sewage. Given the
potential long retention time of sewage in the rising mains, which may increase solids
deposition, it is consider preferable to achieve a higher cleansing velocity of at least 0.7 m/s.
Below the minimum of 0.6 m/s there is a significant risk that deposited solids will not be re-
entrained during pump cycles, leading to anaerobic digestion and production of H 2S, methane
and other gases. Treated wastewater contains significantly less gross and settleable solids and
therefore the minimum acceptable velocities for pumping treated effluent can be relaxed from
those stated above. The minimum acceptable velocity for treated effluent has been assumed to
be 0.3 m/s but this will depend upon the quality of that effluent and the quantity and nature of
total suspended solids (TSS) remaining. These velocities should be reviewed during a
preliminary or detail design stage.
Slime Shearing Velocity (critical pipe wall shear stress of 0.3 kg/m2) is preferred, in raw
sewage rising mains, to help reduce the risk of septicity and odour issues as well as helping to
limit friction losses. Where slime shearing velocities can be achieved the friction losses will be
calculated based upon a pipe roughness of Ks (Colebrook-White) = 0.3mm (HDPE pipe may be
able to achieve a lower Ks but other materials may have higher Ks values). Where slime
shearing cannot be achieved the pipes have been assumed to slime and have a pipe roughness
of Ks (Colebrook-White) = 1.5mm. It is assumed that given the long-length of rising mains under
consideration that it will not be practical to achieve slime shearing velocity without a large
number of intermediate pumping stations to overcome the resulting high friction losses. The
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preliminary and detailed design phase should investigate whether there is a cost benefit to
achieving slime shearing velocities over the on-going cost of chemical dosing/maintenance.
Where the rising main is pumping treated effluent it has been assumed that slime growth will not
be an issue and has therefore not been accounted for. This assumption should be revisited
during the preliminary and detailed design phase.
Slime shearing velocity varies with pipe diameter and is typically higher than normal self -
cleansing velocity target velocities are as follows:
Pipe INTERNAL Critical Slime Shearing Velocity (m/s)
Diameter (ID mm) Shear Stress = 0.3kg/m2
100 0.90
150 0.95
200 0.99
250 1.01
300 1.02
375 1.04
Maximum velocity allowed in the rising main will be limited to less than 3 m/s. Increases in pipe
velocity while helping to keep the pipe clean, result in higher friction losses, pipe pressures,
pump heads and ultimately pumping energy costs. Velocities higher than this maximum become
uneconomic and can damage the rising main and valves.
The target maximum retention time for wastewater within rising mains should be 12 hours.
This helps reduce the risk of septicity but does not eliminate the effects of wastewater arriving at
the next pump station or the downstream WWTP that may already be septic or significantly
aged.
Maximum Total Dynamic Head - (TDH = static lift + friction losses + local losses) for standard
wastewater centrifugal pumps is assumed to be in the order of 60-70m. It should be noted that
this range of TDH can significantly limit choice of manufacturer, available pump types and limit
the range of performance curves. Centrifugal pumps capable of TDH’s above 70m may be
possible with specialist pumps. It is possible to use specialist progressive cavity pumps that can
operate at significantly higher heads. As progressive cavity pumps are non-standard and will
require significantly higher pressure pipe lines this option while feasible is not preferred. It has
been assumed that where high head rising mains are required that it is preferred to build two -
stage pumping stations (where 2 pumps operate in series) to achieve the required head. This
approach requires the rising main be designed for the increase pressure but limits the number of
actual pumping stations.
Assume local losses for the rising main to around 10% of friction losses. In reality these losses
should be less given the terrain being crossed;
Resilience – where the rising main is difficult to access for repair or maintenance purposes, the
rising main should duplicated. This has been assumed to apply for marine or critical
infrastructure crossings (e.g. railways) or where the rising main is greater than 5m deep or
installed via horizontal directional drilling techniques (HDD);
Pumping Station Emergency Overflow and Storage – it has been assumed that an
emergency overflow will not be allowed and that emergency storage will be provided at the
pumping station to allow operational response within a reasonable time. WDC have indicated
that this should be a period of up to 8 hours of DWF storage prior to any overflow occurring. All
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pumping stations will be designed to accept power from an external back-up generator that will
be provided by WDC’s specialist provider within a 1 hour time frame;
Sewage Septicity and Odour is caused by the anaerobic decomposition of raw wastewater
(organic matter containing sulphur and nitrogen). This decomposition produces gases including
hydrogen sulphide (H2S) which can be unsafe and malodourous (e.g. rotten egg smell). Long
rising mains provide anaerobic conditions and significant retention times of wastewater within
the main, leading to a high potential of septicity.
H2S is initially produced in solution, this dissolved H2S then transfers into gaseous H2S. The
longer the retention time within the pipeline the more H2S will be transferred to the gaseous
phase. The issues that can be caused by septicity are listed below:
o H2S can be a health and safety hazard for operators and the public;
o H2S is malodourous and can lead to disturbance and complaints if it reaches certain
concentration levels;
o H2S is released intermittently at rising main air valves as air is released from the main;
o H2S is released at the rising main discharge chamber (break pressure chamber)
whenever the pumps are running;
o H2S will continue to be released from the wastewater as it passes through the
downstream gravity system, especially at locations of turbulence; and
o Where H2S is oxidised by bacteria that are present in condensation/damp pipe walls this
leads to the production of sulphuric acid (H2SO4) which dissolves susceptible materials.
This leads to corrosion where H2S meets these suitable conditions.
Excessively long retention times, where the wastewater organic matter is anaerobically digested,
can also lead to methane production. Methane is flammable and can present a health and safety
issue if not dealt with appropriately in the design process; and
The health and safety risks associated with septicity, methane and other potential gases, are in
relation to the operation of the system, particularly confined spaces and the opening of
manholes/chambers/structures. The risks to operators (and the public in close proximity) can be
managed through appropriate design and operational procedures.
2.6.1 Managing Septicity and Odourous Gases in Conveyance Systems
There are a number of methods that can be employed to manage septicity for raw sewage conveyance,
these are:
The retention time of wastewater in the rising main should typically be kept to less than 12 hours
to avoid septicity. This is an approximate limit of used within the wastewater industry based
upon the standard depletion rates of dissolved oxygen within a main to prevent full anaerobic
conditions. Furthermore it reduces the quantities of dissolved H2S that can be produced. A
detailed septicity modelling study is required to determine what is the acceptable retention time
and would take into account the actual sewage constituents (e.g. chemicals and loads),
temperature, pH and how aged it is when it arrives at the pumping station; and
Control the growth of sewer slime on the rising main pipe wall. This is achieved by intermittently
running the rising main at velocities that increase the shear stress exerted on the wall enough to
strip the slime off and prevent substantial growth. This significantly reduces the production of
H2S, the quantity that transfers to the gas phase and has the additional benefit of
reducing/controlled pipe roughness at the cost of high energy costs.
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2.6.1.1 Chemical Dosing (Liquid Phase Odour Control)
Chemical dosing has a lower capital outlay (chemical storage, dosing and injection equipment) but
reasonably higher on-going operational cost than other methods to avoid septicity (e.g. multiple rising
mains of different sizes, full treatment or full odour treatment and corrosion protection). The most
commonly used approaches are:
Magnesium Hydroxide is a non-hazardous alkali which is added to the wastewater to maintain
a high pH (target of around pH 8.6-9.0 - alkali) and preventing sulphide transfer from the liquid to
gas phase (and therefore the atmosphere). This level of pH also stops methane production.
Magnesium hydroxide can be dosed automatically from relatively small installations, does not
suffer from over-dosing risks (adding too much cannot raise pH above 9), is widely used across
NZ/Australia and is friendly to biological systems (should overflows to the environment occur).
The main disadvantage of dosing with Magnesium Hydroxide is that is costs around four times
as much as Iron salts per treated cubic metre of wastewater. Another potential disadvantage of
Magnesium Hydroxide dosing is that it can leave a chalky residue;
Iron Salts (Ferric or ferrous chloride) can be used to control odour in wastewater networks by
binding the generated sulphides into a non-soluble precipitate. It has also been shown in studies
that ferric dosing could suppress sulphate production and methane generation. This process will
however, cause additional solids to precipitate in the rising main. This chemical can be corrosive
and has Health and Safety issues associated with storage and handling, furthermore spills from
the network to the environment should be avoided. Iron Salts is a quarter of the cost of
magnesium hydroxide per treated cubic metre of wastewater and therefore would have
significant annual cost savings for very large flows; and
Calcium Nitrate prevents the onset of anaerobic conditions by providing an alternative source
of oxygen. Dosing with nitrates can remove generated H2S and reduces any further anaerobic
digestion. Calcium nitrate requires accurate dosing as excess nitrate can impair downstream
treatment processes, which can include uncontrolled denitrification at the wastewater treatment
plant. Under dosing of calcium nitrate may exacerbate H2S release along the sewerage system.
Multiple dosing points may be necessary to achieve the required degree of control.
Magnesium Oxide/Hydroxide is the most benign and easily handled of the above chemicals and is
preferable from a number of aspects, apart from annual running costs. However, the need for chemical
dosing will require a detailed understanding of the upstream wastewater network, sewage age and
should be determined through a detailed Septicity Modelling study as part of further detailed
investigation and design.
2.6.1.2 Odour Treatment (Gas Phase Odour Control)
The aim of gas phase odour control is to reduce the gas phase H2S (and other odour causing compounds)
concentrations to levels below the limit of detection at the nearest receptor site to the air discharge.
Common gas phase technologies that are typically used to remove H2S from foul air discharges that will
are available include:
Biotrickling filters (For larger odour control facilities) - Typically used for larger odour control
facilities, these odour control devices utilise a biomass system whereby foul air is passed
through a medium that supports a bacterial culture (the biomass). The airflow passes through
the medium, where the odorous compounds are absorbed into the liquid film surrounding the
biomass. The biomass consumes the contaminants, hence removing these odorous compounds
from the air;
Activated carbon filters (Carbon canisters for air valves and carbon filters for larger odour
control facilities) - Activated carbon has been used widely over many years for the removal of
contaminants from air and water streams. The adsorption qualities of activated carbon have
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been improved through chemical impregnation using caustic, chlorine based compounds and in
some cases copper; and
Conventional biofiltration (For air valves and larger odour control facilities) - Conventional
biofilters generally consist of compost, bark, peat, heather or other organic material (or a
combination of them) to provide a media for biological growth. They are ideal solutions to treat
odours of low-medium flow with low-medium stable contaminant concentrations. Foul air is
passed through the media bed. These facilities require a water supply to keep the bark moist to
support the biological growth and therefore may not be ideal for isolated locations.
2.6.2 Balancing of Raw Wastewater
The balanced of raw (untreated) wastewater is assessed in some options where raw wastewater could
potentially be balanced in the existing Edgecumbe oxidation ponds. At times of dry weather flow no
balancing would occur, however at times of higher flow, the ponds could be used to temporarily store
excess flows of raw wastewater, prior to conveyance. The matters are relevant when considering
options that propose the storage of raw wastewater. It should be noted that these comments do not
apply to the balancing of treated wastewater at Edgecumbe where the wastewater would be screened
and aerated.
Raw wastewater, even diluted by stormwater, stored in an open pond is a potential health
hazard. This is potentially no different to the current Edgecumbe oxidation pond arrangement
but should be considered against the Health and Safety requirements of an upgraded/improved
facility (e.g. are full height fences, locking gates etc. required).
The stored wastewater may generate odour issues that are difficult to manage (aeration would
be required);
Unscreened wastewater entering the pond will deposit rags, fat, oil, grease and sewage derived
litter on the pond banks – this will be difficult to clean and may become an odour issue and an
attraction to pests/vermin;
The ponds will also collect floatable debris which the pump station may not capture and pass
forward to the conveyance pipeline and downstream WWTP;
The ponds will still settle solids to some degree and will require de-sludging and potentially
some form of treatment to prevent odour as the sludge decomposes;
The pond will likely suffer from algae blooms and mats;
Flow balancing will allow rainwater to contribute to the pumped flow rates – for raw wastewater
transfer this significantly increases the volume requiring chemical dosing and therefore the
annual cost. Ferric iron salts are quite sensitive to load and would need careful monitoring of the
required dosing, which would increase the cost of the installation;
River flooding into the ponds would be a worse quality outcome than if the ponds were in the
process of treatment; and
Should the ponds overflow due to extreme wet weather events the quality of flow entering the
environment would be of worse quality than if the ponds were in the process of treatment.
2.6.3 Balancing of Treated Wastewater
The balancing of treated wastewater at the Edgecumbe ponds is also considered for certain options.
Wastewater entering the ponds would be screened and then aerated in the primary pond. The various
issues traversed in Section 2.6.2 would generally be avoided through this treatment process.
The capacity of the existing Edgecumbe ponds to balance flows from both Matatā and Edgecumbe has
been assessed in Appendix A. This matter is further discussed in later sections of this Report.
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2.7 Concept Design Assumptions - Odour Management of Conveyance Systems
This Report has made the following assumptions to develop the concept options:
The rising main retention time will be kept to less than 12 hours to avoid septicity, where
possible. For this Project it is unlikely that this criteria will be met, given the length of rising main
and the low flows under consideration;
The rising main velocity will be used to control the growth of sewer slime under DWF conditions
if possible and it does not result in excessive friction head (that would require additional
pumping stations to overcome);
Bio-filtration beds/carbon cartridge units have not been allowed for at air valves. Further
investigation is required into the needs and details of this through a septicity and odour study;
Chemical dosing with magnesium hydroxide has been assumed to be required for untreated
wastewater rising mains and has been allowed for. Further invest igation is required into the
needs and details of this through a septicity and odour study; and
Corrosion protection of any gravity sewer sections downstream of the discharge from an
untreated wastewater rising main may need to be considered but has not been specifically
allowed for.
2.8 Concept Design Assumptions – Treatment
A broad treatment concept has been developed for treatment options at Edgecumbe for land application
and Rangitaiki River discharge for the short-listed options. These treatment concepts encompass:
1. Upgrade of the existing oxidation ponds to provide aeration to support the BOD loading on
the primary pond and to supplement to the currently consented 84 kg BOD/ha/day (although a
consent condition change may be required in this respect). This is proposed to be achieved
through the use of mechanical surface aeration;
2. Upgraded Oxidation Pond located at the Edgecumbe site using a combination of:
a. Moving bed bioreactors contain plastic carrier media that are have been designed to provide an
increased protected surface area per unit for microbial biofilm growth. The microorganisms that
grow in the biofilm layer treat influent wastewater by breaking down biodegradable organic
matter. Through use of an anoxic zone and recycle MBBR systems can remove nitrogen (to
concentrations of 10 mg/L or less) from wastewater but this requires dosing to provide a carbon
source and a separate mixing system to keep the carriers suspended. A sieve arrangement at
the outlet of each compartment retains the solids and carrier media within the tank.
b. Actiflo units are sand-ballasted, high-rate clarifiers and combine advantages of weighted
flocculation and lamella settling combined with a small footprint. Coagulant is injected into the
wastewater where rapid mixing begins the coagulation process. The coagulated raw water then
enters the injection tank where microsand and polymer are added. The sand particles provide a
nucleus for flocculation of particulate matter (including algae) and this material is then settled
out within the lamella clarifier. Clarified water is discharged to an overflow trough, while a
hydrocyclone separates the sand and sludge in the solids stream returning the microsand to the
process for reuse.
c. The treated wastewater is disinfected by exposing the flow to ultraviolet (UV) light emitted from
lamps arranged within a UV reactor system. Remaining microbes (after aerobic treatment and
clarification) are irradiated by the light becoming deactivated and unable to replicate reducing
their ability to cause and spread illness.
d. Peak storage pond using the former oxidation pond (for wet weather flow balancing).
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An upgraded Edgecumbe oxidation ponds with MBBR, Actiflo and UV disinfection following the above
concept would typically achieve median treated wastewater quality of:
BOD < 10 mg/L
TSS < 10 mg/L
TN < 10 mg N/L (with carbon dosing)
E.coli < 1000 cfu/100mL (or less)
For options of conveying raw wastewater to the Kawerau WWTP an allowance has been made for the
addition of a foul air management system to mitigate odour release at the inlet works to the Kawerau
WWTP.
For options of conveying raw wastewater to the Whakatāne WWTP an allowance has been made
provide aeration to support the BOD loading on the primary pond and to supplement to the currently
consented 84 kg BOD/ha/day. This is proposed to be achieved through the use of surface aeration.
Appendix B further examines the existing capacity of the Whakatāne oxidation ponds. This matter is
further discussed in later sections of this Report.
For Edgecumbe options that combine with a potential future Matatā standalone WWTP, costs have been
based on the latest AECOM estimate for dated February 2014.
For options that discharge to a potential Land Application Field (LAF) at Thornton, costs for the land
disposal field have been based on the latest AECOM estimate for dated February 2014, with allowances
made for a return flushing pump station (to be located at the LAF) and a return flushing pump station to
the WWTP.
2.9 Natural Hazards and Climate Change
The Whakatāne District and in particular the Bay of Plenty region is at risk of a range of natural hazards
such as earthquakes, flooding, tsunami, debris flows, landslides and volcanic activity. This fact is clearly
spelt out in the planning assumptions section of WDC’s Infrastructure Strategy 2015-2045 and in
Section 7.1.6 ‘Natural Hazards’ of the Matatā Wastewater Scheme AEE (November 2013) and Support
Document 2 to that AEE.
Matatā and Edgecumbe areas have as such witnessed such natural hazard events with the Matatā
debris flows/landslides particularly in the 2005 storm event and Edgecumbe with the 1987 earthquake.
There was also a major flood events in 2004. All these and other potential further events need to be
appropriately considered in the siting, design and operation of new (and existing) infrastructure, as they
have been in the earlier Matatā Wastewater AEE documents.
2.10 Environmental Effects Assessment
Any future discharge consents sought for the discharge of treated wastewater will be subject to the
provisions of the relevant statutory framework from National Policy Statements (NPS) through to the
relevant Regional Plans. As such, detailed Assessment of the Effects on the Environment (AEE) will be
required to support any future resource consent applications.
For the purposes of this study no site-specific assessment of adverse environmental effects has been
undertaken to inform the development and refinement of options. The option assessment process has
however been informed by expert judgement gained by MWH in obtaining consents for the discharge of
treated wastewater to similar land, water and coastal environments and taking into account the relevant
planning instruments discussed in Section 3.
2.11 Land Application Options
To inform the assessment of potential for the land application of treated wastewater in the vicinity of
Edgecumbe, an assessment of potential available land has been undertaken. A screening GIS exercise
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was undertaken of land with 7.5km radius of the Edgecumbe WWTP, to identify land that may be
suitable for land disposal of treated wastewater. The following screening criteria were used:
Land zoning – land zoned residential, commercial or industrial being not available for land disposal;
Ground slope – land with a slope greater than 7 degrees not being suitable for wastewater disposal;
Soil drainage – only soil classed as ‘well drained’ was considered appropriate; and
Flood zones – areas within the 1 in 100 year floodplain of the Rangitaiki and Tarawera Rivers were excluded (flood extent data provided by BOPRC, but did not include flood data to the west of the Tarawera River).
These criteria are generally consistent with the criteria used by AECOM in both the previous and Matatā
standalone options investigations for land application]. The following Figure 2-1 shows the available land
within 7.5km of the WWTP that may be suitable for treated wastewater disposal.
The screening process confirmed that sufficient land potentially suitable for treated wastewater disposal
may exist within a 7.5km radius of the WWTP, this land is to the west and southwest of Edgecumbe on
well drained soils. The land available as being potentially suitable for treated wastewater disposal is
predominantly used for dairying.
During the option development process, WDC coastal reserve land at Thornton was also identified as a
potential site for the application of treated wastewater. A further GIS screening process was undertaken
for this land to inform the assessment of options. The following screening criteria were used:
Proposed Regional Coastal Environment Plan – Biodiversity Sites A and B;
Areas Sensitive to Coastal Hazards 1;
Existing and potential extents of sand extraction activities; and
Western Recreation Reserve Boundary.
Figure 2-1 shows the potentially available land. The broad high level assessment identified
approximately 14.8ha of land that could potentially be used for the land application of treated
wastewater at Thornton Dunes (Figure 2-2).
Part of the large Whakatāne Airport site covering around 225 hectares has also been identified as a
possible land application area (as noted above an area of 14.8ha would be required for a combined
Matatā and Edgecumbe coastal area) . Both the mown grass areas around the runway (which would
benefit from treated wastewater in summer dry periods) and/or some of the dune areas between the
mown grass areas and the coast could be used for land application. Subject to WDC’s ownership and
zoning and the proving of environmental effects associated with sub-surface irrigation and/or low
pressure spray irrigation on the more coastal dune area.
WDC are currently investigating the current possible use of this area as an alternative and maybe more
preferable area than the Thornton WDC Coastal Reserve area, or a nearer Edgecumbe area if one did
become available and proven but at this stage this option is not shortlisted but parked.
This Airport area may also be a further possibility for the discharge of treated wastewater from
Whakatāne’s WWTP after the expiry of the current resource consent in 2026.
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Figure 2-1: Treated Wastewater Land Application Option within 7.5 km of Edgecumbe Wastewater Treatment Plant
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Figure 2-2: Treated Wastewater Land Application Option at Thornton Dunes
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Figure 2-3: Treated Wastewater Land Application Option at Whakatāne Airport
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2.12 Existing Resource Consents
WDC currently holds the following resource consents for the discharge of treated wastewater. These
existing consents are summarised in Table 2-3.
Table 2-3: Existing Resource Consents8
Discharge Location
Number Consent Holder
Purpose Volume / Rate of Discharge
Date of Granting
Expiry Date
Edgecumbe WWTP
20702 Whakatāne District Council
A right to discharge effluent from Edgecumbe oxidation ponds to the Omeheu Canal
500 cubic metres per day
1 May 1980 1 October 2026
Whakatāne WWTP
20368 Whakatāne District Council
A right to discharge treated effluent from oxidation ponds into the Bay of Plenty
8,180 cubic metres per day
8 June 1978
1 October 2026
Tāneatua WWTP
20049 Whakatāne District Council
Right to discharge wastewater from oxidation ponds to be constructed at Tāneatua into the natural waters of the Whakatāne River
0.008627 cubic metres per second
6 April 1971 1 October 2026
Kawerau WWTP
65081 Kawerau District Council
Discharge Treated Municipal Wastewater from Kawerau Wastewater Treatment Plant onto Land (Rapid Infiltration Basins)
22,000 cubic metres over any seven day period
29 October 2009
31 October 2032
In developing the options due consideration has also been taken of finding solutions for both
“Edgecumbe Standalone” and “Joint Matatā and Edgecumbe” that could “fit within” the existing
Whakatāne, Edgecumbe and Kawerau resource consents as appropriate to a particular option. The
basis for these considerations is to find solutions that may/would not require at this time extensive new
resource consents with their consequent (high) costs.
If this is possible, then in each case at least a condition changes would need to be made respective
consents for a particular option to include the wastewater catchment to which the consent applied. For
example if the Whakatāne consent No. 20368 was to include Matatā and Edgecumbe, then Condition 1
purpose would need to be changed to include Matatā and Edgecumbe as well as the Whakatāne urban
area.
A number of options are considered further in this report where wastewater (either raw or treated) is
considered for conveyance from Matatā and Edgecumbe to the existing Whakatāne WWTP.
8 The consents for Edgecumbe, Whakatāne and Tāneatua were granted prior to the RMA 1991 and are correctly referred to as
‘Rights in Respect of Natural Water’. The term ‘resource consent’ has been adopted in this Report for consistency purposes.
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Option WO5 (conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation
ponds treated wastewater for joint Whakatāne ocean outfall discharge via Thornton) and Option WO6
(conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated
wastewater for joint Whakatāne ocean outfall discharge via Awakeri) which use the Whakatāne Ocean
outfall could provide a good fit in terms of operating under existing consents for Edgecumbe and
Whakatāne in terms of the oxidation pond BOD5 loading and retention of the existing consents which
expire on 1 October 2026.
In this case it may be possible to seek consent changes that could be relatively easy to obtain. Option
WO1 (conveyance of Matatā raw sewage to Edgecumbe and combined raw sewage to Whakatāne
WWTP) would involve more changes to the Whakatāne consent in terms of the oxidation pond BOD5
loading but mean the Edgecumbe consent could be surrendered. There would be air discharge matters
still to consider however.
As discussed with WDC Officers and recorded in this section legal and planning advice is required in
this respect.
As set out in Section 4, Cost Estimates, no allowances have been included in the estimates for resource
consent processes. This needs to be well appreciated and taken into account in the next stage of
decision making (refer Section 1.3 of this Report).
2.13 Risk Considerations
A two stage approach has been used in this Report to address the risk assessment of options. This
approach is outlined in Section 7 of this Report. Included in that section are risk matrix tables for the
shortlisted Edgecumbe standalone and combined Matatā and Edgecumbe shortlisted options.
2.14 Discharge / Disposal Options – Land, Freshwater, Marine
The shortlisted options identified for both a standalone Edgecumbe scheme and a combined Matatā and
Edgecumbe scheme cover disposal discharge to land, to the Rangitaiki River and the Pacific Ocean out
to the existing Whakatāne ocean outfall.
There are many advantages/disadvantages of each of these three receiving environments in terms of
discharge and disposal of treated wastewater. Key determinants of these advantages and
disadvantages to the site specific nature of the land, freshwater and marine water and their uses along
with the size of the scheme and the quality of treated wastewater.
The following generalisations based on MWH and other experiences considered appropriate in terms of
the shortlist options assessment in this Project
Key considerations of land disposal options:
Land use;
Groundwater contamination;
Groundwater levels;
Areas with cultural and/or social importance;
Land use – cops/animals/contamination transfer;
Soil contamination;
Surface water contamination;
Habitats and ecosystems;
Aerosol spray drift (for surface application options); and
Implications of the NPS-FM 2014 in terms of ‘maintain and enhance water quality’.
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Long-term sustainability.
Key considerations of freshwater discharges:
Surface water quality effects particularly in terms of BOD, TSS, pathogens and nutrients;
Implications of the NPS-FM 2014 in terms of ‘maintain and enhance water quality’;
Areas with cultural and/or social importance;
Contact recreation uses;
Effects on fish and aquatic ecology; and
Cultural effects.
Key considerations of ocean discharges include:
Any shoreline impacts;
Ocean current movements;
Implications of the NZCPS 2010;
Marine ecosystem including fisheries and wildlife;
Any visual effects; and
Effects on the physical environment e.g. foredunes and sea bed.
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3 Legislation and Planning Instruments
3.1 Overview
There are a number of legislative and planning instruments that provide key drivers for the Project. The
following sections outlines the key legislative and planning instrument requirements.
3.2 National Policy Statement for Freshwater Management 2014
The National Policy Statement for Freshwater Management (2014) (NPS-FM) sets out the objectives
and policies for freshwater management (including groundwater) under the Resource Management Act
1991 (RMA). The NPS-FM is relevant to any discharges to surface water or land. Decision makers on
resource consent applications must have regard to any relevant provisions of the NPS-FM as required
by section 104(1) (b)(iii) of the RMA.
Key policy themes of the NPS-FM include:
Water Quality - safeguarding ecosystems in sustainably managing the use and development of
land and discharges of contaminants. Maintenance or improvement of water quality.
(Objectives A1 and A2);
Integrated Management – Improvement of the integrated management of fresh water and the
use and development of land in catchments. (Objective C1); and
Tāngata Whenua Roles and Interests – To provide for the involvement of iwi and hapū, and to
ensure that tāngata whenua values and interests are identified and reflected in the management
of fresh water including associated ecosystems. (Objective D1).
The most recent case law in relation to wastewater discharge consents being considered under the
NPS-FM is the Matatā Wastewater Environment Court decision 2014 and also the Ngati Kahungunu /
Hawkes Bay Regional Council decision. The implications of these decisions are discussed further in
Section 3.5. There is also the Parliamentary Commission for the Environments recent report on the
NPS-FM and recommendations in Policy A2 to remove the word “region”, as “unders and overs” is not
appropriate.
3.3 New Zealand Coastal Policy Statement 2010
The purpose of the New Zealand Coastal Policy Statement 2010 (NZCPS) is to state policies in order to
achieve the purpose of the RMA in relation to the coastal environment. The NZCPS is relevant to any
discharge within the coastal environment. As per the NPS-FM, decision makers on resource consent
applications must have regard to any relevant provisions as required by section 104(1)(b)(iii) of the
RMA.
Key policy themes of the NZCPS include:
Safeguarding the Coastal Environment – maintaining and enhancing natural biological
processes, protecting representative or significant natural ecosystems, maintaining water
quality, enhancing water quality where it has deteriorated. (Objective 1);
Preserving the Natural Character of the Coastal Environment – recognising characteristics
and qualities that contribute to natural character, features and landscape values of the coastal
environment. (Objective 2, Policies 6 and 13);
Tāngata Whenua – recognising the role of tāngata whenua as kaitiaki, recognising that tāngata
whenua have traditional and cultural relationships with the coastal environment, incorporating
mātauranga Māori in consent processes. (Objective 3, Policy 2);
Public Open Space – maintain and enhance public open space qualities and recreation
opportunities of the coastal environment, recognise the need for public open space within and
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adjacent to the coastal marine area including active and passive recreation. (Objective 4, Policy
18);
Coastal Hazards – To ensure that coastal hazard risks taking account of climate change are
managed by locating new development away from areas prone to such risk. (Objective 5) ;
Providing for People and Communities Four Well-beings – is intended to enable people and
communities to provide for their social, economic, and cultural wellbeing and their health and
safety, (in the coastal marine area). (Objective 6, Policy 6);
Biodiversity – avoiding significant adverse effects on areas of predominantly indigenous
vegetation, habitats of indigenous species, habitats important to migratory species, ecological
corridors. (Policy 11);
Discharge of contaminants – having regard to sensitivity of the receiving environment, the
nature of the contaminants, capacity of the receiving environment to assimilate the
contaminants, avoid significant adverse effects on ecosystems and habitats after reasonable
mixing, use the smallest mixing zone necessary to achieve the required water quality, minimise
adverse effects on the life-supporting capacity of water within a mixing zone. (Policy 23); and
Human sewage – not allow the discharge of human sewage directly to coastal waters without
treatment, not allow the discharge of human sewage to coastal waters unless there has been
adequate consideration of alternative methods, sites and routes for undertaking the discharge
and informed by an understanding of tāngata whenua values and the effects on them. (Policy
23).
3.4 Regional Policy Statement and Regional Plans
3.4.1 Operative and Proposed Regional Policy Statement
The operative and proposed Regional Policy Statement (RPS) will be relevant to any resource consents decision making processes. Key policy themes of the operat ive RPS include:
Tāngata Whenua – To recognise the principles of the Treaty of Waitangi, the rights of tāngata
whenua and individual iwi, provision for the relationship of Maori and their culture and traditions
with their ancestral lands, water, sites, waahi tapu, and other taonga. (Objectives 5.3.1(a) and
5.3.2(a), Policies 5.3.1(b)(i), 5.3.1(b)(iv), 5.3.1(b)(v), 5.3.2(b)(i) and 5.3.2(b)(v))
Well-being - To avoid remedy or mitigate adverse effects on social, economic and cultural well -
being and to manage the use, development and protection of natural and physical resources in a
way, or at a rate, which enables people and communities to provide for their social, economic
and cultural well-being and for their health and safety. (Objective 5.3.6(a), Policies 5.3.6(b)(i),
5.3.6(b)(ii), 6.3.1(b)(viii) and 8.3.1(b)(i))
Land - The adoption of sustainable land use and management practices, to sustain the potential
of land resources to meet the reasonably foreseeable needs of current and future generations,
to safeguard the life-supporting capacity of the soil and associated ecosystems, particularly
indigenous ecosystems, and to protect soil from degradation, to avoid, remedy or mitigate
adverse effects on the environment associated with the inappropriate use and development of
land, to enable land use practices that are consistent with established water quality standards,
to recognise that, subject to appropriate controls, the discharge of contaminants onto or into soil
may be an appropriate method of industrial, agricultural and other waste disposal, to protect
water quality from the adverse effects of land use. (Objective 6.3.1(a), Policies 6.3.1(b)(i),
6.3.1(b)(ii), 6.3.1(b)(iii), 6.3.1(b)(v), 6.3.1(b)(xiii) and 6.3.1(b)(xiv))
Air Emissions - No significant adverse effects on people and the environment result from
discharges of chemical, odorous and particulate contaminants into the air, to provide for the
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discharge of contaminants to air with no significant adverse effects on air quality. (Objective
7.3.2(a), Policies 7.3.2(b)(i), 7.3.2(b)(ii) and 7.3.2(b)(iii))
Water Quality – To maintain/enhance water quality to a level sufficient to safeguard aquatic life,
to sustain the potential of water resources to be used and developed to meet existing and
reasonably foreseeable future needs, and to provide for the protection of aesthetic or cultural
values associated with water. To improve the quality of the region’s water resources by avoiding,
remedying or mitigating the adverse effects of diffuse and point source discharges of
contaminants onto or into land or into water, to maintain/enhance the quality of the region’s
groundwater resources by avoiding, remedying or mitigating the adverse effects of diffuse and
point source discharges of contaminants onto or into land or into water, to avoid, remedy or
mitigate the potential adverse effects on water quality due to the inappropriate location and
management of activities. (Objective 8.3.1(a), Policies 8.3.1(b)(ii), 8.3.1(b)(iii) and 8.3.1(b)(v))
Coastal Environment – Recognition and provision for natural character, outstanding natural
features/landscapes, and significant vegetation and habitats in the coastal environment,
maintain water quality and allow for public access to the coastal marine area. (Objectives
9.3.1(a), 9.3.2(a), 9.3.3(a), Policies 9.3.1(b)(i), 9.3.1(b)(ii), 9.3.1(b)(iii) and 9.3.2(b)(i))
Natural Hazards – The vulnerability to natural hazards of the regions physical resources is
avoided or mitigated. (Objective 11.3.1(a))
Waste Management – Waste production is minimised and residual wastes are disposed of with
no significant adverse effects on the environment (Objective 12.3.3(a), Policy 12.3.3(b)(i))
Built Environment - A built environment that enables efficient use, development and protection
of natural and physical resources while avoiding, remedying and mitigating adverse effects on
the environment, to promote the efficient use and development of existing and future
infrastructure and utility networks. (Objective 13.3.1(a), Policy 13.3.1(b)(v))
Natural Character – Preservation of the natural character of the region, including the protection
of significant indigenous habitats and ecosystems, having particular regard to intrinsic values of
ecosystems, to recognise indigenous marine habitats and ecosystems as being
underrepresented in the reserves network of the Bay of Plenty Region. (Objective 16.3.1(a),
Policies 16.3.1(b)(v) and 16.3.1.(b)(vi))
3.4.2 Regional Air Plan
The Bay of Plenty Regional Air Plan provides for the control of discharges of contaminants into air,
including odour, for the whole of the Bay of Plenty region. Key policy themes of the Regional Air Plan
include:
Air Quality – Maintain and protect high air quality in the Bay of Plenty region including requiring
that the disposal and storage of waste be undertaken in a manner that avoids, remedies or
mitigates adverse effects on air quality. (Objective 1, Policy 6)
3.4.3 Regional Water and Land Plan
The purpose of the Regional Water and Land Plan is to promote the sustainable and integrated
management of land and water resources within the Bay of Plenty Region and includes matters relating
to discharges to land. Key policy themes of the Regional Water and Land Plan include:
Kaitiakitanga – principles of the Treaty of Waitangi are taken into account, water and land
concerns of tāngata whenua are taken into account and addressed, regard to be had to iwi
resource management planning documents, maintenance of mauri of water and land, particular
regard to kaitiakitanga, appropriate consultation with tāngata whenua, avoid, remedy or mitigate
adverse effects on water, land, or sites of spiritual cultural or historical significance to tāngata
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whenua where these resources and sites have been identified by tāngata whenua (Objectives 1,
4, 5, 6, Policies 2, 5, 9, 11, 14, 15, 17, 18 and 20).
Integrated Management of Land and Water – land use and management practices are
appropriate to the environmental characteristics and limitations of the site; maintenance of
cultural, ecological, amenity, natural character and landscape values, maintenance of high
quality groundwater and health of the regions soils; management of riparian margins to protect
and enhance soil conservation, water quality and heritage values; protection of vulnerable areas
from erosion; maintain and improve the protective function of coastal sand dunes; allowance of
resource use and development where there are beneficial effects on the social, cultural and
economic wellbeing of people and communities and adverse effects on the environment are
avoided, remedied or mitigated. (Objectives 8, 9, 10, 15, 17, 19, 20, 21 Policies 21 and 32).
Discharges to Water and Land – Management of discharges of contaminants to land with
respect to the treatment capacity of the soil, run off to surface water, adverse effects on
groundwater. Appropriate management of stormwater. Early and on-going consultation with
tāngata whenua during consideration of wastewater treatment systems, encouragement of
discharge of contaminants to land based treatment and disposal (rather than to water) where
appropriate and environmentally sustainable including disposal of sewage by passage through
land, soil or wetlands. Consideration of contamination of fresh water and ecosystems when
considering applications for discharge consent onto land, requirement for appropriate
management of discharges of contaminants to land where it may enter water, encouragement of
discharge activities to comply with current best engineering practice and best practicable options
to avoid or mitigate adverse effects. (Objectives 26, 31, 32 and 34, Policies 41, 42, 43A, 44, 48
51 and 54)
Under the Regional Water and Plan, the discharge of contaminants (treated wastewater) to water or
land is a discretionary activity under rule 37. For discharges to surface water, these are required to be
assessed against the Water Quality Classification of the receiving water body. The various water bodies
that could be discharged to as part of the options and their classification is as follows:
Omeheu Channel – Modified Watercourse with Ecological Values;
Tarawera River – Fish Purposes Lower Tarawera River;
Rangitaiki River – Contact Recreation - downstream of Te Teko;
Rangitaiki River – Aquatic Ecosystem (Bay of Plenty) – upstream of Te Teko; and
Whakatāne River (near Tāneatua) – Water Supply.
3.4.4 Regional Plan for the Tarawera River Catchment
The purpose of the Bay of Plenty Regional Plan for the Tarawera River Catchment (RPTRC) is to assist
Environment Bay of Plenty to promote the sustainable management of natural and physical resources
within the Tarawera River catchment.
As shown in Figure 3-1, the towns of Matatā and Edgecumbe lie within the Tarawera River catchment.
The Rangitaiki River to the east of Edgecumbe lies outside of the RPTRC boundary.
The RPTRC contain specific rules relating to future discharges to human sewage (or contaminants
derived from human sewage into surface water within the Tarawera River catchment.
The relevant rule in relation to the discharge of treated wastewater is rule 15.8.4(r) which states:
“Except for the provisions of the Operative On-Site Effluent Treatment Regional Plan, and for the provisions for Kawerau township and Edgecumbe township set out in (a) to (d) of this rule, and the provisions of rule 15.8.49x), all new or existing discharges of human sewage or contaminants derived from human sewage into surface water within the Tarawera River catchment will become a Prohibited Activity on the date on which this regional plan becomes operative”.
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When the existing resource consent for the discharge of treated wastewater from the Edgecumbe
WWTP to the Omeheu Canal expires in 2026, and new discharge to into surface water will become a
discretionary activity subject to the following limits as shown in Table 3-1.
Table 3-1: Regional Plan for the Tarawera River Catchment –Limits for Edgecumbe WWTP
Parameter Unit Limit
cBOD5 mg/L < 10
Suspended Solids mg/L < 15
Total Nitrogen mg/L < 25
Faecal coliform No./100mL < 10,000
Rule 15.8.4(r) also contains provisions which limit the source of wastewater that can be discharged at
both Edgecumbe and Kawerau. In the process of assessing the various options WDC obtained legal
advice that confirmed that the discharge of wastewater sourced from outside either Edgecumbe or
Kawerau townships (e.g. the discharge of wastewater sourced from Matatā at Kawerau) would be a
prohibited activity under the RPTRC. A copy of this legal advice is attached as Appendix C.
BOPRC have advised that the review of the TRCMP is scheduled for 2018. While a plan change to the
limits in Figure 3-1 could be expected and justified to use current day practice of median and upper
percentiles (e.g. 90 percentile) limits it is not expected that there will be any relaxation in the limits.
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Figure 3-1: Regional Plan for the Tarawera River Catchment Map
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3.5 Matatā Wastewater Consents and Designation: Environment Court Decision 2015
The decision of the Environment Court related to the Sustainable Matatā appeal against the decision of
the BOPRC (Decision No. [2015]NZEnvC90) contains a number of matters that require careful
consideration in relation to the assessment of effects of wastewater discharges to land and/or
freshwater and air. Key considerations includes:
The effects of the discharge of odour on future papakainga (regardless of whether these are
consented or permitted developments);
The effects of wastewater discharged to land and subsequent effects on surface water quality
and ecology;
The implications of the NPS-FM 2014 in terms of ‘maintain and enhance’ water quality;
Effects on water quality versus effects on aquatic ecology;
Sensitivity of the Tarawera Catchment in terms of nutrient effects related to nitrogen and
phosphorous;
The need to provide an assessment of the quantitative benefits of the removal of septic tank
discharges from the township of Matatā; and
The need to ensure a readily transparent site selection process for the siting of any new WWTP
including the clear recording of the decision making process so that it is readily understood by
others, including mechanisms for reviewing the process if assumptions changes through initially
unforeseen circumstances.
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4 Cost Estimates
4.1 Basis of Cost Estimates
The following assumptions have been made in compiling the cost estimates:
Capital cost estimates have been developed using a ‘bottom-up’ approach as agreed with WDC Officers at the time of defining the Project scope. Costs are based upon recent tendered prices for similar sized projects and specific rates obtained from contractors;
Total capital cost estimates have been determined on the following basis:
o Preliminary and General items 12% of physical works cost
o Commissioning and completion 1.5% of physical works cost
o Design and construction management 14% of construction cost
o Capital contingency 30% of construction cost
For conveyance options, the following assumptions have been made:
o Air valves 1 per 500m
o Scour valves 1 per 2 km
o For river crossing pipeline will be attached to outside of bridges in pipe sleeve
For those options involving upgrading the Edgecumbe oxidation ponds with MBBR, Actiflo and UV treatment the same capital cost estimates have been used for Edgecumbe standalone options and the combined Matatā and Edgecumbe options. This is because for the Actiflo unit it is the minimum commercial size for both options. For the MBBR or UV smaller units could be used for Edgecumbe alone with some saving of that used.
No allowance in capital costs has been made for:
o Goods and services taxes (GST) or any import duties;
o Obtaining resource consents or building consents; (note this is currently being further assessed and the next draft – final may include indicative resource consent costs.
o The use of existing infrastructure for combined schemes e.g. Matatā using the Edgecumbe oxidation ponds and Matatā and Edgecumbe using the Whakatāne WWTP and ocean outfall. Costs are allowed for new plant items e.g. upgrade of Edgecumbe oxidation pond; and
o Any work associated with de-establishment of existing WWTP plant and/or other wastewater infrastructure no longer required under each option or rehabilitation of the site.
Operating cost estimates have been developed on the following basis:
o Energy costs (power) $0.18 per KWh
o Energy (line rental) $5 per day
o Labour $30 per hour
o Specialist labour $60 per hour
o Travel $1.50 per km
o Chemical dosing (conveyance) for raw $0.2 per m3 sewage only (not for treated wastewater conveyance)
o Maintenance and replacement costs (treatment) 0.5% of capital works
o Discharge of wastewater to Kawerau WWTP $1.10 per cubic metre
o Dosing costs (treatment at Edgecumbe options) 50 L/d ethanol
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o Spares and consumables $3000 per pump station pa.
o Labour (conveyance) 2 x 2hr visits per week
o Specialist labour 2 days per annum
Whole of Life Costs or Net Present Value (NPV) - an economic comparison of the respective options has been conducted in an analysis of NPV costs. For the purposes of this assessment, costs have been assessed over a period of 20 years using a discount rate of 6 percent (averaged) as advised by WDC. Mechanical and instrument maintenance and replacement costs have been added at assumed life cycle stages.
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5 Edgecumbe Standalone Options
5.1 Methodology
The assessment of Edgecumbe standalone options has followed a four stage assessment being the:
Stage 1: Compilation of long list options broadly arranged around the groupings of options for conveyance, treatment at Edgecumbe and land application at Edgecumbe, treatment at Edgecumbe and land application at Thornton, treatment at Edgecumbe and discharge to the Tarawera River catchment and treatment at Edgecumbe and discharge to the Rangitaiki River;
Stage 2: Refinement and assessment of the long list to the confirmed long list;
Stage 3: Refinement and assessment of the confirmed long list to the short list;
Stage 4: Compilation of information to enable the short list to be assessed; and
Stage 5: Assessment and ranking of the short-list.
This draft Report has been prepared to stage 4 and will be used to assessment and rank the short listed options stage 5.
5.2 Identification of Long List Options
The following long list of 12 options for the standalone Edgecumbe options were identified under the following subheadings:
These options are described further in Table 5-1 below which identifies the infrastructure components and locations that make up the total option.
Conveyance Options
Option 1 - Conveyance of Edgecumbe to Kawerau WWTP;
Option 2 - Conveyance of Edgecumbe oxidation pond treated wastewater to new ocean outfall around Matatā;
Option 3 - Conveyance of Edgecumbe from new WWTP to new ocean outfall around Matatā ;
Option 4 - Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne ocean outfall;
Option 5 - Conveyance of Edgecumbe raw sewage to Whakatāne WWTP oxidation pond ;
Treatment at Edgecumbe Options and Land Application at Edgecumbe
Option 6 - Upgrade of existing Edgecumbe oxidation ponds and Land Application at Edgecumbe;
Option 7 - New WWTP at Edgecumbe and Land Application at Edgecumbe;
Treatment at Edgecumbe Options and Land Application at Thornton
Option 8 - Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes;
Option 9 - New WWTP at Edgecumbe and Land Application at Thornton Dunes;
An alternative to the land application on the Thornton Dunes maybe land application on the Whakatāne Airport site owned by WDC. Refer discussion in Section 2.11.
Treatment at Edgecumbe Options and Discharge to Tarawera River Catchment
Option 10 - New WWTP at Edgecumbe and Tarawera River Discharge;
Treatment at Edgecumbe Options and Discharge to Rangitaiki River Catchment
Option 11 - New WWTP at Edgecumbe and Rangitaiki River discharge; and
Option 12 - Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki River discharge.
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Table 5-1: Long list Options for Edgecumbe Schemes
Option Code & Number
Option Title Collection system1
Conveyance Treatment
Discharge/Disposal of Treated Wastewater
Use of Existing Infrastructure
(upgraded as appropriate)2
Reference Previous Reports2
Type Type Location
Conveyance Options
Option 1 Conveyance of Edgecumbe raw sewage to Kawerau WWTP
Edgecumbe existing then LPS as per LTP (WDC’s Long Term Plan 2015 – 25)
Edgecumbe pumped to Kawerau
Chemical Treatment (Alum Dosing)
Kawerau
Disposal to land via Rapid Infiltration Beds adjacent to Tarawera River
Kawerau WWTP and RIB’s
Opus July 2013, Option 2
Option 2
Conveyance of Edgecumbe oxidation pond treated wastewater to new ocean outfall around Matatā
Edgecumbe existing then LPS as per LTP
Edgecumbe pumped to Matatā new ocean outfall
Existing Oxidation ponds upgraded
Edgecumbe Discharge to new ocean outfall at Matatā
Edgecumbe oxidation ponds
Option 3
Conveyance of Edgecumbe from new WWTP to new ocean outfall around Matatā
Edgecumbe existing then LPS as per LTP
Edgecumbe pumped to Matatā new ocean outfall
“In tank” treatment with ex oxidation pond for high wet weather flows
Edgecumbe Discharge to new ocean outfall at Matatā
Edgecumbe oxidation ponds for wet weather storage.
Option 4
Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne ocean outfall
Edgecumbe existing then LPS as per LTP
Edgecumbe pumped to Whakatāne WWTP
Existing Oxidation ponds upgraded
Edgecumbe Discharge to existing outfall at Whakatāne ocean outfall
Edgecumbe oxidation ponds
Option 5
Conveyance of Edgecumbe raw sewage to Whakatāne WWTP oxidation pond
Edgecumbe existing then LPS as per LTP
Edgecumbe pumped to Whakatāne WWTP
Whakatāne oxidation ponds
Whakatāne Discharge to existing outfall at Whakatāne WWTP
Edgecumbe oxidation ponds for wet weather storage.
Treatment at Edgecumbe Options (Land Application at Edgecumbe)
Option 6
Upgrade of existing Edgecumbe oxidation ponds and Land Application at Edgecumbe
Edgecumbe existing then LPS as per LTP
N/A
Existing Oxidation ponds upgraded with Actiflo, MBBR and UV disinfectant.
Edgecumbe Disposal to land by slow rate irrigation in general Edgecumbe area
Edgecumbe oxidation ponds
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Option Code & Number
Option Title Collection system1
Conveyance Treatment
Discharge/Disposal of Treated Wastewater
Use of Existing Infrastructure
(upgraded as appropriate)2
Reference Previous Reports2
Type Type Location
Option 7 New WWTP at Edgecumbe and Land Application at Edgecumbe
Edgecumbe existing then LPS as per LTP
N/A
“In tank” treatment with ex oxidation pond for high wet weather flows
At Edgecumbe oxidation pond site (or elsewhere)
Disposal to land by slow rate irrigation in general Edgecumbe area
Edgecumbe oxidation ponds for wet weather storage.
MWH, Jan 2002
Treatment at Edgecumbe Options (Land Application at Thornton)
Option 8
Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes
Edgecumbe existing then LPS as per LTP
Edgecumbe pumped to Thornton Dunes
Existing Oxidation ponds upgraded with Actiflo, MBBR and UV Treatment
Edgecumbe Disposal to land by slow rate irrigation in Thornton dunes area
Edgecumbe oxidation ponds
Option 9
New WWTP at Edgecumbe and Land Application at Thornton Dunes
Edgecumbe existing then LPS as per LTP
Edgecumbe pumped to Thornton Dunes
“In tank” treatment with ex oxidation pond for high wet weather flows
At Edgecumbe oxidation pond site (or elsewhere)
Disposal to land by slow rate irrigation in Thornton dunes area
Edgecumbe oxidation ponds (part of) for wet weather storage.
Treatment at Edgecumbe Options (Discharge to Tarawera River Catchment)
Option 10 New WWTP at Edgecumbe and Tarawera River Discharge
Edgecumbe existing then LPS as per LTP
N/A
“In tank” treatment with ex oxidation pond for high wet weather flows and treatment Standard to meet Regional Plan for Tarawera River Catchment (TCMP) treated wastewater quality
At Edgecumbe oxidation pond site (or elsewhere)
Omeheu Channel, the Tarawera River
Edgecumbe oxidation ponds (part of) for wet weather storage
Existing Omeheu Channel discharge
H&G, 2009
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Option Code & Number
Option Title Collection system1
Conveyance Treatment
Discharge/Disposal of Treated Wastewater
Use of Existing Infrastructure
(upgraded as appropriate)2
Reference Previous Reports2
Type Type Location
Treatment at Edgecumbe Options (Discharge to Rangitaiki River Catchment)
Option 11
New WWTP at Edgecumbe and Rangitaiki River discharge
Edgecumbe existing then LPS as per LTP
N/A
“In tank” treatment with ex oxidation pond for high wet weather flow balancing
Edgecumbe To Rangitaiki River (near Edgecumbe)
Edgecumbe oxidation ponds (part of) for wet weather storage
Edgecumbe oxidation ponds
H&G, 2009 but discounted
Option 12
Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki River discharge
Edgecumbe existing then LPS as per LTP
N/A
Existing Oxidation ponds upgraded with Actiflo, MBBR and UV disinfection
Edgecumbe To Rangitaiki River (near Edgecumbe)
Edgecumbe oxidation ponds
H&G, 2009 but discounted
Matatā AEE Table 6.4
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5.3 Evaluation of Long List Options
This long list of 12 options were then assessed against a range of criteria as described in Table 5-2
below.
Table 5-2: Evaluation Criteria for Long List Options
Criteria Components
Technical/Functional
Reliability
Flexibility
Constructability
Engineering Resilience (refer Glossary of Terms)
Operational
Complexity
Safety
Septicity risk
Odour/noise management
Social/Public Health
Public health protection
Public safety
Visual/amenity
Location/neighbours
Construction effects odour/noise nuisance
Tangata Whenua Considerations (tangata whenua input required)
Discharge to fresh water
Discharge to land
Discharge to coastal water
Maori land
Transfer of wastewater from one rohe to another
RMA Consentability
RMA
NPS - FM (2014)
NZCPS (2010)
Regional & District Planning Instruments including RPTRC
Local Government Act (2002)
Existing and future consents and designation ease or difficulty
Relevant case law
Economic Relative Assessment of indicative capital,
operation and life cycle (NPV) costs
Overall Sustainability
Alignment with WDC’s Sustainability Strategy 2010-2015
Energy use/carbon footprint
Natural hazards/climate change
Adverse effects on natural environment
Sustainable development
Future proofing
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Criteria Components
Key Risks (without mitigation) Note that specific mitigation will be developed
for shortlisted options
Advantages
Disadvantages
Appendix D provides the full assessment of the long list options under a range of criteria. This Appendix
also includes (in summary form) “key advantages and disadvantages” and also a high level key risks
identification. These high level risks are identified before further mitigation measures that could be
identified to reduce the risks further than those allowed fro in the options as developed in Section 8
includes a much more detailed risk assessment on shortlisted options.
Following the assessment of 12 long list options, a confirmed long list of 5 options were taken forward
for further assessment. A WDC officer /MWH workshop was used to advance this assessment. Table
5-3 provides a summary of this long list option assessment.
Legend used in Table 6-3 is:
√ = Option on confirmed long list
X = Option parked – parked means these options are not being proceeded with in the confirmed long list
evaluation – but remain available should the proceeding evaluation process mean they should be
reconsidered.
Table 5-3: Long List Option Assessment Summary
Long List Option Option on Confirmed Long List or
Parked?
Conveyance Options
Option 1 Conveyance of Edgecumbe raw sewage to Kawerau WWTP
√
Option 2 Conveyance of Edgecumbe oxidation pond treated wastewater to new ocean outfall around Matatā
√
Option 3 Conveyance of Edgecumbe from new WWTP to new ocean outfall around Matatā
X
Parked
Significant cultural issues are likely to make future discharge consents difficult to obtain
High capital and operating costs for new WWTP at Edgecumbe and new ocean outfall around Matatā
Option 4 Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne ocean outfall √
Option 5 Conveyance of Edgecumbe raw sewage to Whakatāne WWTP
√
Treatment at Edgecumbe Options (Land Application at Edgecumbe)
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Long List Option Option on Confirmed Long List or
Parked?
Option 6 Upgrade of existing Edgecumbe oxidation ponds and Land Application at Edgecumbe
X
Parked High-risk that any land disposal at Edgecumbe
would be technically unfeasible / unsustainable
Expected high costs which would include land purchase or leasing
Option 7 New WWTP at Edgecumbe and Land Application at Edgecumbe
X
Parked High-risk that any land disposal at Edgecumbe
would be technically unfeasible / unsustainable
Expected high costs which would include land purchase or leasing
Treatment at Edgecumbe Options (Land Application at Thornton)
Option 8 Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes √
Option 9 New WWTP at Edgecumbe and Land Application at Thornton Dunes
√
Treatment at Edgecumbe Options (Discharge to Tarawera River Catchment)
Option 10 New WWTP at Edgecumbe and Omeheu Channel Discharge
√
Treatment at Edgecumbe Options (Discharge to Rangitaiki River Catchment)
Option 11 New WWTP at Edgecumbe and Rangitaiki River discharge √
Option 12 Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki River discharge
√
5.4 Assessment of Confirmed Long List Options
Following the assessment of the long list of 12 options, the nine options taken forward to the confirmed
long list were assessed further in terms of topographical maps and schematic diagrams with a summary
of key features and key matters that would be required in the option assessment and decision making.
These are described in the following sections for each option on the confirmed long list.
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5.4.1 Option 1 (EDG1) - Conveyance of Edgecumbe to Kawerau WWTP
Figure 5-1: Schematic for Option 1
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5.4.2 Option 2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to New Ocean Outfall around Matatā
Figure 5-2: Schematic for Option 2
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5.4.3 Option 4 (EDG 4) - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Whakatāne Ocean Outfall
Figure 5-3: Schematic for Option 4
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5.4.4 Option 5 - Conveyance of Edgecumbe Raw Sewage to Whakatāne WWTP
Figure 5-4: Schematic for Option 5
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5.4.5 Option 8 (EDG 8) - Upgrade of Existing Edgecumbe Oxidation Ponds and Land Application at Thornton Dunes
Figure 5-5: Schematic for Option 8
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5.4.6 Option 9 – New WWTP at Edgecumbe and Land Application at Thornton Dunes
Figure 5-6: Schematic for Option 9
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5.4.7 Option 10 - New WWTP at Edgecumbe and Tarawera River Discharge
Figure 5-7: Schematic for Option 10
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5.4.8 Option 11 - New WWTP at Edgecumbe and Rangitaiki River Discharge
Figure 5-8: Schematic for Option 11
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5.4.9 Option 12 (EDG 12) - Upgrade of existing Edgecumbe Oxidation Ponds and Rangitaiki River discharge
Figure 5-9: Schematic for Option 12
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5.5 Confirmed Long List Assessment Summary
Following the assessment of 9 confirmed long list options, a short list of 5 options were taken forward for
further assessment. Table 5-4 provides a summary of the confirmed long list option assessment showing
in the middle column those options identified for the confirmed long list and the 5 options identified for
the short list as shown in the right hand column ticked ().
This assessment was undertaken in a workshop with WDC Officers, Mr Terry Long of EBOPRC and
MWH staff. The evaluation drew on the material earlier in this section and Appendices E and F in this
Report.
Legend:
√ = Option on confirmed long list or short list
X = Option parked – parked means these options are not being proceeded with in the confirmed long list
evaluation – but remain available should the proceeding evaluation process mean they should be
reconsidered.
Table 5-4: Confirmed Long List Option Assessment Summary
Long List Option Option on Confirmed Long
List or Parked?
Option on Short List
or Parked?
Conveyance Options
(EDG1) Option 1
Conveyance of Edgecumbe raw sewage to Kawerau WWTP
√ √
Option 2
Conveyance of Edgecumbe oxidation pond treated wastewater to new ocean outfall around Matatā
√
X
Parked
Significant cultural issues are likely to make future discharge consents difficult to obtain
Option 3
Conveyance of Edgecumbe from new WWTP to new ocean outfall around Matatā
X
Parked
Significant cultural issues are likely to make future discharge consents difficult to obtain
High capital and operating costs for new WWTP at Edgecumbe and new ocean outfall around Matatā
X
Parked
(EDG4)
Option 4
Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne ocean outfall
√ √
(EDG5)
Option 5
Conveyance of Edgecumbe raw sewage to Whakatāne WWTP
√ √
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Long List Option Option on Confirmed Long
List or Parked?
Option on Short List
or Parked?
Treatment at Edgecumbe Options (Land Application at Edgecumbe)
Option 6
Upgrade of existing Edgecumbe oxidation ponds and Land Application at Edgecumbe
X
Parked High-risk that any land
disposal at Edgecumbe would be technically unfeasible / unsustainable
Expected high costs which would include land purchase or leasing
X
Parked
Option 7 New WWTP at Edgecumbe and Land Application at Edgecumbe
X
Parked High-risk that any land
disposal at Edgecumbe would be technically unfeasible / unsustainable
Expected high costs which would include land purchase or leasing
X
Parked
Treatment at Edgecumbe Options (Land Application at Thornton)
(EDG8)
Option 8
Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes
√ √
Option 9
New WWTP at Edgecumbe and Land Application at Thornton Dunes
√
X
Parked High capital and
operating costs for new WWTP at Edgecumbe
Treatment at Edgecumbe Options (Discharge to Tarawera River Catchment)
Option 10
New WWTP at Edgecumbe and Tarawera River Discharge
√
X
Parked Difficulty in meeting NPS
Freshwater objectives as a result of discharging additional contaminants to Tarawera River catchment than allowed for in the TCMP
Maximum values in future consent may cause issues with future consent compliance i.e. one single sample could cause non-compliance
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Long List Option Option on Confirmed Long
List or Parked?
Option on Short List
or Parked?
High technology and expensive to run WWTP to meet the very high treated wastewater quality in the TCMP
Treatment at Edgecumbe Options (Discharge to Rangitaiki River Catchment)
Option 11
New WWTP at Edgecumbe and Rangitaiki River discharge
√
X
Parked High cost for new
WWTP
Does not use the existing infrastructure at Edgecumbe oxidation ponds
(EDG12)
Option 12
Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki River discharge
√ √
5.6 Comparison of Short Listed Options
Following the assessment of the confirmed Long List of 9 options, then as set out in Section 5-5 a short
list of five options was arrived at. These are further stated for ease of reference in Table 5-5 below.
Each of these options were further developed in respect to Preliminary (high level) concept design of
conveyance, treatment and treated wastewater discharges and disposal.
Table 5-5: Edgecumbe Standalone Shortlisted Options
Short Listed Edgecumbe Standalone Options
(EDG1) Option 1
Conveyance of Edgecumbe raw sewage to Kawerau WWTP
(EDG4)
Option 4
Conveyance of Edgecumbe oxidation pond treated wastewater to Whakatāne ocean outfall
(EDG5)
Option 5
Conveyance of Edgecumbe raw sewage to Whakatāne WWTP
(EDG8)
Option 8
Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes
(EDG12)
Option 12
Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki River discharge
Please refer to
Table 5-1 for the component parts of each option.
The schematics in Section 5-4 for key features.
The marked up topographical plans in Appendix E for conveyance routes used in the assessment.
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Following consultation with BOPRC, a variation of Option 8 was developed with land application at Whakatāne airport (as shown in Figure 2-3). This option was coded Option 8A (schematic shown below).
Figure 5-10: Schematic for Option 8A
5.6.1 Estimated Costs
Section 4 above sets out the basis of cost estimates. These also include those items for which capital cost estimates have not been included. This includes no provision for GST, resource consents, any land purpose and possible WWTP’s upgrades at Whakatāne, Edgecumbe or Kawerau when the respective resource consents expire. Refer to Section 4 for other items.
Table 5-6 below summarises the Estimated Costs for Edgecumbe Standalone Options.
Table 5-6: Estimated Costs for Edgecumbe Standalone Options
CAPEX ($M) OPEX – Year 1 ($M)
OPEX - Year 20
($M)
(for Comparison)
NPV ($M)
Option Conveyanc
e Treatment Total Capital
Maintenance/ Replacement includes KDC Bulk Charge
for EDG1
Power Dosing Total Year 1 - OPEX
Total Year 20 - OPEX
TOTAL COST
EDG1 $10.520 $0.300 $10.820 $0.315 $0.020 $ - $0.335 $0.590 $15.705
EDG4 +Actiflo + UV
$10.080 $0.520 $10.600 $0.040 $0.010 $ - $0.050 $0.125 $11.470
EDG5 + Actiflo + UV
$10.400 $0.440 $10.840 $0.040 $0.035 $0.045 $0.120 $0.290 $12.890
EDG8 $6.150 $5.550 $11.700 $0.085 $0.185 $0.030 $0.295 $1.425 $18.355
EDG8A $7.670 $5.550 $13.220 $0.090 $0.185 $0.03 $0.305 $1.425 $19.895
EDG12 $1.625 $4.315 $5.940 $0.080 $0.185 $0.025 $0.295 $1.410 $12.515
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In addition to the basis of the estimates details for the makeup of these estimated costs are given in
Appendices H, I and J for conveyance, treatment and disposal/discharge and NPV accordingly.
5.6.2 Short List Options: Information Summary
The information contained in this report pertaining to these 5 short listed standalone Edgecumbe options, includes:
Table 5-1 Components Parts of the Options
The Schematics for these options in Section 5-4 above.
The Appendix D Comparison Evaluation Table.
The Appendix E Conveyance Routes
The Estimated Cost Summaries in Section 5-6-1 above, Section 3 of this Report and detailed cost estimates in Appendices H - Conveyance), I - Treatment and Discharge/Disposal and J – Net Present Value (NPV).
The Risk Assessment and Risk Mitigation in Section 8 and Table 8-4 for these options.
Appendix K – Supplier Information on Actiflo and MBBR Treatment processes.
Technical, land application and consenting information in Sections 2 and 3 of this Report.
5.6.3 Ranking of Short Listed Option
The ranking of short listed options was undertaken using a Multi-Criteria Assessment (MCA) tool. Key
considerations to inform the MCA included the following:
The provisions within the Regional Plan for the Tarawera River Catchment that prohibit the discharge of wastewater sourced from outside Kawerau Township at Kawerau;
The various issues associated with the conveyance of raw wastewater long distances that relate to the maintenance of adequate flushing velocities, odour management and mitigation (including the requirement for chemical dosing at pump stations) and the corrosive effects of septic raw wastewater on downstream wastewater treatment facilities;
The relative benefits of conveying treated wastewater from the Edgecumbe oxidation ponds that avoid the adverse effects that relate to the conveyance of raw wastewater;
Preferences expressed for the land application of treated wastewater through the relevant statutory planning framework;
The implications of the National Policy Statement for Freshwater Management 2014 and the interpretation for discharges to freshwater to demonstrate the ‘maintenance and enhancement of water quality’;
The implications of the Matatā wastewater Scheme Environment Court decision in terms of adverse effects of the land application of treated wastewater, the over-allocation of water bodies and the maintenance and enhancement of water quality;
The implications of other key statutory planning documents;
Tāngata whenua preferences and documents such as ‘Pathways of the Rangitaiki’;
The potential risk of submissions and later appeals to any future resource consent process;
The preference to utilise as far as practicable existing infrastructure;
The potential to remove the existing discharge of treated wastewater to the Tarawera River catchment from the Edgecumbe WWTP;
The relative capital, operating and whole of life costs of the various preferred option;
The risks profile of each shortlisted option in terms of likelihood, consequence and mitigation;
The future development of an overall District Wide Wastewater Strategy as part of WDC’s Infrastructure 2015-2025;
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The advantages/disadvantages of combining townships for treatment and discharge compared to standalone schemes;
The likely future pros and cons of where the treated wastewater is disposed/discharged i.e. surface water, land, ocean – assuming beneficial reuse is not available;
For the options based on discharge out of the Whakatāne ocean outfall what is likely to be the consent requirements and (any) additional treatment and/or disposal infrastructure after 2026 when the existing resource consent (Water Right) expires;
Any viable beneficial reuse options for treated wastewater;
The question of whether it is necessary to fully replaced the damaged Edgecumbe collection system if an option that can account for higher wet weather flows is adopted;
The compatibility of options with WDC’s present and planned wastewater schemes; and
The need for ongoing community, other stakeholder and tāngata whenua participation in decision making; and
Whether the Whakatāne Airport site is available and suitable for the land application rather than the Thornton dunes site (in this respect both options were assessed).
An MCA workshop with officers from WDC and BOPRC and representatives from MWH and AECOM
was held at WDC Offices on 31 August 2015. The following Tables are the outputs of that MCA
workshop:
Table 5-7 shows the MCA analysis criteria and associated criteria used for the basis of assessment;
Table 5-8 shows the relative weighting given to each criteria – based on a relative scoring of 1 being the least important and 10 being the most important;
Table 5-9 shows the results of the MCA scoring for each of the short listed options – based on a relative scoring of 1 being the lowest score and 5 being the highest score; and
Table 5-10 shows the rationale for the MCA scoring; and Table 5-11 shows the overall summary results, in terms of overall score excluding cost, overall score includ ing a 30% weighting for cost and an overall score including a 50% weighting for cost.
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Table 5-7: Edgecumbe Standalone Shortlisted Options – MCA Analysis Criteria (Independent of Cost)
Ref Analysis Criteria Criteria Description Notes Classification Qualitative or Quantitative?
G1 Sustainability
Alignment with WDC Sustainability Strategy, Energy
Use/Carbon Footprint, Natural Hazards/Climate Change,
Adverse Effects on the Natural Environment, Sustainable
Development, Future Proofing
Scoring will be influenced by the amount of energy use,
reilience to natural hazards, climate change, potential for
adverse effects on the environment, and ability to respond
to population growth
Other Qualitative
G2 Social / Public Health
Public Health Risk, Safety, Visual Amenity, Proximity to
Neighbours and Effects on Them, Construction Effects,
Public Acceptance
Scoring will be influenced by the degree of public health
risk, removal of direct discharges to freshwater
environments, proximity to neighbours, and overall
likelihood of public acceptance
Social Qualitative
G3 Cultural
Matauranga Maori, Archaeological Sites, Discharge to
Freshwater, Discharge to Land, Discharge to Coastal
Water, cultural sites, Transfer of Wastewater from one
rohe to another
Scoring will be influenced by preference to discharge to
land over freshwater and coastal water, avoidance of
cultural sites and archaeological sites
Cultural Qualitative
G4Planning and
Regulatory
Consentability, RMA, Freshwater NPS, NZCPS, Regional
Plan for the Tarawera River Catchment, complexity and
viability of obtaining future consents and designations
Scoring will be influenced by the need (or not) to obtain
new discharge consents and designations, or whether
existing consent conditions could be changed via a
potentially non-notified process and future resource
consent requirements, the avoidance of discharges to the
Tarawera River catchment and freshwater generally, and
the potential effects on the coastal environment and
ecology. Overall marking will be from a complexity and
viability of consenting/planning process.
Environmental Qualitative
G5 Technical / Functional
Reliability, flexibility, constructability, proven engineering,
engineering resilience, soil type, distance to road,
distance to high voltage, use of existing infrastructure
Scoring will be influenced by proven technolgoy, that is
relatively easy to operate and maximises the use of
existing infrastructure. New and complex options to
contruct options will score more poorly.
Other Qualitative
G6 Operational
Complexity, safety, septicity risk/corrosion, centralised
vs decentralised, complementary to existing
infrastructure, reliability
Scoring will be influenced by the operation of the option
i.e. proven technology and can be supported in NZ, are
there other examples in NZ? Centralisation of treatment
plants is a beneficial factor.
Other Qualitative
G7 OwnershipLease, freehold, Maori land, Council owned/controlled
land and infrastructure
Security and influence of long term access/use. Council
owned or controlled land will score more highly, lease
arrangements will score more poorly.
Other Qualitative
Goal based Analysis Criteria - Independent of Cost
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Table 5-8: Edgecumbe Standalone Shortlisted Options – MCA Analysis Weighting
Attribute
Refs:G1 G2 G3 G4 G5 G6 G7 C13 C14 C15
10 1 1 1 1
9 1
8 1 1
7
6 1 1
5 1
4
3
2
1
0
Cri
teri
a
Su
sta
ina
bilit
y
So
cia
l / P
ub
lic
He
alt
h
Cu
ltu
ral
Pla
nn
ing
an
d
Re
gu
lato
ry
Te
ch
nic
al /
Fu
nc
tio
na
l
Op
era
tio
na
l
Ow
ne
rsh
ip
Ca
pit
al C
os
t
Op
era
tin
g C
os
t
NP
V
Weight: 6 6 8 10 8 5 9 10 10 10
Sum of Goals 52 Sum of Cost 30
Goal Based Analysis Criteria - Independent of Costs Cost Based Criteria
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Table 5-9: Edgecumbe Standalone Shortlisted Options – MCA Scoring Results (Independent of Cost)
# Scenario
Su
stai
nab
ilit
y
So
cial
/ P
ub
lic
Hea
lth
Cu
ltu
ral
Pla
nn
ing
an
d R
egu
lato
ry
Tec
hn
ical
/ F
un
ctio
nal
Op
erat
ion
al
Ow
ner
ship
Criteria Weighting 0.115 0.115 0.154 0.192 0.154 0.096 0.173
1Edgecumbe - EDG1 - Raw
Sewage to Kawerau2 3 4 2 3 2 3
2
Edgecumbe - EDG4 -
Oxidation Pond
Wastewater to Whakatāne
4 4 3 4 4 3 5
3Edgecumbe - EDG5 - Raw
Sewage to Whakatāne3 3 3 4 3 2 5
4
Edgecumbe - EDG8 -
Upgrade Oxidation Ponds
and Land Application at
Thornton
3 3 4 3 3 3 5
5
Edgecumbe - EDG12 -
Upgrade Oxidation Ponds
and Discharge to Rangitāiki
River
2 2 1 1 4 3 5
6
Airport - EDG8A - Upgrade
Oxidation Ponds and Land
Application at Airport
4 4 4 4 3 3 5
7
Edgecumbe - Upgrade
Oxidation Ponds and
Discharge to Omeheu
Channel
2 3 2 2 2 2 5
Goal Based Analysis Criteria - Independent of Cost
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Table 5-10: Edgecumbe Standalone Shortlisted Options – MCA Results Scoring Rationale (Independent of Cost)
# Scenario
Su
stai
nab
ilit
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Criteria Weighting 0.115 0.115 0.154 0.192 0.154 0.096 0.173
1
Edgecumbe -
EDG1 - Raw
Sewage to
Kawerau
2 1. Utilising existing facilities
at Kawerau with surplus
capacity
2. High energy consumption
to pump to Kawerau
3. Long raw sewage pipeline
exposed to multiple active
faults, shorter than from
Matata
4. Risk of NPS to continuity of
service in the future
31. Political support from KDC
2. Removes direct discharge to
freshwater environment
41.Initial anecdotal support
from iwi authority
representatives
2. Rohe to rohe issue may be
lesser due to the same iwi
living in Kawerau and
Edgecumbe
21. NPS for Freshwater
Management
2. Need to vary KDC air and
water discharge consents
31. Long raw sewage pipeline,
shorter than from Matatā
2. Rising main with approx
35m static head
3. Additional complexity to
manage septicity, odour,
corrosion, and friction loss
21. Odour
2. Septicity
3. Safety
4. Costs of pumping
5. Monitoring and
maintenance of valves and
pipelines
6. Control over continuity of
treatment and disposal
systems
31. Owned by KDC
2
Edgecumbe -
EDG4 - Oxidation
Pond Wastewater
to Whakatāne
41. Centralised disposal
solution
2. Use of exisitng Edgecumbe
treatment facility
3. Use of exisitng Whakatāne
treatment facility
4. Conveyance of treated
wastewater from Edgecumbe
to Whakatāne
41. Reduced effects upon
neighbours in comparison
with EDG5
2. Likely to be supported by
the majority of the public
3. Reduces potential health
risk through centralising
wastewater disposal
4.Removes direct discharge of
wastewater to fresh water
environment
31. May not be supported by iwi
2. Rohe to rohe potential
issue, iwi in Whakatāne area
different than Edgecumbe
41. Requires change to exisitng
consents for Whakatāne and
Edgecumbe oxidation ponds
(air and wastewater)
2. Positive effect of ceasing
discharge to Tarawera River
catchment
41. Does not affect spare
capacity and operation of
existing oxidation ponds
2. Uncertainty over upgrade
requirements in the future
(>2026)
3. Complexity in connecting to
existing outfall
4. Upgrade of Edgecumbe
ponds required
31. Costs of pumping
2. Operation of 2 treatment
plants
3. Monitoring and
maintenance of valves and
pipelines
51. Council owned scores 5
3
Edgecumbe -
EDG5 - Raw
Sewage to
Whakatāne
31. Centralised treatment
2. Use of exisitng Whakatāne
treatment facility
3. Retain Edgecumbe ponds
for storage of raw sewage
4. Natural hazard risk from
conveyance of raw sewage
from Edgecumbe to
Whakatāne
31. Neighbours to Whakatāne
oxidation pond likely to not
readily support
2. One facility likely to be
supported by the majority of
the public
3. Minimises potential health
risk through centralising
treatment and disposal
4. Removes direct discharge of
wastewater to fresh water
environment
3 1. May not be supported by iwi
2. Rohe to rohe potential
issue, iwi in Whakatāne area
different than Edgecumbe
41. Requires change to exisitng
consents for Whakatāne
oxidation ponds (air and
wastewater)
2. Positive effect of ceasing
discharge to Tarawera River
catchment and surrender of
consent
31. Conveyance of raw sewage
over long distance
2.Additional complexity to
manage septicity, odour,
corrosion, and friction loss
3. Uncertainty over upgrade
requirements in the future
(>2026)
21. Odour
2. Septicity
3. Safety
4. Costs of pumping
5. Monitoring and
maintenance of valves and
pipelines
51. Council owned scores 5
4
Edgecumbe -
EDG8 - Upgrade
Oxidation Ponds
and Land
Application at
Thornton
31. Retains use of existing
treatment facility at
Edgecumbe
2. Land based disposal
3. Irrigation of treated
wastewater to dunes aids
biodiversity development
4. Tsunami risk 3
5. Coastal erosion to
foredunes
31. Ground water flow direction
unproven
2. Potential impact upon
shellfish and coastal
environment if groundwater
flows towards the coast
3. Number of houses around
200m from site
4 1. No archeological site
2. Distance to marae >500m
3. Potential impact upon
coastal water quality
31. BOPRC planning
documents support land-
based disposal
2. Positive effect of ceasing
discharge to Tarawera River
catchment
3. High public use of reserve
and adjoining coast
31. Cost effective use of
Edgecumbe oxidation pond
2. Design and construct
upgrade of Edgecumbe
oxidation pond
3. High perched ground water
table
31. Costs of pumping
2. Additional maintenance and
operational requirements for
land based disposal
51. Council owned scores 5
5
Edgecumbe -
EDG12 - Upgrade
Oxidation Ponds
and Discharge to
Rangitāiki River
21. Use of upgraded facility at
Edgecumbe
2. Significant upgrading
required to meet discharge
quality criteria of receiving
water
3. Disposal to fresh water
environment
21. Low public acceptance - eg
Rangitāiki River Forum
2. High receational use and
food gathering resource
3. Direct discharge to
freshwater environment
11. Highly likely to be culturally
unacceptable to iwi
11. NPS for Freshwater
Management
2. Removes discharge from
Tarawera River catchment
3. Significant dilution
available in Rangitāiki River
4. Difficult to satisfy RMA
requirements despite plant
upgrade
5. Inconsistent with
philosophy of Pathways to
Rangitaiki document which is
to improve overall water
quality
41. Upgrade treatment
processes compatible with
existing oxidation pond
2. Short conveyancing
distance from treatment plant
to disposal outfall
31. Cost of pumping
2. Higher costs of treatment
and maintenance due to
disposal to freshwater
51. Council owned scores 5
6
Airport - EDG8a -
Upgrade
Oxidation Ponds
and Land
Application at
Airport
41. Retains use of existing
treatment facility at
Edgecumbe
2. Land based disposal
3. Irrigation of treated
wastewater to dunes aids
biodiversity development
41. Ground water flow direction
unproven
2. Potential impact upon
shellfish and coastal
environment if groundwater
flows towards the coast
3. Public acceptance may be
an issue
41. No archeological site
2. Distance to marae >500m
3. Potential impact upon
coastal water quality
4. Likely to be an issue with iwi
acceptance due to Ngāti Awa
Settlement Act provisions
41. BOPRC planning
documents support land-
based disposal
2. Positive effect of ceasing
discharge to Tarawera River
catchment
3. Will require Ministerial
approval as an ancilliary use
to the airport
31. Cost effective use of
Edgecumbe oxidation pond
2. Design and construct
upgrade of Edgecumbe
oxidation pond
3. Potential use of surface
irrigation for a portion of the
land application field?
31. Costs of pumping
2. Additional maintenance and
operational requirements for
land based disposal
51. Council owned scores 5
7
Edgecumbe -
Upgrade
Oxidation Ponds
and Discharge to
Omeheu Channel
21. New high tech WWTP
required with use of existing
ponds for balancing flows
2. Discharge into Omeheu
canal not sustainable in long
term
3. High energy consumption
4. Site subject to flooding
5. Quality of existing
discharge will be improved
31. Direct discharge to
freshwater environment
2. Public acceptance could be
low in comparison with other
options
3. Existing resource consent,
upgrade of the plant and
increased quality of discharge
will improve quality of water in
the Omehu Canal.
21. Unlikely to be supported by
iwi
21. Exisitng discharge not
meeting existing consent
conditions
2. BOPRC Regional Plan for
the Tarawera River Catchment
(TRCMP)
3. NPS for Freshwater
Management
4. May require new air
discharge consent
21. High tech treatment plant
2. Complex design and
construction
3. Requires additional land to
be reclaimed from oxidation
ponds
21. Higher costs of treatment
and maintenance due to
disposal to freshwater than for
disposal to Rangitāiki River
due to TRCMP provisions
51. Council owned scores 5
Goal Based Analysis Criteria - Independent of Cost
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
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Table 5-11: Edgecumbe Standalone Shortlisted Options – MCA Summary Results
# Scenario Capital Cost Operating Cost NPV
Overall
Score of
Analysis
Criteria
Excluding
Cost
RankCost Based
ScoreCost Rank
Overall
Score
including
Cost 30%
Overall Rank
30%
Overall
Score
including
Cost 50%
Overall Rank
50%
1Option 1 - Raw Sewage to
Kawerau10,820,000$ 335,000$ 15,705,000$ 2.75 5.00 1.52 5.00 2.38 7.00 2.14 7.00
2
Option 4 - Oxidation Pond
Wastewater to Whakatāne
WWTP
10,080,000$ 50,000$ 11,470,000$ 3.92 2.00 3.02 1.00 3.65 1.00 3.44 1.00
3Option 5 - Raw Sewage to
Whakatāne WWTP10,400,000$ 120,000$ 12,890,000$ 3.44 4.00 2.61 2.00 3.19 2.00 3.00 2.00
4
Option 8 - Upgrade Oxidation
Ponds and Land Application at
Thornton
11,700,000$ 295,000$ 18,355,000$ 3.50 3.00 1.42 6.00 2.87 4.00 2.53 6.00
5
Option 12 - Upgrade Oxidation
Ponds and Discharge to
Rangitāiki River
5,940,000$ 295,000$ 12,515,000$ 2.58 7.00 2.39 3.00 2.52 6.00 2.50 5.00
6
Option 8A - Upgrade Oxidation
Ponds and Land Application at
Airport
13,220,000$ 305,000$ 19,895,000$ 3.92 1.00 1.12 7.00 3.08 3.00 2.52 3.00
7
Option 13 - Upgrade Oxidation
Ponds and Discharge to
Omeheu Channel
5,940,000$ 295,000$ 12,515,000$ 2.63 6.00 2.39 3.00 2.56 5.00 2.53 4.00
Assessment Criteria Scores and Ranking
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
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5.7 Discussions and Findings
As shown in Table 5-11, the following summary of findings can be made:
In terms of the non-price scoring, Option 8A (Upgraded Oxidation Ponds and Land Application at
Whakatāne Airport) scored the highest, followed by Option 4 (Oxidation Pond Wastewater to
Whakatāne WWTP ) and Option 8 (Upgraded Oxidation ponds and Land Application at
Thornton). However, it should be noted that a scoring margin of 0.3 or greater should be
considered significant and less than that non-significant. Consequently, options 8A and 4 should
be considered equivalent with Option 8 third;
Option 8A scored highly in terms of sustainability, social/public heath, cultural, planning and
regulatory, and ownership and moderately in terms of technical/functional and operational.
Whilst WDC owns the Whakatāne airport site, there are a number of leases to consider and the
land is subject to the Ngati Awa Settlement Act provisions. However, WDC has obtained advice
that land application scheme could be progressed at the site and that this could be
encompassed within the existing airport use of the site;
Option 4, the conveyance of oxidation pond treated wastewater to the Whakatāne WWTP ocean
outfall, scored highly in terms of sustainability, public health, planning and regulatory,
technical/functional and ownership, and moderately in terms of cultural and operational;
In terms of overall scoring once cost was accounted for at a weighting of 30%, Option 4 was
ranked first, followed by Option 5 (Raw Sewage to Whakatāne WWTP) and Option 8A. The
ranking order was unaffected by increasing the cost weighting to 50%.
As discussed in Section 2.6.3 the balancing of treated wastewater at Edgecumbe has significant
advantages over balancing and conveying raw wastewater, particularly in terms of odour management,
corrosion and the maintence of adequate velocities within pipeline to maintain self-cleansing.
Consequently, for these reasons Option 4 scored higher than Option 5.
Additionally, preliminary legal advice has been obtained that it may be possible to apply for a change of
resource consent condition to the existing Whakatāne WWTP discharge consent that would allow the
acceptance of wastewater sourced from Edgecumbe. If this option was to be progressed further, an
application under Section 127 of the RMA would need to be submitted to the BOPRC.
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6 Combined Matatā and Edgecumbe Options
6.1 Matatā Stand Alone Scheme Option
WDC and AECOM Consultants are concurrently assessing potential new sites for a standalone Matatā
WWTP and associated Land Application Field (LAF). The results of this assessed of potential combined
Matatā and Edgecumbe Scheme will be brought together for assessment against the range of
standalone Matatā options as described in Section 1.3.
6.2 Methodology
The assessment of combined Matatā and Edgecumbe options has followed a four stage assessment
being the:
Stage 1: Compilation of long list options broadly arranged around the groupings of options for conveyance to and treatment at Kawerau, conveyance to and treatment at Edgecumbe, conveyance to Matatā, land application at Thornton, and conveyance to Whakatāne;
Stage 2: Refinement and assessment of the long list to the confirmed long list;
Stage 3: Refinement and assessment of the confirmed long list to the short list;
Stage 4: Compilation of information to enable the short list to be assessed alongside Matatā standalone options; and
Stage 5: Assessment and ranking of the short-list.
This draft Report has been prepared to stage 4 and will be used to assessment and rank the short listed
options for stage 5 and compare these to the Shortlisted Standalone Matatā Option though an MCA (and
other) processes.
6.3 Identification of Long List Options
The following long list of 21 options for a combined Matatā and Edgecumbe scheme were identified
under the following subheadings. The bold title (e.g. Kawerau, Edgecumbe etc.) relates to the point of
disposal/discharge of the treated wastewater.
At Kawerau
Option KL1 - Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP - Rapid Infiltration Bed (RIB) Land Disposal.
At Edgecumbe
Option EL1 - Conveyance of Matatā raw sewage to Edgecumbe Oxidation Ponds - Land Application at Edgecumbe
Option EL2 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe – Land Application at Edgecumbe;
Option ER1 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe and Omeheu Channel Discharge;
Option ER2 - Conveyance of Matatā raw sewage to new WWTP at Edgecumbe and discharge to Rangitaiki River; and
Option ER3 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds upgraded as necessary and discharge to Rangitaiki River.
At Matatā
Option ML1 - Conveyance of Edgecumbe raw sewage to new WWTP at Matatā - Land Application at Matatā;
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
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Option ML2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā Land Application. Matatā standalone treatment and joint land application with Edgecumbe at Matatā;
Option MR1 - Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to Lower Tarawera River;
Option MR2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint discharge to Tarawera River;
Option MO1 - Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to ocean at Matatā; and
Option MO2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint ocean discharge at Matatā;
At Thornton
Option TL1 - Conveyance of Edgecumbe raw sewage to Matatā. Joint treatment at Matatā, land application at Thornton;
Option TL2 - Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment and joint land application at Thornton; and
Option TL3 - Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe oxidation ponds and conveyance to land application at Thornton.
An alternative to the land application on the Thornton Dunes maybe land application on the Whakatāne Airport site owned by WDC. Refer discussion in Section 2.11.
At Whakatāne
Option WO1 - Conveyance of Matatā raw sewage to Thornton and Edgecumbe to Thornton – then combined conveyance of Edgecumbe raw sewage to Whakatāne WWTP and Ocean Outfall Discharge;
Option WO2 - Conveyance of Matatā raw sewage to Whakatāne WWTP and Edgecumbe raw sewage to Whakatāne WWTP (via Awakeri) and Ocean Outfall Discharge;
Option WO3 - Conveyance of Matatā to Thornton and Edgecumbe Oxidation Pond treated wastewater to Thornton for joint Whakatāne ocean outfall;
Option WO4 - Conveyance of Matatā to Whakatāne WWTP and Edgecumbe Oxidation Pond treated wastewater to Whakatāne (via Awakeri) for joint Whakatāne ocean outfall ;
Option WO5 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds . Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option A – via Thornton; and
Option WO6 - Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option B – via Awakeri.
These 21 long list options are described further in Table 6-1 below which identifies the infrastructure
components and locations that make up the total option.
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Page 65 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Table 6-1: Long list Options for Combined Matatā and Edgecumbe Schemes
Tre
at
&
Dis
ch
arg
e
Option Code & Number
Option Title Collection system9
Conveyance Treatment
Discharge/Disposal of Treated Wastewater
Use of Existing Infrastructure
(upgraded as appropriate)
Reference Previous Reports
Type Location Type Location
At
Ka
we
rau
Land 1 (KL1)
Conveyance of Matatā raw sewage and Edgecumbe raw sewage to Kawerau WWTP.
Rapid Infiltration Bed (RIB) Land Disposal.
Edgecumbe existing then LPS as per LTP
Matatā LPS
Matatā & Edgecumbe pumped to Kawerau
Refer marked up schematic
Chemical Treatment (Alum Dosing)
Kawerau WWTP
Disposal to land via Rapid Infiltration Beds adjacent to Tarawera River
Kawerau WWTP and Rapid Infiltration Basins (RIB’s)
Opus July 2013, Option 2
Matatā AEE Table 6.4 for Matatā
At
Ed
ge
cu
mb
e Land 1
(EL1)
Conveyance of Matatā raw sewage to Edgecumbe Oxidation Ponds.
Land Application at Edgecumbe.
Edgecumbe existing then LPS as per LTP
Matatā LPS
Matatā pumped to Edgecumbe
Refer marked up schematic
Existing Oxidation ponds upgraded by Actiflo
Edgecumbe Disposal to land by slow rate irrigation in general Edgecumbe area
Edgecumbe oxidation ponds
Land 2 (EL2)
Conveyance of Matatā raw sewage to new WWTP at Edgecumbe – Land Application at Edgecumbe
Edgecumbe existing then LPS as per LTP
Matatā LPS
Matatā pumped to Edgecumbe
Refer marked up schematic
“In tank” treatment with ex oxidation pond for high wet weather flows
At Edgecumbe oxidation pond site (or elsewhere)
Disposal to land by slow rate irrigation in general Edgecumbe area
Edgecumbe oxidation ponds for wet weather storage.
MWH, Jan 2002
9 WDC’s proposal is to replace the damaged Edgecumbe collection system with grinder pump lower pressure system (LPS) grinder pump system. Current assumption is that the reticulation will
be replaced as per the Long Term Plan. After the reticulation system is upgraded raw sewage is assumed (i.e. the oxidation ponds will be decommissioned). However, this decision is being revisited.
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
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Tre
at
&
Dis
ch
arg
e
Option Code & Number
Option Title Collection system9
Conveyance Treatment
Discharge/Disposal of Treated Wastewater
Use of Existing Infrastructure
(upgraded as appropriate)
Reference Previous Reports
Type Location Type Location
River 1 (ER1)
Conveyance of Matatā to new WWTP at Edgecumbe and Omeheu Channel Discharge
Edgecumbe existing then LPS as per LTP
Matatā LPS
Matatā pumped to Edgecumbe
Refer marked up schematic
“In tank” treatment with ex oxidation pond for high wet weather flows and treatment Standard to meet Regional Plan for Tarawera River Catchment treated wastewater quality
At Edgecumbe oxidation pond site (or elsewhere)
Omeheu Channel, the Tarawera River
Edgecumbe oxidation ponds for wet weather storage
Existing Omeheu Channel discharge
H&G, 2009
River 2 (ER2)
Conveyance of Matatā to new WWTP at Edgecumbe and discharge to Rangitaiki River
Edgecumbe existing then LPS as per LTP
Matatā LPS
Matatā pumped to Edgecumbe
Refer marked up schematic
“In tank” treatment with ex oxidation pond for high wet weather flow balancing
Edgecumbe To Rangitaiki River (near Edgecumbe)
Edgecumbe oxidation ponds
H&G, 2009 but discounted
River 3
(ER3)
Conveyance of Matatā to Edgecumbe oxidation ponds upgraded as necessary and discharge to Rangitaiki River
Edgecumbe existing then LPS as per LTP
Matatā LPS
Matatā pumped to Edgecumbe
Refer marked up schematic
Existing Oxidation ponds upgraded by Actiflo, MBBR and UV disinfection
Edgecumbe To Rangitaiki River (near Edgecumbe)
Edgecumbe oxidation ponds
H&G, 2009 but discounted
Matatā AEE Table 6.4
At
Ma
tatā
Land 1 (ML1)
Conveyance of Edgecumbe raw sewage to Matatā joint treatment at Matatā, Land Application
Edgecumbe existing then LPS as per LTP
Matatā LPS
Edgecumbe LPS pump raw sewage
Refer marked up schematic
“In tank” WWTP Matatā Joint Land Application Area
Nil
Land 2
(ML2)
Conveyance of Edgecumbe Oxidation Pond treated wastewater to Matatā Land
Edgecumbe existing
Matatā LPS
Edgecumbe oxidation pond pumped
Refer marked up schematic
“In tank” WWTP for Matatā
Existing Oxidation Pond (upgraded) for
Matatā and Edgecumbe
Joint Land Application Edgecumbe oxidation pond
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
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Tre
at
&
Dis
ch
arg
e
Option Code & Number
Option Title Collection system9
Conveyance Treatment
Discharge/Disposal of Treated Wastewater
Use of Existing Infrastructure
(upgraded as appropriate)
Reference Previous Reports
Type Location Type Location
Application. Matatā standalone treatment and joint land application with Edgecumbe
Edgecumbe by Actiflo, MBBR and UV disinfection
River 1
(MR1)
Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to Lower Tarawera River
Edgecumbe existing then LPS as per LTP
Matatā LPS
Edgecumbe LPS pump raw sewage
Refer marked up schematic
“In tank” WWTP with tidal discharge storage basin
Matatā area
Outgoing tidal discharge to lower reach of Tarawera River (within Coastal Marine Area)
Nil
River 2
(MR2)
Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint discharge to Tarawera River
Edgecumbe existing
Matatā LPS
Edgecumbe oxidation pond pumped
Refer marked up schematic
Edgecumbe Oxidation Pond by Actiflo, MBBR and UV disinfection
Matatā “in tank” WWTP
Oxidation Pond Edgecumbe
Matatā standalone WWTP
Outgoing tidal discharge to lower reach of Tarawera River (within Coastal Marine Area)
Edgewater oxidation pond
Ocean 1 (MO1)
Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to ocean at Matatā
Edgecumbe existing then LPS as per LTP
Matatā LPS
Edgecumbe LPS pump raw sewage
Refer marked up schematic
In Tank with WTP tidal storage basin
Oxidation Pond Edgecumbe
Matatā standalone WWTP
Offshore ocean outfall in general Matatā area
Nil Opus July 2013 Option 3A
Ocean 2 (MO2)
Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint ocean discharge at Matatā
Edgecumbe existing
Matatā LPS
Edgecumbe oxidation pond pumped
Refer marked up schematic
Edgecumbe Oxidation Pond
Matatā “in tank” WWTP
Oxidation Pond Edgecumbe
Matatā standalone WWTP
Offshore ocean outfall in general Matatā area
Edgecumbe oxidation ponds
Opus July 2013 Option 3A
At
Th
orn
ton
At
Th
orn
ton
Land 1 (TL1)
Conveyance of Edgecumbe raw sewage to Matatā. Joint treatment at Matatā, land application at Thornton
Edgecumbe existing then LPS as per LTP
Matatā LPS
Edgecumbe LPS Pump raw sewage
Refer marked up schematic
“In tank” WWTP at Matatā area
Matatā Joint Land Application Area at Thornton
Nil
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Page 68 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Tre
at
&
Dis
ch
arg
e
Option Code & Number
Option Title Collection system9
Conveyance Treatment
Discharge/Disposal of Treated Wastewater
Use of Existing Infrastructure
(upgraded as appropriate)
Reference Previous Reports
Type Location Type Location
Land 2 (TL2)
Conveyance of Edgecumbe Oxidation Pond treated wastewater to Matatā. Matatā standalone treatment and joint land application at Thornton.
Edgecumbe existing
Matatā LPS
Edgecumbe oxidation pond pumped
Refer marked up schematic
“In tank” WWTP for Matatā
Existing Oxidation Pond (upgraded) for Edgecumbe by Actiflo, MBBR and UV disinfection
Matatā and Edgecumbe
Joint Land Application Area at Thornton
Edgecumbe oxidation ponds
Land 3 (TL3)
Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe oxidation ponds and conveyance to land application at Thornton
Edgecumbe existing
Matatā LPS
Edgecumbe oxidation pond pumped
Refer marked up schematic
Existing Oxidation Pond (upgraded) for Edgecumbe and Matatā by Actiflo, MBBR and UV disinfection
Edgecumbe Joint Land Application Area at Thornton
Edgecumbe oxidation ponds
At
Wh
ak
atā
ne
Ocean 1 (WO1)
Conveyance of Matatā raw sewage to Thornton and Edgecumbe raw sewage to Thornton – then combined conveyance to Whakatāne WWTP and Ocean Outfall Discharge
Edgecumbe existing then LPS as per LTP
Matatā LPS
Edgecumbe pumped
Matatā pumped
Joint pipeline from Thornton Pump Station
Refer marked up schematic
Upgraded Whakatāne Oxidation Pond System
Whakatāne WWTP
Out of existing Whakatāne ocean outfall
Whakatāne WWTP and ocean outfall
Opus 2013 Option 4
Matatā AEE Table 6-4
Ocean 2 (WO2)
Conveyance of Matatā raw sewage to Whakatāne WWTP and Edgecumbe raw sewage to Whakatāne WWTP (via Awakeri) and Ocean Outfall Discharge
Edgecumbe existing then LPS as per LTP
Matatā LPS
Edgecumbe pumped
Matatā pumped
Refer marked up schematic
Upgraded Whakatāne Oxidation Pond System
Whakatāne WWTP
Out of existing Whakatāne ocean outfall
Whakatāne WWTP and ocean outfall
Matatā AEE Table 6-4
Ocean 3 (WO3)
Conveyance of Matatā raw sewage to Thornton and Edgecumbe Oxidation Pond treated wastewater to Thornton
Edgecumbe Oxidation Pond Treated wastewater
Matatā LPS
Edgecumbe oxidation pond pumped
Refer marked up schematic
Oxidation Pond at Edgecumbe
Whakatāne WWTP
Edgecumbe
Whakatāne
Whakatāne ocean outfall (by passes Whakatāne WWTP) for Edgecumbe oxidation pond flow
Whakatāne WWTP and ocean outfall
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Tre
at
&
Dis
ch
arg
e
Option Code & Number
Option Title Collection system9
Conveyance Treatment
Discharge/Disposal of Treated Wastewater
Use of Existing Infrastructure
(upgraded as appropriate)
Reference Previous Reports
Type Location Type Location
for joint Whakatāne ocean outfall
Matatā LPS pumped (requires separate conveyance lines from Thornton)
Whakatāne ocean outfall for Matatā flow
Ocean 4 (WO4)
Conveyance of Matatā raw sewage to Whakatāne WWTP and Edgecumbe Oxidation Pond treated wastewater to Whakatāne (via Awakeri) for joint Whakatāne ocean outfall
Edgecumbe Oxidation Pond Treated wastewater
Matatā LPS
Edgecumbe oxidation pumped
Matatā LPS pumped
Refer marked up schematic
Oxidation Pond at Edgecumbe
Whakatāne WWTP upgraded if necessary for Matatā
Edgecumbe
Whakatāne
Whakatāne ocean outfall (by passes Whakatāne WWTP) for Edgecumbe oxidation pond flow
Whakatāne ocean outfall for Matatā flow
Whakatāne WWTP and ocean outfall
At
Wh
ak
atā
ne
Ocean 5 (WO5)
Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option A – via Thornton
Edgecumbe Oxidation Pond Treated wastewater
Matatā LPS
Edgecumbe oxidation pond pumped
Matatā LPS pumped
Refer marked up schematic
Oxidation Pond at Edgecumbe
Edgecumbe Whakatāne ocean
outfall (by passes Whakatāne WWTP)
Edgecumbe oxidation ponds
Whakatāne ocean outfall
Ocean 6 (WO6)
Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option B – via Awakeri
Edgecumbe Oxidation Pond Treated wastewater
Matatā LPS
Edgecumbe oxidation pond pumped
Matatā LPS pumped
Refer marked up schematic
Oxidation Pond at Edgecumbe
Edgecumbe Whakatāne ocean
outfall (by passes Whakatāne WWTP)
Edgecumbe oxidation ponds
Whakatāne ocean outfall
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6.4 Evaluation of Long List Options
The long list of 21 options were assessed against a range of criteria as described in Table 6-2 below.
Table 6-2: Evaluation Criteria for Long List Options
Criteria Components
Technical/Functional
Reliability
Flexibility
Constructability
Engineering Resilience
Operational
Complexity
Safety
Septicity risk
Odour/noise management
Social/Public Health
Public health protection
Public safety
Visual/amenity
Location/neighbours
Construction effects odour/noise nuisance
Tangata Whenua Considerations (tangata whenua input required)
Discharge to fresh water
Discharge to land
Discharge to coastal water
Maori land
Transfer of wastewater from one rohe to another
RMA Consentability
RMA
NPS - FM (2014)
NZCPS (2010)
Regional & District Planning Instruments including RPTRC
Local Government Act (2002)
Existing and future consents and designation ease or difficulty
Relevant case law
Economic Relative Assessment of indicative capital,
operation and life cycle (NPV) costs
Overall Sustainability
Alignment with WDC’s Sustainability Strategy 2010-2015
Energy use/carbon footprint
Natural hazards/climate change
Adverse effects on natural environment
Sustainable development
Future proofing
Key Risks (without mitigation) Note that specific mitigation will be developed
for shortlisted options
Advantages
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Criteria Components
Disadvantages
Appendix F provides the full assessment of the 21 long list options against these criteria. This Appendix
also includes (in summary form) key advantages and disadvantages and also a high level risk
assessment. These high level risks are identified before further mitigation measures that could be
implemented to further reduce these risks overt that allowed in the preliminary options concept
development and cost estimating. Section 8 includes a much more detailed risk assessment of the
Short Listed Options.
Following the assessment of 21 long list options, a confirmed long list of 11 options were taken forward
for further assessment. Table 6-3 provides a summary of the long list option assessment. This
assessment was undertaken by a WDC Officer, Mr Terry Long of the BOPRC and MWH staff workshop.
Legend:
√ = Option on confirmed long list
X = Option parked – parked means these options are not being proceeded with in the confirmed long list
evaluation – but remain available should the proceeding evaluation process mean they should for some
reason that may arise be reconsidered.
Table 6-3: Long List Option Assessment Summary
Long List Option Option on Confirmed Long List or
Parked?
At Kawerau
Land 1 (KL1)
Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP.
Rapid Infiltration Bed (RIB) Land Disposal.
√
Yet to address implications of TCMP
At Edgecumbe
Land 1 (EL1)
Conveyance of Matatā raw sewage to Edgecumbe Oxidation Ponds.
Land Application at Edgecumbe.
X
Parked Discharge of wastewater sourced from outside
Edgecumbe township at Edgecumbe a prohibited activity in TCMP
High-risk that any land disposal at Edgecumbe would be technically unfeasible / unsustainable
Expected high costs which would include land purchase or leasing
Land 2 (EL2)
Conveyance of Matatā to Edgecumbe joint WWTP Land Application
X
Parked Discharge of wastewater sourced from outside
Edgecumbe township at Edgecumbe a prohibited activity in TCMP
High-risk that any land disposal at Edgecumbe would be technically unfeasible / unsustainable
Expected high costs which would include land purchase or leasing
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Long List Option Option on Confirmed Long List or
Parked?
River 1 (ER1)
Conveyance of Matatā raw sewage to Edgecumbe, joint, “in tank” treatment at Edgecumbe and Omeheu Channel Discharge
X
Parked Discharge of wastewater sourced from outside
Edgecumbe township at Edgecumbe a prohibited activity in TCMP
Difficulty in meeting NPS Freshwater objectives as a result of discharging additional contaminants to Tarawera River catchment than allowed for in the TCMP
Maximum values in future consent may cause issues with future consent compliance i.e. one single sample could cause non-compliance
Expected high costs which would include land purchase or leasing
High technology and expensive to run WWTP to meet the very high treated wastewater quality in the TCMP
River 2 (ER2)
Conveyance of Matatā raw sewage to new WWTP at Edgecumbe and discharge to Rangitaiki River
√
River 3
(ER3)
Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds upgraded as necessary and discharge to Rangitaiki River
√
At Matatā
Land 1 (ML1)
Conveyance of Edgecumbe raw sewage to Matatā joint treatment at Matatā, Land Application
X
Parked Not enough land available for land disposal
Difficulty in meeting NPS Freshwater objectives as a result of discharging additional contaminants to Tarawera River catchment
High cost for new WWTP
Does not use the existing infrastructure at Edgecumbe oxidation ponds
Land 2
(ML2)
Conveyance of Edgecumbe Oxidation Pond treated wastewater to Matatā Land Application. Matatā standalone treatment and joint land application with Edgecumbe
X
Parked Not enough land available for land disposal
Difficulty in meeting NPS Freshwater objectives as a result of discharging additional contaminants to Tarawera River catchment
River 1
(MR1)
Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to Lower Tarawera River
X
Parked
Significant cultural issues are likely to make future discharge consents difficult to obtain
Usage of Lower Tarawera River (white baiting, fishing, recreation etc.) and public health protection
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Long List Option Option on Confirmed Long List or
Parked?
River 2
(MR2)
Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint discharge to Tarawera River
X
Parked
Significant cultural issues are likely to make future discharge consents difficult to obtain
Usage of Lower Tarawera River (white baiting, fishing, recreation etc.) and public health protection
Ocean 1 (MO1)
Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to ocean at Matatā
X
Parked High capital and operating costs for new WWTP at
Matatā to cater for Matatā and Edgecumbe flows
Ocean 2 (MO2)
Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint ocean discharge at Matatā
√
At Thornton
Land 1 (TL1)
Conveyance of Edgecumbe raw sewage to Matatā. Joint treatment at Matatā, land application at Thornton
√
Land 2 (TL2)
Conveyance of Edgecumbe Oxidation Pond treated wastewater to Matatā. Matatā standalone treatment and joint land application at Thornton.
√
Land 3 (TL3)
Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe oxidation ponds and conveyance to land application at Thornton
√
At Whakatāne
Ocean 1 (WO1)
Conveyance of Matatā to Thornton and Edgecumbe to Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge
√
Ocean 2 (WO2)
Conveyance of Matatā to Whakatāne WWTP and Edgecumbe to Whakatāne WWTP (via Awakeri) and Ocean Outfall Discharge
X
Parked Very high conveyance operating costs related to
pumping wastewater long distances
Very long pipe distance between Edgecumbe and Whakatāne (via Awakeri)
Ocean 3 (WO3)
Conveyance of Matatā to Thornton and Edgecumbe Oxidation Pond treated wastewater to Thornton for joint Whakatāne ocean outfall
X
Parked Requires separate conveyance lines from Thornton
to Whakatāne
Ocean 4 (WO4)
Conveyance of Matatā to Whakatāne WWTP and Edgecumbe Oxidation Pond treated wastewater to Whakatāne WWTP (via Awakeri) for joint Whakatāne ocean outfall
X
Parked Very high conveyance operating costs related to
pumping wastewater long distances
Very long pipe distance between Edgecumbe and Whakatāne (via Awakeri)
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Long List Option Option on Confirmed Long List or
Parked?
Ocean 5 (WO5)
Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option A – via Thornton
√
Ocean 6 (WO6)
Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option B – via Awakeri
√
6.5 Assessment of Confirmed Long List Options
Following the assessment of the topographic of the 21 long list options, the 10 options taken forward to
the confirmed long list were assessed further in terms of maps and schematic diagrams with a summary
of key features and key matters that would be required in the option assessment and decision making .
These are described in the following sections for each option on the confirmed long list.
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6.5.1 Option KL1 - Conveyance of Matatā and Edgecumbe to Kawerau WWTP
Figure 6-1: Schematic for Option KL1
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
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6.5.2 Option ER2 - Conveyance of Matatā to new WWTP at Edgecumbe and Discharge to Rangitaiki River
Figure 6-2: Schematic for Option ER2
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6.5.3 Option ER3 - Conveyance of Matatā to Edgecumbe Oxidation Ponds Upgraded as Necessary and Discharge to Rangitaiki River
Figure 6-3: Schematic for Option ER3
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6.5.4 Option MO2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Matatā. Matatā Standalone Treatment – Joint Ocean Discharge at Matatā
Figure 6-4: Schematic for Option MO2
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6.5.5 Option TL1 - Conveyance of Edgecumbe Raw Sewage to Matatā. Joint Treatment at Matatā, Land Application at Thornton
Figure 6-5: Schematic for Option TL1
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6.5.6 Option TL2 - Conveyance of Edgecumbe Oxidation Pond Treated Wastewater to Thornton. Matatā Standalone Treatment and Joint Land Application at Thornton
Figure 6-6: Schematic for Option TL2
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6.5.7 Option TL3 - Conveyance of Matatā Raw Sewage to Edgecumbe. Joint Treatment at Edgecumbe Oxidation Ponds and Conveyance to Land Application at Thornton
Figure 6-7: Schematic for Option TL3
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6.5.8 Option WO1 - Conveyance of Matatā to Thornton and Edgecumbe to Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge
Figure 6-8: Schematic for Option WO1
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6.5.9 Option WO5 - Conveyance of Matatā Raw Sewage to Edgecumbe Oxidation Ponds. Edgecumbe Oxidation Ponds Treated Wastewater for Joint Whakatāne Ocean Outfall Discharge Route Option A – via Thornton
Figure 6-9: Schematic for Option WO5
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
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6.5.10 Option WO6 - Conveyance of Matatā Raw Sewage to Edgecumbe Oxidation Ponds. Edgecumbe Oxidation Ponds Treated Wastewater for Joint Whakatāne Ocean Outfall Discharge Route Option B – via Awakeri
Figure 6-10: Schematic for Option WO6
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
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6.6 Confirmed Long List Assessment Summary
Following the assessment of 11 confirmed long list options, a short list of 6 options were taken forward for further assessment. Table 6-4 provides a summary of the confirmed long list option assessment as included in the middle column of the table and the 6 shortlisted options in the right hand column.
Legend:
√ = Option on confirmed long list or short list
X = Option parked – parked means these options are not being proceeded with in the confirmed long list
evaluation – but remain available should the proceeding evaluation process mean they should for some
reason that may arise be reconsidered.
Table 6-4: Confirmed Long List Option Assessment Summary
Long List Option Option on Confirmed Long
List or Parked?
Option on Short List
or Parked?
At Kawerau
Land 1 (KL1)
Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP.
Rapid Infiltration Bed (RIB) Land Disposal.
√
Yet to address implications of TCMP
√
Yet to address implications of TCMP
At Edgecumbe
Land 1 (EL1)
Conveyance of Matatā raw sewage to Edgecumbe Oxidation Ponds.
Land Application at Edgecumbe.
X
Parked Discharge of wastewater sourced
from outside Edgecumbe township at Edgecumbe a prohibited activity in TCMP
High-risk that any land disposal at Edgecumbe would be technically unfeasible / unsustainable
Expected high costs which would include land purchase or leasing
X
Parked
Land 2 (EL2)
Conveyance of Matatā raw sewage to Edgecumbe joint WWTP Land Application
X
Parked Discharge of wastewater sourced
from outside Edgecumbe township at Edgecumbe a prohibited activity in TCMP
High-risk that any land disposal at Edgecumbe would be technically unfeasible / unsustainable
Expected high costs which would include land purchase or leasing
X
Parked
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Long List Option Option on Confirmed Long
List or Parked?
Option on Short List
or Parked?
River 1 (ER1)
Conveyance of Matatā raw sewage to Edgecumbe, joint, “in tank” treatment at Edgecumbe and Tarawera River Discharge
X
Parked Discharge of wastewater sourced
from outside Edgecumbe township at Edgecumbe a prohibited activity in TCMP
Difficulty in meeting NPS Freshwater objectives as a result of discharging additional contaminants to Tarawera River catchment than allowed for in the TCMP
Maximum values in future consent may cause issues with future consent compliance i.e. one single sample could cause non-compliance
Expected high costs
High technology and expensive to run WWTP to meet the very high treated wastewater quality in the TCMP
X
Parked
River 2 (ER2)
Conveyance of Matatā raw sewage to Edgecumbe, joint “in tank” treatment at Edgecumbe and discharge to Rangitaiki River
√
X
Parked High cost for new WWTP
Does not use the existing infrastructure at Edgecumbe oxidation ponds
River 3
(ER3)
Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds upgraded as necessary and discharge to Rangitaiki River
√ √
At Matatā
Land 1 (ML1)
Conveyance of Edgecumbe raw sewage to Matatā joint treatment at Matatā, Land Application
X
Parked Not enough land available for land
disposal
Difficulty in meeting NPS Freshwater objectives as a result of discharging additional contaminants to Tarawera River catchment
High cost for new WWTP
Does not use the existing infrastructure at Edgecumbe oxidation ponds
X
Parked
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Long List Option Option on Confirmed Long
List or Parked?
Option on Short List
or Parked?
Land 2
(ML2)
Conveyance of Edgecumbe Oxidation Pond treated wastewater to Matatā Land Application. Matatā standalone treatment and joint land application with Edgecumbe
X
Parked Not enough land available for land
disposal
Difficulty in meeting NPS Freshwater objectives as a result of discharging additional contaminants to Tarawera River catchment
X
Parked
River 1
(MR1)
Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to Lower Tarawera River
X
Parked
Significant cultural issues are likely to make future discharge consents difficult to obtain
Usage of Lower Tarawera River (white baiting, fishing, recreation etc.) and public health protection
X
Parked
River 2
(MR2)
Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint discharge to Tarawera River
X
Parked
Significant cultural issues are likely to make future discharge consents difficult to obtain
Usage of Lower Tarawera River (white baiting, fishing, recreation etc.) and public health protection
X
Parked
Ocean 1 (MO1)
Conveyance of Edgecumbe raw sewage to Matatā joint treatment and discharge to ocean at Matatā
X
Parked High capital and operating costs for
new WWTP at Matatā to cater for Matatā and Edgecumbe flows
X
Parked
Ocean 2 (MO2)
Conveyance of Edgecumbe oxidation pond treated wastewater to Matatā. Matatā standalone treatment – joint ocean discharge at Matatā
√
X
Parked
At Thornton
Land 1 (TL1)
Conveyance of Edgecumbe raw sewage to Matatā. Joint treatment at Matatā, land application at Thornton
√
X
Parked
Significant cultural issues are likely to make future discharge consents difficult to obtain
Land 2 (TL2)
Conveyance of Edgecumbe Oxidation Pond treated wastewater to Thornton. Matatā standalone treatment and joint land application at Thornton.
√ √
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Long List Option Option on Confirmed Long
List or Parked?
Option on Short List
or Parked?
Land 3 (TL3)
Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe oxidation ponds and conveyance to land application at Thornton
√ √
At Whakatāne
Ocean 1 (WO1)
Conveyance of Matatā raw sewage to Thornton and Edgecumbe raw sewage to Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge
√ √
Ocean 2 (WO2)
Conveyance of Matatā to Whakatāne raw sewage WWTP and Edgecumbe to Whakatāne WWTP (via Awakeri) and Ocean Outfall Discharge
X
Parked Very high conveyance operating
costs related to pumping wastewater long distances
Very long pipe distance between Edgecumbe and Whakatāne (via Awakeri)
X
Parked
Ocean 3 (WO3)
Conveyance of Matatā raw sewage to Whakatāne WWTP via Thornton and Edgecumbe Oxidation Pond treated wastewater via Thornton for joint Whakatāne ocean outfall
X
Parked Requires separate conveyance
lines from Thornton to Whakatāne
X
Parked
Ocean 4 (WO4)
Conveyance of Matatā to Whakatāne WWTP and Edgecumbe Oxidation Pond treated wastewater to Whakatāne WWTP (via Awakeri) for joint Whakatāne ocean outfall
X
Parked Very high conveyance operating
costs related to pumping wastewater long distances
Very long pipe distance between Edgecumbe and Whakatāne (via Awakeri)
X
Parked
Ocean 5 (WO5)
Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option A – via Thornton
√ √
Ocean 6 (WO6)
Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne ocean outfall discharge Route Option B – via Awakeri
√
X
Parked
Very long pipe distance between Edgecumbe and Whakatāne (via Awakeri)
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6.7 Assessment of Short-Listed Options
Following the assessment of the confirmed Long List of 9 options, then as set out in section 5-5 a short list of 6 options was arrived at. These are further stated for ease of reference in Table 6-5 below. Each of these options were further developed in respect to Preliminary (high level) concept design of conveyance, treatment and treated wastewater discharges and disposal.
Table 6-5: Matatā and Edgecumbe Standalone Shortlisted Options
Short Listed Matatā and Edgecumbe Standalone Options
At Kawerau Land 1 (KL1)
Conveyance of Matatā and Edgecumbe raw sewage to Kawerau WWTP
At Edgecumbe River 3 (ER3)
Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds upgraded as
necessary and discharge to Rangitaiki River
At Thornton Land 2 (TL2)
Conveyance of Edgecumbe Oxidation Pond treated wastewater to Thornton. Matatā standalone treatment and joint land application at Thornton.
Land 3 (TL3) Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at Edgecumbe oxidation ponds and conveyance to land application at Thornton.
At Whakatāne Ocean 1 (WO1)
Conveyance of Matatā raw sewage to Thornton and Edgecumbe raw sewage to Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge.
Ocean 5 (WO5) Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe oxidation ponds treated wastewater for joint Whakatāne Ocean Outfall discharge Route Option A – via Thornton.
Please refer to
Table 6-1 for the component parts of each option.
The schematics in Section 6-4 for key features.
The marked up topographical plans in Appendix E for conveyance routes used in the assessment.
As with the Edgecumbe standalone options, following consultation with BOPRC, a variation of the
Thornton land applications were developed with land application at Whakatāne airport (as shown in
Figure 2-3). These options were coded TL2A and TL3A (schematics shown below).
An option of conveying Matatā standalone wastewater directly to Whakatāne WWTP (MW1). This option
has been developed as the Project has progressed to compare directly with standalone Matatā
wastewater treatment and disposal options.
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Figure 6-11: Schematic for Option TL2A
Figure 6-12: Schematic for Option TL3A
6.7.1 Estimated Costs
Section 4 above sets out the basis of cost estimates. These also include those items for which capital
cost estimates have not been included. This includes no provision for GST, resource consents, any land
purpose and possible WWTP’s upgrades at Whakatāne, Edgecumbe or Kawerau when the respective
resource consents expire. Refer to section 4 for other items.
Table 6-6 below summarises the Estimated Costs for the Combined Matatā and Edgecumbe Options.
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Table 6-6: Estimated Costs for Combined Matatā and Edgecumbe Options
CAPEX ($M) OPEX – Year 1 ($M)
OPEX - Year 20 ($M) (for
Comparison)
NPV ($M)
Option Matatā
Reticulation Conveyance Treatment Total Capital
Maintenance/ Replacement includes KDC Bulk Charge
for KL1
Power Dosing Total Year 1
- OPEX Total Year 20 - OPEX
TOTAL COST
KL1 $6.000 $18.955 $0.300 $25.255 $0.365 $0.030 $0.065 $0.460 $0.855 $32.085
ER3 $6.000 $9.765 $5.155 $20.920 $0.115 $0.200 $0.045 $0.360 $1.540 $28.495
TL2 $6.000 $10.490 $8.985 $25.475 $0.115 $0.255 $0.040 $0.410 $1.625 $33.810
TL2A $6.000 $13.585 $8.985 $28.570 $0.120 $0.255 $0.040 $0.415 $1.630 $36.945
TL3 $6.000 $13.310 $6.540 $25.850 $0.120 $0.200 $0.045 $0.365 $1.555 $33.515
TL3A $6.000 $14.835 $6.540 $27.375 $0.120 $0.200 $0.045 $0.365 $1.555 $35.045
WO1 + Actiflo + UV
$6.000 $16.240 $0.625 $22.865 $0.090 $0.020 $0.065 $0.175 $0.410 $25.705
WO5 + Actiflo + UV
$6.000 $17.125 $0.700 $23.825 $0.075 $0.025 $0.015 $0.115 $0.280 $25.760
MW1 + Actiflo + UV
$6.000 $9.410 $0.180 $15.590 $0.060 $0.010 $0.015 $0.085 $0.185 $16.915
In addition to the basis of the estimates details for the makeup of these estimated costs are given in
Appendices H, I and J for conveyance, treatment and disposal/discharge and NPV accordingly.
6.7.2 Short List Options: Information Summary
The information contained in this report pertaining to these 6 short listed standalone Matatā and
Edgecumbe options, includes:
Table 6-1 Components Parts of the Options
The Schematics for these options in Section 6-4 above.
The Appendix D Comparison Evaluation Table.
The Appendix E Conveyance Routes
The Estimated Cost Summaries in Section 6-7-1 above, Section 3 of this Report and detailed cost estimates in Appendices H - Conveyance), I - Treatment and Discharge/Disposal and J – Net Present Value (NPV).
The Risk Assessment and Risk Mitigation in Section 8 and Table 8-5 for these options.
Appendix K – Supplier Information on Actiflo and MBBR Treatment processes.
Technical, land application and consenting information in Sections 2 and 3 of this Report.
6.7.3 Ranking of Short Listed Option
The ranking of short listed options is proposed to be undertaken using a Multi-Criteria Assessment (MCA) tool alongside the Matatā standalone options being developed. Key considerations to inform the MCA include the following:
The provisions within the Regional Plan for the Tarawera River Catchment that prohibit the discharge of wastewater sourced from outside Kawerau Township at Kawerau;
The various issues associated with the conveyance of raw wastewater long distances that relate
to the maintenance of adequate flushing velocities, odour management and mitigation (including
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the requirement for chemical dosing at pump stations) and the corrosive effects of septic raw
wastewater on downstream wastewater treatment facilities;
The relative benefits of conveying treated wastewater from the Edgecumbe oxidation ponds that
avoid the adverse effects that relate to the conveyance of raw wastewater;
Preferences expressed for the land application of treated wastewater through the relevant
statutory planning framework;
The implications of the National Policy Statement for Freshwater Management 2014 and the
interpretation for discharges to freshwater to demonstrate the ‘maintenance and enhancement of
water quality’;
The implications of the Matatā wastewater Scheme Environment Court decision in terms of
adverse effects of the land application of treated wastewater, the over-allocation of water bodies
and the maintenance and enhancement of water quality;
The implications of other key statutory planning documents;
Tāngata whenua preferences and documents such as ‘Pathways of the Rangitaiki’;
The potential risk of submissions and later appeals to any future resource consent process;
The preference to utilise as far as practicable existing infrastructure;
The potential to remove the existing discharge of treated wastewater to the Tarawera River
catchment from the Edgecumbe WWTP;
The potential to remove the discharge of on-site wastewater discharges to the Tarawera River
catchment from the Matatā township;
Public health benefits of removing the discharge of on-site wastewater from Matatā township;
The relative capital, operating and whole of life costs of the various preferred option;
The position with respect to retaining the Ministry of Health and BOPRC subsidy for a Matatā
Wastewater Scheme;
The risks profile of each shortlisted option in terms of likelihood, consequence and mitigation;
The future development of an overall District Wide Wastewater Strategy as part of WDC’s
Infrastructure 2015-2025;
The advantages/disadvantages of combining townships for treatment and discharge compared
to standalone schemes;
The likely future pros and cons of where the treated wastewater is disposed/discharged i.e.
surface water, land, ocean – assuming beneficial reuse is not available;
For the options based on discharge out of the Whakatāne ocean outfall what is likely to be the
consent requirements and (any) additional treatment and/or disposal infrastructure after 2026
when the existing resource consent (Water Right) expires;
Any viable beneficial reuse options for treated wastewater;
The question of whether it is necessary to fully replaced the damaged Edgecumbe collection
system if an option that can account for higher wet weather flows is adopted;
The compatibility of options with WDC’s present and planned wastewater schemes; and
The need for ongoing community, other stakeholder and tāngata whenua participation in
decision making.
Whether the Whakatāne Airport site is available and suitable for the land application rather than the Thornton dunes site
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An MCA workshop with officers from WDC and BOPRC and representatives from MWH and AECOM
was held at WDC Offices on 31 August 2015. The following Tables are the outputs of that MCA
workshop:
Table 6-7 shows the MCA analysis criteria and associated criteria used for the basis of assessment;
Table 6-8 shows the relative weighting given to each criteria – based on a relative scoring of 1 being the least important and 10 being the most important;
Table 6-9 shows the results of the MCA scoring for each of the short listed options – based on a relative scoring of 1 being the lowest score and 5 being the highest score;
Table 6-10 shows the rationale for the MCA scoring; and Table 6-11 shows the overall summary results, in terms of overall score excluding cost, overall score including a 30% weighting for cost and an overall score including a 50% weighting for cost.
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015
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Table 6-7: Combined Matatā/Edgecumbe Shortlisted Options – MCA Analysis Criteria (Independent of Cost)
Ref Analysis Criteria Criteria Description Notes Classification Qualitative or Quantitative?
G1 Sustainability
Alignment with WDC Sustainability Strategy, Energy
Use/Carbon Footprint, Natural Hazards/Climate Change,
Adverse Effects on the Natural Environment, Sustainable
Development, Future Proofing
Scoring will be influenced by the amount of energy use,
reilience to natural hazards, climate change, potential for
adverse effects on the environment, and ability to respond
to population growth
Other Qualitative
G2 Social / Public Health
Public Health Risk, Safety, Visual Amenity, Proximity to
Neighbours and Effects on Them, Construction Effects,
Public Acceptance
Scoring will be influenced by the degree of public health
risk, removal of direct discharges to freshwater
environments, proximity to neighbours, and overall
likelihood of public acceptance
Social Qualitative
G3 Cultural
Matauranga Maori, Archaeological Sites, Discharge to
Freshwater, Discharge to Land, Discharge to Coastal
Water, cultural sites, Transfer of Wastewater from one
rohe to another
Scoring will be influenced by preference to discharge to
land over freshwater and coastal water, avoidance of
cultural sites and archaeological sites
Cultural Qualitative
G4Planning and
Regulatory
Consentability, RMA, Freshwater NPS, NZCPS, Regional
Plan for the Tarawera River Catchment, complexity and
viability of obtaining future consents and designations
Scoring will be influenced by the need (or not) to obtain
new discharge consents and designations, or whether
existing consent conditions could be changed via a
potentially non-notified process and future resource
consent requirements, the avoidance of discharges to the
Tarawera River catchment and freshwater generally, and
the potential effects on the coastal environment and
ecology. Overall marking will be from a complexity and
viability of consenting/planning process.
Environmental Qualitative
G5 Technical / Functional
Reliability, flexibility, constructability, proven engineering,
engineering resilience, soil type, distance to road,
distance to high voltage, use of existing infrastructure
Scoring will be influenced by proven technolgoy, that is
relatively easy to operate and maximises the use of
existing infrastructure. New and complex options to
contruct options will score more poorly.
Other Qualitative
G6 Operational
Complexity, safety, septicity risk/corrosion, centralised
vs decentralised, complementary to existing
infrastructure, reliability
Scoring will be influenced by the operation of the option
i.e. proven technology and can be supported in NZ, are
there other examples in NZ? Centralisation of treatment
plants is a beneficial factor.
Other Qualitative
G7 OwnershipLease, freehold, Maori land, Council owned/controlled
land and infrastructure
Security and influence of long term access/use. Council
owned or controlled land will score more highly, lease
arrangements will score more poorly.
Other Qualitative
Goal based Analysis Criteria - Independent of Cost
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Status: Final 22 September 2015
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Table 6-8: Combined Matatā/Edgecumbe Shortlisted Options – MCA Analysis Weighting
Attribute
Refs:G1 G2 G3 G4 G5 G6 G7 C13 C14 C15
10 1 1 1 1
9 1
8 1 1
7
6 1 1
5 1
4
3
2
1
0
Cri
teri
a
Su
sta
ina
bilit
y
So
cia
l / P
ub
lic
He
alt
h
Cu
ltu
ral
Pla
nn
ing
an
d
Re
gu
lato
ry
Te
ch
nic
al /
Fu
nc
tio
na
l
Op
era
tio
na
l
Ow
ne
rsh
ip
Ca
pit
al C
os
t
Op
era
tin
g C
os
t
NP
V
Weight: 6 6 8 10 8 5 9 10 10 10
Sum of Goals 52 Sum of Cost 30
Goal Based Analysis Criteria - Independent of Costs Cost Based Criteria
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015
Project number: 805 08148 Page 96 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Table 6-9: Combined Matatā/Edgecumbe Shortlisted Options – MCA Scoring Results (Independent of Cost)
# Scenario
Su
stai
nab
ilit
y
So
cial
/ P
ub
lic
Hea
lth
Cu
ltu
ral
Pla
nn
ing
an
d R
egu
lato
ry
Tec
hn
ical
/ F
un
ctio
nal
Op
erat
ion
al
Ow
ner
ship
Criteria Weighting 0.115 0.115 0.154 0.192 0.154 0.096 0.173
1KL1 - Raw Sewage to
Kawerau WWTP2 3 4 1 2 1 3
2
ER3 - Upgraded
Edgecumbe Oxidation
Ponds and Discharge to
Rangitaiki River
2 2 1 1 4 3 5
3
TL2 - Upgraded
Edgecumbe Oxidation
Pond and Discharge at
Thornton Dunes. Matata
standalone WWTP and
discharge at Thornton
Dunes.
3 3 4 3 3 2 5
4
TL3 - Matata to Upgraded
Edgecumbe Oxidation
Pond and Discharge at
Thornton Dunes
3 3 4 3 3 3 5
5WO1 - Raw Sewage to
Whakatane WWTP3 3 3 4 2 2 5
6
WO5 - Oxidation Pond
Treated Wastewater to
Whakatane WWTP
4 4 3 4 4 3 5
7
TL2A - Upgraded
Edgecumbe Oxidation
Pond and Discharge at
Whakatane Airport. Matata
standalone WWTP and
discharge at Whakatane
Airport.
3 4 4 4 3 3 5
8
TL3A - Matata to Upgraded
Edgecumbe Oxidation
Pond and Discharge at
Whakatane Airport
3 4 4 4 3 3 5
Goal Based Analysis Criteria - Independent of Cost
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Page 97 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Table 6-10: Combined Matatā/Edgecumbe Shortlisted Options – MCA Results Scoring Rationale (Independent of Cost)
# Scenario
Su
stai
nab
ilit
y
So
cial
/ P
ub
lic
Hea
lth
Cu
ltu
ral
Pla
nn
ing
an
d
Reg
ula
tory
Tec
hn
ical
/
Fu
nct
ion
al
Op
erat
ion
al
Ow
ner
ship
Criteria Weighting 0.115 0.115 0.154 0.192 0.154 0.096 0.173
1KL1 - Raw Sewage to
Kawerau WWTP
21. Utilising existing facilities
at Kawerau with surplus
capacity
2. High energy consumption
to pump to Kawerau
3. Long raw sewage pipelines
exposed to multiple active
faults
4. Risk of NPS to continuity of
service in the future
31. Political support from KDC
2. Removes direct discharge to
freshwater environment
41.Initial anecdotal support
from iwi authority
representatives
2. Rohe to rohe issue
11.Prohibited activity under
BOPRC Regional Plan for the
Tarawera River Catchment
(TRCMP)
2. NPS for Freshwater
Management
3. Need to vary KDC air and
water discharge consents
21. Longest raw sewage
pipeline in provincial NZ
2. Rising main with approx
35m static head
3. Additional complexity to
manage septicity, odour,
corrosion, and friction loss
11. Odour
2. Septicity
3. Safety
4. Costs of pumping
5. Monitoring and maintenance
of valves and pipelines
6. Control over continuity of
treatment and disposal
systems
31. Owned by KDC
2
ER3 - Upgraded
Edgecumbe Oxidation
Ponds and Discharge
to Rangitaiki River
21. One treatment facility
2. Use of upgraded facility at
Edgecumbe
3. Significant upgrading
required to meet discharge
quality criteria of receiving
water
4. Natural hazard risk
associated with conveyance
of raw sewage from Matatā to
Edgecumbe
5. Disposal to fresh water
environment
21. Low public acceptance - eg
Rangitāiki River Forum
2. High receational use and
food gathering resource
3. Direct discharge to
freshwater environment
11. Highly likely to be culturally
unacceptable to iwi
11. NPS for Freshwater
Management
2. Removes discharge from
Tarawera River catchment
3. Significant dilution available
in Rangitāiki River
4. Difficult to satisfy RMA
requirements despite plant
upgrade
5. Inconsistent with
philosophy of Pathways to
Rangitaiki document which is
to improve overall water
quality.
41. Upgrade treatment
processes compatible with
existing oxidation pond
2. Short conveyancing
distance from treatment plant
to disposal outfall
3. 16km raw sewage
conveyance distance from
Matatā to Edgecumbe
31. Odour
2. Septicity
3. Safety
4. Costs of pumping
51. Council owned scores 5
3
TL2 - Upgraded
Edgecumbe Oxidation
Pond and Discharge at
Thornton Dunes.
Matata standalone
WWTP and discharge
at Thornton Dunes.
31. Two treatment facilities
2. Conveyance of treated
wastewater only over long
distances
3. Retains use of existing
treatment facility at
Edgecumbe
4. Land based disposal
5. Irrigation of treated
wastewater to dunes aids
biodiversity development
6. Tsunami risk 3
7. Coastal erosion to
foredunes
31. Ground water flow direction
unproven
2. Potential impact upon
shellfish and coastal
environment if groundwater
flows towards the coast
3. Number of houses around
200m from site
41. No archeological site
2. Distance to marae >500m
3. Potential impact upon
coastal water quality
31. BOPRC planning documents
support land-based disposal
2. Matatā WWTP site requires
designation and resource
consents
3. Until site identified
uncertainty will remain
4. Positive effect of ceasing
discharge to Tarawera River
catchment
5. Proximity to lifestyle blocks
31. One new treatment plant to
design and construct and one
to design and implement
upgrade
2. Only conveying treated
wastewater
3. 2 separate pipelines from
WWTPs to land disposal area
4. High perched ground water
table
21. Maintaining and operating 2
separate and different
treatment systems
2. Maintaining and operating 2
separate rising mains
3. Increased costs associated
with above
51. Council owned scores 5
4
TL3 - Matata to
Upgraded Edgecumbe
Oxidation Pond and
Discharge at Thornton
Dunes
31. One treatment facility
2. Natural hazard risk
associated with conveyance
of raw sewage from Matatā to
Edgecumbe
3. Retains use of existing
treatment facility at
Edgecumbe
4. Land based disposal
5. Irrigation of treated
wastewater to dunes aids
biodiversity development
6. Tsunami risk 3
7. Coastal erosion to
31. Ground water flow direction
unproven
2. Potential impact upon
shellfish and coastal
environment if groundwater
flows towards the coast
3. Number of houses around
200m from site
4. Use of enhaced existing
treatment facility likley to be
perceived better than
providing a new facility for
Matata
41. No archeological site
2. Distance to marae >500m
3. Potential impact upon
coastal water quality
31. BOPRC planning documents
support land-based disposal
2. Positive effect of ceasing
discharge to Tarawera River
catchment
3. No need for designation for
standalone WWTP at Matatā
4. Proximity to lifestyle blocks
31. Cost effective use of
Edgecumbe oxidation pond
2. Design and construct
upgrade of Edgecumbe
oxidation pond
3. Conveyance of raw sewage
from Matatā to Edgecumbe
4. High perched ground water
table
31. Maintaining and operating
one treatment system
2. Maintaining and operating
one rising main of raw sewage
from Matatā to Edgecumbe
3. Odour
4. Septicity
5. Safety
6. Costs of pumping
51. Council owned scores 5
5WO1 - Raw Sewage to
Whakatane WWTP
31. Centralised treatment
2. Use of exisitng Whakatāne
treatment facility
3. Retain Edgecumbe ponds
for storage of raw sewage
4. Natural hazard risk from
conveyance of raw sewage
from Matatā and Edgecumbe
to Whakatāne
5. Shared conveyance line
from Thornton to Whakatāne
31. Neighbours to Whakatāne
oxidation pond likely to not
readily support
2. One facility likely to be
supported by the majority of
the public
3. Minimises potential health
risk through centralising
treatment and disposal
4. Removes direct discharge of
wastewater to fresh water
environment
31. May not be supported by iwi
2. Rohe to rohe potential issue
41. Requires change to exisitng
consents for Whakatāne
oxidation ponds (air and
wastewater)
2. Positive effect of ceasing
discharge to Tarawera River
catchment and surrender of
consent
3. No need for designation for
standalone WWTP at Matatā
4. Does not require new
wastewater site designation or
consents for a Matata WWTP
scheme
21. Conveyance of raw sewage
over long distance
2.Additional complexity to
manage septicity, odour,
corrosion, and friction loss
3. Uncertainty over upgrade
requirements in the future
(>2026)
21. Odour
2. Septicity
3. Safety
4. Costs of pumping
5. Monitoring and maintenance
of valves and pipelines
51. Council owned scores 5
6
WO5 - Oxidation Pond
Treated Wastewater to
Whakatane WWTP
41. Centralised disposal
solution
2. Use of exisitng Edgecumbe
treatment facility
3. Use of exisitng Whakatāne
treatment facility
4. Conveyance of raw sewage
from Matatā to Edgecumbe
5. Conveyance of treated
wastewater from Edgecumbe
to Whakatāne
41. Reduced effects upon
neighbours in comparison
with WO1
2. Likely to be supported by
the majority of the public
3. Reduces potential health
risk through centralising
wastewater disposal
4.Removes direct discharge of
wastewater to fresh water
environment
31. May not be supported by iwi
2. Rohe to rohe potential issue
41. Requires change to exisitng
consents for Whakatāne and
Edgecumbe oxidation ponds
(air and wastewater)
2. Positive effect of ceasing
discharge to Tarawera River
catchment
3. No need for designation for
standalone WWTP at Matatā
4. Does not require new
wastewater site designation or
consents for a Matata WWTP
scheme
41. Does not affect spare
capacity and operation of
existing oxidation ponds
2. Uncertainty over upgrade
requirements in the future
(>2026)
3. Complexity in connecting to
existing outfall
4. Upgrade of Edgecumbe
ponds required
31. Odour
2. Septicity
3. Safety
4. Costs of pumping
5. Monitoring and maintenance
of valves and pipelines
51. Council owned scores 5
7 TL2A - Airport
31. Two treatment facilities
2. Conveyance of treated
wastewater only over long
distances
3. Retains use of existing
treatment facility at
Edgecumbe
4. Land based disposal
5. Irrigation of treated
wastewater to dunes aids
biodiversity development
41. Ground water flow direction
unproven
2. Potential impact upon
shellfish and coastal
environment if groundwater
flows towards the coast
3. Public acceptance may be
an issue
41. No archeological site
2. Distance to marae >500m
3. Potential impact upon
coastal water quality
4. Likely to be an issue with
iwi acceptance due to Ngāti
Awa Settlement Act provisions
41. BOPRC planning documents
support land-based disposal
2. Matatā WWTP site requires
designation and resource
consents
3. Until site identified
uncertainty will remain
4. Positive effect of ceasing
discharge to Tarawera River
catchment
5. Will require Ministerial
approval as an ancilliary use
to the airport
31. One new treatment plant to
design and construct and one
to design and implement
upgrade
2. Only conveying treated
wastewater
3. 2 separate pipelines from
WWTPs to land disposal area
4. Potential use of surface
irrigation for a portion of the
land application field?
31. Maintaining and operating 2
separate and different
treatment systems
2. Maintaining and operating 2
separate rising mains
3. Increased costs associated
with above
51. Council owned scores 5
8 TL3A - Airport
31. One treatment facility
2. Natural hazard risk
associated with conveyance
of raw sewage from Matatā to
Edgecumbe
3. Retains use of existing
treatment facility at
Edgecumbe
4. Land based disposal
5. Irrigation of treated
wastewater to dunes aids
biodiversity development
41. Ground water flow direction
unproven
2. Potential impact upon
shellfish and coastal
environment if groundwater
flows towards the coast
3. Use of enhaced existing
treatment facility likley to be
perceived better than
providing a new facility for
Matata
4. Public acceptance may be
an issue
41. No archeological site
2. Distance to marae >500m
3. Potential impact upon
coastal water quality
4. Likely to be an issue with
iwi acceptance due to Ngāti
Awa Settlement Act provisions
41. BOPRC planning documents
support land-based disposal
2. Positive effect of ceasing
discharge to Tarawera River
catchment
3. No need for designation for
standalone WWTP at Matatā
4. Positive effect of ceasing
discharge to Tarawera River
catchment
5. Will require Ministerial
approval as an ancilliary use
to the airport
31. Cost effective use of
Edgecumbe oxidation pond
2. Design and construct
upgrade of Edgecumbe
oxidation pond
3. Conveyance of raw sewage
from Matatā to Edgecumbe
4. One pipeline from WWTPs to
land disposal area
4. Potential use of surface
irrigation for a portion of the
land application field?
31. Maintaining and operating
one treatment system
2. Maintaining and operating
one rising main of raw sewage
from Matatā to Edgecumbe
3. Odour
4. Septicity
5. Safety
6. Costs of pumping
51. Council owned scores 5
Goal Based Analysis Criteria - Independent of Cost
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015
Project number: 805 08148 Page 98 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Table 6-11: Combined Matatā/Edgecumbe Shortlisted Options – MCA Summary Results
# Scenario Capital Cost Operating Cost NPV
Overall
Score of
Analysis
Criteria
Excluding
Cost
RankCost Based
ScoreCost Rank
Overall
Score
including
Cost 30%
Overall Rank
30%
Overall
Score
including
cost 50%
Overall Rank
50%
1KL1 - Raw Sewage to
Kawerau WWTP25,255,000$ 460,000$ 32,085,000$ 2.31 8.00 1.33 7.00 2.01 8.00 1.82 8.00
2
ER3 - Upgraded Edgecumbe
Oxidation Ponds and
Discharge to Rangitaiki River
20,920,000$ 360,000$ 28,495,000$ 2.58 7.00 1.95 3.00 2.39 7.00 2.26 7.00
3
TL2 - Upgraded Edgecumbe
Oxidation Pond and
Discharge at Thornton Dunes.
Matata standalone WWTP and
discharge at Thornton Dunes.
25,475,000$ 410,000$ 33,810,000$ 3.40 5.00 1.40 5.00 2.80 6.00 2.40 6.00
4
TL3 - Matata to Upgraded
Edgecumbe Oxidation Pond
and Discharge at Thornton
Dunes
25,850,000$ 365,000$ 33,515,000$ 3.50 4.00 1.53 4.00 2.91 5.00 2.51 4.00
5WO1 - Raw Sewage to
Whakatane WWTP22,865,000$ 175,000$ 25,705,000$ 3.29 6.00 2.50 2.00 3.05 3.00 2.89 2.00
6
WO5 - Oxidation Pond Treated
Wastewater to Whakatane
WWTP
23,825,000$ 115,000$ 25,760,000$ 3.92 1.00 2.63 1.00 3.53 1.00 3.27 1.00
7
TL2A - Upgraded Edgecumbe
Oxidation Pond and
Discharge at Whakatane
Airport. Matata standalone
WWTP and discharge at
Whakatane Airport.
28,570,000$ 415,000$ 36,945,000$ 3.81 2.00 1.13 8.00 3.00 4.00 2.47 5.00
8
TL3A - Matata to Upgraded
Edgecumbe Oxidation Pond
and Discharge at Whakatane
Airport
27,375,000$ 365,000$ 35,045,000$ 3.81 2.00 1.40 6.00 3.09 2.00 2.60 3.00
Assessment Criteria Scores and Ranking
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6.8 Discussions and Findings
As shown in Table 6-11, the following summary of findings can be made:
In terms of the non-price scoring, Option WO5 (Matatā Raw Sewage to Edgecumbe. Edgecumbe
Oxidation Pond Treated Wastewater to Whakatāne WWTP Ocean Outfall) scored the highest,
followed by Option TL2A (Matatā Raw Sewage to Edgecumbe Upgraded Oxidation Pond and
Discharge at Whakatāne Airport Land Application Field. Matatā Standalone WWTP and
discharge at Whakatāne Airport) and TL3A (Matatā Raw Sewage to Edgecumbe Upgraded
Oxidation Pond and Discharge at Whakatāne Airport Land Applica tion Field) joint second.
Option WO5, the conveyance of oxidation pond treated wastewater to the Whakatāne WWTP
ocean outfall, scored highly in terms of sustainability, social/public health, planning and
regulatory, technical/functional and ownership, and moderately in terms of cultural and
operational;
Options TL2A and TL3A scored highly in terms of social/public heath, cultural, planning and
regulatory, and ownership and moderately in terms of sustainability, technical/functional and
operational. Whilst WDC owns the Whakatāne airport site, there are a number of leases to
consider and the land is subject to the Ngati Awa Settlement Act provisions. However, WDC has
obtained advice that land application scheme could be progressed at the site and that this cou ld
be encompassed within the existing airport use of the site;
In terms of overall scoring once cost was accounted for at a weighting of 30%, Option WO5 was
ranked first, followed by Option TL3A and Option WO1 (Raw Sewage to Whakatāne WWTP) .
At a cost weighting of 50%, Option WO5 continued to be ranked first, with WO1 ranked second
and TL3A ranked third.
As discussed in Section 2.6.3 the balancing of treated wastewater at Edgecumbe has significant
advantages over balancing and conveying raw wastewater, particularly in terms of odour management,
corrosion and the maintence of adequate velocities within pipeline to maintain self -cleansing.
Consequently, for these reasons Option WO5 scored higher than Option WO1.
Preliminary legal advice has been obtained that it may be possible to apply for a change of resource
consent condition to the existing Whakatāne WWTP discharge consent that would allow the acceptance
of wastewater sourced from Edgecumbe. If this option WO5 was to be progressed further, an application
under Section 127 of the RMA would need to be submitted to the BOPRC.
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7 Conveyance Issues and Considerations for Short Listed Options
There are a number of potentially significant issues that require suitable consideration at a further
detailed assessment and design stage including the previously mentioned septicity/odour assessment.
For long raw sewage rising mains this includes the LPS systems. These are discussed below:
7.1 Vertical Alignment
Several of the rising main routes have high (more elevated) spots along their length. Typically it is
preferred for the discharge end to be the highest point on the rising main. This keeps the rising main full
at all times. Where this is not the case it can lead to the following issues:
The rising main will sit, at times, with portions empty (full of air) – this air needs to be expelled
for the main to run full. The expelled air can be malodourous and may need odour treatment.
The air release points need to be carefully selected to ensure the main does not air -lock;
While the rising main is filling it may not be able to run at its design flow/head. This will require
the injection of a volume of flow before the main is full and will run at the designed rate;
When the pumps turn off, the rising main will empty under gravity – this will draw more air in. This will require selection of two-way air valves, in some locations, to prevent negative pressure and potential pipe collapse; and
Depending on the length of rising main that will drain and the daily volume of flow served the
pipe may never run full. The volume of wastewater pumped in may not fill the air gap before the
pumps turn off again. In this case main does may never run at design flows. Sections of rising
main that form permanent air pockets will collected fat/grease and may become
operational/maintenance issues. These sections will effective operate as gravity sewers and will
require to draw in and expel air regularly, potentially requiring odour treatment.
These issues can be overcome for the rising mains on this Project by considering the following options
but they add complexity, cost and risk to the Project.
The downstream of the rising main is raised above ground to the same level as the highest
elevation on the rising main to keep it full. This type of barometric loop is normally built as a
tower. These types of towers can be up to 10m.
Lay the rising main deeper along sections that are at the high points. This can be very costly
depending upon the length of the high point. Ideally this is used where the rising main can be
easily trenched deeper or the high point is only a short distance. Rising mains have been
directionally drilled on some projects to remove the high point but this can lead to access issues
and high cost replacement should the main suffer a burst. This can be combined with a short
barometric loop to achieve best cost. The costs estimates have been prepared on the basis of
trenching down the, by and large, reasonably wide grass verges in the WDC road reserve;
Provide a valve at the discharge end of the rising main. It is intended that this valve shuts when
the pumps are not running to keep the main full. The complexity of this option is that the pumps
must start against a closed valve and the valve must open before the pump increase speed. This
adds significant pump control/SCADA communication complexity and risk of failure.
The sections of rising main that drain could be designed to operate as gravity pressure
lines/inverted siphons. This may require careful consideration of air/odour management and self -
cleansing velocities in all portions of the main. Sections of the rising main around scour valves,
river crossing and local dips may collect solids and wi ll need to consider cleaning /main pigging
options.
Select an alternate route that removes the high point (e.g. across fields or private land).
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7.1.1 Individual Short-List Route Option Long-sections
The following long-sections have been developed from a bare-earth digital terrain model (DTM)
developed from WDC LIDAR topographical data provided. The data provided has been taken at face
value and requires confirmation prior to detailed design. This information was deemed suitable for this
high level concept options investigation. Table 7-1 below summarises the route lengths and static (head)
lifts.
Matatā Pumping Station to Edgecumbe WWTP (along Greig Road) (KL1, ER3, TL3 and WO5)
This route is used for options KL1, ER3, TL3 and WO5 and was used in the cost estimates as decided with WDC Officers rather than the alternate State Highway 2 route. The route is relatively flat with a few minor high points around the 3-3.5m level. The ground level at both ends of the rising main are around 1-1.5m lower than this. It is expected that the Tarawera River will be bridged and therefore raise the main above ground level at this location. For this option a 2m barometric loop has been allowe d for at the Edgecumbe WWTP to keep the rising main full.
Matatā Pumping Station to Edgecumbe WWTP (along State Highway) (KL1, ER3, TL3 and WO5)
This route is an alternative route for the transfer of flows from Matatā to Edgecumbe along State
Highway 2 (Matatā Road). This route is approximately 11.5 km long compared to the longer Greig Road
route of 16.7 km as discussed above. This route could be used for options KL1, ER3, TL3 and WO5.
The route rises rapidly from Matatā to a high point of around 20m as SH2 passes around the base of
hills between Matatā and Flax Road. The route then falls slowly to the Tarawera River and then is
relatively flat to Edgecumbe. It is expected that the Tarawera River will be bridged and therefore raise
the main above ground level at this location.
For this route a 20m barometric loop would be required which is consider impractical;
Running the fall section of rising main as a gravity line is unlikely to achieve suitable velocities
as there is not enough fall to Edgecumbe. A second pumping station just to the north of
Awakaponga to pump to Edgecumbe may allow a short gravity section from the high point to
Awakaponga. This gravity section would probably require deep sections and given the diameter
of the line this would seem inappropriate; and
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The most feasible option for this alignment would probably be to control the draining of the rising
main with a terminal valve. This will add complexity to the Project and may pose optional risk as
the valve and pumping station will need to communicate to ensure seem less operation. Typical
SCADA telemetry over radio may not be suitable as this can be disrupted by interference and
other atmospheric effects such as lightning.
For this study the complexities of this route led to this being dropped at the long-list stage and the longer
but less complicated route along Greig Road selected. There were a number of reasons for this:
No construction on a State Highway (construction would be cheaper, traffic management simpler and less disruption to public);
Improved access for maintenance along a non-State Highway;
Wider berms and construction space along Greig Road; and
Greig Road was a flatter less complicated route.
When the Project is taken forward to preliminary design it is appropriate that this route is re-examined to
confirm whether this shorter route can be cost-effectively delivered compared to the Greig Road
preferred option.
Edgecumbe WWTP to Kawerau WWTP (KL1)
The route from Edgecumbe WWTP to Kawerau WWTP is used for option KL1. Overall the rising main
would rise from around 2m ground level to around 27m at the Tarawera River crossing. The WWTP has
a ground level of around 26m. It has been assumed that a 2m barometric loop has been allowed for at
the Kawerau WWTP to keep the rising main full.
Matatā to Thornton (TL2, WO1)
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This route is used for options TL2 and W01 and transfers wastewater from Matatā to Thornton, either for
local disposal or for conveyance further on to Whakatāne. Overall the alignment is relatively flat and can
either be catered for by the rise to the sand dunes at Thornton for land application or by slightly deeper
trenching along the route.
Edgecumbe to Thornton (TL2, TL3, WO1 and WO5) (Land Application Shown)
This route transfers flow from Edgecumbe to Thornton either for local disposal or for conveyance further
on to Whakatāne. The route has a local rise of ground level of up to 5m along its route. The ground level
at Thornton is 7.5m and therefore for the local disposal options TL2 and TL3 this is acceptab le. For
further transfer onto Whakatāne (WO1 and WO5), the Thornton pumping station is likely to be at a
slightly lower level and may require a short barometric loop. It has been assumed that a 2m barometric
loop will be required at the Thornton pump station for options WO1 and WO5, to keep the rising main
full.
Edgecumbe to Whakatāne (WO1 and WO5)
This route shows the full length transfer of flows from Edgecumbe to Whakatāne which is used for
options WO1 and WO5. Only option WO1 accepts additional flow at Thornton from Matatā. In option
WO5 Matatā is transferred to Edgecumbe first. Overall the route from Thornton to Whakatāne is flat but
may require a short 2m barometric loop at the Whakatāne WWTP to keep the rising main full. Table 7-1
provides a summary of the main conveyance routes and relevant considerations.
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Table 7-1: Summary of Main Conveyance Routes for Shortlisted Options
Route Included in
Option Length
(km) Static
Lift (m) Comments
Matatā Pumping Station to Edgecumbe WWTP (Greig Road)
KL1, ER3, TL3, WO5
16.7 5.25 2m barometric loop assumed at Edgecumbe WWTP
Matatā Pumping Station to Edgecumbe WWTP (along State Highway) (KL1, ER3, TL3 and WO5)
KL1, ER3, TL3, WO5
11.5 5.25 Dropped at long list stage - should be reconsidered at preliminary design stage
Edgecumbe WWTP to Kawerau WWTP
KL1
Edgecumbe 4, 5
18.5 27.5 2m barometric loop assumed at Kawerau WWTP
Matatā to Thornton TL2
MW1 10.4 9.7 -
Edgecumbe to Thornton (TL2, TL3, WO1 and WO5) (Land Application Shown)
TL2, TL3
Edgecumbe option 4 & 8
9.8 8.9 -
Thornton to Whakatāne WWTP WO1, WO5,
MW1 8.4 3.2
2m barometric loop assumed at Thornton PS
Edgecumbe WWTP to Rangitaiki River Outfall
ER2, ER3, Edgecumbe
4, 11, 12 1.9 -
7.2 Start-up Flows
It is expected that start-up flows from Matatā will be low and the retention times of wastewater in the
rising main will be high. Even for fully developed future flows the retention time of wastewater in the
rising main is significant. Given the length of the rising mains under consideration it is not considered
economic to build a smaller initial rising main to be upgraded or duplicated in the future. The start -up
and low flow conditions will need to be managed. It has been assumed that chemical dosing will be
required from the outset to manage odour and septicity; and this will mitigate low flows. It will be
important to make sure that the majority of the connections to existing properties are bought on -line as
quickly as possible to increase daily flows and reduce the risk of operational issues. Furthermore
potable water (both Edgecumbe and Matatā have mains water supply) can be used to supplement initial
wastewater flows and be used as a flushing volume (for the pumping of raw sewage) if required.
7.3 Other Considerations
Other key considerations include:
Low Pressure System Power Outage – the planned low pressure sewer network for Matatā
requires power to operate. In the event of a power outage all of the pumps will stop operating
and store wastewater. The transfer pumping station will also stop operating but the low pressure
sewer network will only be discharging what can be driven under gravity. Providing back up
power or generators for the transfer pumping station only has a benefit if flow is arriving. When
power is restored to the low pressure network a large number of pumps will attempt to turn on
and empty. Most of these pumps will turn off as the pressure in the main will be too high – but
there is the risk of an immediate high peak flow arriving at the transfer pumping station that will
need to be allowed for either through wet well capacity or by using a valve that wi ll limit the flow
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discharge from the main into the pump station. The details of this arrangement will need to be
considered further at later Project stages.
Air Valving - Long flat rising mains with numerous watercourse crossings will need to carefully
consider the number and locations of air valves. Given that air valves often require a suitable
seating pressure (5m or more) some of them may occasionally leak. There will be no nearby
sewers to drain air valve chambers to. This issue as well as potential management of emitted
odours will need careful consideration.
Wash-out/Scour Chambers – Long sewer pumping mains even of small diameter hold
significant volumes of wastewater. Scour chambers will not be located near to existing sewers to
be drained to and therefore need to consider suitable tanker access. A large number of tankers
will be required to completely empty the rising main as a single tanker can hold only around 8m 3.
Sections of such a long-rising main may not achieve desirable scour velocities and consideration
should be given during the design for the ability to clean sections of the rising main using
‘pigging’ techniques.
Energy - Long conveyance rising mains of this nature require significant energy to pump the
flow against the friction head. The cost of energy over the life of the asset is uncertain and a
potential risk.
Slime – Sewer slime builds up on the pipe wall of the rising main where there is not sufficient
velocity to strip it away. Bacteria within sewer slime around the pipe wall are the largest (90%)
producer of sulphides within sewer mains and potentially significant risk of hydrogen sulphide
(H2S) production (see Sewage septicity and odour below). Furthermore sewer slime takes up a
portion of the pipe capacity effectively increasing the pipe friction losses.
Septicity Study - A specialist septicity study will be required to fully determine the issues and
requirements of designing and operating the selected option for the pumping of raw sewage.
This will identify and quantify the risks and determine suitable mitigation measures to address
any septicity issues. This will provide more accurate cost estimates for chemical dosing and
odour treatment facilities and annual operation costs.
Surge Analysis - Due to the significant length of rising mains under consideration, specialist
surge analysis will be required as part of the design process in order to define the risks and
requirements of the selected option.
For the options conveying oxidation pond treated wastewater, or otherwise treated
wastewater from Edgecumbe, the comments on a slime and a septicity study do not apply. As
previously outlined pumping treated wastewater over long distances over long conveyance lines
has considerable advantages over pumping raw sewage.
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8 Risk Assessment, Management and Mitigation
8.1 Risk Management Background and Approach
Prudent wastewater management includes the activities of risk assessment and management and
adoption of appropriate mitigation measures. Local government statutes and procedures including
those in AS/NZS ISO 31000: 2009 Standard on Risk set out appropriate procedures. These are
summarised below.
The risk assessment performed previously and continued in this Report was designed to be consistent
with recognised good practice and the requirements of AS/NZS ISO 31000: 2009 Standard on Risk
Management, which states:
“Risk management is the term applied to a logical and systematic method of establishing the context,
identifying, analysing, evaluating, treating, monitoring and communicating risks associated with any
activity, function or process in a way that will enable organisations to minimise losses and maximise
opportunities. Risk management is as much about identifying opportunities as avoiding or mitigating
losses.”
This risk is a combination of the severity of potential undesirable events or outcomes (here collectively
termed the consequences), the likelihood (probability or frequency) that these consequences occur and
the degree of exposure of people, assets or the environment to those consequences.
As this Project also includes RMA consenting, risk management consideration in terms of the RMA, are
encompassed by the interpretation of ‘effects’. The interpretation includes:
“Any potential effect of a high probability” and “any potential effect of a low probability which
has a high potential impact.”
Risk management categories titled as Hazard Threat Risk were identified at a relatively high level and
grouping of light risks. Each of the hazard/risk types were also grouped under the source of generic risk
grouping which included ‘Environmental’, ‘Economic’, ‘Social’, ‘Cultural’ and ‘Other’. The ‘Other’
category included factors such as predicted growth in wastewater generation not eventuating.
A two stage high level Risk Assessment approach:
Stage 1 involved a high level key risk identification for all options in scoping Long List for both
Edgecumbe “alone”. These are included in the “Key Risks (without mitigation)” in Appendix D
and F respectively;
Stage 2 takes the shortlisted options for Edgecumbe stand alone and joint Matatā and
Edgecumbe and further expands the key risks of these options by identifying additional risks and
their assessing these as to “likelihood” “consequences” and “risks”. These are set out in Table
8-1 and Table 8-2 respectively along with mitigation measures over those allowed for in the
Option concept and development to date that would further reduce or manage each of the risk
categories – this is shown in Table 7-4 and 7-5.
The assessment approach is generally following the accepted AU/NZ 4360:1999 Risk Management
Standard adopted by NZ local authorities.
Initial work shows main identified risks can be well mitigated against, although remains the question of
natural disasters with long pipelines – partly mitigated through resilient engineering and appropriate
infrastructure location and operation.
The above-referenced appraisal is considered to be consistent with the interpretation of risk based
‘effects’ under the RMA.
The output of the risk assessment would be further used in the determination of procedures to avoid,
remedy and mitigate measures associated with potential and actual adverse effects of the Scheme
implemented.
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8.2 Evaluation of Risk
In Table 8-4 and 8-5, some 30 separate hazards or threats were identified in brain-storming discussions
amongst the MWH project team. The hazards or threats were recorded within a spread sheet system,
the Risk Register, and the associated level of risk for each option was assessed. In general, different
levels of risk were assigned to a specific hazard or threat depending on the disposa l / discharge option
being considered and hence, overall, the different options may be seen as more or less risky.
The risk arising from each of the hazards or threats was determined by allocating five category semantic
scales to the likelihood that the hazards or threats would occur, and the level of consequence that would
result. These five category scales are defined in Table 8-1 and Table 8-2 below. If the instance that a
particular hazard or threat does not apply to the option being assessed, its associated likelihood and
consequence was denoted as ‘N/A’ (Not Applicable).
Table 8-1: Likelihood Scale
The definitions of likelihood given in the table above were used to guide the evaluation and assignment of the likelihood that each hazard or threat would occur for each of the options. Similarly the definitions of consequences given in the table above were used to guide the assignment of consequence categories.
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Table 8-2: Consequence Scale
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The level of risk associated with the likelihood – consequence category combinations were then
determined using the Risk Matrix definition given in the Table 6-3 below.
Table 8-3: Risk Matrix Definitions
LIKELIHOOD CONSEQUENCES
1 2 3 4 5
Rare L L M H H
Unlikely L L M H E
Possible L M H E E
Moderate M M H E E
Almost Certain M H H E E
Key: Consequence - 1: Insignificant, 2: Minor, 3: Severe, 4: Major, 5: Catastrophic Risk - L: Low, M: Medium, H: High, E: Extreme
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Table 8.4 Edgecumbe Stand Alone Short Listed Options – Further Possible Risk Mitigation Measures for the Short Listed Options
Option 1 – Conveyance of Edgecumbe Raw Sewage to Kawerau WWTP Option 4 – Conveyance of Edgecumbe oxidation pond treated
wastewater to Whakatāne ocean outfall Option 5 Conveyance of Edgecumbe raw sewage to Whakatāne WWTP
NO Source /
Well-being Hazard Threat Risk
Likelihood Rating
Consequence Rating
Current Risk Further Risk
Mitigation Measures Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
Env Natural Environment - Receiving the Discharge
1 Fails to meet “maintain and enhance” the water quality body. Expected Improvement not achieved in the receiving environment
Moderate Severe High
Work with Regional Council on Tarawera
Plan and future consents. Flexibility in WWTP for upgrades
Unlikely Severe Medium Flexibility in
Edgecumbe WWTP upgrade
Unlikely Severe Medium Flexibility in WWTP to
upgrade
2 Unexpected other contaminant issues, e.g. micro-organisms
Possible Minor Medium Flexibility in WWTP for
upgrades Unlikely Severe Medium
Flexibility in Edgecumbe WWTP
upgrade Unlikely Severe Medium
Flexibility in Whakatāne WWTP to
upgrade
3 Soils become saturated in land application Unlikely Severe Medium Maintain large area of rapid infiltration beds
appropriately
NA NA NA NA NA NA NA NA
4 Contaminant break through inland application Possible Severe High
Flexibility in WWTP for upgrades and also maintain large land
area
NA NA NA NA
NA NA NA NA
5 Long term sustainability not achieved Possible Severe High
Flexibility in WWTP for upgrades and also maintain large land
area
Unlikely Medium Low
Flexibility in Edgecumbe WWTP
and to upgrade/lengthen Whakatāne outfall
Unlikely Medium Low
Flexibility in Whakatāne WWTP and
to upgrade/lengthen outfall
6 Unexpected effects on ecology including wild food Unlikely Severe Medium
Flexibility in WWTP for upgrades and also maintain large land
area
Unlikely Severe Medium
Flexibility in Edgecumbe WWTP
and to upgrade/lengthen Whakatāne outfall
Unlikely Severe Medium
Flexibility in Whakatāne WWTP and
to upgrade/lengthen outfall
Existing Infrastructure
1 Unexpected problems in using existing infrastructure
Moderate Severe High
Pre-treatment of raw sewage prior to
entering Kawerau WWTP
Unlikely Minor Low
Flexibility in operating Edgecumbe oxidation pond and Whakatāne
ocean outfall
Possible Minor Medium Upgrade oxidation
pond at Whakatāne
2 Greater costs/difficulties than expected from future upgrades of existing infrastructure to meet new consents and/or WWTP upgrades
Moderate Severe High
Thorough investigations prior to future consents and
obtaining appropriate consents
Possible Minor Medium
Flexibility in operating Edgecumbe oxidation pond and Whakatāne
ocean outfall
Possible Minor Medium Flexibility in
Whakatāne oxidation pond upgrade
Ec Economic - Capital, Operating, Community
1 Capital cost: Unexpectedly higher than estimates/reviews
Possible Severe High Thorough site
investigations and appropriate design
Possible Minor Medium
Appropriate investigation and
design and securing sufficient land
Possible Severe High
Appropriate investigation and
design and securing sufficient land
2 Operating cost: Unexpectedly significantly higher than estimates/reviews e.g. power cost increase; chemical usage
Possible Severe High Appropriate long term
agreement with Kawerau DC
Possible Minor Medium
Appropriate investigation and
design and operating flexibility
Possible Severe High
Appropriate investigation and
design and operating flexibility
3 Population/demand increase over design capacity Possible Major Extreme
Flexibility in design and particularly pumping
rate for as far as practical
Possible Severe High
Flexibility in design and particularly pumping
rate for as far as practical
Possible Severe High
Flexibility in design and particularly pumping
rate for as far as practical
4 Population/demand decrease over design capacity Possible Minor Medium
Having appropriate septicity and odour
management in conveyance
Possible Insignificant Low
Flexibility in design and particularly pumping
rate for as far as practical
Flexibility in design and particularly pumping
rate for as far as practical
T Technical/Construction
1 Septicity/Corrosion of infrastructure greater than expected.
Possible Severe High
Appropriate design and operation of the total
conveyance system to Kawerau WWTP
Possible Severe High
Appropriate design and operation of the
Edgecumbe oxidation pond and conveyance
system, use of Whakatāne Maturation
pond
Possible Minor Medium Appropriate design and operation of the Matatā
conveyance system
2 Climate change impacts - peak and prolonged wet weather and dry periods
Unlikely Severe Medium Ensure sealed LPS
system to minimise wet weather flows
Possible
Ensure adequate storage at Edgecumbe
oxidation pond Ensure appropriate
operation of Whakatāne ocean
outfall
Possible Minor Medium
Ensure appropriate upgrade of Whakatāne
oxidation ponds and ocean outfall operation
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Option 1 – Conveyance of Edgecumbe Raw Sewage to Kawerau WWTP Option 4 – Conveyance of Edgecumbe oxidation pond treated
wastewater to Whakatāne ocean outfall Option 5 Conveyance of Edgecumbe raw sewage to Whakatāne WWTP
NO Source /
Well-being Hazard Threat Risk
Likelihood Rating
Consequence Rating
Current Risk Further Risk
Mitigation Measures Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
3 Equipment and System not as proven and as reliable as thought. Predicted treatment/reduction not achieved
Unlikely Severe Low
Select appropriate systems and ensure Kawerau WWTP can
accept LPS raw sewage
Unlikely Minor Low Appropriate upgrade of Edgecumbe oxidation
pond Unlikely Minor Low
Appropriate upgrade Whakatāne oxidation
ponds
4 Future flexibility for capacity changes and changed consent conditions
Possible Severe High
Long conveyance system needs careful
design with future flexibility. Kawerau
WWTP to be assessed for future flexibility
Possible Minor Medium
Ensure flexibility in Whakatāne and
Edgecumbe WWTP and Whakatāne ocean
outfall
Possible Minor Medium
Ensure future flexibility to upgrade Whakatāne
oxidation ponds and ocean outfall operation
5 Unexpected Geotechnical risks (instability, water tables, etc.)
Possible Severe High Thorough
investigation, route selection and design
Possible Minor Medium Thorough
investigation, route selection and design
Possible Minor Medium
Thorough investigation, route
selection and design
6 Available power supply Possible Severe High Thorough
investigation, route selection and design
Possible Minor Medium Thorough
investigation, route selection and design
Possible Minor Medium
Thorough investigation, route
selection and design
7 Insufficient construction corridor in roads Possible Minor Medium Thorough
investigation, route selection and design
Possible Minor Medium Thorough
investigation, route selection and design
Possible Minor Medium
Thorough investigation, route
selection and design
OP Operating and Maintenance
1 Septicity and odour nuisance and corrosion: Unexpectedly more difficult to mitigate
Possible Major Extreme Appropriate design and
operation Unlikely Minor Low
Appropriate Edgecumbe oxidation pond treatment and
conveyance
Possible Severe High Appropriate design and
operation
2 Technical and Operational: Operational Resilience - unexpected critical failure to key elements of solution e.g. power failure at pump stations, WWTP
Possible Severe High Appropriate design and
operation of long conveyance system
Possible Minor Medium
Appropriate design and operation and
contingency plan including more storage
at Edgecumbe oxidation pond
Possible Severe High
Appropriate design and operation of Matatā
conveyance and upgraded Whakatāne
WWTP
3 Natural hazard risks, e.g. earthquakes, floods, landslips, coastal zones etc
Moderate Severe High
Thorough investigation, route
selection, design and resilient engineering
Possible Minor Medium
Appropriate investigation design, resilient engineering
and contingency planning
Possible Severe High
Thorough investigation, route
selection, design and resilient engineering
PC Planning, Consenting, Approvals
1 Land for treatment and disposal: Unexpectedly more difficult to find, purchase, and secure long term leases and consents
NA NA NA NA NA NA NA NA NA NA NA NA
2
Resource consents: Unexpectedly more difficult to obtain. Conveyance mains alignment and pump stations, unexpectedly more difficulty to get approval
Possible Severe High Applies to future
Kawerau DC consent also
Possible Minor Medium
Maximise advantage of using existing
Whakatāne outfall consent and
Edgecumbe oxidation pond consent for
treatment (not discharge) as far as
possible
Possible Severe High
Maximise advantage of using existing
Whakatāne consent as far as possible
3 More stringent future Tarawera Catchment Management Plan requirements than anticipated
Possible Severe High Full involvement with Regional Council at time of plan review
NA NA NA NA NA NA NA NA
PH/S/CE Public Health/Social/Community Environment
1 Resistance to treatment and disposal facilities near/on private property
Unlikely Severe Medium Consultation and appropriate siting
Unlikely Severe Medium
Effective consultation and appropriate
consent conditions, but these are existing treatment facilities
Unlikely Minor Low
Effective consultation and appropriate
consent conditions
2 Public Health: Unexpectedly risks/ high impact e.g. micro-organisms not treated effectively
Possible Severe High
Based on current WWTP experience.
UV disinfection could be reinstalled
Possible Severe High
3 Unexpected noise effects from facilities on individual properties
Unlikely Severe Medium Appropriate siting and
design operation Possible Severe High
WWTP design and operation with effective
disinfection Unlikely Severe Medium
WWTP design and operation with effective
disinfection
4 Public Health nuisance from any overflows/breakdowns
Possible Severe Medium Appropriate siting and design operation and contingency planning
Possible Severe Medium Appropriate siting and design operation and contingency planning
Possible Severe Medium
Appropriate siting and design operation and contingency planning
MC Maori Cultural – WDC to Advise TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD
O Other
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Page 112 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Option 1 – Conveyance of Edgecumbe Raw Sewage to Kawerau WWTP Option 4 – Conveyance of Edgecumbe oxidation pond treated
wastewater to Whakatāne ocean outfall Option 5 Conveyance of Edgecumbe raw sewage to Whakatāne WWTP
NO Source /
Well-being Hazard Threat Risk
Likelihood Rating
Consequence Rating
Current Risk Further Risk
Mitigation Measures Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
1 Unexpected difficulties as WDC do not have ownership of the Kawerau District Council wastewater infrastructure
Moderate Severe High
Ensure effective long term agreement
between WDC and KDC
NA NA NA NA NA NA NA NA
2 Other ??? TBD TBD TBD TBD TBD TBD TBD
TBD TBD TBD TBD TBD
Notes This table identifies additional procedures and approaches that could be adopted to reduce the risk category generally a llowed for in the options conceptual development to date and allowed for in the indicative cost estimates. Such further risk mitigation matters can be expected to have additional cost implications. En - Environmental Ec - Economic T - Technical OP – Operating and Maintenance PC – Planning, Consenting, Approvals PH/S/CE – Public Health/Social/Community Environment MC Maori Culture – WDC to Advise O - Other NA Not Applicable TBD – To Be Determined
Risk Colour Coding as follows: Low Grey Medium Yellow High Blue Extreme Red
Refer Table 7.1 likelihood scale classification Table 7.2 consequence style classification Table 7.3 Risk Classification
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Page 113 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Table 8.4 Edgecumbe Stand Alone Short Listed Options – Further Possible Risk Mitigation Measures for the Short Listed Options
Option 8 Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes
Option 12 – Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki river discharge
NO Source /
Well-being Hazard Threat Risk
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
Env Natural Environment - Receiving the Discharge
1 Fails to meet “maintain and enhance” the water quality body. Expected Improvement not achieved in the receiving environment
Possible Severe High Flexibility in WWTP for upgrades to maintain ground water quality
Possible Severe High Flexibility in WWTP for
upgrades
2 Unexpected other contaminant issues, e.g. micro-organisms
Possible Severe High Flexibility in WWTP’s
for upgrades Unlikely Minor Medium
Flexibility in WWTP for upgrades
3 Soils become saturated in land application Possible Severe High Reserve land in application area
NA NA NA NA
4 Contaminant break through inland application Possible Severe High
Flexibility in WWTP for upgrades.
Reserve land in application area
NA NA NA NA
5 Long term sustainability not achieved Possible Severe High
Flexibility in WWTP for upgrades.
Reserve land in application area
Unlikely Severe Medium
Future flexibility in upgrades – greater river dilution and
dispersion
6 Unexpected effects on ecology including wild food Unlikely Minor Low
Flexibility in WWTP for upgrades.
Reserve land in application area
Unlikely Minor Low Flexibility in WWTP for
upgrades
Existing Infrastructure
1 Unexpected problems in using existing infrastructure
Unlikely Severe Medium Flexibility in WWTP for
upgrades Unlikely Severe Medium
Flexibility in WWTP for upgrades
2 Greater costs/difficulties than expected from future upgrades of existing infrastructure to meet new consents and/or WWTP upgrades
Possible Minor Medium Flexibility in WWTP for upgrades
Possible Minor Medium
Future flexibility in upgrades – greater river dilution and
dispersion
Ec Economic - Capital, Operating, Community
1 Capital cost: Unexpectedly higher than estimates/reviews
Possible Severe High
Appropriate investigation and
design and securing sufficient land
Possible Minor Medium
Appropriate investigation and
design
2 Operating cost: Unexpectedly significantly higher than estimates/reviews e.g. power cost increase; chemical usage
Unlikely Severe Medium
Appropriate investigation and
design and operating flexibility
Possible Minor Medium
Appropriate investigation and
design and operating flexibility
3 Population/demand increase over design capacity Possible Severe High
Flexibility in design and particularly pumping conveyance and in having a generous
reserve area and land application
Possible Severe High Flexibility in WWTP
design
4 Population/demand decrease over design capacity Possible Minor Medium
Having appropriate flexibility in WWTP;s
and conveyance systems and land application area
Possible Minor Medium Flexibility in WWTP
design
T Technical/Construction
1 Septicity/Corrosion of infrastructure greater than expected.
Unlikely Minor Low
Appropriate design and operation of the Matatā
WWTP and Edgecumbe oxidation
pond
Possible Minor Low
Appropriate design and operation of the to River conveyance
system
2 Climate change impacts - peak and prolonged wet weather and dry periods
Possible Severe High
Ensure adequate variable storage at
Edgecumbe oxidation pond and adequate
land application area
Possible Minor Medium
Ensure adequate variable storage at
Edgecumbe oxidation pond
3 Equipment and System not as proven and as reliable as thought. Predicted treatment/reduction not achieved
Unlikely Minor Low
Ensure appropriate upgrade design of Matatā WWTP and
Edgecumbe oxidation ponds
Unlikely Minor Medium
Ensure appropriate upgrade of Edgecumbe
oxidation pond plus additional (WWTP)
treatment processes
4 Future flexibility for capacity changes and changed consent conditions
Possible Minor Medium Ensure flexibility to upgrade WWTP.
Ensure spare capacity Possible Minor Medium
Ensure flexibility to upgrade WWTP
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Page 114 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Option 8 Upgrade of existing Edgecumbe oxidation ponds and Land Application at Thornton Dunes
Option 12 – Upgrade of existing Edgecumbe oxidation ponds and Rangitaiki river discharge
NO Source /
Well-being Hazard Threat Risk
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
in land treatment system
5 Unexpected Geotechnical risks (instability, water tables, etc.)
Possible Minor Medium Thorough
investigation, route selection and design
Possible Minor Medium
Thorough investigation, route
selection and design
6 Available power supply Possible Minor Medium Thorough
investigation, route selection and design
Possible Minor Medium
Thorough investigation, route
selection and design
7 Insufficient construction corridor in roads Unlikely Minor Low Route investigations,
lay in carriage if necessary
Unlikely Minor Low
Route investigations, lay in carriageway if
necessary
O Operating and Maintenance
1 Septicity and odour nuisance and corrosion: Unexpectedly more difficult to mitigate
Unlikely Minor Low Appropriate design and
operation Unlikely Minor Low
Appropriate design and operation
2 Technical and Operational: Operational Resilience - unexpected critical failure to key elements of solution e.g. power failure at pump stations
Possible Minor Medium
Appropriate design and operation of Matatā
conveyance and upgraded WWTP
Possible Minor Medium
Appropriate design and operation of upgraded
WWTP and conveyance line
3 Natural hazard risks, e.g. earthquakes, floods, landslips, coastal zones etc
Possible Severe High
Appropriate design and operation of Matatā
conveyance and upgraded WWTP
Possible Severe High
Appropriate design and operation upgraded
WWTP
PC Planning, Consenting, Approvals
1 Land for treatment and disposal: Unexpectedly more difficult to find, purchase, and secure long term leases and consents
Possible Severe High
Thorough investigations of the use of WDC coastal
reserve
NA NA NA NA
2
Resource consents: Unexpectedly more difficult to obtain. Conveyance mains alignment and pump stations, unexpectedly more difficulty to get approval
Possible Severe High
Thorough investigations of the use of WDC coastal
reserve
Possible Severe High
Thorough investigation and consultation and working with Regional
Council
3 More stringent future Tarawera Catchment Management Plan requirements than anticipated
NA NA NA NA NA NA NA NA
PH/S/CE Public Health/Social/Community Environment
1 Resistance to treatment and disposal facilities near/on private property
Possible Severe High
Effective consultation and appropriate
consent conditions, but these are existing treatment facilities
Unlikely Severe Medium
Consultation and appropriate siting but WWT at Edgecumbe Oxidation Pond site
maybe extended a little
2 Public Health: Unexpectedly risks/ high impact e.g. micro-organisms not treated effectively
Possible Minor Medium WWTP design and
operation with effective disinfection
Possible Minor Medium
WWTP design and operation with effective
disinfection
3 Unexpected noise effects from facilities on individual properties
Unlikely Severe Medium Appropriate siting and
design operation Unlikely Minor Low
Appropriate siting and design operation
4 Public Health nuisance from any overflows/breakdowns
Possible Severe Medium Appropriate siting and design, operation and contingency planning
Possible Minor Medium
Appropriate siting and design, operation and contingency planning
C Maori Cultural – WDC to Advise TBD TBD TBD TBD TBD TBD TBD TBD
O Other
1 Unexpected difficulties as WDC do not have ownership of the Kawerau District Council wastewater infrastructure
NA NA NA NA NA NA NA NA
2 Other ??? TBD TBD TBD TBD TBD TBD TBD TBD
Notes This table identifies additional procedures and approaches that could be adopted to reduce the risk category generally allowe d for in the options conceptual development to date and allowed for in the indicative cost estimates. Such further risk mitigation matters can be expected to have additional cos t implications. En - Environmental Ec - Economic T - Technical OP – Operating and Maintenance PC – Planning, Consenting, Approvals PH/S/CE – Public Health/Social/Community Environment MC Maori Culture – WDC to Advise O - Other NA Not Applicable TBD – To Be Determined
Risk Colour Coding as follows: Low Grey Medium Yellow High Blue Extreme Red
Refer Table 7.1 likelihood scale classification Table 7.2 consequence style classification Table 7.3 Risk Classification
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Page 115 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Table 8.5 Combined Edgecumbe and Matatā Schemes Short Listed Options – Further Possible Risk Mitigation Measures for the Short Listed Options
At Kawerau Land 1 (KL1) At Edgecumbe River 3 (ER3) At Thornton Land 2 (TL2)
NO Source /
Well-being Hazard Threat Risk
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures Possible
Env Natural Environment - Receiving the Discharge
1 Fails to meet “maintain and enhance” the water quality body. Expected Improvement not achieved in the receiving environment
Moderate Severe High
Work with Regional Council on Tarawera Plan
and future consents. Flexibility in WWTP for
upgrades
Possible Severe High Flexibility in WWTP
for upgrades Possible Severe High
Flexibility in WWTP for upgrades to maintain ground water quality
2 Unexpected other contaminant issues, e.g. micro-organisms
Possible Minor Medium Flexibility in WWTP for
upgrades Unlikely Minor Medium
Flexibility in WWTP for upgrades
Possible Severe High Flexibility in WWTP’s for
upgrades
3 Soils become saturated in land application Unlikely Severe Medium Maintain large area of rapid infiltration beds
appropriately NA NA NA NA Possible Severe High Reserve land in application
area
4 Contaminant break through inland application Possible Severe High Flexibility in WWTP for
upgrades and also maintain large land area
NA NA NA NA Possible Severe High
Flexibility in WWTP for upgrades.
Reserve land in application area
5 Long term sustainability not achieved Possible Severe High Flexibility in WWTP for
upgrades and also maintain large land area
Unlikely Severe Medium
Future flexibility in upgrades – greater river dilution and
dispersion
Possible Severe High
Flexibility in WWTP for upgrades.
Reserve land in application area
6 Unexpected effects on ecology including wild food
Unlikely Severe Medium Flexibility in WWTP for
upgrades and also maintain large land area
Unlikely Minor Low Flexibility in WWTP
for upgrades Unlikely Minor Low
Flexibility in WWTP for upgrades.
Reserve land in application area
Existing Infrastructure
1 Unexpected problems in using existing infrastructure
Moderate Severe High Pre-treatment of raw
sewage prior to entering Kawerau WWTP
Unlikely Severe Medium
Flexibility in WWTP for upgrades including
odour management for Matatā inflow
Unlikely Severe Medium Flexibility in WWTP’s for
upgrades
2 Greater costs/difficulties than expected from future upgrades of existing infrastructure to meet new consents and/or WWTP upgrades
Moderate Severe High
Thorough investigations prior to future consents
and obtaining appropriate consents
Possible Minor Medium
Future flexibility in upgrades – greater river dilution and
dispersion
Possible Minor Medium Flexibility in WWTP’s for upgrades
Ec Economic - Capital, Operating, Community
1 Capital cost: Unexpectedly higher than estimates/reviews
Possible Severe High Thorough site
investigations and appropriate design
Possible Minor Medium Appropriate
investigation and design
Possible Severe High
Appropriate investigation and design and securing
sufficient land
2 Operating cost: Unexpectedly significantly higher than estimates/reviews e.g. power cost increase; chemical usage
Possible Severe High Appropriate long term
agreement with Kawerau DC
Possible Minor Medium
Appropriate investigation and
design and operating flexibility
Unlikely Severe Medium
Appropriate investigation and design and operating
flexibility
3 Subsidies: DoH acceptance/approval not obtained for Matatā
TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD
4 Population/demand increase over design capacity
Possible Major Extreme Flexibility in design and
particularly pumping rate for as far as practical
Possible Severe High
Flexibility in WWTP design and
particularly pumping rates for Matatā as far
as practical
Possible Severe High
Flexibility in design and particularly pumping
conveyance and in having a generous reserve area
and land application
5 Population/demand decrease over design capacity
Possible Minor Medium
Having appropriate septicity and odour
management in conveyance
Possible Minor Medium
Having appropriate septicity and odour
management in Matatā conveyance
Possible Minor Medium
Having appropriate flexibility in WWTP;s and
conveyance systems
T Technical/Construction
1 Septicity/Corrosion of infrastructure greater than expected.
Possible Severe High
Appropriate design and operation of the total
conveyance system to Kawerau WWTP
Possible Minor Medium
Appropriate design and operation of the Matatā conveyance
system
Unlikely Minor Low
Appropriate design and operation of the Matatā WWTP and Edgecumbe
oxidation pond
2 Climate change impacts - peak and prolonged wet weather and dry periods
Unlikely Severe Medium Ensure sealed LPS
system to minimise wet weather flows
Possible Minor Medium
Ensure adequate variable storage at
Edgecumbe oxidation pond
Possible Severe High
Ensure adequate variable storage at Edgecumbe
oxidation pond and adequate land application
area
3 Equipment and System not as proven and as reliable as thought. Predicted treatment/reduction not achieved
Unlikely Severe Low
Select appropriate systems and ensure Kawerau WWTP can
accept LPS raw sewage
Unlikely Minor Medium
Ensure appropriate upgrade of
Edgecumbe oxidation pond plus additional (WWTP) treatment
processes
Unlikely Minor Low
Ensure appropriate upgrade design of Matatā WWTP and Edgecumbe
oxidation ponds
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Page 116 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
At Kawerau Land 1 (KL1) At Edgecumbe River 3 (ER3) At Thornton Land 2 (TL2)
NO Source /
Well-being Hazard Threat Risk
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures Possible
4 Future flexibility for capacity changes and changed consent conditions
Possible Severe High
Long conveyance system needs careful design with future flexibility. Kawerau WWTP to be assessed for
future flexibility
Possible Minor Medium Ensure flexibility to
upgrade WWTP Possible Minor Medium
Ensure flexibility to upgrade WWTP. Ensure
spare capacity in land treatment system
5 Unexpected Geotechnical risks (instability, water tables, etc.)
Possible Severe High Thorough investigation,
route selection and design
Possible Minor Medium Thorough
investigation, route selection and design
Possible Minor Medium Thorough investigation,
route selection and design
6 Available power supply Possible Severe High Thorough investigation,
route selection and design
Possible Minor Medium Thorough
investigation, route selection and design
Possible Minor Medium Thorough investigation,
route selection and design
7 Insufficient construction corridor in roads Possible Minor Medium Thorough investigation,
route selection and design
Unlikely Minor Low
Based on Greig Road route. Higher risk for state highway route
option
Unlikely Minor Low Route investigations, lay in
carriage if necessary
O Operating and Maintenance
1 Septicity and odour nuisance and corrosion: Unexpectedly more difficult to mitigate
Possible Major Extreme Appropriate design and
operation Possible Severe High
Appropriate design and operation
Possible Severe High Appropriate design and
operation
2
Technical and Operational: Operational Resilience - unexpected critical failure to key elements of solution e.g. power failure at pump stations, WWTP
Possible Severe High Appropriate design and
operation of long conveyance system
Possible Minor Medium
Appropriate design and operation of
Matatā conveyance and upgraded WWTP
Possible Minor Medium
Appropriate design and operation of Matatā
conveyance and upgraded WWTP
3 Natural hazard risks, e.g. earthquakes, floods, landslips, coastal zones etc
Moderate Severe High Thorough investigation, route selection, design
and resilient engineering Possible Severe High
Appropriate design and operation of
Matatā conveyance and upgraded WWTP
Possible Severe High
Appropriate design and operation of Matatā
conveyance and upgraded WWTP
PC Planning, Consenting, Approvals
1 Land for treatment and disposal: Unexpectedly more difficult to find, purchase, and secure long term leases and consents
NA NA NA NA NA NA NA NA Possible Severe High
Thorough investigations of the use of WDC coastal
reserve
2
Resource consents: Unexpectedly more difficult to obtain. Conveyance mains alignment and pump stations, unexpectedly more difficulty to get approval
Possible Severe High Applies to future Kawerau
DC consent also Possible Severe High
Thorough investigation and consultation and
working with Regional Council
Possible Severe High
Thorough investigations of the use of WDC coastal
reserve
3 More stringent future Tarawera Catchment Management Plan requirements than anticipated
Possible Severe High Full involvement with
Regional Council at time of plan review
NA NA NA NA NA NA NA NA
PH/S/CE Public Health/Social/Community Environment
1 Resistance to treatment and disposal facilities near/on private property
Unlikely Severe Medium Consultation and appropriate siting
Unlikely Severe Medium Consultation and appropriate siting
Possible Severe High Consultation and appropriate siting
2 Public Health: Unexpectedly risks/ high impact e.g. micro-organisms not treated effectively
Possible Severe High
Based on current WWTP experience. UV
disinfection could be reinstalled
Possible Minor Medium WWTP design and
operation with effective disinfection
Possible Minor Medium
WWTP design and operation with effective
disinfection
3 Unexpected noise effects from facilities on individual properties
Unlikely Severe Medium Appropriate siting and
design operation Unlikely Minor Low
Appropriate siting and design operation
Unlikely Severe Medium Appropriate siting and
design operation
4 Public Health nuisance from any overflows/breakdowns
Possible Severe Medium Appropriate siting and design operation and contingency planning
Possible Minor Medium Appropriate siting and design operation and contingency planning
Possible Severe Medium
Appropriate siting and design operation and contingency planning
C Maori Cultural – WDC to Advise TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD
O Other
1 Unexpected difficulties as WDC do not have ownership of the Kawerau District Council wastewater infrastructure
Moderate Severe High
Ensure effective long term agreement between
WDC and KDC NA NA NA NA NA NA NA NA
2 Other ??? TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD
Notes
This table identifies additional procedures and approaches that could be adopted to reduce the risk category generally allowe d for in the options conceptual development to date and allowed for in the indicative cost estimates. Such further risk mitigation matters can be expected to have additional cost implications. En - Environmental Ec - Economic T - Technical OP – Operating and Maintenance PC – Planning, Consenting, Approvals PH/S/CE – Public Health/Social/Community Environment MC Maori Culture – WDC to Advise O - Other NA Not Applicable TBD – To Be Determined
Risk Colour Coding as follows: Low Grey Medium Yellow High Blue Extreme Red
Refer Table 7.1 likelihood scale classification Table 7.2 consequence style classification Table 7.3 Risk Classification
Wastewater Review and Options Study for Edgecumbe and Matatā Contract 15-069 - Work Streams 2a and 2b
Status: Final 22 September 2015 Project number: 805 08148 Page 117 Our ref: WW Review and Options Study for Edgecumbe & Matata Report Final 22-09-15
Table 8.5 Combined Edgecumbe and Matatā Schemes Short Listed Options – Further Possible Risk Mitigation Measures for the Short Listed Options
At Thornton Land 3 (TL3) At Whakatāne Ocean 1 (WO1) At Whakatāne Ocean 5 (WO5)
NO Source /
Well-being Hazard Threat Risk
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures Possible
Env Natural Environment - Receiving the Discharge
1 Fails to meet “maintain and enhance” the water quality body. Expected Improvement not achieved in the receiving environment
Possible Severe High Flexibility in WWTP to
upgrade Unlikely Severe Medium
Flexibility in WWTP to upgrade
Unlikely Severe Medium Flexibility in Edgecumbe
WWTP upgrade
2 Unexpected other contaminant issues, e.g. micro-organisms
Possible Severe High Flexibility in WWTP Unlikely Severe Medium Flexibility in WWTP to
upgrade Unlikely Severe Medium
Flexibility in Edgecumbe WWTP upgrade
3 Soils become saturated in land application Possible Severe High Reserve land application
area NA NA NA NA NA NA NA NA
4 Contaminant break through inland application Possible Severe High Flexibility in WWTP NA NA NA NA NA NA NA NA
5 Long term sustainability not achieved Possible Severe High Flexibility in WWTP
Unlikely Medium Low
Flexibility in Whakatāne WWTP
and to upgrade Lengthen outfall
Unlikely Medium Low
Flexibility in Edgecumbe WWTP to upgrade Lengthen outfall
6 Unexpected effects on ecology including wild food
Unlikely Severe Medium Flexibility in WWTP
Reserve land application area
Unlikely Severe Medium
Flexibility in Whakatāne WWTP
and to upgrade Lengthen outfall
Unlikely Severe Medium
Flexibility in Edgecumbe WWTP to upgrade Lengthen outfall
Existing Infrastructure
1 Unexpected problems in using existing infrastructure
Unlikely Minor Low Only uses Edgecumbe
oxidation ponds Possible Minor Medium
Upgrade oxidation pond at Whakatāne
Unlikely Minor Low
Flexibility in operating Edgecumbe oxidation pond and Whakatāne
ocean outfall
2 Greater costs/difficulties than expected from future upgrades of existing infrastructure to meet new consents and/or WWTP upgrades
Possible Minor Medium Flexibility in Edgecumbe
WWTP upgrade Possible Minor Medium
Flexibility in Whakatāne oxidation
pond upgrade Possible Minor Medium
Flexibility in operating Edgecumbe oxidation pond and Whakatāne
ocean outfall
Ec Economic - Capital, Operating, Community
1 Capital cost: Unexpectedly higher than estimates/reviews
Possible Severe High Appropriate investigation and design and securing
sufficient land Possible Severe High
Appropriate investigation and
design and securing sufficient land
Possible Minor Medium
Appropriate investigation and design and securing
sufficient land
2 Operating cost: Unexpectedly significantly higher than estimates/reviews e.g. power cost increase; chemical usage
Unlikely Severe Medium Appropriate investigation and design and operating
flexibility Possible Severe High
Appropriate investigation and
design and operating flexibility
Possible Minor Medium
Appropriate investigation and design and operating
flexibility
3 Subsidies: DoH acceptance/approval not obtained for Matatā
TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD
4 Population/demand increase over design capacity
Possible Severe High
Flexibility in design and particularly pumping
conveyance and in having a generous reserve area
and land application
Possible Severe High
Flexibility in design and particularly
pumping rate for as far as practical
Possible Severe High
Flexibility in design and particularly pumping rate
for as far as practical
5 Population/demand decrease over design capacity
Possible Minor Medium Having appropriate
flexibility in WWTP;s and conveyance systems
Flexibility in design and particularly
pumping rate for as far as practical
Possible Insignificant Low
Flexibility in design and particularly pumping rate
for as far as practical
T Technical/Construction
1 Septicity/Corrosion of infrastructure greater than expected.
Possible Severe High Appropriate design and operation of the Matatā
conveyance system Possible Severe High
Appropriate design and operation of the
Matatā and Edgecumbe raw
sewage conveyance system
Possible Minor Medium Appropriate design and operation of the Matatā
conveyance system
2 Climate change impacts - peak and prolonged wet weather and dry periods
Possible Severe High
Ensure adequate variable storage at Edgecumbe
oxidation pond and adequate land application
area
Possible Minor Medium
Ensure appropriate upgrade of
Whakatāne oxidation ponds and ocean outfall operation
Possible
Ensure adequate storage at Edgecumbe oxidation
pond Ensure appropriate
operation of Whakatāne ocean outfall
3 Equipment and System not as proven and as reliable as thought. Predicted treatment/reduction not achieved
Unlikely Minor Medium Ensure adequate variable
storage at Edgecumbe oxidation pond
Unlikely Minor Low Appropriate upgrade Whakatāne oxidation
ponds Unlikely Minor Low
Appropriate upgrade of Edgecumbe oxidation
pond
4 Future flexibility for capacity changes and changed consent conditions
Possible Minor Medium
Ensure flexibility to upgrade WWTP. Ensure
spare capacity in land treatment system
Possible Minor Medium Ensure future
flexibility to upgrade Whakatāne oxidation
Possible Minor Medium
Ensure flexibility in WWTP and Whakatāne and
Edgecumbe ocean outfall
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At Thornton Land 3 (TL3) At Whakatāne Ocean 1 (WO1) At Whakatāne Ocean 5 (WO5)
NO Source /
Well-being Hazard Threat Risk
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures
Possible
Likelihood Rating
Consequence Rating
Current Risk
Further Risk Mitigation Measures Possible
ponds and ocean outfall operation
5 Unexpected Geotechnical risks (instability, water tables, etc.)
Possible Minor Medium Thorough investigation,
route selection and design
Possible Minor Medium Thorough
investigation, route selection and design
Possible Minor Medium Thorough investigation,
route selection and design
6 Available power supply Possible Minor Medium Thorough investigation,
route selection and design
Possible Minor Medium Thorough
investigation, route selection and design
Possible Minor Medium Thorough investigation,
route selection and design
7 Insufficient construction corridor in roads Unlikely Minor Low
Based on Greig Road route. Higher risk for state highway route
option
Possible Minor Medium Thorough
investigation, route selection and design
Possible Minor Medium Thorough investigation,
route selection and design
O Operating and Maintenance
1 Septicity and odour nuisance and corrosion: Unexpectedly more difficult to mitigate
Possible Severe High Appropriate design and
operation Possible Severe High
Appropriate design and operation
Unlikely Minor Low
Appropriate Edgecumbe oxidation pond treatment
and conveyance
2
Technical and Operational: Operational Resilience - unexpected critical failure to key elements of solution e.g. power failure at pump stations
Possible Minor Medium
Appropriate design and operation of Matatā
conveyance and upgraded WWTP
Possible Severe High
Appropriate design and operation of
Matatā conveyance and upgraded
Whakatāne WWTP
Possible Minor Medium
Appropriate design and operation and contingency
plan including more storage at Edgecumbe
oxidation pond
3 Natural hazard risks, e.g. earthquakes, floods, landslips, coastal zones etc
Possible Severe High Appropriate design and
operation of Matatā conveyance and WWTP
Possible Severe High
Thorough investigation, route
selection, design and resilient engineering
Possible Minor Medium
Appropriate investigation design, resilient engineering and
contingency planning
PC Planning, Consenting, Approvals
1 Land for treatment and disposal: Unexpectedly more difficult to find, purchase, and secure long term leases and consents
Possible Severe High Thorough investigations
of the use of WDC coastal reserve
NA NA NA NA NA NA NA NA
2
Resource consents: Unexpectedly more difficult to obtain. Conveyance mains alignment and pump stations, unexpectedly more difficulty to get approval
Possible Severe High
Thorough investigation and effective consultation and appropriate resource
consent conditions
Possible Severe High
Maximise advantage of using existing
Whakatāne consent as far as possible
Possible Minor Medium
Maximise advantage of using existing Whakatāne
outfall consent and Edgecumbe oxidation
pond consent for treatment (not discharge) as far as
possible
3 More stringent future Tarawera Catchment Management Plan requirements than anticipated
NA NA NA NA NA NA NA NA NA NA NA NA
PH/S/CE Public Health/Social/Community Environment
1 Resistance to treatment and disposal facilities near/on private property
Possible Severe High Consultation and appropriate siting
Unlikely Minor Low
Effective consultation and appropriate
consent conditions, but these are existing
treatment facilities
Unlikely Severe Medium
Effective consultation and appropriate consent
conditions
2 Public Health: Unexpectedly risks/ high impact e.g. micro-organisms not treated effectively
Possible Minor Medium WWTP design and
operation with effective disinfection
Possible Severe High
3 Unexpected noise effects from facilities on individual properties
Unlikely Severe Medium Appropriate siting and
design operation Unlikely Severe Medium
WWTP design and operation with
effective disinfection Possible Severe High
WWTP design and operation with effective
disinfection
4 Public Health nuisance from any overflows/breakdowns
Possible Severe Medium Appropriate siting and design operation and
contingency plan Possible Severe Medium
Appropriate siting and design operation and contingency planning
Possible Severe Medium
Appropriate siting and design operation and contingency planning
C Maori Cultural – WDC to Advise TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD
O Other
1 Unexpected difficulties as WDC do not have ownership of the Kawerau District Council wastewater infrastructure
NA NA NA NA NA NA NA NA NA NA NA NA
2 Other ??? TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD
TBD
Notes
This table identifies additional procedures and approaches that could be adopted to reduce the risk category gener ally allowed for in the options conceptual development to date and allowed for in the indicative cost estimates. Such further risk mitigation matters can be expected to have additional cost implications. En - Environmental Ec - Economic T - Technical OP – Operating and Maintenance PC – Planning, Consenting, Approvals PH/S/CE – Public Health/Social/Community Environment MC Maori Culture – WDC to Advise O - Other NA Not Applicable TBD – To Be Determined
Risk Colour Coding as follows: Low Grey Medium Yellow High Blue Extreme Red Refer Table 7.1 likelihood scale classification Table 7.2 consequence style classification Table 7.3 Risk Classification
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9 Tāneatua and Te Teko Options
9.1 Tāneatua
Tāneatua is located on the Whakatāne River approximately 15km from Whakatāne. The WWTP is
located to the west of the town and is currently authorised to discharge wastewater to the Whakatāne
River as described in Section 2.12 until 1 October 2026.
WDC currently monitors the volumes of treated wastewater discharged to the Whakatāne River which
varies between 50 and 150 m3/day. Microbiological samples are collected upstream and downstream of
the discharge every two months.
WDC Officers note that during summer there are times when there is no observable discharge from the
WWTP itself. It is likely at these times that a combination of treated wastewater seeping through the
base of the ponds, along with low inflow volumes and high levels of evapotranspiration, lead to this
occurrence.
Any future discharge to water consent sought would be treated as a discretionary activity and would
need to be assessed against the ‘potable water’ classification of the Whakatāne River in the Regional
Land and Water Plan. Given this, should a direct to water discharge continue to be preferred in the
future, additional treatment including possible disinfection, may be required.
However, although no site investigations have been undertaken, the area surrounding Tāneatua
appears to have well drained soils, and this along with the relatively low volumes of wastewater
requiring treatment, means that a local land based treatment and disposal system may be appropriate.
A number of site specific investigations/assessments are recommended ahead of expiry of the existing
Tāneatua discharge consent including:
Develop an outline programme of works for the resource consent application ahead of the
current consent expiry date;
Review of the existing monitoring programme to determine appropriateness of inform any future
resource consent application;
Assess the effects of the existing discharge on the water quality and ecology of the Whakatāne
River, guided by the relevant BOPRC planning framework (particularly the potable water
classification of the Whakatāne River) and the NPS-FM;
Investigate the feasibility of a local land application/treatment option;
Investigate the feasibility of conveying raw sewage to the Whakatāne oxidation ponds and also
the option of Tāneatua oxidation pond treated wastewater to the Whakatāne ocean outfall or the
Whakatāne maturation pond(s); and
Reflecting on the overall WDC Wastewater Strategy and considering a future option that is
compatible with that going into the future e.g. standalone schemes or regional (conveyance)
type schemes.
9.2 Te Teko Options
A number of investigations have been undertaken to potential wastewater treatment and disposal
options for the currently unsewered township of Te Teko.
Harrison and Grierson (2009) both oxidation pond and package WWTP options including discharge
scenarios to the Rangitaiki River, land disposal to the Rangitaiki Plains, spray irrigation to forestry and
land disposal to the Te Teko golf course.
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The preferred option for treatment and disposal was an appropriate and robust package WWTP with
disposal to the golf course, as compared to the other systems assessed whilst still producing high
quality effluent.
This Report has not assessed Te Teko in any further detail at this stage. It is noted that the combined
Matatā and Edgecumbe option KL1 standalone or the Edgewater Option 1, which both convey raw
sewage to Kawerau, passes through Te Teko. If either of these options were progressed Te Teko could
be connected to this conveyance line at a later date. Alternatively, wastewater sourced from Te Teko
could be conveyed to Edgecumbe for either storage, treatment or conveyance for treatment and
discharged elsewhere (e.g. Whakatāne WWTP) in one of those Edgecumbe options.
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10 Conclusions and Next Steps
10.1 Conclusions
10.1.1 Edgecumbe Standalone Options
A large number of options have been considered for the future treatment, conveyance and disposal of wastewater sourced from Edgecumbe. Taking into account a range of considerat ions including cost, the ranking of the top three options were:
1. Option 4 – Oxidation Pond Wastewater to Whakatāne WWTP Ocean Outfall;
2. Option 5 – Raw Sewage to Whakatāne WWTP; and
3. Option 8A – Upgraded Oxidation Ponds and Land Application at Whakatāne Airport.
Options 4 and 5 propose the conveyance of either wastewater treated in the oxidation ponds at Edgecumbe or raw sewage to Whakatāne WWTP. Both options utilise the existing infrastructure at the Edgecumbe and Whakatāne WWTP’s, and would require a condition change to the existing resource consent for the discharge of treated wastewater from the Whakatāne WWTP, or a new consent to be applied for.
Land application at the Whakatāne Airport also ranks highly, and may be possible to combine with a future treatment option at the Whakatāne WWTP, where land application of treated wastewater from the Whakatāne ponds may be possible in the future.
10.1.2 Matatā/Edgecumbe Combined Options
Similar to the Edgecumbe standalone options considered above, a wide range of future treatment, conveyance and disposal options were considered for a combined Matatā and Edgecumbe wastewater scheme. Taking into account a range of considerations including cost, the ranking of the top three options were:
1. Option WO5 – Conveyance of Matatā raw sewage to Edgecumbe oxidation ponds. Edgecumbe
oxidation ponds treated wastewater for joint Whakatāne Ocean Outfall discharge
2. Option WO1 – Conveyance of Matatā raw sewage to Thornton and Edgecumbe raw sewage to
Thornton – then combined to Whakatāne WWTP and Ocean Outfall Discharge; and
3. Option TL3A - Conveyance of Matatā raw sewage to Edgecumbe. Joint treatment at
Edgecumbe oxidation ponds and conveyance to land application at the Whakatāne Airport.
Similar to the Edgecumbe standalone options, the conveyance of treated wastewater to Whakatāne in option WO5 has a number of advantages over the conveyance of raw sewage in WO1. Land application at Whakatāne airport also ranks highly and should be included in further considerations.
10.1.3 Taneatua and Te Teko
A number of site specific investigations/assessments are recommended ahead of expiry of the existing
Tāneatua discharge consent including:
Develop an outline programme of works for the resource consent application ahead of the
current consent expiry date;
Review of the existing monitoring programme to determine appropriateness of inform any future
resource consent application;
Assess the effects of the existing discharge on the water quality and ecology of the Whakatāne
River, guided by the relevant BOPRC planning framework (particularly the potable water
classification of the Whakatāne River) and the NPS-FM;
Investigate the feasibility of a local land application/treatment option;
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Investigate the feasibility of conveying raw sewage to the Whakatāne oxidation ponds and also
the option of Tāneatua oxidation pond treated wastewater to the Whakatāne ocean outfall or the
Whakatāne maturation pond(s); and
Reflecting on the overall WDC Wastewater Strategy and considering a future option that is
compatible with that going into the future e.g. standalone schemes or regional (conveyance)
type schemes.
No specific actions have been identified for Te Teko, although it remains a possibility that future wastewater treatment options include conveyance of wastewater to the existing Edgecumbe oxidation ponds for treatment, and either conveyance or discharge.
10.2 Next Steps
It is recommended that the following options are taken forward for consultation as the Project progresses:
Edgecumbe standalone:
Options 4, 5 and 8A.
Combined Matatā/Edgecumbe options:
Options WO1, WO5, TL3A.
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11 Acknowledgements Terry Long and Paul Futter – Bay of Plenty Regional Council
Whakatāne District Council Officers
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12 References Whakatāne District Council
Wastewater Contract 15-069 Work Stream 2a and Variation for2b: MWH Compilation of Reference Documents
1. Appendix A#2 Electro Care Technologies Ltd Edgecumbe Sewers 3 – 5
Electrical Report
2. Appendix B#2 Edgecumbe Wastewater Reticulation Repairs – Pumping
Station (Feb 2011 -May 2011
3. Appendix C Rainfall Figures - Thornton Rain Gauge 23042011 – 30042011
4. Appendix D Plans#2
5. AWT Cost Estimate Report - April 2013
6. AWT Matatā Wastewater Servicing Peer Review – Oct 2011
7. AWT Whakatāne & Ohope Wastewater Treatment Ponds – Capacity
Review October 2010 – Final
8. Bay of Plenty Regional Council Resource Consent Application and Consent No. 62659 for
Whakatāne Air Discharge Permit
9. Bay of Plenty Regional Council Rights in Respect of Natural Water (for Whakatāne Consent
No 02 0368 granted 28 July 1978 & Edgecumbe Effluent
Discharges – Edgecumbe Consent No. 02 0702 granted 1 May
1980 – both expire 1/10/2026)
10. Bay of Plenty Regional Council Workbook for Edgecumbe Oxidation Pond Discharge to
Omeheu Canal – 1998 to 2015
11. Bay of Plenty Regional Council Workbook for Whakatāne Oxidation Pond Discharge to the
Bay of Plenty Marine Environment – 2000 to 2015
12. Bay of Plenty Regional Council Operative Regional Policy Statement
Regional Water & Land Plan
Regional Plan for Tarawera River Catchment
Regional Coastal Environment Plan
13. CPG Matatā Wastewater Treatment Scheme Review – Nov 2011
14. Appendix A#2 Electro Care Technologies Ltd Edgecumbe Sewers 3 – 5
Electrical Report
15. Harrison Grierson Detailed Design Report (A421400) Feb 2014
16. Harrison & Grierson First Time sewerage for the community of Matatā Preliminary
Design Report Dec 2009
17. Harrison Grierson Wastewater Scheme for the Towns of Edgecumbe, Matatā and
Te Teko Options Report Sept 2004
18. Iwi Environmental Management Yet to be determined.
19. Plans & Settlement Acts
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20. MWH Review of the Whakatāne District Sewage Treatment and
Disposal Schemes Jan 2002
21. MWH Wastewater Review and Options Study for Edgecumbe
Wastewater Treatment and Disposal – Proposal 15-069 May
2012
22. MWH Edgecumbe: Options for Upgrading Wastewater Treatment
and Disposal 2002 (show as 2014 on cover)
23. MWH, URS, WDC Matatā Wastewater Scheme – Resource Consents and
Notices of Requirement Assessment of Effects on the
Environment - November 2013
Support Documents
1 Matatā Wastewater Scheme – Consultation Strategy
2 Natural Hazards, Constraints and Risk Assessment
3 Flowrates and Mass Land Assessment for Determination of Land Disposal Field Requirements
4 Alternatives Assessment Information
5 Matatā Wastewater Scheme – Wastewater Land Application Groundwater Assessment
6 Matatā Wastewater Scheme – Receiving Water Quality, Ecological and Public health Risk Assessment
7 Ecological Assessment of Potential Sites for the Proposed Matatā Wastewat4er Treatment Plant and Disposal Filed – Amended following Selection of the Disposal Field Site
8 Assessment of Landscape and Visual Effects for the Proposed Matatā Wastewater Treatment Plant
9 Draft Restoration and Enhancement Plan for the Mitigation and Management of the Proposed Matatā Wastewater Treatment Disposal Field and Adjacent Dunelands
10 Consultation Records
24. MWH Matatā Review of Design Flows Final 03.03.14
25. NZ Government NPS for Freshwater Management 2014
NZ Coastal Policy Statement 2010
Local Government Act 2002
NZ Government Treasury Report Guidelines 30 Year Infrastructure Strategies
Reserve Act 1977
26. Opus Technical Memo Whakatāne WWTP Mill Rd Abattoir Loading
March 2015
27. Opus Wastewater Treatment and Management Options for
Edgecumbe and Matatā – 15 July 2013
28. Opus WDC Contract 12/001 – Edgecumbe Wastewater Upgrade –
Preliminary Design Report – Jan 2012
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29. Opus Whakatāne Wastewater Treatment Plant – Optimisation
Report – Nov 2011
30. Opus Edgecumbe Reticulation Preliminary Design Report – Oct
2011 plus Appendices Plans A2, B2, C & D
31. Opus Whakatāne District Wastewater Treatment Ponds: Desludging
Requirements May 2010
32. Opus Edgecumbe Ponds Wastewater Discharge – Effects on the
Omeheu Canal Water Quality – 2009
33. Opus Edgecumbe Wastewater Treatment – Design Report – June
2007??
34. Opus Whakatāne Wastewater Treatment Plant – Optimisation
Report – Nov 2007
35. Opus Whakatāne and Ohope Ocean Outfall Condition Survey Date
??
36. URS (Letter) Matatā Wastewater Scheme – High level Cost
Estimate Review – 7 March 2014
37. URS R004 - Matatā WWTP flowrate and mass load Assessment
Memo Rpt20130614 Final - June 2013
38. Whakatāne District Council Long Term Plan 2015-2025
39. Whakatāne District Council 15-069 Professional Services for Wastewater Review &
Options – Study for Edgecumbe Wastewater Treatment &
Disposal – June 2015
40. Whakatāne District Council Draft Infrastructure Strategy 2015 – 45 (vA821419)
41. Whakatāne District Council 2013/2014 Wastewater Asset Management Plan
42. Whakatāne District Council Matatā Options Strategic Review and Edgecumbe Options
Part 5
43. Whakatāne District Council Sustainability Strategy 2010-2015
44. Whakatāne District Council Operative & Proposed District Plan
45. Whakatāne District Council LIDAR Information
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13 Glossary of Terms and Abbreviations
Activated Carbon Filters A bed of activated Carbon through which foul air is passed to remove odour compounds
Actiflo Refer Section 2.8 of Report – a treatment process for clarifying wastewater and removing phosphorus.
ADF Average daily volume/flow in mᶟ/day
ADWF Average dry weather flow in mᶟ/day
AECOM (URS)
Consultants involved in the Matatā standalone options investigations – Formally URS Consultants.
AEE Assessment of Effects on the Environment for Matatā Consents and Designations dated December 2013
Best Practicable Option (BPO)
In terms of the Resource Management Act 1991 – “in relation to a discharge of contaminant or an emission of noise, means the best method for preventing or minimizing the adverse effects on the environment having regard, among other things, to: The nature of the discharge or emission and the sensitivity of the receiving environment to adverse effects; The financial implications, and the effects on the environment, of that option when compared with others options; and The current state of technical knowledge and the likelihood that the option can be successfully applied.”
Biochemical Oxygen Demand (BOD, cBOD5)
Carbonaceous biochemical oxygen demand (cBOD5) measured as 5 day standard test. It is a measure of organic matter or organic strength of the water, reported as the mass of oxygen consumed per L of water (mg/L). A quicker measure of the organic strength is COD, which is measured through chemical oxygen. The COD in urban wastewater is roughly twice the BOD.
Biofilters, Biotrickling Filters Refer Section 2.6 & 1.2 of this Report - odour control treatment processes
BoPRC Bay of Plenty Regional Council, also referenced to as the Regional Council
BPTRC = TMCP Bay of Plenty Regional Plan for Tarawera River Catchment
Conveyance Terminology Refer to Section 2.6 of this Report
DWF Dry Weather Daily Flow
EDG Edgecumbe
Effluent Treated Wastewater (effluent is considered an outdated word)
Engineering Resilience The material selection, design and generation of infrastructure to add resistance/future proofing against natural hazards and other unexpected events
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Faecal Coliform (FC)
Faecal coliform (FC) are bacteria. Their presence may indicate that the water has been contaminated with faecal material from of humans or other animals. Like E.coli this bacteria is used as an indicator micro-organism for pathogenic (germ) micro-organisms.
GIS Geographic Information System
Grinder Pumps Small pumps that are housed in factory made pump stations that grind the raw sewage up for collection and conveyance
H&G Harrison and Grierson – Consultants
HDPE High Density Polyethylene Pipe as used for estimating in the
Conveyance options
KDC Kawerau District Council
L Land Application of Treated Wastewater
LAF Land Application Field as previously applied to the earlier Matatā Wastewater Consenting project
LGA Local Government Act 2002
LPS Low Pressure Wastewater Collection System (LPS) involving grinder pumps on each individual serviced property.
LTP Whakatāne District Councils Long Term Plan 2015 - 2025
M Matatā
MBBR Refer Section 2.8 of this Report. A treatment process for removing organic matter and nutrients particularly Nitrogen
MCA Multi criteria Assessment – a decision making tool to compare evaluation criteria and options
mg/L Milligrams per litre is a concentration measure of a contaminant in liquid, is the same as mg/L is the same as g/m3 and is in effect the same as parts per million (ppm)
MWH Consultants undertaking this contract 15-069 project
NA or N/A Not Applicable
No/100mL Number of micro-organisms per 100 ml of sample
NPS - FM National Policy Statement on Freshwater Management 2014
NPV Net Present Value – The estimated costs of capital and annual operating costs taken on a 20 year basis (refer Section 4.1 of this Report)
NZCPS New Zealand Coastal Policy Statement 2010
O Whakatāne Ocean Outfall (as the discharge point)
O&M Operating and Maintenance
Option Same as “alternatives” in terms of RMA definitions
Opus Consultants
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OPW Oxidation Pond Treated Wastewater
Oxidation Ponds A natural pond type of wastewater treatment as presently used at Edgecumbe and Whakatāne. The treatment capacity can be increased by addition of mechanical aerators
PE
Population equivalents – Determine by dividing the ADWF (average daily wastewater volume by the average per capita production of wastewater (at 225 litres per head per day) to determine the number of PE’s. Can also be calculated on a BOD or other contaminant basis especially if there is a significant trade waste discharge included
Peaking Factor The increase of a PWWF from an ADWF or other determined lower flow e.g. ADF
PS Pump Station
PWWF Peak wet weather flow in L/sec or mᶟ/day
Q&A Questions and Answers
Retention Time The time the raw sewage or treated wastewater is retained in the conveyance system or a treatment process (refer to section 2.6 of this Report)
RIB’s Rapid Infiltration Basis – rapid land soakage beds at KDC’s WWTP
Rising Main A conveyance main where the raw sewage or treated wastewater is pumped (Refer to Section 2.6 of this Report)
Risk Assessment Categories
As set out in Section 7 of this Report
RMA Resource Management Act, 1991
Rohe Maori boundary, district, region, territory, area, border (of land)
Septicity Where raw sewage or partly treated sewage goes septic (sour) through anaerobic decomposition and emits hydrogen sulphide and other odourous gases (refer to Section 2.6 of this Report)
Suspended Solids SS = TSS Suspended Solids equals Total Suspended Solids (SS=TSS)
T Thornton
TBD To Be Determined
TMCP = BPTRC Bay of Plenty Regional Plan for Tawerau River Catchment
TN Total Nitrogen
URS Consultants who are involved in the Matatā standalone investigations – now AECOM
USEPA United States of America, Environmental Protection Agency
WWTP Wastewater Treatment Plant
√ Option confirmed for the Long List
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X Option Parked – option not included in confirmed long list but could be reconsidered later if required
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Edgecumbe Oxidation Ponds Flow Balancing Technical Memorandum
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Whakatāne Oxidation Ponds – Capacity Assessment Technical Memorandum
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Legal Advice on Regional Plan for the Tarawera River Catchment
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Edgecumbe Standalone Options – Long List Assessment
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Edgecumbe Standalone Options – Short List Route Alignments
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Matatā and Edgecumbe Combined Options – Long List Assessment
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Matatā and Edgecumbe Combined Options – Short List Route Alignments
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Conveyance Capital and Annual Operating and Maintenance Costs
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Treatment and Disposal / Discharge Capital and Annual Operating and Maintenance Costs
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Net Present Value Estimated Costs
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Actiflo® and MBBR Treatment Processes Supplier Information