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Pūhoi to Warkworth Motorway PPP

Erosion and Sediment Control Plan Doc No: 025‐MGP‐003‐NX2

Contract No: NZTA PA4030

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EROSION AND SEDIMENT CONTROL PLAN

DOCUMENT DETAILS

Document Name Status Document No. Author

Erosion and Sediment Control Plan Rev 01 025‐MGP‐003‐NX2 Mike McConnell

DOCUMENT HISTORY AND STATUS

Revision Date Author Position Status

A 23/03/2016 Mike McConnell ESC Specialist First Draft

B 06/10/2016 Mike McConnell ESC Specialist Full Draft

B.01 25/11/2016 Mike McConnell ESC Specialist Full Draft

B.02 12/12/2016 Mike McConnell ESC Specialist Full Draft

C 20/12/2016 Mike McConnell ESC Specialist Final Draft

C.01 12/01/2017 Mike McConnell ESC Specialist Final Draft

01 26/01/2017 Mike McConnell ESC Specialist Version 01

APPROVALS

Action Name Position Organisation Date Signature

Approved by Hugh Leersnyder

Planning & Environmental Lead Technical Director

CJV 26/01/2017

Transport Agency review finalised

Transport Agency

20/12/2016

REVISION DETAILS

Revision Details

A Included as part of NX2’s Tender Submission

B Updated to address Transport Agency and Hōkai Nuku comments

B.01 Updated to address Transport Agency and Hōkai Nuku comments

B.02 Updated to address Transport Agency comments No further comments from Transport Agency 20/12/2016

C Final Draft – to Auckland Council for approval 20/12/2016

C.01 Final Draft – updated to include comments received from Auckland Council 09/01/2017 Approved by Auckland Council 13/01/2017

01 In Use

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CONTENTS

1 INTRODUCTION 1

1.1 Project Overview 1 1.2 Purpose and Scope 1 1.3 Key erosion and sediment control philosophies 2

Erosion and Sediment Control Planning 3 Erosion and sediment control implementation 3 Erosion and Sediment Control Monitoring 4

1.4 Relevant Consent Conditions 4

2 DOCUMENT STATUS 13

2.1 Relationship with other plans 13 2.2 Responsibility for the ESCP 13 2.3 Plan updates and revisions 13 2.4 Construction Erosion and Sediment Control Plans (CESCP) 13 2.5 ESCP Audience 14

3 DESIGN GUIDELINES AND STANDARDS 15

3.1 General 15 3.2 Auckland Council TP90 / GD05 15 3.3 Construction Water Assessment Report (CWAR) 15

CWAR Estimated Sediment Yield 15

3.4 Maximum Open Earthwork Limits 16 3.5 Earthworks Season Restriction 16 3.6 Additional Consent Requirements 16 3.7 Chemical Treatment Management 17 3.8 Kauri Dieback Biosecurity 17

4 ROLES AND RESPONSIBILITIES 18

4.1 Introduction 18 4.2 Management team structure 18 4.3 ESCP implementation 19 4.4 Specific roles of key environmental personnel 19

SPV Project Director 19 D&C Project Director 20 Construction Manager 20 Key Relationship Manager 21

Environmental Manager Construction 22 Senior Environmental Advisor North / South 22 Senior Environmental Advisor Compliance 23 Environmental Supervisor 24 Erosion and Sediment Control Management Team 25 Training 26

5 EROSION AND SEDIMENT CONTROL IMPLEMENTATION 27

5.1 Structural vs Non‐structural Controls 27 5.2 Innovation 28

Proactive Innovation 28 Reactive Innovation 28

6 EROSION AND SEDIMENT CONTROL MINIMUM STANDARDS 30

6.1 Maximum open earthwork area limits 30 Maximum open earthwork area monitoring 30 Progressive Stabilisation 30

6.2 Earthworks season restriction 31 6.3 Erosion and Sediment Control Requirements 31

Minimise disturbance 32 Erosion control 32 Sediment control 33 Last Line of Defence 36 Chemical Treatment Management Plan 36 Streamworks 36 Coastal Works 37 Vegetation Removal 39 Decommissioning of Controls 39 Dewatering 40

6.4 Watercare 40 6.5 Precast Yard 40 6.6 Personnel 40 6.7 Review, monitor and adjust 40

Evolving plan 40 Inspect, assess and adjust 41 Assign responsibilities and accountabilities 41

7 INCIDENT RESPONSE 42

7.1 Incident Definition 42 7.2 Incident Identification 42 7.3 Incident Notification 42 7.4 Corrective Actions 43

8 CONSTRUCTION EROSION AND SEDIMENT CONTROL PLANS 44

8.1 Introduction 44 8.2 Preparation 44 8.3 Hōkai Nuku Engagement in the preparation of CESCPs 44 8.4 Content 45 8.5 Revision 46

Minor Changes 47 Major Changes 47

9 MONITORING 48

9.1 Weather Monitoring 48 9.2 Reporting 48 9.3 Environmental performance metrics 48

APPENDIX 1 CHEMICAL TREATMENT MANAGEMENT PLAN 50

APPENDIX 2 HŌKAI NUKU ENGAGEMENT MEMO 76

APPENDIX 3 DEWATERING MANAGEMENT GUIDELINES 84

APPENDIX 4 DEVICE SPECIFIC DETAILS 101

FIGURES Figure 1: Indicative alignment in relation to chainage along the alignment 1

Figure 2: Example Maximum Open Area Histogram 30

Figure 3: Efficiency hierarchy 34

TABLES Table 1: Construction Staging 2

Table 2: Erosion and Sediment Control Conditions 5

Table 3: CWAR Estimated Sediment Yield 15

Table 4: SPV Project Director 19

Table 5: D&C Project Director 20

Table 6: Construction Manager 20

Table 7: Key Relationship Manager 21

Table 8: Environmental Manager Construction 22

Table 9: Senior Environmental Advisor North / South 22

Table 10: Senior Environmental Advisor Compliance 23

Table 11: Environmental Supervisor 24

Table 12: Erosion and Sediment Control Management Team 25

Table 13: Examples of Structural and Non‐structural Controls 27

Table 14: The Transport Agency contractor's field guide checklists 49

GLOSSARY OF ABBREVIATIONS AND TERMS Acronym Definition

ha Hectare

m metre

m2 Square metre

m3 Cubic metre

Anti‐seep collar A projecting collar built around the outside of a pipe, tunnel, or conduit under or through an embankment dam to lengthen the seep path along the outer surface of the conduit.

AC Auckland Council

AEP Annual exceedance probability

AMP Adaptive Monitoring Plan

ARI Average return interval

Batch dosing Application of flocculant (during flocculant treatment) in a single dose, rather than through a continuous flow proportional dosing system).

BPO Best Practicable Option

CEMP Construction Environmental Management Plan

CESCP Construction Erosion and Sediment Control Plan

Check dam A small, often temporary, dam constructed across a swale, drainage ditch, or waterway to counteract erosion by reducing water flow velocity.

Clean Water Water runoff that is free of sediment or pollutants. In an ESC context this usually refers to water from above a work site that has not run through the works area.

Construction Works

Activities undertaken to construct the Project, excluding Enabling Works

Contour Drain Temporary excavated channels or ridges, or a combination of both, that are constructed slightly off the slope contour. The purpose of a contour drain is to break overland flow that is draining down disturbed slopes, by reducing the slope length, and thereby reducing the erosive power of runoff. The drain also diverts sediment‐laden water to appropriate controls via stable outlets.

ChemTMP Chemical Treatment Management Plan

CWAR Construction Water Assessment Report (Further North Alliance August 2013)

DEB Decanting Earth Bund

Dewatering The removal of water from excavations, tunnelling, trenches and sediment control devices. Dewatering may be the removal of either surface water or groundwater that has collected.

Dirty Water Sediment‐laden runoff. In an ESC context this usually refers to water that has run through a works' area. This water requires treatment prior to discharge.

Acronym Definition

Diversion Channels and Bunds

A non‐erodible channel and/or bund for the conveyance of clean or dirty water runoff that is constructed for a specific design storm.

EM Environmental Manager

Enabling Works Preliminary activities, including such things as geotechnical investigations (including access for such investigations), sealing roads, and establishment of mitigation measures (such as earth bunds and planting)

ESCP Erosion and Sediment Control Plan

Filter Sock A tubular stormwater sediment control and filtration device, consisting of a mesh tube filled with a filter material (e.g. compost, sawdust, wood bark, straw) used to intercept and filter runoff. They are also referred to as ‘silt socks’.

Flat Country That part of the Project to the north of the Perry Road Viaduct (Chainage 53400)

Flocculent Treatment

A sediment control practice that involves the addition of reagents to sediment‐laden runoff to increase the rate of settlement of fine soil particles. Flocculent treatment relies on two basic processes: ‘coagulation’ and ‘flocculation’.

Flume A temporary pipe structure or constructed flume placed from the top of a slope to the bottom of a slope. The structure is designed to convey a concentrated flow of either clean or dirty surface runoff down a slope or through or around a work area without causing erosion.

GD05 Erosion and Sediment Control Guide for Land Disturbing Activities in the Auckland Region – June 2016 (Guideline Document 2016/005)

Geotextile Permeable fabric which, when used in association with soil, has the ability to stabilise and protect.

Grassing The planting and establishment of quick growing and/or perennial grass to provide temporary and/or permanent stabilisation on exposed areas. The practice is often undertaken in conjunction with the placement of topsoil.

Hill Country That part of the Project to the south of the Perry Road Viaduct (Chainage 53400)

Hotmix diversion bund

A bund constructed of hotmix directly on the impervious surface.

Hydroseeding The application of seed, fertiliser and paper or wood pulp with water in the form of a slurry, which is sprayed over an area to provide for re‐vegetation

Mulching A soil stabilisation practice that involves the application of a protective layer of straw or other suitable material to the soil surface.

NZTA New Zealand Transport Agency

PAC Polyaluminium chloride

Rip‐rap A layer of large stones used to protect soil/shorelines from erosion in areas of concentrated runoff or scour.

RoNS Roads of National Significance

Acronym Definition

Runoff Surface water runoff (also known as overland flow) is the flow of water that occurs when excess stormwater, meltwater, or other sources flows over the earth's surface.

SEAN Senior Environmental Advisor North

SEAS Senior Environmental Advisor South

SEAC Senior Environmental Advisor Compliance

Sedimentation The deposition of eroded soil.

Sediment yield The amount of sediment discharged from a catchment reaching or passing a point of interest in a given period of time. Sediment yield estimates are normally given as tonnes per year or kilograms per year.

SF Silt Fence

SPV Special Purpose Vehicle (the NX2 Group) is a separate legal entity that contracts to the NZ Transport Agency for the design, construct, maintenance and financing of the P2Wk project. The SPV subcontracts (and passes down all its contractual obligations) of the project works to the design and build subcontractor, and separately the asset management and maintenance to a separate subcontractor. The SPV is also responsible for obtaining all debt and equity funding required for the project.

SSF Super Silt Fence

SRP Sediment Retention Pond

Stabilisation The activity to achieve a Stabilised Area

Stabilised Area An area inherently resistant to erosion such as rock, or rendered resistant by the application of aggregate, geotextile, vegetation or mulch. Where vegetation is to be used on a surface that is not otherwise resistant to erosion, the surface is considered stabilised once an 80% vegetation cover has been established.

Team Leader Auckland Council Team Leader Compliance and Monitoring – Northern Resource Consenting and Compliance (Orewa) or the person subsequently exercising those functions and powers

TP90 Auckland Council Technical Publication 90 ‐ Erosion and Sediment Control Guidelines for Land Disturbing Activities in the Auckland Region 1999 (updated 2007)

TSS Total Suspended Solids

USLE Universal Soil Loss Equation

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EROSION AND SEDIMENT CONTROL PLANEROSION AND SEDIMENT CONTROL PLAN PAGE 1 PŪHOI TO WARKWORTH PPP – RESTRICTED – COMMERCIAL

1 INTRODUCTION This Erosion and Sediment Control Plan (ESCP) has been prepared for the Pūhoi to Warkworth section of the Ara Tūhono Pūhoi to Wellsford Road of National Significance (RoNS) in accordance with the requirements of Resource Consent Condition RC18B.

It has been prepared by Northern Express Group (NX2) as part of its obligations under the Project Agreement. Implementation of this ESCP will ultimately be the responsibility of the Construct Joint Venture (CJV).

The Construction Sub‐contractor is referred to throughout this plan as the CJV. The word ‘sub‐contractor’ in this plan relates to sub‐contractors, which the CJV will engage on the Project.

During the preparation of this ESCP NX2 has engaged with the Iwi Advisor. During this engagement Hōkai Nuku provided cultural indicators which were addressed during the preparation of this ESCP.

1.1 Project Overview The Pūhoi to Warkworth section of the Ara Tūhono Pūhoi to Wellsford RoNS (the Project) will be an 18.5 km extension of the existing Northern Motorway from the termination of the Northern Gateway Toll Road at the Johnstone’s Hill tunnels to State highway 1 (SH1) just south of the Kaipara Flats Road intersection, north of Warkworth. The Project will provide a new and alternative alignment to the existing SH1 route, traversing land to the west of the existing SH1 and bypassing to the western side of Warkworth. Specifically, the Project will comprise a four‐lane dual carriageway motorway divided by a central median with a safety barrier.

The indicative alignment is shown by the green line in Figure 1, along with the Project designation (red line) and main construction zones – northern, central north, central south and southern (including associated chainages). The final alignment and design has been developed to minimise earthworks and exposed area as far as is practicable.

Figure 1: Indicative alignment in relation to chainage along the alignment

1.2 Purpose and Scope This ESCP forms part of the suite of plans that form the broader Construction Environmental Management Plan (CEMP) for the Project. The ESCP covers all stages of Project construction, as outlined in Table 1 below.


Table 1: Construction Staging

Defined in Designation conditions as:

Stage Description of Works Approx. Duration

ENABLING WORKS Enabling Works As defined by the designation definitions and consent conditions as preliminary activities, including: geotechnical investigations road sealing establishment of mitigation

measures.

October 2016 – June 2017

Duration:

9 months

CONSTRUCTION WORKS

Early Works Comprising activities required to facilitate an efficient start to main construction works that are not within the scope of Enabling Works.

February 2017 – July 2018

Duration:

18 months

CONSTRUCTION WORKS

Main Construction Works

Core construction works associated with permanent aspects of the Project that are not included in the Early Works stage

October 2017‐October 2021

The principal purpose of this Erosion and Sediment Control Plan (ESCP) is to ensure that the works associated with the Project are undertaken in a manner that ensures the potential or actual discharges of sediment as a result of the works are minimised to the greatest possible extent.

The achievement of the above will ensure that the objectives of Resource Consent Condition RC17 are met, specifically:

RC17 The Consent Holder shall implement all Construction Works in accordance with the best methods available at the time of construction to:

(a) Minimise the volume and area of the proposed earthworks required for the Project through the design of batter slopes appropriate to expected soil types and geology;

(b) Maximise the effectiveness of erosion and sediment control measures associated with earthworks by minimising potential for sediment generation and sediment yield; and

(c) Minimise effects on freshwater and marine water environments within or beyond the Project boundary, with particular regard to reducing the likelihood that the Project will generate sediment at the trigger level specified in Condition RC36(d). (Refer Project Adaptive Management Plan)

The philosophies to be utilised to achieve the above objective will be accomplished by following the methods and measures detailed within this document.

Compliance with the requirements of this document will ensure that the Project works meet the requirements of Resource Consent Conditions, industry best practice, client and stakeholder expectations.

1.3 Key erosion and sediment control philosophies Northern Express Group (NX2) has developed philosophies to be adopted in relation to the provision of erosion and sediment controls during construction of the Project. These philosophies are outlined in the following section.


There are three main philosophies in achieving successful erosion and sediment control outcomes:

Planning Implementation Monitoring.

It is to be noted that a key component of the above philosophies is that the erosion and sediment control measures referred to in this document include both structural and non‐structural controls.

Erosion and Sediment Control Planning

The planning of erosion and sediment control will be an integral part of works planning and will be considered throughout the construction planning process.

The initial stage of the planning is the design phase. During this phase the volume and area of the earthworks will be reduced as much as practical. This will be achieved by utilising a design which minimises the footprint of the works by utilising batters specifically designed for the geology, in particular steep batters in rock cuts and utilisation of rock material in fills to allow a steeper fill batter to be utilised. This design also will select a horizontal and vertical alignment that minimises the volume of surplus or unsuitable material to be disposed of.

The above considerations are an iterative design process which also considers minimum alignment standards and criteria and also constructability and urban and landscape design considerations.

For each area of work where earthworks or streamworks will be undertaken a Construction Erosion and Sediment Control Plan (CESCP) will be prepared and submitted, in accordance with Resource Consent Conditions RC28 and RC29. Further details of the preparation of CESCPs is detailed in Section 8.

The preparation of each CESCP will consider a number of factors including:

The construction activity to be undertaken The magnitude of the works, including area and volume The soil types to be encountered The location of the works with particular consideration of the immediate receiving environment, The duration of the works The time of the year that the works are to be undertaken.

Further information regarding the preparation of these plans is included in Section 9.3.

Erosion and sediment control implementation

In regards to the required erosion and sediment controls, these physical controls are relatively traditional, refer Section 3, and the implementation of such controls is also a well understood process that has been successfully implemented by the NX2 partners on a number of large earthwork projects.

The management of this process is the key to ensuring that the implementation of these controls results in the greatest possible reduction in sediment discharge as a result of the works. This greatest possible reduction in sediment discharge will in turn minimise effects on freshwater and marine water environments within or beyond the Project boundary and will minimise the likelihood that the Project will generate sediment at the trigger level specified in Condition RC36(d). (Refer Project Adaptive Management Plan).

This will be achieved by developing and maintaining a strong environmental culture within the Project team that highlights the requirement of minimising sediment discharges as one of the key environmental outcomes of the Project.

This culture will be founded on a basis of ownership and accountability.


As part of initial site inductions and regular tool box training sessions, the values of the receiving environments, the potential effects of sediment discharges and the options for minimising these discharges will be discussed.

A critical factor in maintaining this culture will be providing feedback to the site staff. This will detail what levels of sediment are being discharged, what effects these discharges are having on the receiving environments and how the various sediment control measures are reducing the sediment discharges from the site.

This process on updating staff on the success of their efforts has been found to be a significant factor in achieving a high level of environmental success.

Erosion and Sediment Control Monitoring

A critical component of the success of the erosion and sediment control measures will be the successful monitoring of these devices.

This monitoring is specifically addressed within the Adaptive Monitoring Plan (AMP).

This monitoring will be undertaken in a number of phases:

Initial monitoring will be undertaken of the construction of the controls to ensure that the controls have been installed in accordance with the approved CESCP. This monitoring will include the preparation and submission of a CESCP As‐built Certification in accordance with Resource Consent Condition RC31

Ongoing monitoring of the performance of the device will also be necessary to ensure that the devices are operating at the design efficiency

Regular and triggered monitoring in accordance with the Adaptive Monitoring Plan (prepared in accordance with resource consent conditions RC33 – RC37) will also be undertaken to confirm that the effects of the discharged sediment are also within the expected parameters.

This monitoring will not only be used as a compliance tool, but predominantly as a tool to enable incremental improvements in the efficiency of controls and subsequently a reduction in the volume of sediment discharged from the site to the greatest extent practicable.

1.4 Relevant Consent Conditions Table 2 outlines the Resource Consent Conditions relevant to this ESCP and where they are addressed in this Plan.


Table 2: Erosion and Sediment Control Conditions

Condition No.

Condition Relevant section of Plan

Earthworks

RC17 The Consent Holder shall implement all Construction Works in accordance with the best methods available at the time of construction to:

(a) Minimise the volume and area of the proposed earthworks required for the Project through the design of batter slopes appropriate to expected soil types and geology;

(b) Maximise the effectiveness of erosion and sediment control measures associated with earthworks by minimising potential for sediment generation and sediment yield; and

(c) Minimise effects on freshwater and marine water environments within or beyond the Project boundary, with particular regard to reducing the likelihood that the Project will generate sediment at the trigger level specified in Condition RC36(d).

1.2

Erosion and Sediment Control Plan

RC19 The ESCP shall include the following:

General

(a) Identification of a suite of appropriate structural and non‐structural erosion and sediment control measures to be installed prior to and during all Construction Works for representative parts of the Project, including earthworks, coastal works and works within watercourses;

(b) The approach and procedures for ensuring advance warning of a rainfall event;

(c) The procedures for decommissioning the erosion and sediment control measures;

(ca) The procedures for determining staging and sequencing of earthworks;

(cb) A procedure to establish and define minor changes to erosion and sediment control, which would not require further certification by the Team Leader prior to implementation; and

(cc) Methods for amending and updating the ESCP as required.

Responsibilities

(d) Identification of:

i. Appropriately qualified and experienced staff to manage the erosion and sediment control devices, associated maintenance procedures and monitoring requirements;

ii. Staff directly responsible for supervising installation, maintenance and decommissioning of erosion and sediment control devices and the associated works;

iii. A chain of responsibility for both the Project and its stages, including the overall manager (with authority to stop works), for managing erosion and sediment control on site;

5.1

9.1

6.3.9

6.1.1

8.5.1

6.7

4.4

4.4

4.4


Condition No.


iv. An erosion and sediment control management team (including representatives from the contractor, Council and the Consent Holder) to meet and review erosion and sediment control practices and procedures as required; and

v. Training requirements for staff.

Incident Management

(e) Identification of the process to ensure compliance with Condition RC32.

(f) Identification of the process to notify Watercare if any of the incidents in Condition RC32 occur upstream of the water take at NZTM 1748780 mE 5970390 mN (Auckland Council Permit No. 35555).

Chemical Treatment Management

(g) A Chemical Treatment Management Plan (ChemTMP) which shall include as a minimum:

i. Specific design details of the chemical treatment system based on a rainfall activated and manual batch dosing methodology for the site's sediment retention ponds (SRPs), decanting earth bunds (DEBs) and container impoundment systems and any other sediment detention or flow device system as may be employed on site;

ii. Monitoring, maintenance (including post storm) and contingency programme (including a record sheet);

iii. Details of optimum dosage (including assumptions);

iv. Results of initial chemical treatment trial;

v. A spill contingency plan;

vi. Details of the person or bodies that will hold responsibility for the operation and maintenance of the chemical treatment system and the organisational structure which will support this system; and

vii. Details of the process to notify Watercare if any flocculants spillage occurs upstream of the water take at NZTM 1748780 mE 5970390 mN (Auckland Council Permit No. 35555).

4.4.9

4.4.10

6.4, 7

6.4, 7

3.7, 6.3.5, 4.4, App 1

Approval of ESCP

RC20A At least 20 working days prior to commencement of Construction Works, the Consent Holder shall submit a hard paper copy of the ESCP to the Team Leader for approval. If the Consent Holder has not received any response (short of approval) from the Team Leader within 20 working days of submitting the ESCP, the ESCP will be deemed approved.

Note

RC20B A copy of the approved ESCP shall be forwarded to Watercare for their information. 6.4

RC20C The Consent Holder shall implement the approved ESCP for the duration of the Construction Works.

4.3

Erosion and Sediment Control Standards

Maximum Open Earthwork Area Limits

RC25 Unless otherwise varied in accordance with the Adaptive Monitoring Programme (set out in Conditions RC33 to RC37), the maximum open area of earthworks limitations shall apply as follows:

6.1, 8.4


Condition No.


(a) Pūhoi Catchment (ie south of Moirs Hill Road) – 41ha at any one time; and

(b) Mahurangi Catchment (ie north of Moirs Hill Road) – 41ha of Hill Country and 21.5 ha of Flat Country (or equivalent ratios) at any one time.

Equivalent Ratios:

A one ha increase in open area of earthworks in the Flat country (above the 21.5 ha limit discussed above) will require a corresponding 0.467 ha reduction in open areas of earthworks in the Hill Country.

The reverse situation is equally applicable, in that a 1 ha increase in open area of earthworks within the Hill Country, (above the 41 ha limit discussed above) will require a corresponding 2.14 ha reduction of open area of earthworks in the Flat country, subject to a maximum open area of earthworks within the Hill Country of 51.05 ha which will result in no earthworks activity being permitted to take place within the Flat country during the same time period.

Calculation of Open Area:

The calculation of open area shall include all temporarily stabilised areas but exclude all permanently stabilised areas.

Earthworks Season Restriction

RC26 For earthworks activity taking place within the indurated rock of the Pakiri Formation geology, no seasonal limitation shall apply, but a revised CESCP providing for winter work in Pakiri formation shall be submitted to the Team Leader by 15 April of the year in which the winter works are proposed.

3.5, 6.2, 8.3

RC26A For all other areas, earthworks activities shall not occur between 30 April and 1 October (winter period) in any one year unless otherwise approved by the Team Leader. Approval of earthworks occurring within the winter period will be based on:

(a) Previous compliance;

(b) The AMP procedures and outcomes as specified in Conditions RC35 to RC37;

(c) The nature of the specific works proposed to be undertaken in the winter period;

(d) The location of the specific works; and

(e) Ability to comply with Condition RC28.

6.2

RC26B In accordance with Condition RC27(i), all areas not subject to earthwork activities during any given winter period shall be stabilised by 30 April of that year. 3.5, 6.2, 8.4

Erosion and Sediment Control Device Requirements

RC27 Unless otherwise agreed with the Team Leader, the Consent Holder shall design, construct and maintain all erosion and sediment control devices to achieve compliance with TP90 and also with the following design requirements (some of which do not form part of TP 90):

(aa) All erosion and sediment control devices shall be located outside the 20 year ARI flood level, unless no other viable location exists.

(ab) Clean and dirty water diversion channels, shall be sized to accommodate the flow from a 100 year ARI storm event where practicable, and at a minimum, the flow from a 20 year ARI storm event and an additional 300mm freeboard.

3.0, 6.0, 8.4


Condition No.


(ac) All temporary stream crossings and temporary culverts shall be sized to accommodate the flow from a 20 year ARI storm event and include a stabilised overland flow path for runoff exceeding the flow expected in a 20 year ARI storm event.

(ad) At all practical times, streamworks activities and associated works shall be undertaken with stream diversions in place to accommodate up to the 20 year ARI rain event. All stream flows above the 20 year ARI rain event shall be diverted, via systems (such as overland flow paths) capable of conveying the 100 year ARI rain event flow around the works area.

(a) Pumping of all sediment laden runoff and groundwater during Construction Works shall be to SRPs, DEBs, grass buffer zones or temporary sediment retention devices such as container impoundment systems;

(b) All DEBs and SRPs that serve a catchment area greater than 500m2 shall be treated via a rainfall activated chemical treatment system. SRPs shall each have two flocculation sheds (or equivalents) installed;

(c) All DEB volumes are to be designed based on 2% of the contributing catchment area and all DEBs shall be fitted with floating decants that are designed to discharge at a rate of 3 litres/sec/ha;

(d) All construction yard areas shall achieve the detention requirements as detailed within the draft NZ Transport Agency’s Erosion and Sediment Control Standard for State Highway Infrastructure (August 2010);

(e) For the pre‐cast yard facility, pH levels for all discharges shall be within the range of 6.5 to 8.5;

(f) All SRP volumes are to be designed based on 3% of the contributing catchment area and will contain reverse slopes in the base of ponds, baffles and decant pulley systems and a forebay with a volume of 10% of the pond volume;

(g) All dirty water diversion channels shall be designed and constructed with sediment sumps at locations specified in the Construction Erosion and Sediment Control Plans (CESCPs) with a minimum volume of 2m3 per sump; and

(h) The erosion and sediment control for the site shall include the installation of a last line of defence as described in the CWAR, which shall include protection of the freshwater receiving environments with additional bunding, silt fence, super silt fence or alternative as defined in the CESCP for that particular stage.

(i) Earthworks shall be subject to Stabilisation in a progressive manner as earthworks are completed. If an area is not subject to earthworks activity for a 14 day period it shall be stabilised. This shall include completed sections of vertical cut faces and fill batters.

Construction Erosion and Sediment Control Plans

RC28 The Consent Holder shall prepare specific CESCPs for each Stage of the Project and streamworks in accordance with the ESCP, which shall demonstrate how the objectives of Condition RC17 will be met, and compliance with the criteria in Conditions RC25 to RC27. The Consent Holder shall engage with the Iwi Advisor while preparing the CESCPs.

8.0, 8.3

RC28A The CESCPs shall:

(a) Identify how the standards in Conditions RC25 to RC27 will be met (where applicable); and

8.4,


Condition No.


(b) Include, but not be limited to:

i. Streamwork construction methodologies and stream assessments, fish species assessment, fish migration assessment and any required fish relocation provisions;

ii. Details of the presence and management of any unexpected geological conditions such as high or low pH soil conditions;

iii. Identification of areas susceptible to erosion and sediment generation and implementation of erosion and sediment control measures appropriate to each situation with particular emphasis on high‐risk areas (including those identified and determined through sediment yield calculations). This risk identification process shall also include identification of:

I the water take downstream at NZTM 1748780 mE 5970390 mN (Auckland Council Permit No. 35555); and

II the stream and SH1 culvert located approximately 340m north of the driveway access to 1488 State Highway 1.

iv. A schedule of current and planned open earthworks areas as applicable to that CESCP at the time of preparation of the CESCP;

v. Estimated sediment yield for the Stage of work, as extrapolated from the yield predicted in the CWAR for the relevant focus area;

vi. Detailed design specifications for all erosion and sediment control measures including supporting calculations where appropriate, contributing catchment area, retention volume of structure (dead storage and live storage measured to the top of the primary spillway); shape of structure (dimensions of structure); safety and access, position of inlets and outlets; stabilisation of the structure, and maintenance provisions;

vii. Identification of erosion and sediment control contingency measures to be employed;

viii. Identification of the location of all discharge points to watercourses; and

ix. A site plan showing contours at suitable intervals, cut and fill operations, the specific location of all sediment and erosion control measures and catchment boundaries for the erosion and sediment controls.

x. Chemical treatment design and details specific to the stage, consistent with the ChemTMP.

RC29 At least 10 working days prior to the commencement of work in each Stage of the Project, the Consent Holder shall submit a hard paper copy CESCP for that Stage of the Project to the Team Leader for certification that the CESCP has been prepared in accordance with the ESCP and meets the requirements of Condition RC28A. Work shall not commence in any Stage of the Project until the Consent Holder has received the Team Leader’s written certification of the CESCP for that Stage. If the Consent Holder has not received a response (short of certification) from the Team Leader within 10 working days of submitting a CESCP, the Consent Holder will be deemed to have certification and can commence earthworks.

1.3.1, 8.2

Other

RC29AA If Lot 1 DP 321568 is to be used for construction vehicle access, a CESCP shall demonstrate that any works to form such access avoid the discharge of sediment‐laden runoff to the south onto Pt Lot 2 DP 151082 as far as practicable. A copy of the certified CESCP shall be provided to the owners of Pt Lot 2 DP 151082 for their information.

8.1


Condition No.


RC29A A copy of certified CESCPs for works in the catchment upstream of the water take at NZTM 1748780 mE 5970390 mN (Auckland Council Permit No. 35555) shall be forwarded to Watercare for their information.

6.4

RC30A The Consent Holder shall implement the CESCP for each Stage of works for the duration of the applicable Construction Works within that Stage.

8.2

Pre‐cast Yard

RC30AA A CESCP shall be prepared that is specific to the construction and operation of the pre‐cast yard. That CESCP shall include the relevant matters of Conditions RC25 to RC27 and the following:

(a) methods for monitoring the pH of yard runoff;

(b) provisions for detention of all runoff during yard operation and measures to ensure runoff remains with a pH range of 6.5 to 8.5 (Condition RC27(e));

(c) the location and method of storage of any environmentally hazardous substances, in accordance with relevant regulations;

(d) measures to avoid the discharge of dust beyond the pre‐cast yard site boundary; and

(e) an emergency spill response plan specific to that site.

6.5

RC30AB The construction and operation of the pre‐cast yard shall comply with the CESCP prepared for that site.

Advice Note: Condition RC30AA applies solely to consent no 33/016.

6.5

CESCP As‐built Certification

RC31 Prior to Construction Works in the Stage that the CESCP applies (excluding the construction of the erosion and sediment controls themselves) as‐built plans signed by an appropriately qualified and experienced erosion and sediment control practitioner shall be submitted to the Team Leader for information as confirmation that the erosion and sediment control measures for that CESCP have been constructed in accordance with the relevant CESCP. Bulk earthworks within the stage shall not commence until the as‐built plan confirming compliance with the CESCP has been submitted to the Team Leader.

1.3.3

Incident Management

RC32A The Consent Holder shall notify the Team Leader and Auckland Council within 1 working day after identifying that any contaminants (including sediment) or materials have been released in the undertaking of the Work and entered any water body due to any of the following incidents:

(a) discharges from non‐stabilised areas that are not treated by erosion and sediment control measures as required under this consent; and/or

(b) failure of any erosion and sediment control measures; and/or;

(c) discharge of a hazardous substances, including cement, to a water body; and/or

(d) failure of any temporary stream diversion; and/or

(e) un‐consented removal, loss or damage to vegetation or other habitats; and/or

7


Condition No.


(f) any other incident which either directly or indirectly causes, or is likely to cause, adverse ecological effects in any water body that is not authorised by a resource consent held by the Consent Holder;

(g) Any other incident which is likely to adversely affect the quality of the water used for public reticulated water purposes.

This notification shall be either by telephone or email, or via an alternative method as agreed with the Team Leader.

RC32 If any of the incidents identified in condition RC32A occur, the Consent Holder shall:

(a) re‐establish control measures where these have failed or have not been implemented in accordance with the relevant management plan as soon as practicable;

(b) liaise with the Team Leader to establish what remediation or rehabilitation is required and whether such remediation or rehabilitation is practical to implement;

(c) carry out any remedial action as required by and to the satisfaction of the Team Leader; and

(d) maintain a permanent record of the incident at the site, which shall include the date and time of the incident, the nature, manner and cause of the release of the contaminants, weather conditions at the time of the incident and the steps taken to prevent any further incidents and to remedy any adverse effects.

This notification (if not in person) shall be either by telephone or email, or via an alternative method as agreed with the Team Leader.

7.4

RC32B The consent holder shall notify Watercare if any incident listed in Condition RC32 occurs upstream of the water take at NZTM1748780 mE 5970390 mN (Auckland Council Permit No. 35555).

7.3

Amendments

RC40A The consent holder may seek to amend the ESCP, any CESCP or the AMP in accordance with the process proscribed for their initial approval/certification in the above conditions.

6.7.1

Coastal Works

RC70 Construction Works in the coastal marine area shall be undertaken in accordance with a CESCP. Such CESCP shall be prepared in accordance with Conditions RC28 to RC29.

6.3.7

RC71 The Consent Holder shall maintain the construction site in good order and where appropriate remedy any damage and disturbance of the foreshore and seabed caused by plant and equipment during construction.

6.3.7

RC72 The Consent Holder shall ensure all equipment, erosion and sediment control measures and construction materials are removed from the coastal marine area within 40 days following completion of Construction Works.

6.3.7


Condition No.


RC73 Prior to commencement of Construction Works within the Okahu Inlet, adult mud snails (Amphibola crenata) present on the mudflat within the construction footprint shall be collected by hand, and relocated to a similar area of mudflat at least 20 metres from the outer limits of the construction area. The time between collection of snails and relocation should not exceed two hours, in order to minimise stress on the snails. Collection and relocation of snails shall be carried out by a suitably qualified marine ecologist. The Consent Holder shall engage with the Iwi Advisor to ensure the Iwi Advisor (or representative of Hōkai Nuku) is invited to be present during the collection and relocation of the snails.

6.3.7

RC74 The area of mangrove and saltmarsh removal within Okahu Inlet shall be minimised as far as practicable and the total area of disturbance shall be no greater than 2500m2 within the CMA.

6.3.7

RC75 Mangrove and saltmarsh removal shall be undertaken by hand between 1 March and 31 July in order to avoid the wading bird primary breeding season.

6.3.7

RC76 Where mangrove or saltmarsh removal is required, the vegetation shall be removed from the estuary and disposed of at an approved facility in order to avoid potential adverse effects from decaying vegetation on mudflat habitat.

6.3.7


2 DOCUMENT STATUS

2.1 Relationship with other plans As detailed in section 1.2, this ESCP forms part of the suite of plans that form the broader Construction Environmental Management Plan (CEMP) for the Project.

The Chemical Treatment Management Plan (ChemTMP), as required by Consent Condition RC19(g), is attached as Appendix 1. This ChemTMP details the initial optimum dosage rate of 3mg/L of PAC and how this dosage rate will be refined and updated during construction.

The performance of specific erosion and sediment control devices will be confirmed by the monitoring detailed in the Adaptive Monitoring Plan (AMP). The outcomes of this monitoring will also be used to inform modifications to erosion and sediment control devices or methodologies to ensure continuous improvement is achieved.

The key relationship of this ESCP is with the Construction Erosion and Sediment Control Plans, see section 2.4 and section 6.

2.2 Responsibility for the ESCP The SPV Project Director has the overall responsibility for meeting the requirements of this ESCP. The Environmental Manager will implement the ESCP, including all required monitoring and management, and lead the review of monitoring results with appropriate communication to Auckland Council. Refer to the Project CEMP for more detail on the key Project roles and responsibilities.

This ESCP will be implemented for the duration of the construction works (December 2016 to late‐2021) with a copy kept in an accessible location in each of the site offices for the duration of the Project.

2.3 Plan updates and revisions This ESCP may require review and amendment during the life of the Project to reflect changes to activities, risks, mitigation measures, responsibilities and management processes and to comply with the relevant Consent conditions. The ability to make changes to the ESCP is vital to maintain its effectiveness and relevance. Modification may also be required to accommodate additional consents and/or designations once detailed design and construction methods are finalised.

Revisions to the ESCP will be made:

As NX2 considers necessary Promptly on any material change (including named personnel changes) If requested by Auckland Council (AC) As and when reasonably required by the Transport Agency.

Any changes to the approved ESCP will be made by submission of the updated Plan pursuant to the Review procedures, prior to the updated Plan being submitted to Auckland Council for approval in accordance with Resource Consent Condition RC20A.

2.4 Construction Erosion and Sediment Control Plans (CESCP) This Erosion and Sediment Control Plan is an overarching document which details the minimum standards and management practices to be used on site.

Specific details include designs, implementation and decommissioning methodologies will be included in Construction Erosion and Sediment Control Plans (CESCP)

A specific Construction Erosion and Sediment Control Plan will be prepared for each area of work.


2.5 ESCP Audience The primary audience of this ESCP is the Management staff of the project and as a reference guide to the Senior Environmental Advisors, Project and Site Engineers.

This ESCP will also provide details of the erosion and sediment control management practices to be utilised on the project to stakeholders including AC, TA and the general community.

The required site specific details, as a result of compliance with this document will be detailed in the CESCPs, it is these documents that will be used to provide the onsite staff with the information needed to ensure that the approved erosion and sediment controls, both structural and non‐structural are implemented on site.

This separation of information and tailoring the included information to the intended audience is critical to ensuring that the erosion and sediment control measures are correctly designed, understood, implemented, maintained and improved.


3 DESIGN GUIDELINES AND STANDARDS

3.1 General All erosion and sediment control devices to be utilised on site will be designed, installed, operated and maintained to the highest standard and to sound industry best practice.

The development and design of these controls will be undertaken by the Senior Environmental Advisor North / South.

3.2 Auckland Council TP90 / GD05 The initial design standard for erosion and sediment control devices on site is the Auckland Council’s Technical Publication No90 "Erosion and Sediment Control Guidelines for Land Disturbing Activities in the Auckland Region” 1999 (updated 2007), in accordance with RC27.

This document has, since the granting of consents, been updated and replaced by Auckland Council Guideline Document GD2016/005 (GD05). As this is the latest version GD05 will be used as the initial design standard.

Additional requirements required by consent conditions are detailed in Section 3.6 below.

3.3 Construction Water Assessment Report (CWAR) In support of the consent applications Further North prepared a Construction Water Assessment Report (CWAR). This report was based on the indicative alignment and expected construction methodologies and was prepared to describe the methods and practices to be implemented to minimise environmental effects, in particular relating to construction related water management.

The consent conditions were developed in response to this document, it is therefore expected that compliance with the consent conditions will ensure that the intended outcomes of this report are achieved.

Notwithstanding this, the CWAR may be referred to in order to clarify the intent of consent conditions, note this will be undertaken in consultation with AC to ensure an agreed interpretation.

CWAR Estimated Sediment Yield

The CWAR provided a comprehensive assessment of anticipated sediment yields for the various catchment areas of the site.

The results of this assessment were summarised in Table 31 of the CWAR. This summary showed that the following average sediment yields were anticipated from the project.

Table 3: CWAR Estimated Sediment Yield

Area Construction Sediment Yield

t/ha/year

Mahurangi Flat Country 22.9

Mahurangi Hill Country 49.1

Pūhoi Hill Country 49.1

In each CESCP this sediment yield will be used to determine the estimated sediment yield for that stage of work. These estimated sediment yields will be confirmed by the monitoring undertaken in accordance with the Adaptive Monitoring Plan.


3.4 Maximum Open Earthwork Limits Resource Consent Condition No RC25 places limits on the maximum open areas of earthworks on site at any one time, specifically:

RC 25 Unless otherwise varied in accordance with the Adaptive Monitoring Programme (set out in Conditions RC33 to RC37), the maximum open area of earthworks limitations shall apply as follows:

(a) Pūhoi Catchment (i.e., south of Moir Hill Road) –41ha at any one time

(b) Mahurangi Catchment (i.e., north of Moir Hill Road) –41ha of Hill Country and 21.5 ha of Flat Country (or equivalent ratios) at any one time.

Equivalent Ratios

A 1 ha increase in open area of earthworks in the Flat country (above the 21.5 ha limit discussed above) will require a corresponding 0.467 ha reduction in open areas of earthworks in the Hill Country.

The reverse situation is equally applicable, in that a 1 ha increase in open area of earthworks within the Hill Country, (above the 41 ha limit discussed above) will require a corresponding 2.14 ha reduction of open area of earthworks in the Flat country, subject to a maximum open area of earthworks within the Hill Country of 51.05 ha which will result in no earthworks activity being permitted to take place within the Flat country during the same time period.

3.5 Earthworks Season Restriction The earthworks on site are restricted by relatively ‘standard’ earthwork season restrictions for earthworks undertaken within the Auckland Region, Resource Consent Conditions No RC26, RC26A & RC26B:

RC26 For earthworks activity taking place within the indurated rock of the Pakiri Formation geology, no seasonal limitation shall apply, but a revised CESCP providing for winter work in Pakiri formation shall be submitted to the Team Leader by 15 April of the year in which the winter works are proposed.

RC26A For all other areas, earthworks activities shall not occur between 30 April and 1 October (winter period) in any one year unless otherwise approved by the Team Leader. Approval of earthworks occurring within the winter period will be based on:

(a) Previous compliance

(b) The AMP procedures and outcomes as specified in Conditions RC35 to RC37

(c) The nature of the specific works proposed to be undertaken in the winter period

(d) The location of the specific works

(e) Ability to comply with Condition RC28.

RC26B In accordance with Condition RC27(i), all areas not subject to earthwork activities during any given winter period shall be stabilised by 30 April of that year.

3.6 Additional Consent Requirements In addition to the requirements of TP90 there are a number of increased standards that are required by consent condition RC27, specifically:

(aa) All erosion and sediment control devices shall be located outside the 20 year ARI flood level, unless no other viable location exists.

(ab) Clean and dirty water diversion channels, shall be sized to accommodate the flow from a 100 year ARI storm event where practicable, and at a minimum, the flow from a 20 year ARI storm event and an additional 300mm freeboard.

(ac) All temporary stream crossings and temporary culverts shall be sized to accommodate the flow from a 20 year ARI storm event and include a stabilised overland flow path for runoff exceeding the flow expected in a 20 year ARI storm event.


(ad) At all practical times, streamworks activities and associated works shall be undertaken with stream diversions in place to accommodate up to the 20 year ARI rain event. All stream flows above the 20 year ARI rain event shall be diverted, via systems (such as overland flow paths) capable of conveying the 100 year ARI rain event flow around the works area.

(a) Pumping of all sediment laden runoff and groundwater during Construction Works shall be to SRPs, DEBs, grass buffer zones or temporary sediment retention devices such as container impoundment systems;

(b) All DEBs and SRPs that serve a catchment area greater than 500m2 shall be treated via a rainfall activated chemical treatment system. SRPs shall each have two flocculation sheds (or equivalents) installed;

(c) All DEB volumes are to be designed based on 2% of the contributing catchment area and all DEBs shall be fitted with floating decants that are designed to discharge at a rate of 3 litres/sec/ha;

(d) All construction yard areas shall achieve the detention requirements as detailed within the draft NZ Transport Agency’s Erosion and Sediment Control Standard for State Highway Infrastructure (August 2010);

(e) For the pre‐cast yard facility, pH levels for all discharges shall be within the range of 6.5 to 8.5;

(f) All SRP volumes are to be designed based on 3% of the contributing catchment area and will contain reverse slopes in the base of ponds, baffles and decant pulley systems and a forebay with a volume of 10% of the pond volume;

(g) All dirty water diversion channels shall be designed and constructed with sediment sumps at locations specified in the Construction Erosion and Sediment Control Plans (CESCPs) with a minimum volume of 2m3 per sump; and

(h) The erosion and sediment control for the site shall include the installation of a last line of defence as described in the CWAR, which shall include protection of the freshwater receiving environments with additional bunding, silt fence, super silt fence or alternative as defined in the CESCP for that particular stage.

(i) Earthworks shall be subject to Stabilisation in a progressive manner as earthworks are completed. If an area is not subject to earthworks activity for a 14 day period it shall be stabilised. This shall include completed sections of vertical cut faces and fill batters.

3.7 Chemical Treatment Management A Chemical Treatment Management Plan (ChemTMP) is also required by Resource Consent Conditions No RC19(g). This is included as an appendix to this document.

3.8 Kauri Dieback Biosecurity Designation Condition D63 requires the submission of a Kauri Dieback Biosecurity Plan (KDBP). This plan in particular places restrictions on the uses of soil within 30m of any Kauri tree.

The specific requirements of this KDBP will be reiterated within the CESCP’s for any area within 30m of a Kauri tree.


4 ROLES AND RESPONSIBILITIES

4.1 Introduction As noted in section 1.3 a key component of the successful implementation of the ESCP is the successful implementation of both structural and non‐structural measures. This implementation will be directed and monitored by the environmental management team.

4.2 Management team structure The key management roles in relation to environmental management during the construction of the Project are outlined in Table 4 below.

Table 4: Environmental management responsibilities

Organisation Role Responsibilities

The Transport Agency

Consent Holder

Compliance with the RMA and with any condition of the designations and resource consents.

Applications for alterations to the designations or resource consents or applications for new resource consents and designations and renewal of expired resource consents.

Auckland Council Environmental representative

Certification of Contractors’ Construction Environmental Management Plans.

NX2 SPV Project Director

SPV Technical Director

Overall responsibility for environmental management.

Reviewing and reporting on environmental performance.

Outline Plan of Works and other RMA approvals.

Inspection of works to assess compliance with the CEMP and sub plans.

Inspections, auditing and checking of environmental management practices and procedures.

CJV (major sub‐contractor)

D&C Project Director

Environmental Manager

Construction Manager

Communication & Stakeholder Manager

Responsibility for site environmental management.

Reviewing and reporting on environmental performance.

Outline Plan of Works and other RMA approvals.

Inspection of works to assess compliance with the CEMP and sub plans.

Inspections, auditing and checking of environmental management practices and procedures.

On‐site compliance with consent and designation conditions and other requirements and tracking compliance information on CS‐VUE.

Report to the Transport Agency changes to construction techniques or natural environmental changes which require alterations or new resource consents and designations.

Prepare, review and update of Construction Erosion and Sediment Control Plans and other Management Plans.

Facilitate and oversee environmental monitoring.

Update and maintain the Environmental Risk Register.


Organisation Role Responsibilities

Maintain Complaints, Incidents, and Non Compliance forms.

Training of all staff including subcontractors.

Minor subcontractors

On‐site managers and senior personnel

Adherence to the CEMP and sub‐plans.

Preparation/variation of specific CEMP, and relevant sub‐plans as required.

Auckland Council Consents Manager

Certifying Construction Erosion and Sediment Control Plans.

Auditing to assess that consent and designation conditions are being met.

4.3 ESCP implementation Responsibility for achieving environmental management objectives and KPIs is shared across the NX2 Team. This means environmental issues are allocated to the most appropriate functional person, thereby encouraging ‘ownership’ of the system. However, specific groups and individuals have been assigned responsibility for leading and managing the achievement of environmental performance objectives.

The ESCP will be implemented for the duration of the construction works and will be overseen by the SPV (Special Purposes Vehicle) Project Director and CJV Project Director, along with specific direction from the Environmental Manager Construction.

4.4 Specific roles of key environmental personnel

SPV Project Director

Table 4: SPV Project Director

Role: SPV Project Director

Name: Ray Wilson

Reports to: SPV (Special Purposes Vehicle) Board, the Transport Agency

Summary of Role: Single interface for the Transport Agency. Responsible for managing the delivery of the Project.

Key responsibilities: Acts as single point of contact for both the Transport Agency and

the D&C Project Director Oversees the CJV environmental performance.


D&C Project Director

Table 5: D&C Project Director

Role: D&C Project Director

Name: Alan Orange

Reports to: SPV Director

Summary of Role:

Building and leading a high performance team to deliver the Project to a successful completion by meeting the project objectives and the minimum requirements whilst ensuring the inputs and requirements of participants are met.

Key responsibilities:

Ensuring there is an appropriate organisation structure with clear roles and responsibilities.

Ensuring there are appropriate project systems. Ensuring there are appropriately training, experience and culturally

aligned people. Creating a high performance team through the development and

implementation of an HP Plan. Ensure there are appropriate systems and resources to procure the

materials, plant, equipment and others resources for the project. Report on critical internal and external performance measure and

information. Keep the Senior Leadership Team informed through reporting and

interactions. Defining the critical success factors for the project. Ensuring the project objectives are met

Construction Manager

Table 6: Construction Manager

Role: Construction Manager

Name: Francisco Jimenez Martin

Reports to: D&C Project Director

Summary of Role: Leadership and delivery of all aspects of construction


Overall responsibility for planning, coordination and execution of all construction activities.

Responsible for creating and implementing a strong health and safety culture based on the latest and most stringent safety standards and bringing it into everyday use.

Overviewing and meeting the consenting obligations during construction activity

Manages the meeting of construction targets and milestones Verifies and checks that construction processes are carried out in a

manner that satisfies statutory and project safety, environmental and quality plan policies and processes

Reviews and co‐authorises all construction procedures and project plans


Role: Construction Manager

Assigns role and responsibilities to zone managers, engineers, supervisors and construction staff

Monitors project programme and reviews construction techniques and sequences

Participates in risk management processes and manages the implementation of risk control plans

Liaises with the SPV Technical Director on construction issues. Has the authority to cease works

Key Relationship Manager

Table 7: Key Relationship Manager

Role: Key Relationship Manager

Name: Hugh Leersnyder

Reports to: D&C Project Director

Summary of Role:

Support the business objectives by managing relationships with all key stakeholders both internally and externally, ensuring they are well informed and appropriately consulted to meet both project objectives and legalisation requirements. The position holder will also be responsible for developing and implementing communication strategies and tactics that meet NZTA’s procedures.


Works with Environmental Manager and Community Liaison Officers to proactively inform, identify and facilitate the resolution of stakeholder issues

Oversees the preparation of communications plans, with detailed and justified clear accountabilities, and obtain sign‐off

Maintain relationships with community groups, relevant Ministers, regional and territorial authorities, public interest groups, external suppliers and media

Defines and plan public relations strategies that align with NZTA’s national and regional strategies

Supports NZTA Media Manager to engage successfully with media Ensures effective project communications and community

expectations in relation to communicating project progress. Develops and maintains internal relationships Develops and implements relevant and effective communications

for the project which provides regular progress updates which meet community expectations and project objectives through a variety of media outlets


Environmental Manager Construction

Table 8: Environmental Manager Construction

Role: Environmental Manager Construction

Name: Karsten Stevenson

Reports to: Key Relationship Manager

Summary of Role: Accountable for on‐site environmental performance and compliance with consent conditions


Provides leadership to motivate staff to achieve environmental standards, and comply with all resource consent and designation conditions

Develops, implements and reviews environmental management systems including the EMSAP and other environmental plans for the Project

Provides an initial point of contact for Auckland Council Develops and maintains a collaborative working relationship with

Auckland Council Co‐ordinates the interfaces and communications with external

agencies and stakeholders in relation to environmental management on the Project in conjunction with the Stakeholder and Communications Manager.

Directing ESCP and CESCP audits and reviews, as set out within this document

Development and provision of training materials on the implementation of the ESCP and the CEMPs, and specific environmental management controls

Oversee the implementation of the plans by the Project team

Senior Environmental Advisor North / South

Table 9: Senior Environmental Advisor North / South

Role: Senior Environmental Advisor North / South

Name: Jason Hambrook – North

Simon Butler ‐ South

Reports to: Environmental Manager / Construction Manager

Summary of Role: Leadership and implementation of Environmental Controls


Manage the input into the design of environmental controls within a project zone to ensure compliance with the suite of Designations and Resource Consents and related management plans and minimise the effect of the operation on the environment.

Work closely with the Construction team to ensure that environmental issues are identified and addressed in a proactive manner and without programme delay.

Supervise the installation, maintenance and decommissioning of erosion and sediment controls.


Role: Senior Environmental Advisor North / South

Undertake environmental monitoring and inspections of zones; including: Erosion and sediment control inspections Erosion and sediment control “as built’ certifications Monitoring exposed areas and ensuring progressive stabilisation is

completed in accordance with consent requirements Organise and prepare Construction Erosion and Sediment Control Plans Ensures compliance with Construction Erosion and Sediment Control Plans

Liaise with archaeologists and iwi advisors Assist with onsite management of Kauri die back prevention programme Assist with spill response and investigation. Assist with training initiatives (including inductions, environmental awareness, daily briefings, toolbox meetings, etc).

Oversee the ongoing monitoring and maintenance of erosion and sediment controls

Manage environmental budget for zone activities Develop and support environmental innovations and promoting best practice.

Liaise and manage with the Construction Manager, Environmental Manager Compliance and Environmental Supervisor on all erosion and sediment control and environmental issues

Senior Environmental Advisor Compliance

Table 10: Senior Environmental Advisor Compliance

Role: Senior Environmental Advisor Compliance

Reports to: Environmental Manager Construction

Summary of Role: Manage monitoring and documentation of environmental compliance


Work closely with the Construction team to ensure that environmental issues are identified and addressed in a proactive manner and without programme delay.

Prepare Construction Noise and Vibration Management Plans, and undertake Construction Noise and Vibration Monitoring

Undertake environmental monitoring and inspections of zones; including:

Dust monitoring, as required Water take monitoring Sediment pond sampling / testing and design of chemical

treatment devices Liaise with and manage ecologists including associated monitoring

and management programmes. Manage environmental contracts and contractors, including

suppliers of environmental monitoring equipment, waste management and other contractors as necessary.

Provide input and monitor the requirements for Greenroads and CS‐Vue


Role: Senior Environmental Advisor Compliance

Liaise and manage with the Construction Manager, Environmental Manager North / South and Environmental Supervisor on all erosion and sediment control and environmental issues

Reporting to the Environmental Manager, Senior Environmental Advisors North / South and Construction Manager on environmental performance

Ordering and maintaining environmental supplies

Environmental Supervisor

Table 11: Environmental Supervisor

Role: Environmental Supervisor

Reports to: Senior Environmental Advisor North / South; Zone Superintendent; Construction Manager

Summary of Role: Implementation and management of Environmental Control Measures


Organisation of Plant and Labour across the Project specifically relating to environmental issues.

Managing the build of ESC devices Manages checking and maintenance of ESC devices

The Environmental Manager Construction (EMC) has the direct responsibility for overall environmental compliance.

The EMC is a supervisory role whose key responsibility is to ensure that the other parts of the environmental management team are adequately resourced and trained to ensure that environmental issues are adequately identified and addressed. The EMC will ensure that a collaborative working relationship is formed and maintained with all stakeholders, in particular AC to ensure that the environmental aspects of the project are managed on a no surprises, transparent basis.

The SEA North and South (SEAN & SEAS) will have the direct responsibility for environmental compliance in the two main zones of the project, specifically north and south of Moirs Hill Road. The SEA’s will work closely with the Construction Manager and other members of the construction team to ensure that environmental issues are identified as part of the construction planning (JSEA) process sufficiently in advance of construction to allow appropriate management and mitigation measures to be developed and approved. The SEA’s will then work closely with the Environmental Supervisor to ensure that these environmental measures are correctly installed and maintained. The SEA’s will maintain a significant onsite presence to allow significant interaction between the construction and environmental teams to develop and maintain a robust relationship where construction and environmental issues and drivers continue to be considered concurrently. The SEA’s will undertake the inspections of the installed environmental controls (including erosion and sediment controls) to confirm compliance with the approved plans and to certify these controls in accordance with consent requirements (RC31). The SEA’s will then undertake regular site inspections of environmental controls including pre and post storm event inspections.

The SEA Compliance will be a key role providing monitoring support across the project. This SEA will direct or undertake the various monitoring requirements as defined in the AMP and CNVMP. This SEA will also direct or undertake dust monitoring and water take monitoring. A key responsibility of this SEA will be the collation of the required monitoring and the interpretation of this monitoring, in conjunction


with the Environmental Manger Construction, to verify and or monitor the performance and compliance of the project.

The Environmental supervisor will ensure that the construction teams are adequately supported and resourced during construction and maintenance of environmental controls.

Erosion and Sediment Control Management Team

An erosion and sediment control management team will be created. This team will meet regularly to review erosion and sediment control practices and procedures.

This team will meet regularly following and before of each earthworks season, May and September and also in response to any incidents.

This team will consist of the following members:

Table 12: Erosion and Sediment Control Management Team

Company Position Name Contact

NX2 Environmental Manager Construction

Karsten Stevenson

027 452 8308

[email protected]

NX2 Senior Environmental Advisor North

Jason Hambrook

TBA

NX2 Senior Environmental Advisor South

Simon Butler 027 5409778

[email protected]

NX2 Senior Environmental Advisor Compliance

TBA

Auckland Council

Senior Earthworks and Streamworks Specialist ‐ Compliance

Graham Jones 027 2307908

[email protected]

Auckland Council

Senior Earthworks & Streamworks Monitoring Advisor

Matthew Byrne 021 755013

[email protected]

Transport Agency

Senior Erosion Sediment Specialist

Graeme Ridley 0275 800584

[email protected]

Transport Agency

Senior Project Manager

Gary Choromanski

021 621966

[email protected]

Hōkai Nuku Ahu Kaupapa

Marina Hetaraka

021 405 200 [email protected]


Training

Where identified as appropriate, specific TP90 / GD05 training will be provided for key personnel. Training will be tailored to the individual / teams experience in key areas of ESC.

One of the outcomes of the above Erosion and Sediment Control Management Team meetings will be to identify any training requirements.

Erosion and Sediment Control issues will also form part of regular tool box discussion topics.

Training and Education Programmes are further detailed in the Construction Environmental Management Plan (CEMP).


5 EROSION AND SEDIMENT CONTROL IMPLEMENTATION The erosion and sediment controls to be implemented are to be implemented in two ways, structural controls and non‐structural controls.

The structural controls are those physical controls or devices including sediment retention ponds, silt fences etc.

The non‐structural controls are those management practices or methodologies which are implemented to ensure that environmental outcomes, including the minimisation of sediment discharge, are maximised.

These two control approaches are interrelated and the successful minimisation of a sediment discharge will require the implementation of both measures.

5.1 Structural vs Non‐structural Controls The utilisation of structural and non‐structural control measures is best practice in regards to erosion and sediment control. This follows the guiding principle of minimising erosion (typically by a combination of structural and non‐structural controls) and then implementing controls (typically structural controls) to retain as much of the sediment that has been generated as practical.

The interrelationship of these control approaches means that the effectiveness of a certain structural or non‐structural measure will inform which other controls are appropriate.

In general terms the non‐structural controls are implemented first to minimise the amount of erosion and therefore the volume of sediment to be controlled.

The selection of the structural controls will then be informed by the effectiveness of the non‐structural controls.

Note, this will often be an iterative process where a restriction on what structural control can be installed, will then inform a revision of the non‐structural controls. A simple example of this is where there is insufficient room for a compliant sediment retention pond to be constructed, a change to non‐structural controls (limiting catchment area, altering staging, revised construction methodology, etc) or additional structural controls (rapid stabilisation, multiple smaller retention devices, etc) may be appropriate.

Examples of Structural and Non‐structural controls are listed in table 4 below:

Table 13: Examples of Structural and Non‐structural Controls

Structural Control Non‐structural Control

Cleanwater Diversion Bund or Drain Sediment Laden Diversion Bund or

Drain Contour Drain Silt Fence Super Silt fence Sediment Retention Pond Decanting Earth Bund Chemical Treatment (rain activated) Stabilisation (Mulch, Geotextile,

Aggregate etc)

Interactive planning with Construction Team Staging of Earthworks Monitoring of weather forecasts, and reacting

to these forecasts Monitoring of the performance of structural

controls Ongoing interaction with construction teams Development of a strong environmental culture Chemical Treatment (batch dosing) Innovation


5.2 Innovation In order to minimise the potential or actual sediment discharged from the project works, as a result of the physical constraints of the site, and in response to the results of the adaptive monitoring plan it will necessary to utilise some degree of innovation in regards to the management and or implementation of erosion and sediment controls.

In regards to the above, the term ‘innovation’ refers to the utilisation of control measures that are not in accordance with the requirements of TP90/GD05 or industry best practice, referred to as ‘traditional controls’.

This innovation is expected to be both proactive and reactive.

Proactive Innovation

Proactive innovation is that innovation where, through the planning stages it is identified that ‘traditional controls’ cannot be utilised due to site constraints, safety in design constraints or as a result of knowledge gained from monitoring undertaken in similar situations or areas of the site. This monitoring may highlight that a ‘traditional control’ is not performing to the anticipated standard in certain situations, or it may identify measures that can be implemented that may or will improve the efficiency of a ‘traditional control’.

In this instance the proposed innovative measure will be detailed in the CESCP covering those works. These details will include:

The innovative practice proposed, The reasons why a ‘traditional control’ is not appropriate, Any monitoring undertaken that supports the innovation, The anticipated performance of the innovation, The monitoring that will be undertaken to verify the performance of the innovation, Contingency measures in the event that the innovation does not perform as anticipated. Examples of proactive innovation include: The use of any reactive innovation measure that has been found to be effective, The use of new chemical treatment agents, Alternative methods of chemical dosing The use of container sediment retention devices, The use of polymers as stabilisation agents, The use of sediment control devices in series, Modifications to SRP or DEB design.

Reactive Innovation

Reactive innovation is that innovation where, through the monitoring or inspections undertaken on site it is identified that the installed controls, either traditional or innovative, are not performing to the anticipated level.

In this instance, initially any contingency measures for an innovative control (as per the approved CESCP) will be implemented. For a ‘traditional control’ the actions taken will depend on the level to which the control is under‐performing. For significant under‐performance, best practice measures of reducing catchment area and or stabilising exposed areas will typically be the first measure.

For minor underperformance and or following the reduction of catchment area and stabilisation, investigations will be made to identify or suggest reasons for the under‐performance. Potential measures to address these reasons will be determined along with any specific monitoring to be undertaken to verify that these measures have worked. These measures will be discussed and agreed with AC and incorporated in a revised CESCP. These measures will then be implemented and the performance verified through the proposed monitoring.


In the event that the monitoring does not verify that the anticipated performance has been achieved the investigation / modification process will be repeated until a level of performance agreed with AC has been achieved.

This investigation / modification / verification process will also be utilised for situations where innovative practices are to be trialled to improve the efficiency of controls as part of the continuous improvement culture to be implemented on site.

Examples of reactive innovation include: The use of new chemical treatment agents, Alternative methods of chemical dosing, The use of container sediment retention devices, The use of polymers as stabilisation agents, The use of sediment control devices in series, Modifications to SRP or DEB design.


6 EROSION AND SEDIMENT CONTROL MINIMUM STANDARDS

The following section details how the specific requirements of Section 3 will be addressed and implemented. These are to be considered the minimum standard of control on site.

6.1 Maximum open earthwork area limits The minimisation of open areas is a key component in reducing actual or potential erosion and subsequent sediment discharges.

Maximum open earthwork area monitoring

The area of each earthwork cut and fill zone has been included as an attribute attached to that activity in the construction programme. This allows the assessment of the maximum exposed area at any time to be made as detailed in the following histogram:

Figure 2: Example Maximum Open Area Histogram

During construction this attribute will be updated regularly as the exposed area in each cut and fill zone is increased or reduced as a result of extended earthwork areas or as a result of progressive stabilisation.

A monthly update of the total open earthwork area will be provided to AC.

Progressive Stabilisation

Progressive stabilisation will be undertaken to achieve a number of objectives:

To minimise the potential for erosion and subsequent sediment generation To allow subsequent areas of earthworks to be commenced To ensure compliance with resource consent conditions RC25 & RC27(i).

As required by resource consent condition RC25, this progressive stabilisation will be undertaken utilising permanent stabilisation measures.

6.1.2.1 Permanent Stabilisation Measures

Permanent Stabilisation, in accordance with resource consent condition RC25 will be achieved by a number of means including:

Bark Mulch Aggregate (including permanent paving and site won aggregate) Grassing.


Where grassing is to be used as the permanent stabilisation measure, this stabilisation measure will not be achieved until a minimum of 80% grass cover has been achieved. To promote this grass growth, specific seed and fertilizer blends will be used specifically formulated for the soil types encountered at the location of grassing. A further critical measure in ensuring adequate grass growth will be to water any grassed areas. This will be undertaken by a combination of water carts and/or a fixed sprinkler systems with water supplied by relocatable storage tanks. Any watering will continue until weather conditions, or the grass health, allow the cessation of the watering.

6.1.2.2 Stabilisation Performance Verification

The monitoring of the performance of sediment retention devices, as required by the Adaptive Monitoring Plan, will be utilised to verify the efficiency of the stabilisation measures. This monitoring will also be used to assess the efficiency of alternative stabilisation measures, such as geotextile or site won aggregate, to determine if these stabilisation measures can be (with approval of AC) considered a permanent stabilisation measure in accordance with resource consent condition RC25.

6.2 Earthworks season restriction As detailed previously, the earthworks season restrictions are ‘standard’ and form part of the programme.

As works within rock materials, in particular the indurated rock of the Pakiri Formation geology, can be undertaken efficiently during winter months with minimal increases in environmental risk, these works will be programmed to continue in this period.

This programming of works within rock will be subject to approvals to also continue works in areas where the excavated rock material will be placed. Monitoring results of the sediment discharges from these areas (Section 6.1.2.2) will be used to confirm that the sediment discharges from these ‘rock’ fill areas is not dissimilar to those from the rock cut areas.

A revised CESCP for these works will be submitted to AC by the 15th of April in each year that these works are proposed.

In all other works where the undertaking of earthworks in this winter period is considered appropriate, and the potential increased risks (environmental, HS, and quality) can be adequately mitigated, a request to undertake these works will also be made to AC in the form of a revised CESCP, submitted for approval in accordance with resource consent condition RC26A. This will be submitted by the 15th of April in each year that these works are proposed.

Where works are not proposed to be undertaken during the winter period, they will be stabilised by permanent or temporary means in accordance with resource consent condition RC26B. Note, resource consent condition RC27(i) also requires the stabilisation of earthwork areas not subject to earthwork activities for a 14 day period.

Through the majority of the earthwork areas the required stabilisation for winter closedown will be achieved by utilising the site won aggregate. This will either be used as a sacrificial layer, or the works will be programmed to achieve a fill level that coincides with a rock layer within the fill.

6.3 Erosion and Sediment Control Requirements The additional (over and above the requirements of TP90) erosion and sediment control device requirements, as detailed within resource consent condition RC27, are adopted as standard requirements and are included within the designs and methodologies detailed within the CESCPs.

These requirements will be implemented through compliance with the following principles:


Minimise disturbance

The design team have developed an alignment which minimises the footprint of the direct works of the Project, and also achieves an earthwork balance which minimises the requirement for borrow areas and spoil disposal sites.

Construction methodologies specifically focused on material usage have been developed to allow the maximisation of material usage, and subsequent minimisation of earthwork footprint.

The location of access roads has also been optimised, and will continue to be optimised through the construction process to minimise any additional earthwork areas outside of the permanent works footprint.

During the planning stages of each section of work, the required exposed area will be determined and added to the current exposed area.

The current exposed area will be monitored across the site to ensure compliance with the Maximum Open Earthwork Area limits as detailed in resource consent condition RC25. This monitoring will include any completed sections of stabilisation and will be recorded weekly. (Refer Section 6.1.1)

This progressive stabilisation will be a key philosophy. Completed areas will be rapidly stabilised and any area not being actively earthworked will also be closed down within 14 days of works being temporarily suspended (RC27(i)).

This will require careful planning on the part of each of the Construction Team Leads in liaison with the SEA’s, so that the earthworks are staged but not constrained.

Site stabilisation will be a weekly agenda item as part of the zone construction meetings.

Our draft construction programme has tracked the Maximum Open Earthwork Area limits to ensure these limits are not exceeded.

Erosion control

The philosophy of erosion control is to simply reduce the amount of exposed soil that can be eroded by either rainfall or surface runoff. Erosion by wind is addressed by the Construction Dust Management Plan (CDMP), which will be finalised at least 20 business days prior to the commencement of construction works on site.

An initial control measure is to ensure that the overall exposed area is as small as practical by compliance with the above. To minimise the potential for runoff from this minimised exposed area the following principles will be followed:

6.3.2.1 Control upper catchment clean water

Isolating the construction site from the surrounding environment is the most effective means to achieve this principle. It means that water outside of the construction site will not be contaminated by construction generated sediment and can be considered ‘clean’.

Where possible, perimeter controls will be installed to divert upper catchment runoff by interception around the construction area. This limits water running through the construction site, the size of the sediment control device(s) required and cost to install and maintain the controls.

All clean water diversions will be sized to convey the 100 year ARI storm event where practical. As a minimum standard these diversions will be sized to convey runoff from the 20 year ARI storm event with 300mm freeboard (RC27(ab)). Where applicable the extents of the 20 year ARI flood level will be shown on the drawings associated with each CESCP.

There will however be situations where this is not possible (due to topography), and clean water may need to flow through the construction site, in particular during streamworks. In this case, specific controls will be installed to separate the clean water from dirty water through the site. Alternatively, specific methodologies will be employed to stabilise exposed areas daily so that potential clean water flows over a stabilised and controlled flowpath outside of work hours.


Where it is impractical to divert all upslope flows, typically due to the topography of an area, the catchment area of these flows will be included in the design of the associated sediment retention device.

Preference is given to utilising bunds rather than drains. Where bunds are utilised, stabilisation of the outside faces will be achieved by a number of means. For longer term bunds that are able to be constructed early, the outside faces will be grassed and watered to promote grass growth. Subject to the location of these bunds, contributing catchment areas and slopes, these grassed faces may also be hay mulched. Steeper sections of bunds will be stabilised with geotextile.

Wherever drains are utilised as cleanwater diversions these will be stabilised, typically with securely fixed geotextile. The leading edges of any geotextile will be keyed or trenched into the existing surface to ensure that surface flows flow over the geotextile rather than under.

In steeper areas of concentrated flow where drains or bunds are inappropriate flexible flumes or timber flumes may be utilised. Sand bags and Filter Socks will also be utilised as diversion bunds in steep sections.

On sealed roads where cleanwater diversion is required, hotmix bunds will be utilised for long term diversions and Filter Socks or sand bags will be used for shorter duration diversions.

6.3.2.2 Protect steep slopes

Where possible, the clearing of steep slopes will be avoided. In all cases, our philosophy will be to retain as much existing vegetation as possible and to clear only the minimum area of vegetation required to safely and practically complete the Project.

Where cut and fill slopes are created through earthworks activities, diversion of runoff from the top of the slopes around the construction site will be undertaken where possible. This may not always be possible on very steep slopes where machinery cannot operate and may result in the sediment control devices being enlarged to cater for the additional catchment. These matters will be addressed through the preparation of CESCPs.

6.3.2.3 Stabilisation of Exposed Areas

Constructed slopes through cutting and filling will be progressively stabilised to ensure compliance with conditions RC25 and RC27(i).

This stabilisation will be by a number of means, each stabilisation measure selected to address the specific issues at each location.

The exposed rock cuts will not receive any stabilisation as the surfaces themselves are considered stabilised.

For all other areas, preference will be given to undertaking permanent stabilisation in accordance with the final landscaping requirements for vegetated areas, and by pavement layers for those areas to be paved.

Where the application of permanent stabilisation is not practical temporary stabilisation will be undertaken utilising a number of measures including:

Hay Mulch Bark Mulch Geotextile Aggregate.

Sediment control

The philosophy of sediment control is to collect and retain as much sediment laden runoff as practical, for as long as practical in order to allow settlement of suspended material to occur. This settlement process is likely to be enhanced by chemical additives in accordance with the ChemTMP.

A number of devices will be utilised to achieve this principle of sediment control.


For each area of earthworks, the sediment retention device with the greatest efficiency that can be practically implemented will be utilised. This hierarchy is shown in Figure 3.

Figure 3: Efficiency hierarchy

The selection of each device will be based on a number of factors including:

Contributing Catchment Area Slope of Contributing Catchment Area Duration of Works Availability of space to construct a device.

6.3.3.1 Chemically Treated Sediment Retention Ponds

The preferred sediment retention device on site will be a chemically treated sediment retention pond (SRP) as this device will (typically) have the highest efficiency. In addition to the requirements of TP90/GD05 these devices will be constructed to the following minimum standards:

Minimum storage of 3% of the contributing catchment (300m3 for each 1ha of contributing catchment)

Reverse slopes on the base of the pond Baffles Decant Pulley Systems A forebay with a volume of 10% of the pond volume.

6.3.3.2 Sediment Retention Pond

The second preferred sediment retention device on site will be an untreated sediment retention pond, these devices will only be used where it is determined that there is no benefit in providing chemical treatment, in practice it is expected that this may only be applicable to rock catchments. This benefit will be confirmed by bench testing in accordance with the ChemTMP. In addition to the requirements of TP90, these devices will be constructed to the following minimum standards:

Minimum storage of 3% of the contributing catchment (300m3 for each 1ha of contributing catchment)

Reverse slopes on the base of the pond Baffles Decant Pulley Systems A forebay with a volume of 10% of the pond volume.

6.3.3.3 Chemically Treated Decanting Earth Bunds

Chemically Treated Decanting Earth Bunds (DEB) will be utilised for smaller catchments, typically less than 3,000m2 where concentrated flows are encountered. In accordance with RC27(b), DEBs will be

Chemically Treated Sediment Retention Pond

Sediment Retention Pond

Chemically Treated Decanting Earth Bund

Decanting Earth Bund

Container Impoundment Devices

Super Silt Fence

Silt Fence

Filter Socks

Highest Efficiency

Lowest Efficiency


chemically treated with a rainfall activated chemical treatment system where the contributing catchment is greater than 500m2. In addition to the requirements of TP90, DEBs will be constructed to the following minimum standards:

Minimum storage of 2% of the contributing catchment (20m3 for each 1,000m of contributing catchment)

A floating decant discharging at 3L/s/ha.

6.3.3.4 Decanting Earth Bund

As with untreated SRPs, untreated Decanting Earth Bunds (DEB) will only be used where it is determined that there is no benefit in providing chemical treatment, in practice it is expected that this may only be applicable to rock catchments. This benefit will be confirmed by bench testing in accordance with the Chemical Treatment Management Plan. In addition to the requirements of TP90, DEBs will be constructed to the following minimum standards:

Minimum storage of 2% of the contributing catchment (20m3 for each 1,000m of contributing catchment)

A floating decant discharging at 3L/s/ha.

6.3.3.5 Container Impoundment Devices

Container Impoundment Devices will be utilised in localised areas where it is impractical to install traditional controls. These locations will typically be at the base of the steep gullies where short term controls are required. These devices are only practical for small catchments and generally receive flows via pumps, as such they are also useful for dewatering activities. To ensure that the discharges from these devices are to the same standard as those from other devices on site, it is probable that these devices will also include chemical treatment (subject to site specific ground conditions).

The design of each Container Impoundment Device is site specific and will be detailed within the appropriate CESCP. This will include anticipate efficiencies and the method by which these efficiencies will be monitored and contingency measures in the event that the efficiencies are not achieved.

6.3.3.6 Super Silt Fence

Super Silt Fences (SSF) will be utilised where DEBs or SRPs are impractical and or not appropriate due to catchment size or activity duration. Super Silt Fences will control sheet flows from short steep catchments or larger flat catchments.

6.3.3.7 Silt Fences

As with SSFs, Silt Fences (SF) will be utilised where DEBs or SRPs are impractical and or not appropriate due to catchment size or activity duration. They will typically be used for smaller or flatter catchments than SSFs.

6.3.3.8 Filter Socks

Filter Socks (FS) will be the least preferred sediment control as they are only appropriate for very small catchments. The main advantage of Filter Socks is that they are quick to implement and can be utilised on sealed surfaces, as such they are useful for cesspit protection on sealed roads.

6.3.3.9 Sediment Laden Diversions

Sediment diversion bunds or drains will be used to divert sediment laden runoff to the various sediment retention devices. All cleanwater diversions will be sized to convey the 100 year ARI storm event where practical. As a minimum standard these diversions will be sized to convey runoff from the 20 year ARI storm event with 300mm freeboard (RC27(ab)).

Where runoff within the site is required to traverse steeper areas of the site, erosion in these areas will be minimised by utilising some of the above drain stabilisation measures or alternatives including flexible and timber flumes.

Sediment Laden Diversions will also include sediment sumps at appropriate locations, these locations and minimum spacing will be specified in the applicable CESCP.


Sediment laden diversions will be monitored for erosion, where erosion is observed a number of mitigation measures will be considered and implemented, these will include additional sumps, geotextile or rock lining or realignment to avoid erodible soils or to ease grades.

Last Line of Defence

In accordance with RC27(h) high risk areas of the site (as defined in section 5.2 of the CWAR) will include a ‘Last Line of Defence’. This will include the protection of the freshwater receiving environments with additional bunding, silt fence, super silt fence or alternative approved measure.

The specific Last Lines of defence will be detailed in the applicable CESCP.

Chemical Treatment Management Plan

As detailed above chemical additives are expected to be required to enhance the efficiency of the majority of sediment retention devices. The ChemTMP required by RC19(g) will detail how this will be achieved.

A number of chemicals will be considered and will be trialled with the various site soils to determine which chemicals, or blends of chemicals will be utilised to gain the greatest efficiency out of each sediment retention device. The management and optimisation of the chemical treatment process will be a function of the site environmental team.

A key component in gaining the maximum benefit from chemical treatment will be the interaction between the chemical treatment process and the confirmation of the benefits of this as a result of the Adaptive Monitoring undertaken on site (RC33 ‐ RC37).

Streamworks

There will be three main areas of Streamworks, those associated with temporary culverts required for access, those required for permanent culvert installation and the permanent stream diversions.

The methodologies for each of these will largely be the same, specifically that existing stream flows will be diverted during the works.

In accordance with RC27(ad) the diversions utilised will, at all practical times, be sized to convey the flow from the 20 year ARI storm event. Additional overland flowpaths or methods will be included to divert any runoff in excess of the 20 year ARI storm event.

It is to be noted that for a number of streams, due to the incised nature of the streams and the size of the contributing catchments that it is not practical to provide a diversion sized to convey flow from the 20 year ARI storm event at all times.

The design of each stream diversion is site specific and will take into account the following factors:

Catchment area, Type of stream, permanent or intermittent, Fish passage requirements, Length of culvert, Size of culvert, Ground conditions, Construction methodology (note construction methodology will be influenced by the above factors), Duration of culvert installation works, Earthwork activities to take place following culvert installation.

The specific methods of diversion for each stream diversion will be included in the applicable CESCP.

As a general principle, the culverts or diversions will be designed so that they can be constructed ‘offline’. Notwithstanding this each end of the culvert or diversion will still require the existing flows to be diverted during the tie in works.

During works where flows need to be diverted three basic diversion options will be used:


6.3.6.1 Dam and over pump.

This option will be used for either short term diversions and or for very low flows. Typically, when pumping over 24 hours, this method will require pump redundancy and regular or automated monitoring. This option will most likely be restricted to temporary culverts, the tie ins, or as part of installing the other temporary diversions.

6.3.6.2 Diversion via flexible flume (or rigid pipe)

This option is likely to be the preferred option for smaller watercourses as it is easily relocated around work activities. This option requires an upstream dam with a solid pipe at or about stream level which connects to a flexible pipe which is laid through the site to discharge beyond the extent of works at the downstream end of the streamworks. This may require a further temporary dam, and may also need to accommodate sediment retention ponds at the lower end of earthworks.

These flexible flumes will be sized (in conjunction with the height of the upstream dam) to maximise the volume of flow that can be diverted before the upstream dam is overtopped. In the event of the upstream dam being overtopped, a lined diversion channel will be provided through the site. This channel will increase the capacity of the diversion to the 100‐year event.

These flumes will have as a minimum, the capacity to convey the base flow within the stream. Where practical this flume will have capacity to divert the 20‐year event. Where this is not practical a contingency method will be detailed that defines the capacity of the flume and relates this to a rainfall event. This contingency will include how the rainfall event will be forecast to ensure that there is sufficient warning before the rainfall event to install a lined diversion through the work area capable of conveying flows in excess of the flumes capacity.

This contingency will define what size or type of additional diversion will be installed for various forecast rainfall events. This breakdown of diversion sizing and type will depend on the capacity of the flume and the magnitude of the change in flows as a result of varying levels of rainfall and, critically, the ability to accurately forecast these rainfall events.

The design of the flume or ridged pipe will need to consider fish passage.

6.3.6.3 Diversion via lined diversion channel

This form of diversion will be used where there is a significant flow (in excess of the capacity of flexible flumes) and/or where there is a requirement to provide fish passage that cannot be incorporated in a flume or piped diversion. These diversions will be sized as large as practical, where possible to the 100‐year event to avoid having to install additional diversions in high rainfall events.

These channels will be lined with geotextile and will include appropriate fish passage measures, most likely ‘spat’ ropes or rock rip rap in the base of the channel.

Coastal Works

The works to be undertaken within Coastal Marine Areas (CMA), specifically the construction of the Okahu Viaduct, will take specific consideration of the environmental issues associated with works in this environment. While the construction of the Pūhoi Bridge is not technically within a Coastal Marine Area, from an erosion and sediment control perspective the measures and methods utilised will be the same.

Typically, these measures and methods will be such that the construction activities are undertaken in a manner where exposed areas or excavated material does not come into contact with flowing water.

6.3.7.1 Okahu Viaduct

In regards to the Okahu Viaduct access to the construction area within the CMA will be via a combination of rock causeway and piled staging on the western side of the structure. The rock causeway will be formed at low tide by initially clearing any mangroves within the proposed footprint by hand, followed by laying geotextile and geogrid over the surface of the seabed. A 1.3m (approx.) thick layer of clean rock and aggregate will then be laid over the geotextile and geogrid. This causeway will extent to the second pier.


At this point a raised staging will be constructed perpendicular to the bridge on the southern side of the second pier. This raised staging will extend from west of the causeway to the eastern side of the viaduct. This process will be continued across the Okahu Inlet, each raised section of causeway will provide a flowpath for tidal flows. In total four flowpaths will be provided. This raised staging will be constructed progressively from the causeway and then completed sections of staging. The construction is simple vibro‐driven piles supporting a steel and concrete deck structure

At no time during the above construction of access will construction plant operate on the seabed.

The piling works for the Okahu Viaduct will be undertaken within sheetpile coffer dams constructed around the pilecaps. These coffer dams and work areas will be accessed from the raised staging and will isolate these work areas from tidal flows.

Sediment laden water as a result of the piling activities will be pumped to one of the Sediment Retention Ponds located on either side of the inlet.

Excavated material from the piles and the pilecaps will be loaded into sealed trucks which will transport the material along the staging and causeway for disposal within one of the onsite spoil disposal areas.

The causeway and raised staging will be monitored and kept clean at all times. Any dropped material will be removed immediately.

The removal of the causeway and the raised staging will be undertaken in a reverse process of the installation. It is expected that the causeway will settle and will also displace some seabed material. As part of the removal the causeway material will be removed to slightly below seabed level. The displaced seabed material will be respread over this remaining causeway material to reinstate the area.

In addition to the above the CESCP to be prepared for the works within the Okahu inlet will include management measures to address RC73:

Prior to commencement of Construction Works within the Okahu Inlet, adult mud snails (Amphibola crenata) present on the mudflat within the construction footprint shall be collected by hand, and relocated to a similar area of mudflat at least 20 metres from the outer limits of the construction area. The time between collection of snails and relocation should not exceed two hours, in order to minimise stress on the snails. Collection and relocation of snails shall be carried out by a suitably qualified marine ecologist. The Consent Holder shall engage with the Iwi Advisor to ensure the Iwi Advisor (or representative of Hōkai Nuku) is invited to be present during the collection and relocation of the snails.

6.3.7.2 Pūhoi Viaduct

As previously detailed while the construction of the Pūhoi Bridge is not technically within a Coastal Marine Area, from an erosion and sediment control perspective the measures and methods utilised will be the same.

Due to the depth of the Pūhoi River at this location, a causeway is not practical and would also affect the navigability of the river. Therefore in this location a raised piled staging similar to that used in the Okahu Inlet will be utilised.

In this location however sheetpile coffer dams are not required as the pile casings will seal the piles preventing river flows from coming into contact with the piling operations.

Sediment laden water as a result of the piling activities will be pumped to the Sediment Retention Ponds located on the northern side of the river.

Excavated material from the piles will be loaded into sealed trucks which will transport the material along the staging for disposal within one of the onsite spoil disposal areas.


The raised staging will be monitored and kept clean at all times. Any dropped material will be removed immediately.

The removal of the causeway and the raised staging will be undertaken in a reverse process of the installation.

Vegetation Removal

There are two scenarios for vegetation removal. The removal of vegetation within the forestry areas, undertaken as a forest harvesting operation, and the removal of vegetation in other areas.

In regards to erosion and sediment controls for these operations the following standards are to be followed and detailed in the CESCP covering that area of vegetation removal.

For the areas where the vegetation removal is undertaken as a forest harvesting operation the erosion and sediment control measures and methodologies detailed in the Auckland Council Technical Publication No 223 “Forestry Operations in the Auckland Region – A Guideline for Erosion and Sediment Control, (TP223 – September 2007)” are to be implemented.

For all other areas, erosion and sediment controls as detailed in this ESCP are to be implemented.

Decommissioning of Controls

The decommissioning of controls shall not occur until the contributing catchment has been fully stabilised or alternative sediment retention devices (in accordance with an approved CESCP) have been implemented.

The decommissioning of controls will be authorised by the SEAN & SEAS in consultation with AC.

The specific details of decommissioning of controls, in particular any required staging of this decommissioning will be detailed in the CESCP for the area.

This decommissioning will meet the following standards:

The decommissioning of sediment retention ponds or decanting earth bunds will be undertaken to achieve the appropriate geotechnical standard. This standard will define what material is to be used for backfill and what compaction standards are to be met.

Prior to backfilling of any devices the silt fence or super silt fences that were utilised during the installation devices will be reinstated if required (particularly over the spillways), note this requirement will be subject to the duration of the backfilling.

Any accumulated sediment is to be removed as part of this decommissioning and will be disposed of in one of the site spoil disposal areas.

The exposed areas as a result of sediment retention pond or decanting earth bund decommissioning will be rapidly stabilised in accordance with the final landscaping for the area. Where this final landscaping requires grassing, hessian or similar erosion control blankets may be appropriate. This will be defined in the CESCP.

Any recyclable materials as the result of silt fence or super silt fence removal, waratahs, wire, tensioners, waratah caps etc will be retained and reused as practical.

The geotextile from the silt fences or super silt fences is not (typically) suitable for reuse so will be removed from site as waste.

As with the silt fence material, geotextile used for site stabilisation will be recycled if practical, where this is not practical it will be removed from site as waste.

Though out the duration of the project the ability to salvage and recycle silt fence and geotextile will continue to be investigated. Off‐site recycling opportunities will also be investigated.


Dewatering

The required construction works will result in excavations and other related activities that will require dewatering by pumping.

A Dewatering & Pumping Management Plan for the overall site has been prepared to ensure that the required level of sediment retention is achieved during this operation.

Dewatering will be managed by a Permit to Pump process which will be managed by the Senior Environmental Advisor North / South.

This plan is attached as Appendix 3.

6.4 Watercare Condition 20B requires that a copy of this approved ESCP be forwarded to Watercare for their information. Condition RC29A, requires that a copy of any approved CESCP in the catchment upstream of the watertake is provided to Watercare.

Condition RC28A(iii) requires that the water take at NZTM 1748780mE 5970390mN – 6 Brown Road, SH1 Warkworth (AC Permit No. 35555) be identified as part of the risk identification process to be undertaken during the preparation of CESCPs.

Condition RC32B requires that Watercare be notified of any incidents upstream of the above water take.

As part of the initial stakeholder consultation Watercare will be consulted with to determine the most effective way of achieving compliance with the above. Specifically, this will determine lines of communication, contact numbers etc.

Once completed these contact details will be added to the project contact register.

6.5 Precast Yard Current construction methodology does not require the utilisation of the precast yard and as such the precast yard conditions RC30AA and RC30AB are not triggered.

6.6 Personnel The effective implementation of a successful erosion and sediment control programme relies on effective management.

This management will be delivered by a dedicated team whose primary function is to ensure that the required discharge standards and environmental outcomes are achieved.

This environmental team will be responsible for the installation, maintenance and decommissioning of the ESC practices onsite. This team will take a proactive approach with regard to ESC management through planning and adapting during construction.

NX2 has appointed highly experienced Construction Team Leads and ESC Specialist to plan, design, manage and oversee the installation, maintenance and decommissioning of the ESC practices. These people will have direct responsibility for implementing, monitoring and maintaining all ESC.

An additional key responsibility of this team will be to develop and foster a high performing collaborative ownership of erosion and sediment control performance throughout the management and construction team.

6.7 Review, monitor and adjust

Evolving plan

In order for the erosion and sediment control measures to be effective it is critical that the erosion and sediment control plan can, and does, evolve with changing site conditions, weather conditions and in


particular in response to the results of monitoring undertaken in accordance with the Adaptive Monitoring Plan.

Any modifications to this ESCP will be submitted to AC for approval in accordance with resource consent condition RC40A.

This modification of the erosion and sediment control measures will be managed by the site environmental management team in accordance with the amendment provisions of the Resource Consents (RC40A).

Inspect, assess and adjust

In order to identify and define any modifications to the ESCP or the CESCPs a regime of inspections and monitoring has been developed within the Adaptive Monitoring Plan (AMP). This AMP will provide the basis for any proposed modifications.

Assign responsibilities and accountabilities

In order for the Project to be a success, a culture of environmental ownership will be developed and maintained through the works. This will be built using two main strategies:

Communication – planning, toolbox meetings, tailgates Measurement of performance with feedback – celebration of success and lessons learnt from near

misses or failures.

The AC is also expected to monitor environmental performance throughout construction of the Project, scoring performance between 1 (excellent) and 4 (serious issues). These scores will also be used as a regular external measure of our performance.


7 INCIDENT RESPONSE Incident response is to be undertaken in accordance with the requirements of the Incident Management Plan (prepared in accordance with Resource Consent Conditions RC32 & RC32A) detailed in the Construction Environmental Management Plan (CEMP).

7.1 Incident Definition An incident is defined as:

discharges from non‐stabilised areas that are not treated by erosion and sediment control measures as required under this consent; and/or

failure of any erosion and sediment control measures; and/or; discharge of a hazardous substances, including cement, to a water body; and/or failure of any temporary stream diversion; and/or un‐consented removal, loss or damage to vegetation or other habitats; and/or any other incident which either directly or indirectly causes, or is likely to cause, adverse ecological

effects in any water body that is not authorised by a resource consent held by the Consent Holder; Any other incident which is likely to adversely affect the quality of the water used for public

reticulated water purposes.

7.2 Incident Identification Incidents will primarily be identified by site observations.

These site observations will be a result of general site observations by all site staff, including external parties such as Auckland Council, and will also be a result of specific inspections undertaken by the Senior Environmental Advisor North / South following rainfall.

An incident may also be identified as the result of monitoring undertaken in accordance with the AMP.

Complaints and other public feedback may also result in investigations that could identify incidents.

7.3 Incident Notification Following the identification of an incident as defined in RC32A, the Senior Environmental Advisor North / South will be informed immediately (if they were not the person who identified the incident).

RC32A The Consent Holder shall notify the Team Leader and Auckland Council within 1 working day after identifying that any contaminants (including sediment) or materials have been released in the undertaking of the Work and entered any water body due to any of the following incidents:

(a) discharges from non‐stabilised areas that are not treated by erosion and sediment control measures as required under this consent; and/or

(b) failure of any erosion and sediment control measures; and/or;

(c) discharge of a hazardous substances, including cement, to a water body; and/or

(d) failure of any temporary stream diversion; and/or

(e) un‐consented removal, loss or damage to vegetation or other habitats;and/or

(f) any other incident which either directly or indirectly causes, or is likely to cause, adverse ecological effects in any water body that is not authorised by a resource consent held by the Consent Holder;

(g) Any other incident which is likely to adversely affect the quality of the water used for public reticulated water purposes.


This notification shall be either by telephone or email, or via an alternative method as agreed with the Team Leader.

As above, the Senior Environmental Advisor North / South will notify the Team Leader, Auckland Council, NZTA and Hōkai Nuku within 1 working day after identifying the incident.

In accordance with RC 32B, Watercare is also be notified of any incidents upstream of water take 6 Brown Road, SH1 Warkworth, for clarity this relates to any incidents within the designation north of Moir Hill Road.

This notification will initially be by telephone with a following email to document the incident.

RC32B The consent holder shall notify Watercare if any incident listed in Condition RC32 occurs upstream of the water take at NZTM1748780 mE 5970390 mN (Auckland Council Permit No. 35555).

7.4 Corrective Actions As soon as practical after being notified of an incident the Senior Environmental Advisor North / South will, in consultation with the Environmental Manager Construction and the Construction Manager, determine the immediate actions in accordance with RC32, to be taken to:

(a) re‐establish control measures where these have failed or have not been implemented in accordance with the relevant management plan as soon as practicable;

These corrective actions will be implemented as soon as practical taking into account health and safety issues.

(b) liaise with the Team Leader to establish what remediation or rehabilitation is required and whether such remediation or rehabilitation is practical to implement;

Subject to the nature and magnitude of the discharge these clean up actions may require input from the Ecologist, Hōkai Nuku and agreement from the Team Leader. These proposed clean up actions may also require specific approvals from AC.

(c) carry out any remedial action as required by and to the satisfaction of the Team Leader; and

(d) maintain a permanent record of the incident at the site, which shall include the date and time of the incident, the nature, manner and cause of the release of the contaminants, weather conditions at the time of the incident and the steps taken to prevent any further incidents and to remedy any adverse effects. This notification ( if not in person) shall be either by telephone or email, or via an alternative method as agreed with the team leader.

In addition to the above requirements the incident report will include the following details:

Description and location of incident; Description of the weather conditions before the incident; Description of work being carried out at the time of the incident and how the incident occurred; Corrective actions taken to rectify the situation and mitigation measures to be taken to minimise the

adverse effects on the environment; Causes of the incident; and Environmental controls in place at the time of the incident.

Additional monitoring may be required to be enacted as a result of the incident and changes may be required to be made to the ESCP or approved and future CESCPs.

Any such changes will be made in accordance with the revision provisions of this document.


8 CONSTRUCTION EROSION AND SEDIMENT CONTROL PLANS

8.1 Introduction For each area of work where earthworks or streamworks will be undertaken a Construction Erosion and Sediment Control Plan (CESCP) will be prepared and submitted for certification.

The CESCPS are the key document which will inform those on site as to the specific controls and measures to be installed in each specific area and or for specific activities.

A specific CESCP shall be developed in accordance with Condition RC29AA.

To be effective, it has been found on successful projects that these documents should be as brief as possible and be formatted in a ‘bullet pointed’ manner to show the specific requirements.

8.2 Preparation These plans will be prepared by the SEA’s and will be developed as an iterative process between the construction team and the environmental team. This collaborative approach is key to ensuring that all actual or potential issues are identified and addressed. It also ensures that ownership of the issues and mitigation measures is fundamental to the onsite activities.

This preparation will also involve consultation with AC. This again develops an understanding of the issues, the options for mitigation and the reasons why certain options are selected. This collaboration during preparation leads to a quicker certification process and develops an open book, no surprises relationship between the two parties.

This collaborative relationship between the two parties is key to minimising delays to project approvals.

CESCPs will be submitted to AC a minimum of 10 days before commencement of works for certification in accordance with RC29.

Each CESCP will detail how the objectives of RC17 will be met with reference to methods detailed within the Erosion and Sediment Control Plan (ESCP) and the Adaptive Monitoring Plan (AMP)

Implementation of the certified CESCPs for each stage of works will be undertaken for the duration of works within that stage in accordance with Condition RC30A.

8.3 Hōkai Nuku Engagement in the preparation of CESCPs The preparation of specific CESCPs requires:

the consent holder shall engage with the Iwi Advisor while preparing the CESCPs; and the preparation of any management plan requires the Iwi Advisor to provide cultural indicators. The

consent holder shall have regard to any cultural indicators provided in the preparation of any management plan required under the conditions.

During the preparation of the specific CESCPs, the consent holder will engage with the Iwi Advisor as outlined in the Designation and Resource Consent Conditions – Compliance Procedures.1 This process will include, if necessary, Hōkai Nuku providing an assessment of effects and mitigation measures on the Hōkai Nuku Cultural Footprint as required by RC28.

The Hōkai Nuku Cultural Footprint is described as:

Mana Tangata – acknowledging and upholding the mana or the people that whakapapa to the area; Mana Whenua – Identifying the features of the physical landscape that are of cultural importance;

1 Reference: Hetaraka, M (2016) Designation and Resource Consent Conditions – Compliance Procedures


Putake – addressing particular historical and contemporary issues within the area, and any future aspirations.

Hōkai Nuku will also provide cultural indicators as required by RC7, these cultural indicators include, but are not limited to:

Awa Ngahere

Rakau

Manu

Ngāngara

Rongoa Ika Haukahe, Kohikohi Pūnaha Taupuhi Kaiao Taketake

The outcomes of the above engagement will be included within the CESCPs to ensure that the cultural indicators have been adequately addressed.

8.4 Content The required content of the CESCPs is defined in RC28A:

The CESCPs shall:

(a) Identify how the standards in Conditions RC25 to RC27 will be met (where applicable); and

RC25 refers to the Maximum Open Earthwork Area Limits. In each CESCP the total exposed area associated with the works will be detailed.

The monthly update (section 6.1.1) will inform AC of the cumulative total on site. This will also be summarised in monthly reports.

RC26 & RC26A detail the requirements relating to winter works. Where the works detailed within a CESCP is intended to continue during winter this will be noted.

Any applications for works during winter, either within indurated rock of the Pakiri Formation (RC26) or in other areas (RC26A) will be made by 15 April in each year.

For those areas where earthworks are not intended to continue between 30 April and 1 October (Winter) in any year, these areas will be stabilised by 30 April in accordance with RC26B.

RC27 refers to the minimum requirements of Erosion and Sediment Control Devices, this has been addressed in section 6.3.

(b) Include, but not be limited to:

i. Streamwork construction methodologies and stream assessments, fish species assessment, fish migration assessment and any required fish relocation provisions;

Details of the stream assessments, fish species assessments, fish migration assessments are included within the Ecological Management and Monitoring Plan.

Each CESCP where streamworks are required will include a reference to the fish relocation methodology to be utilised and to where the fish will be relocated.

A specific methodology will be detailed for each section of streamworks following the principles detailed in section 6.3.6.

ii. Details of the presence and management of any unexpected geological conditions such as high or low pH soil conditions;

Where unexpected geological conditions are encountered, these will be addressed in accordance with the provisions of section 5.2.2 Reactive Innovation.


iii. Identification of areas susceptible to erosion and sediment generation and implementation of erosion and sediment control measures appropriate to each situation with particular emphasis on high‐risk areas (including those identified and determined through sediment yield calculations). This risk identification process shall also include identification of:

I the water take downstream at NZTM 1748780 mE 5970390 mN (Auckland Council Permit No. 35555); and

II the stream and SH1 culvert located approximately 340m north of the driveway access to 1488 State Highway 1.

A risk assessment will be included in each CESCP, in particular this will highlight those areas that were considered high risk in the CWAR. For simplicity this is considered to be those works within 50m of a watercourse or coastal area and those works within slopes of greater than 15 degrees (25%, 1:4).

iv. A schedule of current and planned open earthworks areas as applicable to that CESCP at the time of preparation of the CESCP;

See Section 6.1.1 v. Estimated sediment yield for the Stage of work, as extrapolated from the yield predicted in the

CWAR for the relevant focus area; An estimation of sediment yield will be provided in accordance with section 3.3.1 of the ESCP. vi. Detailed design specifications for all erosion and sediment control measures including

supporting calculations where appropriate, contributing catchment area, retention volume of structure (dead storage and live storage measured to the top of the primary spillway); shape of structure (dimensions of structure); safety and access, position of inlets and outlets; stabilisation of the structure, and maintenance provisions;

In addition to the site plan required by (ix) below a standard spreadsheet will be attached to all CESCPs. This spreadsheet will include minimum design criteria for diversions of various catchments. These options will be numbered and referred to on the site plan. This spreadsheet will also include standard dimensions for sediment retention ponds and decanting earth bunds, these dimensions will be provided for increments of 0.25ha.

vii. Identification of erosion and sediment control contingency measures to be employed;

As appropriate for the works detailed in the CESCP contingency measures will be detailed.

viii. Identification of the location of all discharge points to watercourses; and

Discharge points will be shown on the Site Plan.

ix. A site plan showing contours at suitable intervals, cut and fill operations, the specific location of all sediment and erosion control measures and catchment boundaries for the erosion and sediment controls.

The site plan will include the above details and any other details (such as staging) required to clearing define the required erosion and sediment control details and methodologies.

x. Chemical treatment design and details specific to the stage, consistent with the ChemTMP.

The spreadsheet detailed in response to (vi) will include these details.

8.5 Revision As with any live document it is critical that updates can be made to the ESCP in order to ensure that any changes required on site to ensure the highest level of sediment control efficiency are documented.

This requirement for documentation needs to be balanced with the ability to make decisions and changes on site without the need for AC approval.

These changes are referred to as Minor Changes


Minor Changes

Minor changes are those changes where the outcome of the change would not increase the risk associated with the control measure being changed or the overall anticipated environmental outcome.

Minor Changes will only be implemented following approval by the SEA’s.

It is expected that the definition of a Minor Change will evolve during the undertaking of the works as a greater knowledge is gained by both NX2 and the AC regarding which issues are commonly encountered which require changes to be made on site.

Examples of Minor Changes are:

The installation of additional controls, where the approved control is not removed, Stabilisation of exposed areas, The enlargement of retention devices such as sediment retention ponds or decanting earth bunds, The relocation of diversion bunds where it does not result in a catchment area that exceeds the

capacity of the receiving sediment control device. The relocation of silt fences or super silt fences where this does not affect the compliance status of

the device in regards to Tables 12 and 13 of GD05 (see below).

The modification of controls within the design criteria of TP90/GD05.

Major Changes

Where a change is determined to be necessary on site and this change does not meet the above criteria of a Minor Change a revised CESCP will prepared and submitted for certification prior to implementation.

The exception to this would be where ‘emergency’ works are needed to address unforeseen situations including significant weather events, device failures or other unforeseen circumstances. In these instances, the required remedial actions will be directed by the Senior Environmental Advisor North / South who will advise AC of the actions as soon as practical. These changes will be detailed on an updated CESCP as soon as practical.


9 MONITORING The monitoring of the Project’s erosion and sediment controls will be the responsibility of the Senior Environmental Advisors, North, South and Compliance.

Monitoring of the Project’s erosion and sediment controls devices is addressed through the Adaptive Monitoring Plan.

Monitoring will include:

Certification of all ESC devices Inspection after rainfall event Weekly audits Pre and post rain event audits, including heavy rain and stabilisation trigger events Triggered monitoring as a result of rainfall, ecological exceedances or failure of sediment retention

device.

9.1 Weather Monitoring Three automated weather stations are to be installed on site.

One will be installed at each of the main site yards, Pūhoi, Moir Hill and Wyllie Road. These weather stations will monitor a number of weather parameters including:

Rainfall Depth Rainfall Intensity Wind Speed Wind Direction Air Temperature.

These devices will also have the ability to send text and email messages when rainfall or wind triggers have been exceeded.

In addition to these devices a robust, regular process of monitoring weather forecasts utilising web based services including MetService and MetVUW will be developed.

The results of these forecasts will be correlated with onsite observations and weather to develop an understanding of the site specific variances and intricacies of weather forecasts.

The results of this forecasting will be disseminated daily to site staff.

9.2 Reporting Reporting requirements of the above and other monitoring is detailed within the AMP.

9.3 Environmental performance metrics Erosion and Sediment Control processes will remain a key environmental performance metric during the construction process, demonstrating how NX2 shall proactively design, implement, maintain, monitor and where necessary reinforce precautions to protect the environment beyond the site boundary. It is anticipated that over the life of the construction period many thousands of individual scores will be issued by AC.

Once a week, NX2’s Environmental team will undertake a documented self‐audit of all ESC practices on site. Each control will be assessed by using the Transport Agency Contractor's Field Guide checklists and assigned a rating of 1‐4, with 1 being best practice and 4 meaning a practice is absent or poorly constructed resulting in an uncontrolled discharge of sediment.


Table 14: The Transport Agency contractor's field guide checklists

Rating Construction/Maintenance/Operation Example (not exhaustive)

1 Best practice – no further action required.

2 Minor technical issue with the ESC device, where the purpose of the guideline/standard, consent condition, management plan has been met.

Works to be carried out within 7 days.

No silt fence support

Minor holes in silt fence

Minor discrepancy in dead/live storage

Minor lack of volume in sediment retention device

3 Controls absent or construction of device is poor that it leads to or is likely to lead to failure as an efficient device

Works to be carried out within 3 days.

No returns in silt fence

Internal pond embankment collapses

Erosion at outlet of device

Diversions channels inadequately sized or stabilised

4 Controls absent or construction of device is poor that it leads failure as an efficient device, resulting in uncontrolled discharge.

Work to be carried out immediately.

It is anticipated that AC will also inspect the site on a weekly basis. Any actions identified through these audits will be addressed in the timeframes stipulated.


APPENDIX 1 Chemical Treatment Management Plan

PŪHOI TO WARKWORTH MOTORWAY PPP

CHEMICAL TREATMENT

MANAGEMENT PLAN DOC NO: 025‐MGP‐004‐NX2

CONTRACT NO: NZTA PA4030

CHEMICAL TREATMENT MANAGEMENT PLAN

DOCUMENT DETAILS


Chemical Treatment Management Plan Rev 01 025‐MGP‐004‐NX2 Mike McConnell



A 23/03/2016 Mike McConnell Environmental Consultant First Draft

B 18/10/2016 Mike McConnell Environmental Consultant Full Draft

B.01 25/11/2016 Mike McConnell Environmental Consultant Full Draft

B.02 12/12/2016 Mike McConnell Environmental Consultant Full Draft

C 20/12/2016 Mike McConnell Environmental Consultant Final Draft

C.01 12/01/2017 Mike McConnell Environmental Consultant Final Draft

01 26/01/2017 Mike McConnell Environmental Consultant Version 01

APPROVALS


Approved by Hugh Leersnyder Planning & Environmental Lead Technical Director

CJV 26/01/2017


Transport Agency

20/12/2016

REVISION DETAILS

Revision Details

A Included as part of NX2’s Tender Submission

B Full Draft for Transport Agency Review

B.01 Updated to address Transport Agency review comments

B.02 Updated to address Transport Agency review comments

C Final Draft – Auckland Council for approval 20/12/2016

C.01 Final Draft – updated to include comments received from Auckland Council 09/01/2017

01 In Use

CONTENTS

1 INTRODUCTION 1

1.1 Purpose & Scope 1

1.2 Relevant Consent Conditions 2

1.3 Responsibility for the ChemTMP 2

1.4 Plan updates and revisions 2

2 USE OF CHEMICAL ADDITIVES 4

2.1 Soil Testing 4

2.1.1 Introduction 4

3 DOSING OPTIONS 6

3.1 Introduction 6

3.2 Rainfall Activated Dosing ‐ PAC 6


3.2.2 Rainfall catchment tray 7

3.2.3 Header tank 7

3.2.4 Displacement tank 7

3.2.5 Flocculent reservoir 7

3.3 Rainfall Activated Dosing ‐ HaloKlear 7

3.4 Batch Dosing 8


3.4.2 Dosing Trigger Level 8

3.4.3 PAC Batch Dosing Methodology 8

4 MONITORING AND MAINTENANCE 10

4.1 Monitoring 10

4.1.1 Sampling 10

4.1.2 Required standards 11

4.2 Maintenance 11

4.3 Storage of Flocculation Chemicals 12

4.4 Transportation of Flocculation Chemicals 12

5 FLOCCULATION CHEMICAL SPILL CONTINGENCY PLAN 14

5.1 Watercare water take 14

5.2 Spill contingency procedure 14

APPENDIX A: INSTRUCTIONS FOR OBSERVATION OF WATER QUALITY IN SEDIMENT CONTROLS 16

APPENDIX B: PAC DOSING INSPECTION SHEET (TO BE REPRODUCED FOR EACH SRP OR DEB) 17

APPENDIX C: HALOKLEAR DOSING INSPECTION SHEET (TO BE REPRODUCED FOR EACH SRP OR DEB) 18

APPENDIX D: MSDS 19

APPENDIX E : HŌKAI NUKU MEMO 32

FIGURES Figure 1: Typical PAC Rainfall Activated System Layout 6

Figure 2: HaloKlear Floc Sock Typical Installation 8

TABLES Table 1: Construction Staging 1

Table 2: Chemical Treatment Management Conditions 2

CHEMICAL TREATMENT MANAGEMENT PLAN PAGE 1 PŪHOI TO WARKWORTH PPP – RESTRICTED – COMMERCIAL 025‐MGP‐004‐NX2

1 INTRODUCTION This Chemical Treatment Management Plan (ChemTMP) forms part of the Erosion and Sediment Control Plan and has been prepared in accordance with the requirements of Resource Consent Condition RC19(g).

It has been prepared by Northern Express Group (NX2) as part of its obligations under the Project Agreement. Implementation of this ChemTMP will ultimately be the responsibility of the Construct Joint Venture (CJV).

The Construction Sub‐contractor is referred to throughout this plan as the CJV. The word ‘sub‐contractor’ in this plan relates to sub‐contractors, which the CJV will engage on the Project.

During the preparation of this ESCP NX2 has engaged with the Iwi Advisor. Any issues raised during this consultation have been resolved to the satisfaction of both parties.

1.1 Purpose & Scope

This ChemTMP forms part of the suite of plans that form the broader Construction Environmental Management Plan (CEMP) for the Project. The ChemTMP covers all stages of Project construction, as outlined in Table 1 below.

Table 1: Construction Staging

Defined in Designation conditions as:

Stage Description of Works Approx. Duration

ENABLING WORKS

Enabling Works As defined by the designation definitions and consent conditions as preliminary activities, including: geotechnical investigations road sealing establishment of mitigation measures.

October 2016 – June 2017 Duration: 9 months

CONSTRUCTION WORKS

Early Works Comprising activities required to facilitate an efficient start to main construction works that are not within the scope of Enabling Works.

February 2017 – July 2018 Duration: 18 months

CONSTRUCTION WORKS

Main Construction Works

Core construction works associated with permanent aspects of the Project that are not included in the Early Works stage

October 2017‐October 2021

The principle purpose of this Chemical Treatment Management Plan (ChemTMP) is to ensure that the works associated with the Project are undertaken in a manner that ensures the potential or actual discharges of sediment as a result of the works are minimised to the greatest possible extent.

The philosophies to be utilised to achieve the above objective will be accomplished by following the methods and measures detailed within this document.

Compliance with the requirements of this document will ensure that the Project works meet the requirements of Resource Consent Conditions, industry best practice, client and stakeholder expectations.


1.2 Relevant Consent Conditions

Table 2 outlines the Resource Consent Conditions relevant to this ChemTMP and where they are addressed in this Plan.

Table 2: Chemical Treatment Management Conditions

Condition No.


Chemical Treatment Management

RC19 (g) A Chemical Treatment Management Plan (ChemTMP) which shall include as a minimum: i. Specific design details of the chemical treatment system based on a rainfall activated and manual batch dosing methodology for the site's sediment retention ponds (SRPs), decanting earth bunds (DEBs) and container impoundment systems and any other sediment detention or flow device system as may be employed on site; ii. Monitoring, maintenance (including post storm) and contingency programme (including a record sheet); iii. Details of optimum dosage (including assumptions); iv. Results of initial chemical treatment trial; v. A spill contingency plan; vi. Details of the person or bodies that will hold responsibility for the operation and maintenance of the chemical treatment system and the organisational structure which will support this system; and vii. Details of the process to notify Watercare if any flocculant spillage occurs upstream of the water take at NZTM 1748780 mE 5970390 mN (Auckland Council Permit No. 35555).

3.0 4.0 2.1.1 2.1.1 5.2 1.3 5.1

1.3 Responsibility for the ChemTMP

The SPV Project Director has the overall responsibility for meeting the requirements of this ChemTMP. The Environmental Manager (EM) will implement the ChemTMP, including all required monitoring and management, and lead the review of monitoring results with appropriate communication to Auckland Council. Refer to the Project CEMP for more detail on the key Project roles and responsibilities.

This ChemTMP will be implemented for the duration of the construction works (October 2016 to late‐2021) with a copy kept in an accessible location in each of the site offices for the duration of the Project.

The onsite implementation of the requirements of this ChemTMP is the responsibility of the Senior Environmental Advisor North / South, supported by the Senior Environmental Advisor Compliance.

1.4 Plan updates and revisions

This ChemTMP may require review and amendment during the life of the Project to reflect changes to activities, risks, mitigation measures, responsibilities and management processes and to comply with the relevant Consent conditions. The ability to make changes to the ChemTMP is vital to maintain its effectiveness and relevance. Modification may also be required to accommodate additional consents and/or designations once detailed design and construction methods are finalised.

Revisions to the ChemTMP will be made:


As NX2 considers necessary Promptly on any material change (including named personnel changes) If requested by Auckland Council (AC) As and when reasonably required by the Transport Agency (TA).

Any changes to the approved ChemTMP will be made by submission of the updated Plan pursuant to the Review procedures, prior to the updated Plan being submitted to Auckland Council for approval in accordance with Resource Consent Condition RC40A.


2 USE OF CHEMICAL ADDITIVES The use of chemical additives (commonly referred to as flocculation) can decrease the settlement time within sediment retention devices and therefore increase the sediment removal efficiency of these devices.

In order to maximise the efficiency of sediment retention devices (including Sediment Retention Ponds, Decanting Earth Bunds and Container Impoundment Systems) and therefore minimise the adverse environmental effects associated with the discharge of sediment the use of chemical additives is to be investigated for all sediment retention devices on site.

For each area of work a Construction Erosion and Sediment Control Plan (CESCP) will be prepared, in accordance with Resource Consent Conditions RC28 and RC29.

As part of the development of the CESCP consideration will be given to the benefits of using chemical treatment for any of the sediment retention devices detailed within the CESCP. The details of the specific chemical treatment, including chemical to be used, optimum dosage rates and dosage methodology will be included in the CESCPs.

Typically, Chemical Treatment for a Sediment Retention device will be provided unless:

Bench testing of soils in the contributing catchment confirms there is no benefit from chemical treatment, or

Where the duration of the earthworks is very short

2.1 Soil Testing

2.1.1 Introduction

Prior to earthworks commencing in an area an assessment of the effectiveness of chemical treatment on the site’s soils will be undertaken. This will be achieved by testing representative samples of the soils with a variety of chemicals to determine reactivity and the subsequent improvement in settlement efficiencies.

This assessment of the additive to be used will also determine the most efficient method of dosing (refer Section 5).

The “Water Assessment Factual Report 2 – Tests for Chemical Treatment” prepared for Further North determined the soils on site were reactive to PAC at relatively low rates. This report determined that for the upper soil layers (those to be first encountered) a dosage rate of between 5 ‐ 10ppm achieved an acceptable clarity. A dose rate of 10ppm equals a dose rate of 3mg/L. This dose rate will be used as the initial dose for sizing of floc sheds to ensure that adequately sized sheds are allowed for in the initial ponds.

During the initial geotechnical investigations (commencing 21 November 2016) soil samples will be taken and will be bench tested to determine initial chemical treatment options for those soils, including chemical to be used, optimum dosage rates and dosage methodology. The results from this testing will also be used to inform the initial sizing.

This bench testing will also identify any soils where the existing pH is outside of the GD05 baseline range of 5.5 – 8.5.

These initial chemical treatment options will be detailed in the CESCPs.

During the excavation of each chemically treated sediment retention device a sample of soil from the excavation will be bench tested to confirm final sizing.


In accordance with the monitoring and maintenance detailed in section 4.0, as the soil types in each area changes, as a result of deeper cuts and altering fill sources, the optimum chemical treatment option may also change.

Any changes to the chemical treatment for a device will be recorded as part of the monitoring records for that device.

A weekly summary of changes to chemical treatment will be forwarded to AC.

2.1.1.1 Test Procedure

Testing is undertaken by mixing a representative sample of soil from the site with water to produce a weak slurry, representative of sediment laden runoff from the site.

Four samples of this are then taken and placed in clear jars along with a fifth reference sample.

Potential chemical additives are then added at varying concentrations (where appropriate).

At regular intervals, 10 minutes, 30 minutes and 60 minutes, the depth of clarity is measured in each sample to determine which dosage of chemical provides the greatest level of settlement.

The pH of each sample is also measured after 60 minutes to ensure that this remains within the required limits, 5.5 – 8.5.

The appropriate dosage rate is then used to calculate the sizes of the various components of the rainfall activated treatment devices.

For some additives, in particular the HaloKlear GelFloc or Liquifloc a dose rate is not required and the chemicals are simply tested for reactivity.

2.1.1.2 Potential Chemicals

A number of potential chemical additives are available, however experience with the typical soils in the area indicate that the greatest increases in efficiency will be provided by:

Polyaluminium Chloride (PAC) HaloKlear GelFloc, HaloKlear Liquifloc, Magnasol, or CrystalFloc.

As industry experience changes during the course of the project, other additives or blends of additives will be considered as appropriate.

Each of these additives can be used in a rainfall activated or a batch dosing method.

Note to achieve this can require a dilution of the liquid form of the additive. Any such use including methodology will be detailed in the specific details of chemical treatment contained within the appropriate CESCP.

The use of chemicals in addition to PAC or HaloKlear products will be included in a revision to this ChemTMP.

The revisions to address this will identify the chemicals, the dosing procedures and testing and sampling proposed to ensure that residual chemicals are monitored and within acceptable limits.

These revisions to identify additional reactants will be undertaken in consultation with Hōkai Nuku and Watercare.


3 DOSING OPTIONS

3.1 Introduction

There are two main forms of dosing, Rainfall Activated and Batch Dosing.

In the rainfall activated process during rainfall the dosing system is automatically activated to provide the appropriate volume of additive to the sediment laden runoff.

The batch dosing process is typically undertaken following rainfall or to treat an impounded volume of pumped sediment laden water. This is a manual process where the volume of impounded water is determined and from this the appropriate volume of additive determined, added and mixed.

The specific ChemTMP’s included with each CESCP will detail the method of dosing.

Condition RC27(b) requires that all Decanting Earth Bunds (DEBs) and Sediment Retention Ponds (SRPs) that serve a catchment area greater than 500m2 shall be treated via a rainfall activated chemical treatment system.

Condition RC27(b) requires that SRPs shall each have two flocculation sheds (or equivalents) installed.

The installation of rainfall activated chemical treatment systems including provision of flocculation sheds will be in accordance with the above and will be detailed in the applicable CESCP.

3.2 Rainfall Activated Dosing ‐ PAC

3.2.1 Introduction

The flocculation systems to be used will be designed in accordance with GD05.

The basic design will be a rainfall activated system (typically) using Polyaluminium Chloride (PAC) to dose the Sediment Retention Ponds (SRP). However, for any smaller controls, specifically Decanting Earth Bunds (DEB), in particular those with minor contributing catchments and a short duration of earthworks, a rainfall activated system utilising FlocSocks may be utilised.

Figure 1: Typical PAC Rainfall Activated System Layout


3.2.2 Rainfall catchment tray

The rainfall catchment tray will be sized to provide treatment at the design dose rate for 100% of the runoff from exposed earthwork areas and for 60% of the runoff from any stabilised areas within the catchment.

A 50mm storm event will been used for calculating the size of the tray in accordance with TP227.

3.2.3 Header tank

The header tank design provides for 12mm of rainfall before dosing commences.

At this point a low rate outlet hose with a 3mm orifice is installed.

The high rate outlet hose with a 10mm orifice is installed at the level reached by a further 12mm of rain above the low flow outlet.

The header tank has a minimum freeboard of 50mm above the high rate outlet.

The header tank typically has a diameter of 580mm (a recycled PAC drum).

3.2.4 Displacement tank

The displacement tank will be a neat fit inside the flocculent reservoir tank.

The minimum displacement tank capacity will be the equivalent of a 100mm rainfall event.

3.2.5 Flocculent reservoir

The flocculent reservoir tank will have a minimum capacity to store sufficient flocculent to dose runoff from a 100mm rainfall event.

3.3 Rainfall Activated Dosing ‐ HaloKlear

The dosing procedure using HaloKlear specifically involves using a segmented geosynthetic sock filled with a dry flake form of HaloKlear GelFloc or Liquifloc.

In order to provide the correct dosing a HaloKlear sock(s) will be laid in each diversion drain approximately 5m upstream of the forebay of the SRP or DEB.

Each sock has 10 segments, each of which is capable of providing the required dose to approximately 50m3 of runoff. This equates to 50mm of rainfall for each 1,000m2 of contributing catchment.

Therefore for a 3,000m2 DEB catchment the sock will be maintained with a minimum of three full segments within the design flow depth at all times.

In order for the flows have maximum contact with the socks the socks must be placed in a defined channel that ensures the socks will come into contact with the full flow depth within the channel for all rainfall events up to and including the 5% AEP event (maximum flow diverted by the diversion bunds).

These socks are to be installed in accordance with the following diagram, Figure 2.


Figure 2: HaloKlear Floc Sock Typical Installation

3.4 Batch Dosing

3.4.1 Introduction

Batch dosing will typically be undertaken using PAC.

Where specific retention devices require an alternative additive (i.e., in those areas where the soils are unreactive to PAC) a specific procedure will be detailed in the specific ChemTMP for that device.

The following contingency procedure will be utilised for PAC batch dosing, typically within any DEBs if it is determined necessary.

3.4.2 Dosing Trigger Level

The trigger level for batch dosing will be 100mm clarity, i.e., when the clarity of impounded sediment laden runoff falls below 100mm batch dosing will be undertaken in accordance with the following batch dosing methodology.

3.4.3 PAC Batch Dosing Methodology

The outlet of any impounded runoff will be blocked. This may be done either with a pre‐installed valve or a crimped (folded) section of lay flat hose connected to the outlet of the decant or other methods such as raising the decant.

Following rainfall, the clarity will be checked and if less than 100mm, Polyaluminium Chloride (PAC) will be added by spraying it on the surface of the DEB or by careful application using a bucket or other small container to evenly disperse the PAC over the surface of the DEB.

The PAC will be added at the standard rate of dosing for the devices on site, this rate expressed as a litre of PAC per 10m3 of impounded runoff will be included within the specific ChemTMP for that device.

The impounded water will then be mixed with the PAC using one of the following methods:

Mixing with a pole, paddle or oar Mixing by circulating the impounded flows through a pump Mixing by dragging semi‐submerged floats through the surface area of the impounded water.

Once settlement has occurred, typically 2‐3 hours the pH and clarity within the device will be checked. If the pH is between the range of 5.5 and 8.5 and the clarity is greater than 100mm the decant will be opened and the device drained.


If the clarity is less than 100mm a further dose of PAC will be added at 50% of the original rate and a further settlement period of 2‐3 hours allowed before retesting.

If the pH levels fall outside the acceptable range of 5.5 to 8.5 the Senior Environmental Advisor North / South or Senior Environmental Advisor Compliance will be contacted to determine appropriate actions which could include off site removal of impounded water or adding alternate chemicals, such as sodium carbonate or sodium bi‐sulphate, to alter the pH.

Subject to the weather conditions at the time and the level by which the range has been exceeded it may be appropriate to use the impounded water for dust control.


4 MONITORING AND MAINTENANCE

4.1 Monitoring

Monitoring of the Project’s erosion and sediment control devices, including the chemical treatment devices is addressed through the Adaptive Monitoring Plan (AMP).

Compliance with the AMP will ensure that the objectives of the Erosion and Sediment Control Plan (as defined by RC17) are met.

Monitoring will include:

Certification of all ESC devices Inspection after rainfall event Weekly audits Pre and post rain event audits, including heavy rain and stabilisation trigger events Triggered monitoring as a result of rainfall, ecological exceedances or failure of sediment retention

device.

The specific monitoring of the Flocculation system will be undertaken by the Senior Environmental Advisor Compliance with regular checks of this monitoring made by the Environmental Manager Construction.

This monitoring will be undertaken weekly and following heavy rain events of the following items:

Rainfall in previous 24 hours Depth of water in displacement tank Volume of flocculent used (added) pH of the pond Initial header tank level Any changes in degree of stabilisation of the site Appearance of pond (relative turbidity) Estimated level of accumulated sediment within pond.

Refer to APPENDIX 1, APPENDIX 2 and APPENDIX 3 for further information.

The frequency of this testing may be increased during extended periods of heavy rainfall or reduced during dry periods.

Additionally, prior to any forecast heavy rain or if the site is to be unattended for more than 48 hours the flocculent reservoir tank will be filled to ensure that chemical treatment will occur through the following (or potential) 50mm of rainfall.

The results of pH sampling will be used to determine if any modifications are required to the dosage rate. The acceptable limits for the pH is between 5.5 and 8.5. If the pH levels fall outside these ranges the Senior Environmental Advisor North / South or Senior Environmental Advisor Compliance will determine appropriate actions which could include decommissioning the flocculation unit or adding alternate chemicals, such as sodium carbonate or sodium bi‐sulphate, to alter the pH.

4.1.1 Sampling

In addition to the above monitoring, the discharges from the sediment retention devices will be sampled on a regular and triggered basis in accordance with the Adaptive Monitoring Plan (AMP).

This sampling will provide information on the efficiency of the various sediment retention devices and therefore allow modifications to be made to ‘fine tune’ the chemical treatment measures utilised on each device.

This testing of samples taken from site will be undertaken at the onsite ‘laboratory’.


This laboratory will also be used by the Senior Environmental Advisor Compliance to undertake the soil testing detailed in Section 2.1. The retesting of soils will be undertaken whenever:

There is an obvious change in soil types within the contributing catchment of the device, or Where the AMP sampling has indicated a reduction in device efficiency.

The ability to undertake this sampling and testing on site will allow rapid decisions and modifications to the chemical treatment management measures to be made. This in turn will ensure the devices operate at the highest possible efficiency, significantly reducing the potential for consent non‐compliance.

4.1.2 Required standards

Trigger levels are defined within the AMP whereby specific monitoring is required. As an iterative process as a result of this monitoring a standard or standards of discharge will be developed. It is anticipated that two standards will be appropriate, one standard for discharges where the device is not overtopped and a second standard for the instance where the device is overtopped.

As an initial standard the following criteria will be used (adopted from ‘standard’ AC discharge criteria across the Auckland Region)

4.1.2.1 pH

The pH of discharges from any sediment retention device shall remain within the range of 5.5 – 8.5, unless site specific analysis has shown that the pH of the receiving water body, unaffected by site discharges is outside of this range. Where the pH in the receiving water body, unaffected by site discharges, is outside of the range 5.5 – 8.5 then this existing pH level shall be the upper or lower pH limit for discharges from the site.

Monitoring of pH will be a key indicator of the potential for residual aluminium discharges. Specifically, overdosing of PAC may cause a reduction in pH, raising the potential for aluminium within the PAC to react, forming toxic aluminium compounds that are bioavailable to fresh and marine water organisms.

4.1.2.2 Clarity

The initial standard for clarity of discharges from any sediment retention device shall be 100mm. This clarity will be correlated with Total Suspended Solids (TSS) and turbidity as a result of sampling and testing undertaken as part of the AMP.

This sampling and testing will be used to verify that 100mm is an appropriate level of clarity for discharges. As detailed above it is anticipated that a final standard will account for events where the sediment retention devices are overtopped.

4.1.2.3 Residual Chemicals

Subject to the additives utilised testing for residual chemicals, including aluminium will be undertaken.

As detailed in 4.1.2.1 overdosing of PAC may cause a reduction in pH, raising the potential for aluminium within the PAC to react, forming toxic aluminium compounds that are bioavailable to fresh and marine water organisms

The soluble aluminium concentration of discharges from any sediment retention pond shall not exceed 0.2 grams per cubic meter unless site specific analysis has shown that the soluble aluminium concentration of the receiving water body, unaffected by site discharges is outside of this range.

The frequency of sampling for residual aluminium will be undertaken at a rate of 1 sample for each 5,000m3 discharged from each device being chemically treated with PAC.

4.2 Maintenance

The Senior Environmental Advisor North / South will have responsibility for the maintenance of the chemical treatment devices in their respective areas.


The maintenance of the chemically treated sediment retention devices will be similar to that of non‐chemically treated devices. The exception will be that the devices will require removal of the accumulated sediment more frequently. This accumulated sediment will be removed, dried and placed in fill areas of the site when this volume exceeds 20% of the pond storage volume or otherwise decreases the efficiency of the pond.

Additional maintenance requirements will vary depending on the chemical treatment system being utilised.

For the HaloKlear System this is typically limited to ensuring that the GelFloc socks are located within an area of high flow and that there is sufficient GelFloc within each sock for the predicted rainfall.

For a PAC system the maintenance will include checking that the catchment tray is kept clear of leaves etc., and that the outlet point of the delivery hose is encouraging adequate mixing of the flocculent with inflows. All hoses, connections etc. will be checked to ensure they are sound and that there is no leakage. Flocculent levels etc. will be topped up and the displacement tank emptied at this time.

The daily maintenance of the system will also include the setting of the header tank level. This level allows a degree of rainfall to take place prior to dosing occurring. This initial level will be set to the following parameters:

When the site is dry, the header tank will be left empty so that 12mm of rain will fall prior to discharge of flocculent

During extended periods of rainfall or if the site is already saturated (i.e., runoff will occur as soon as rain begins) the header tank will be filled to the level of the low rate outlet.

As the area of the contributing catchment and the degree of stabilisation within the contributing catchment alters the area of the catchment tray will be altered to account for these changes.

The catchment tray area will also be used as a method of controlling the pH and dissolved aluminium levels.

The results of the daily and weekly inspections and sampling will be retained for inspection as requested.

4.3 Storage of Flocculation Chemicals

The storage of the bulk flocculation chemicals required to replace used flocculent will be in accordance with standard practice for storage of hazardous materials on site, specifically that bulk volumes these chemicals will be stored in a secure bunded facility.

The Safety Data Sheets (SDS) for each chemical will be retained in a site register and will also be stored with the chemicals.

The storage of the flocculent within the flocculation system at each pond site will be within a secure locked shed. Additional drums adjacent to each shed (as required) will be within a bunded area, and or adequately secured and protected to minimise the potential for accidental or deliberate (vandalism) spillage.

This requirement will also apply to any chemicals required for pH balance, however as the use of these chemicals will be infrequent, the storage of these chemicals will be at central depots.

4.4 Transportation of Flocculation Chemicals

The transportation of Flocculation Chemicals (including chemicals for pH balance) to and from the Project will be undertaken in accordance with the required Hazardous Goods, Traffic and Transport regulations.


On site the chemicals will be transported in sealed containers, securely retained within the site vehicle. These containers will be small enough to be easily handled and only the expected required volume will be transported.

The use of these chemicals will be in accordance with the Construction Health and Safety Management Plan.


5 FLOCCULATION CHEMICAL SPILL CONTINGENCY PLAN

5.1 Watercare water take

Watercare hold a permit (AC Permit No 35555) to take water from the Mahurangi River, immediately west of SH1 in Warkworth.

In the event of a spill of a flocculent (or any other chemical) within the Mahurangi Catchment, area upstream of this point, in particular any spill to a watercourse, there is a potential for this chemical to contaminate this water take.

To ensure the potential for this is avoided all flocculation devices within the Mahurangi Catchment (i.e., north of Moir Hill Road) will include signage requiring the immediate reporting of any spill of a chemical to the Senior Environmental Advisor North.

The Senior Environmental Advisor North will then inform Watercare of the spill on the Watercare emergency no (09) 442 2222. Following contract award a meeting will be arranged with Watercare to confirm if any more appropriate contact details or arrangements can be made.

5.2 Spill contingency procedure

Any spills of flocculation chemicals will be controlled in accordance with the Construction Environmental Management Plan (CEMP).

In the event of a spill to ground the following procedures will be followed:

The source of the spill will be identified and further spillage prevented by plugging burst hoses, standing up overturned containers etc.

The area of the spill will be impounded as appropriate. Any free flocculent will be soaked up by sawdust (from the spill containment kit) or similar and

disposed of in the spill container Any contaminated soil will be excavated and also disposed of in the spill container, if the volume is

too great a similar appropriate container or sealed body truck will be used Contaminated soil will be disposed of at a registered landfill Details of the spill and remedial actions are to be recorded For spills to ground of more than 20L the Auckland Council is to be notified immediately (09) 377

3107 For spills to ground of more than 20L within the Mahurangi Catchment, Watercare is to be notified as

above.

In the event that a spill occurs to a sediment retention pond, the outlet to this pond will be sealed and the water within the pond will be tested to confirm whether it exceeds the acceptable levels of pH. If these levels are exceeded this water will be pumped into a watercart and sprayed on an appropriate earthwork area or alternate chemicals, such as soda ash, will be added to reduce the pH.

In the event of a spill to a watercourse the following procedure is to be followed:

The source of the spill will be identified and further spillage prevented by plugging burst hoses, standing up overturned containers etc.

If the stream is small and the flow minor, every effort should be made to dam the stream below the spill to prevent further downstream migration of the chemical

Subject to the volume and nature of the spill, the chemical should be removed, by pumping for chemicals which have become diluted by the stream water or by using absorbent pads for chemicals which float

Any pumping is to be directed to a suitable impoundment area or tank Any absorbent pads are to be disposed of in the spill container


Details of the spill and remedial actions are to be recorded For spills to water of more than 1L the Auckland Council is to be notified immediately (09) 377 3107 For any spills more than 1L to water within the Mahurangi Catchment Watercare is to be notified as

above.


Appendix A: Instructions for Observation of Water Quality in Sediment Controls OBSERVATION OF WATER QUALITY IN SEDIMENT CONTROLS

The water quality within sediment controls will be observed at least weekly, and the clarity determined using a black disk and recorded on the monitoring sheet. Clarity is measured using a black disk lowered vertically into the water to be tested. A small black disc of 50‐80mm diameter is attached to a 1m long stick with a centimetre scale starting at the disc. The disc is lowered into the water until it disappears, and then is raised until it just reappears. The depth of reappearance is recorded as the clarity of the water. If the clarity drops below 100mm advise Senior Environmental Advisor North / South immediately. Water with a clarity of 100mm or greater is considered to be acceptable for discharge.

pH shall be recorded once the pond has filled up to ensure that chemical dosing does not have an unacceptable effect. If the pH drops below 5.5 dosing should cease immediately and the Senior Environmental Advisor North / South advised.

MONITORING RECORDS

A separate sheet is provided for monitoring records for each month. The information to be recorded is as follows:

pH Check:

Measure pH at least weekly at the outlet of the sediment controls and record the pH on the monitoring record sheet.

Pond Clarity:

Record using black disc near pond outlet. (Refer above)


Appendix B: PAC Dosing Inspection Sheet (to be reproduced for each SRP or DEB)

Device Name:

Date Rainfall (mm)

Flocculent Added (litres)

Header Tank Depth (mm)

Catchment Stabilisation (%)

Appearance of Device

Estimated Sediment Depth (m)

pH of Device

Inspected By (sign)


Appendix C: HaloKlear Dosing Inspection Sheet (To be reproduced for each SRP or DEB)

Device Name:

Date Rainfall (mm)

Sock Replaced Catchment Stabilisation (%)

Appearance of Device

Estimated Sediment Depth (m)

pH of Device

Inspected By (sign)


Appendix D: MSDS

Safety Data Sheet

1. IDENTIFICATION OF THE MATERIAL AND SUPPLIER

Product Name: LIQUIPAC (POLYALUMINIUM CHLORIDE) Other name(s): Liquipac * Liquid PAC * Liquid polyaluminium chloride * PAC solution * Polyaluminium

chloride solution Recommended use of the chemical and restrictions on use:

Flocculating agent for potable water and industrial water treatments.

Supplier: Orica New Zealand Limited Street Address: Orica Chemnet House

Level four, 123 Carlton Gore RoadNewmarket, AucklandNew Zealand

Telephone Number: +64 9 368 2700Facsimile: +64 9 368 2710Emergency Telephone: 0 800 734 607 (ALL HOURS)

2. HAZARDS IDENTIFICATION

Not classified as a Dangerous Good under NZS 5433:2012 Transport of Dangerous Goods on Land. Classified as hazardous according to criteria in the HS (Minimum Degrees of Hazard) Regulations 2001. SIGNAL WORD: WARNING Subclasses: Subclass 6.1 Category D - Substances which are acutely toxic. Subclass 6.3 Category A - Substances that are irritating to the skin. Subclass 6.4 Category A - Substances that are irritating to the eye.

Water Treatment Chemicals (Subsidiary Hazard) Group Standard 2006

Hazard Statement(s):H302 Harmful if swallowed.H315 Causes skin irritation.H319 Causes serious eye irritation. Precautionary Statement(s):

Prevention:P102 Keep out of reach of children.P264 Wash hands thoroughly after handling.P270 Do not eat, drink or smoke when using this product.P280 Wear protective gloves/protective clothing/eye protection/face protection.

Product Name: LIQUIPAC (POLYALUMINIUM CHLORIDE) Issued: 17/01/2013Substance No: 000000015710 Version: 4

Page 1 of 6

Safety Data Sheet

Response:P301+P312 IF SWALLOWED: Call a POISON CENTER or doctor/physician if you feel unwell.P330 Rinse mouth.P302+P352 IF ON SKIN: Wash with plenty of soap and water.P321 Specific treatment (see First Aid Measures on the Safety Data Sheet).P332+P313 If skin irritation occurs: Get medical advice/attention.P362 Take off contaminated clothing before re-use.P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.P337+P313 If eye irritation persists: Get medical advice/attention. Storage:No storage statements. Disposal:P501 In case of a substance that is in compliance with a HSNO approval other than a Part 6A (Group Standards) approval, a label must provide a description of one or more appropriate and achievable methods for the disposal of a substance in accordance with the Hazardous Substances (Disposal) Regulations 2001. This may also include any method of disposal that must be avoided.

3. COMPOSITION/INFORMATION ON INGREDIENTS

Components CAS Number Proportion Hazard Codes Water 7732-18-5 >60% -Polyaluminium chloride 1327-41-9 30-60% H302 H315 H319 4. FIRST AID MEASURES

For advice, contact a Poisons Information Centre (e.g. phone Australia 131 126; New Zealand 0800 764 766) or a doctor. Inhalation:Remove victim from area of exposure - avoid becoming a casualty. Remove contaminated clothing and loosen remaining clothing. Allow patient to assume most comfortable position and keep warm. Keep at rest until fully recovered. Seek medical advice if effects persist. Skin Contact:If skin or hair contact occurs, immediately remove any contaminated clothing and wash skin and hair thoroughly with running water. If swelling, redness, blistering or irritation occurs seek medical assistance. Eye Contact:If in eyes, hold eyelids apart and flush the eye continuously with running water. Continue flushing until advised to stop by a Poisons Information Centre or a doctor, or for at least 15 minutes. Ingestion:Rinse mouth with water. If swallowed, give a glass of water to drink. If vomiting occurs give further water. Seek immediate medical assistance. Indication of immediate medical attention and special treatment needed:Treat symptomatically.

5. FIRE FIGHTING MEASURES

Suitable Extinguishing Media:Not combustible, however, if material is involved in a fire use: Extinguishing media appropriate to surrounding fire conditions. Specific hazards arising from the substance or mixture:Non-combustible material.


Page 2 of 6

Safety Data Sheet

Special protective equipment and precautions for fire-fighters:Decomposes on heating emitting toxic fumes, including those of hydrogen chloride . Fire fighters to wear self-contained breathing apparatus and suitable protective clothing if risk of exposure to products of decomposition.

6. ACCIDENTAL RELEASE MEASURES

Emergency procedures/Environmental precautions: Clear area of all unprotected personnel. If contamination of sewers or waterways has occurred advise local emergency services. Personal precautions/Protective equipment/Methods and materials for containment and cleaning up:Slippery when spilt. Avoid accidents, clean up immediately. Wear protective equipment to prevent skin and eye contact. Contain - prevent run off into drains and waterways. Use absorbent (soil, sand or other inert material). Collect and seal in properly labelled containers or drums for disposal.

7. HANDLING AND STORAGE

Precautions for safe handling: Avoid skin and eye contact and breathing in vapour, mists and aerosols. Conditions for safe storage, including any incompatibilities: Store in a cool, dry, well ventilated place and out of direct sunlight. Store away from incompatible materials described in Section 10. Keep containers closed when not in use - check regularly for leaks.

8. EXPOSURE CONTROLS/PERSONAL PROTECTION

Workplace Exposure Standards: No value assigned for this specific material by the New Zealand Department of Labour (Health & Safety). However, Workplace Exposure Standard(s) for constituent(s):

Aluminium, as Al: Soluble salts WES-TWA 5 mg/m3

As published by the New Zealand Department of Labour (Health & Safety).

WES - TWA (Workplace Exposure Standard - Time Weighted Average) - The eight-hour, time-weighted average exposure standard is designed to protect the worker from the effects of long-term exposure.

These Workplace Exposure Standards are guides to be used in the control of occupational health hazards. All atmospheric contamination should be kept to as low a level as is workable. These workplace exposure standards should not be used as fine dividing lines between safe and dangerous concentrations of chemicals. They are not a measure of relative toxicity.

Appropriate engineering controls: Ensure ventilation is adequate and that air concentrations of components are controlled below quoted Workplace Exposure Standards. Keep containers closed when not in use. Individual protection measures, such as Personal Protective Equipment (PPE):The selection of PPE is dependant on a detailed risk assessment. The risk assessment should consider the work situation, the physical form of the chemical, the handling methods, and environmental factors.

Orica Personal Protection Guide No. 1, 1998: C - OVERALLS, SAFETY SHOES, CHEMICAL GOGGLES, GLOVES.


Page 3 of 6

Safety Data Sheet

Wear overalls, chemical goggles and impervious gloves. Always wash hands before smoking, eating, drinking or using the toilet. Wash contaminated clothing and other protective equipment before storage or re-use.

If risk of inhalation exists, wear suitable mist respirator meeting the requirements of AS/NZS 1715 and AS/NZS 1716.

9. PHYSICAL AND CHEMICAL PROPERTIES

Physical state: Clear LiquidColour: Pale AmberOdour: MildSolubility: Soluble in water.Specific Gravity: 1.20 @20°C (at 10.1% Al2O3)Relative Vapour Density (air=1): Not availableVapour Pressure (20 °C): Not availableFlash Point (°C): Not applicableFlammability Limits (%): Not applicableAutoignition Temperature (°C): Not applicableBoiling Point/Range (°C): Not availableDecomposition Point (°C): Not availablepH: 2.6 +/- 0.3 @25°CFreezing Point/Range (°C): -12.0 (approx.)

10. STABILITY AND REACTIVITY

Chemical stability: Slowly corrodes metals. Possibility of hazardous reactions: Reacts with calcium hypochlorite , acids , and alkalis . Conditions to avoid: None known. Incompatible materials: Incompatible with calcium hypochlorite , acids , alkalis , and metals . Hazardous decomposition products:

Hydrogen chloride.

11. TOXICOLOGICAL INFORMATION

No adverse health effects expected if the product is handled in accordance with this Safety Data Sheet and the product label. Symptoms or effects that may arise if the product is mishandled and overexposure occurs are: Ingestion: Swallowing can result in nausea, vomiting, diarrhoea, and gastrointestinal irritation. Eye contact: An eye irritant. Skin contact: Contact with skin will result in irritation. Inhalation: Breathing in mists or aerosols may produce respiratory irritation.


Page 4 of 6

Safety Data Sheet

Acute toxicity: No LD50 data available for the product. However, for constituent(s) POLYALUMINIUM CHLORIDE:Oral LD50 (rat): 681 mg/kg.Oral LD50 (mice): 316 mg/kg. Chronic effects: No information available for the product.

12. ECOLOGICAL INFORMATION

Ecotoxicity Avoid contaminating waterways.

13. DISPOSAL CONSIDERATIONS

Disposal Methods: Refer to local government authority for disposal recommendations. Dispose of material through a licensed waste contractor. Normally suitable for disposal at approved land waste site.

14. TRANSPORT INFORMATION

Road and Rail TransportNot classified as a Dangerous Good under NZS 5433:2012 Transport of Dangerous Goods on Land. Marine TransportNot classified as Dangerous Goods by the criteria of the International Maritime Dangerous Goods Code (IMDG Code) for transport by sea; NON-DANGEROUS GOODS. Air TransportNot classified as Dangerous Goods by the criteria of the International Air Transport Association (IATA) Dangerous Goods Regulations for transport by air; NON-DANGEROUS GOODS.

15. REGULATORY INFORMATION

Classification:Classified as hazardous according to criteria in the HS (Minimum Degrees of Hazard) Regulations 2001. Subclasses: Subclass 6.1 Category D - Substances which are acutely toxic. Subclass 6.3 Category A - Substances that are irritating to the skin. Subclass 6.4 Category A - Substances that are irritating to the eye.

Water Treatment Chemicals (Subsidiary Hazard) Group Standard 2006 Hazard Statement(s):H302 Harmful if swallowed.H315 Causes skin irritation.H319 Causes serious eye irritation.

16. OTHER INFORMATION

`Registry of Toxic Effects of Chemical Substances'. Ed. D. Sweet, US Dept. of Health & Human Services: Cincinatti, 2012.


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Safety Data Sheet

Reason(s) for Issue:5 Yearly Revised Primary SDS

This SDS summarises to our best knowledge at the date of issue, the chemical health and safety hazards of the material and general guidance on how to safely handle the material in the workplace. Since Orica Limited cannot anticipate or control the conditions under which the product may be used, each user must, prior to usage, assess and control the risks arising from its use of the material.

If clarification or further information is needed, the user should contact their Orica representative or Orica Limited at the contact details on page 1.

Orica Limited's responsibility for the material as sold is subject to the terms and conditions of sale, a copy of which is available upon request.


Page 6 of 6


Appendix E : Hōkai Nuku Memo

Memo

To: Stuart Chapman, Fletcher Construction – Nx2

CC: Gena Moses-Te Kani, Pou Tātaki, Hōkai Nuku

From: Marina Hetaraka, Ahu Kaupapa, Hōkai Nuku

Date: 11 November 16

Subject: Ara Tūhono – Pūhoi to Wellsford Road of National Significance: Pūhoi to Warkworth Section:

Hōkai Nuku input into the Northern Express Group Chemical Treatment Plan

Kia ora Stuart,

Please find attached Hōkai Nuku input into Chemical Treatment Plan (CTP) as required by the

relevant Project Designation and Resource Consent conditions. The relevant conditions are:

D9/RC7 - The Requiring Authority shall invite the Iwi Advisor to provide cultural indicators

covering traditional association, mahinga kai and cultural stream health measures. The

Requiring Authority shall have regard to any cultural indicators provided in the preparation

of any management plan required under these conditions.

The relevant Hōkai Nuku protocols and Management Plans relevant to the preparation of the CTP

provided for by the Project Designation and Resource Consent are:

Cultural Monitoring Protocol (22 December 2015);

Hōkai Nuku Cultural Harvest & Use Protocol (5 February 15);

Ki Uta, Ki Tai - Hōkai Nuku Freshwater & Marine Cultural Indicators Framework and

Monitoring Plan (2 February 2016).

Please let me know if you need any further discussion of any of the above or review input from

Hōkai Nuku. I would appreciate you acknowledging receipt of this memo and response to the various

Hōkai Nuku requests as appropriate. Ngamihi Marina

Designation Condition 9/Resource Consent Condition 7

Table 1 provides cultural indicators relevant to the preparation of the CTP undertaking of the

geotechnical investigations for the Enabling Works Phase. Hōkai Nuku will actively support field and

relevant staff to understand the importance of the cultural indicators when undertaking field work.1

Table 1: Provision for Cultural Indicators in the preparation of any Management Plans

Relevant Management Plan & specific reference

Cultural Indicator & Description

Hōkai Nuku management tool

Approach for having regard for the Cultural Indicators

Chemical Treatment Plan - Monitoring –

particularly in

receiving water bodies.

- Awa: cultural health stream assessment sustained & healthy with ngahere.

- Hōkai Nuku Ki Uta, Ki Tai Freshwater & Marine Cultural Indicators

- The Requiring Authority invited the Iwi Advisor to provide cultural indicators for the Chemical Treatment Plan at the development phase of the plan.

- The Requiring Authority will ensure any works that extend into a water course and or if an environmental incident may occur; inform Hōkai Nuku at the earliest convenience.

- Hōkai Nuku will provide the necessary cultural induction for field staff to support the Requiring Authority to meet this requirement.

- As required Hōkai Nuku will be made aware of any environmental incidents through

relevant staff.

1 Through regular toolbox inductions as per CHAMP protocols, pg. 17.


APPENDIX 2 Hōkai Nuku Engagement Memo

Memo

To: Stuart Chapman, Fletcher Construction – Nx2

CC: Gena Moses-Te Kani, Pou Tātaki, Hōkai Nuku

From: Marina Hetaraka, Ahu Kaupapa, Hōkai Nuku

Date: 6 November 16

Subject: Ara Tūhono – Pūhoi to Wellsford Road of National Significance: Pūhoi toWarkworth Section:

Hōkai Nuku engagement for Erosion and Sediment Control Plan (RC18B);

Kia ora Stuart,

Please find attached Hōkai Nuku input into the Erosion and Sediment Control Plan as required by the

relevant Project Designation and Resource Consent condition. The relevant condition is:

RC18B The Consent Holder shall prepare an Erosion and Sediment Control Plan (ESCP) for

the Construction Works for the entire Project to identify how Condition RC17 will be met.

The Consent Holder shall engage with the Iwi Advisor while preparing the ESCP.

Please let me know if you need any further discussion of any review input from Hōkai Nuku.

I would appreciate you acknowledging receipt of this memo and response to the various Hōkai Nuku

requests as appropriate. On receipt of the final ESCP finalised for certification, Hōkai Nuku will

provide the necessary email confirmation to close out the process requirements of RC18B.

Ngamihi

Marina Hetaraka, Ahu Kaupapa - Hōkai Nuku

BackgroundAs described in the Hōkai Nuku Cultural Effects Assessment (2013) the Project will have significanteffects on the cultural values of Hōkai Nuku. Table 1 outlines the cultural values of Hōkai Nuku, theHōkai Nuku Cultural Footprint Framework and Ki Uta, Ki Tai – cultural indicators. The purpose of Table1 is to indicate specific areas of cultural significance to Hōkai Nuku.

Table 1: Hōkai Nuku Cultural Values1

Hōkai Nuku Cultural Values & Cultural Footprint Framework

Hōkai Nuku Cultural Values – key principles2

Mauri – all elements of the natural environment, including people, possess mauri (life force) and allforms of life are related;

Kaitiakitanga – Māori therefore, have an obligation to protect and enhance the mauri of all naturalresources, for the benefit of ourselves, other people living in our homeland and for futuregenerations;

Ki Uta, Ki Tai – the mauri of waterways is also viewed holistically and includes from the source of thewaterway to the sea;

Hauhake, Kohikohi – the use of flora and fauna to sustain the people.

Hōkai Nuku Cultural Footprint Framework3

Mana Tangata – acknowledging and upholding the mana or the people that whakapapa to the area;

Mana Whenua – Identifying the features of the physical landscape that are of cultural importance;

Putake – addressing particular historical and contemporary issues within the area, and any futureaspirations.

Hōkai Nuku Ki Uta Ki Tai Freshwater & Marine Cultural Indicators4

The mauri of the waterways is viewed holistically and includes from the source of the waterway tothe sea;

The application of specific cultural indicators is provided for in the Project by Designation Condition9, the requirement is for the Iwi Advisor to provide cultural indicators for any management planrequired by the Designation and Resource Consent Conditions.

1 Reference: Moses-Te Kani, G (2013) 500-049 Cultural Effects Assessment Report2 Reference: Moses-Te Kani, G (2013) 500-049 Cultural Effects Assessment Report, pg 83 Reference: Moses-Te Kani, G (2013) 500-049 Cultural Effects Assessment Report, pg 94 Reference: Ki Uta, Ki Tai - Hōkai Nuku Freshwater & Marine Cultural Indicators Framework and MonitoringPlan

Hōkai Nuku Cultural Effects AssessmentTable 2 provides an overview of the potential significant effects, of activities to be outlined within thedevelopment of CECSPs, on the Hōkai Nuku Cultural Footprint. This provides an indication at theoutset, but is not limited to, of activities that are of high interest for Hōkai Nuku for the preparationof the ESCP. Hōkai Nuku is particularly interested in the mitigation of effects on:

Activities within the proximity of waterways;

Activities that require vegetation removal;

Activities that require earthworks.

Detailed management approaches will be provided for by Hōkai Nuku as required by RC28.

Table 2: Hōkai Nuku Cultural Values assessment of effects against ESCP activities.5

Erosion and Sediment ControlAssociated Activities6

Hōkai Nuku Cultural EffectsAssessment7

Proposed mitigation andmanagement of effects on HōkaiNuku Cultural Footprint

Erosion and Sediment ControlRequirements

Activities associated with earthworks,vegetation removal, streamworks,water treatment will cause significanteffects on Ki Uta, Ki Tai and Hauhake,Kohikohi cultural values.

Detailed management approacheswill be provided for by Hōkai Nukuas required by RC28.

Coastal Works Activities associated with works to beundertaken within the coastalenvironment and works associatedwith Pūhoi Viaduct will causesignificant effects on Ki Uta, Ki Tai andHauhake, Kohikohi, Hōkai NukuCultural Footprint.

Detailed management approacheswill be provided for by Hōkai Nukuas required by RC28 and providedfor by RC49, RC73.

Vegetation Removal Activities associated vegetationremoval will cause significant effectson Ki Uta, Ki Tai and Hauhake,Kohikohi cultural values.

5 Reference: Moses-Te Kani, G (2013) 500-049 Cultural Effects Assessment Report6 Definition provided for by designation and resource consent conditions7 As summarised by Table 1 with further explanation provided for by Moses-Te Kani, G (2013) 500-049 CulturalEffects Assessment Report

Hōkai Nuku Specific Comments Erosion PlanRC18B requires - the Consent Holder shall prepare an Erosion and Sediment Control Plan (ESCP) for theConstruction Works for the entire Project to identify how Condition RC17 will be met. The ConsentHolder shall engage with the Iwi Advisor while preparing the ESCP. For the purposes of meeting therequirements of RC18B, Hōkai Nuku requests the specific amendments and or comments beconsidered while finalising the final ESCP for certification.

1. Text in red be added where appropriate:

Construction Erosion and Sediment Control Plans

a. Preparation (Section 8, pg 42 – screen shot below).

Hōkai Nuku Engagement in the Preparation of CESCPS

The preparation of specific CESCPs requires:

- the consent holder shall engage with the Iwi Advisor while preparing the CESCPs; and

- the preparation of any management plan requires the Iwi Advisor to provide cultural

indicators. The consent holder shall have regard to any cultural indicators provided in the

preparation of any management plan required under the conditions.

During the preparation of the specific CESCPs, the consent holder will engage with the Iwi Advisor as

outlined in the Designation and Resource Consent Conditions – Compliance Procedures.8 This

process will include, if necessary, Hōkai Nuku providing an assessment of effects and mitigation

measures on the Hōkai Nuku Cultural Footprint as required by RC28.

The Hōkai Nuku Cultural Footprint is described as:

Mana Tangata – acknowledging and upholding the mana or the people that whakapapa to

the area;

Mana Whenua – Identifying the features of the physical landscape that are of cultural

importance;

Putake – addressing particular historical and contemporary issues within the area, and any

future aspirations.

Hōkai Nuku will also provide cultural indicators as required by RC7, these cultural indicators include,

but are not limited to:

Awa

Ngahere

o Rakau

o Manu

o Ngāngara

Rongoa

Ika

Haukahe, Kohikohi

Pūnaha Taupuhi Kaiao Taketake

8 Reference: Hetaraka, M (2016) Designation and Resource Consent Conditions – Compliance Procedures


APPENDIX 3 Dewatering Management Guidelines

PŪHOI TO WARKWORTH MOTORWAY PPP

SITE WIDE DEWATERING & PUMPING GUIDELINE

DOC NO: 025‐GDL‐001‐NX2

CONTRACT NO: NZTA PA4030

SITE WIDE DEWATERING & PUMPING GUIDELINE

DOCUMENT DETAILS


Dewatering & Pumping Guideline Rev 01 025‐GDL‐001‐NX2 Mike McConnell



A 23/11/2016 Mike McConnell Environmental Advisor First Draft

B 25/11/2016 Mike McConnell Environmental Advisor Full Draft

C 20/12/2016 Mike McConnell Environmental Advisor Final Draft

C.01 12/01/2017 Mike McConnell Environmental Advisor Final Draft

01 26/01/2017 Mike McConnell Environmental Advisor Version 01

APPROVALS


Approved by Hugh Leersnyder

Planning & Environmental Lead Technical Director

CJV 26/01/2017


Transport Agency

20/12/2016

REVISION DETAILS

Revision Details

A Full Draft submission with ESCP

B Updated to address Transport Agency and Hōkai Nuku comments

C Final Draft – to Auckland Council for approval 20/12/2016

C.01 Final Draft – updated to include comments received from Auckland Council 09/01/2017. Approved by Auckland Council 13/01/2017

01 In Use

CONTENTS

1 OVERVIEW 1

2 GENERAL PROCEDURES 2

2.1 Option one: direct pumping 2

2.2 Option two: batch dosing 2

2.3 Option three: continuous PAC dosing 4

2.4 Option four: continuous haloclear dosing 5

APPENDIX A: MONITORING SHEET 6

APPENDIX B: BATCH DOSING TO STORAGE TANK SKETCH 10

TABLES Table 1: Pump sizes and associated PAC dosing rates 4

SITE WIDE DEWATERING & PUMPING GUIDELINE PAGE 1 PŪHOI TO WARKWORTH PPP – RESTRICTED – COMMERCIAL 025‐GDL‐001‐NX2

1 OVERVIEW The required construction works on the Ara Tūhono Pūhoi to Wellsford Road of National Significance: Pūhoi to Warkworth Section will result in excavations and other related activities that will require dewatering by pumping.

This Dewatering & Pumping Guideline for the overall site has been prepared to ensure that the required level of sediment retention is achieved during this operation.


2 GENERAL PROCEDURES There will be various procedures for dewatering around the site; each of these procedures has a specific methodology for ensuring that the sediment retention achieved by the procedure is in accordance with best industry practice.

The six procedures are:

OPTION 1:

Batch dose the water if required and pump directly from the excavation to a stream

OPTION 2:

Pumping to a SRP, DEB, impoundment area or storage tank where the flows will be stored, batch dosed with PAC and then discharged to a stream or storm water piped network

OPTION 3:

Pumping continuously to an SRP with a continuous dose of PAC allowing continuous discharge off site.

OPTION 4:

Pumping continuously to a SRP with a continuous dose of Haloclear allowing continuous discharge off site.

2.1 Option one: direct pumping

This option is the least likely to be utilised in practice and relies on impounded flows within the excavation having a greater clarity than 100mm and the ability of the pump to be able to remove the impounded water without disturbing any sediments. This method is not to be used for dewatering depths of less than 500mm.

The procedure for pumping directly to a stream will be as follows

The monitoring sheet for pumping activities is to be completed (refer appendix A) If required, the correct volume of PAC will depend on the optimum dose rate based on soil sample

bench testing. Refer to the relevant approved CESCP for the correct PAC volume to storm water volume required.

This PAC is to be added to the surface of the water. Prior to pumping the clarity of the impounded water is to be confirmed as being greater than

100mm, pH is to be checked to be between 5.5 – 8.5 The inlet to the pump is to be supported no less than 500mm above the base of the excavation in a

location and manner where the inlet will not disturb settled sediments within the excavation, The outlet of the pump is to be located and stabilised to prevent erosion. It is preferable to

discharge the pump to a piped storm water system. During pumping the clarity of the impounded water is to be checked and recorded every 30 minutes.

If the clarity drops below 100 mm pumping is to stop and an alternative pumping procedure used.

2.2 Option two: batch dosing

In this method impounded flows are to be pumped to a sediment retention pond (SRP), a decanting earth bund (DEB), impoundment area or storage tank where it will be stored and batch dosed with PAC. When the clarity has increased to greater than 100mm and the pH has been checked and confirmed to be within the range of 5.5 – 8.5 then the stored flows will be discharged as detailed in the procedures below.


NOTE: No pumping to a SRP, DEB or Impoundment Area which is also receiving surface runoff is permitted during the following weather conditions

On the day of forecast rain During rainfall Immediately following heavy rainfall

If pumping during wet conditions is needed, adopt option three continuous dosing procedures.

The procedure for batch dosing to a SRP, DEB or impoundment area is as follows:

The monitoring sheet for pumping activities is to be completed (refer appendix A) The outlet of the SRP, impoundment or DEB to receive the pumped flows will have the floating

decants lifted above the maximum level to prevent a discharge during filling. The pumped flows are to be discharged to the forebay of the SRP to enter the SRP via the level

spreader, or discharged in a manner that minimises disturbance within the impoundment area or DEB.

Pumping is to continue until complete or until the SRP, impoundment area or DEB has filled to the level of the primary spillway or to just below the tee bar decant. Pumping is not to continue once this level has been reached.

Once pumping is complete the volume of stored water is to be noted and the correct volume of PAC added. A graduated timber post will be positioned permanently in the sediment pond or the manhole riser appropriately marked to determine the actual volume of pumped storm water

The correct volume of PAC will depend on the optimum dose rate based on soil sample bench testing. Refer to the relevant approved CESCP for a correct PAC volume to storm water volume required.

This PAC is to be added to the surface of the pond, impoundment area or DEB. The SRP, impoundment area or DEB is to than be left until the discharge parameters are met. Check and record the clarity and pH In the event that the clarity is still less than 100mm and the pH is still within the range of 5.5 ‐ 8.5 a

25% dose of the original dose of PAC is to be added and recorded. Check the clarity and pH again to see if the discharge parameters are met. This iterative process can be undertaken a maximum of 4 times, i.e. a maximum total additional dose of 100% of the original PAC volume is permitted. Following this the SRP, impoundment or DEB must be allowed to settle for 24 hours and the environmental manager notified.

In the event that after 24 hours the clarity of the SRP or DEB is still less than 100mm, specialist advice is to be sought.

In the event that once the clarity of the SRP or DEB is greater than 100mm, the pH is outside the limits of 5.5 – 8.5 then specialist advice is to be sought regarding correction of this pH.

Once the clarity of the SRP, impoundment area or DEB is greater than 100mm and the pH is within the range of 5.5 – 8.5, the SRP is to be discharged by removing the plug or by releasing the decants. The time of this discharge and the pH and clarity are to be recorded on Monitoring Sheet for Pumping Activities.

The procedure for batch dosing to a storage tank is as follows (refer to Appendix B sketch detail for a typical storage tank application):

The monitoring sheet for pumping activities is to be completed Turn the outlet valve to the “close” position to prevent dewatering during pumping The pumped flows are to discharge in through the top of the storage tank Continue pumping until the storage tank reaches capacity Once pumping is complete, the volume of stored water will be determined by dipping a graduated

timber post through the top of the storage tank. Follow steps 6 to 13 as per the above procedure for batch dosing to a SRP, DEB or impoundment area


Once the clarity of the stored water is greater than 100mm and the pH is within the range of 5.5 – 8.5, the storage tank outlet valve will be turned to the “open” position. The time of this discharge and the pH and clarity are to be recorded on Monitoring Sheet for Pumping Activities.

2.3 Option three: continuous PAC dosing

During Continuous Dosing the outlet of the pumps are again directed to the forebay of a SRP, however the outlet of the SRP is not plugged nor are the decants lifted. Note continuous dosing is not to be undertaken in a DEB. In this procedure PAC is continuously added to the inlet flows from the pump. This is achieved by a 25 litre container of PAC discharging via a 13mm hose (standard reinforced garden hose) that is fitted with an orifice at the outlet directly above the outlet of the pump. The 25 litre container is set 1m about the outlet to ensure the correct discharge rate which ‘drips’ directly onto the flows being discharged to the forebay.

3 potential pumps with a specific orifice size to achieve a dose rate of 5mg/L is shown in the table below. This data will be revised and will be specific to the optimum dose rates determined from bench testing for the relevant work area.

Table 1: Pump sizes and associated PAC dosing rates

Pump Size Discharge Rate

Required PAC discharge

Orifice size at 1m head

Time for 25 L to discharge (approx.)

80mm (3 inch) 20 l/s 0.0013 l/s 0.75mm 5 hours

100mm (4 inch) 25 l/s 0.0018 l/s 1.0mm 4 hours

150mm (6 inch) 80 l/s 0.0050 l/s 1.5mm 1 hour

The procedure for continuous dosing is as follows:

The attached Monitoring Sheet for Pumping Activities sheet is to be completed (refer appendix A) The appropriate pump is selected. The outlet of the pump is to be secured within the SRP forebay. The appropriate orifice is selected according to pump size. The 25 litre container of PAC is to be placed 1m above the outlet point which is to be secured directly

above (100‐200mm) the pump outlet. The PAC is to be turned on. The pump is to be started. The PAC container is to be checked hourly to ensure sufficient volume remains Each hour of pumping the clarity and pH is to be checked at the outlet. In the event that the clarity falls below 100mm or the pH falls outside of the range of 5.5 – 8.5,

pumping is to stop and the outlet plugged or decants lifted and dewatering continued as a batch dosed procedure.

Procedure Modification

It is expected that as the project progresses, modification of the dosage rates may be required due to changing soil types etc. This is to be undertaken following additional sampling and testing and acceptance from the Auckland Council


2.4 Option four: continuous haloclear dosing

During Haloclear dosing the outlet of the pumps are directed to the upstream side of the Haloclear sock which is positioned in the invert of the inlet channel of the pond. The decants in the pond are not lifted.

The procedure for Haloclear dosing is as follows:

Prior to pumping commencing

Ensure the pump outlet/s is directed to the upstream side of the Haloclear sock (fill out the monitoring sheet, refer appendix A).

Ensure the Haloclear sock has gel in it (fill out the monitoring sheet).

Start the pump and ensure pumped flows are discharged over the Haloclear sock The Haloclear sock is checked hourly to ensure it has gel in it (fill out the monitoring sheet) Each hour the clarity and pH of the water at the outlet of the pond is checked. In the event that the

clarity falls below 100mm or the pH falls outside of the range of 5.5 – 8.5, pumping is to stop and the outlet plugged or decants lifted. At this point the Environmental Manager is to be contacted and he/she will advise the best alternative method to continue dewatering (as detailed in the Dewatering and Pumping Management Plan).


Appendix A: Monitoring Sheet


Appendix B: Batch Dosing to Storage Tank Sketch


APPENDIX 4 Device Specific Details Device Specific Details ‐ Sediment Retention Ponds

All dimensions based on a 3:1 length to width ratio and 2:1 side slopes

Catchment Area

Min Storage

Length at Spillway

Width at Spillway

Length at Base

Width at Base

Depth No of Decants

Height above base of lowest decant

Holes per Decant

Primary Spillway

Outlet Pipe

Spillway width

0.3ha 60m3 17m 6m 11.5m 3.5m 1.1m 1 0.45m 40 100mm 100mm 2.0m

0.5ha 150m3 22.5m 10.0m 13.5m 3m 1.8m 1 0.69m 67 100mm 100mm 2.0m

0.75ha 225m3 26.5m 11.5m 17.5m 4m 1.8m 1 0.65m 100 100mm 100mm 2.5m

1.0ha 300m3 28m 12.25m 16.25m 3.25m 2.3m 1 0.94m 133 100mm 100mm 2.5m

1.25ha 375m3 30.25m 13.25m 18.75m 4.0m 2.3m 1 0.91m 166 100mm 100mm 3.0m

1.5ha 450m3 32.5m 14.0m 21.0m 4.75m 2.3m 2 0.88m 100 150mm 150mm 3.5m

1.75ha 525m3 34.5m 14.5m 23.25m 5.5m 2.3m 2 0.86m 116 150mm 150mm 4.25m

2.0ha 600m3 36.5m 15.25m 25m 6m 2.3m 2 0.85m 133 150mm 150mm 4.75m

2.25ha 675m3 38.25m 15.75m 27m 6.75m 2.3m 2 0.83m 150 150mm 150mm 5.25m

2.5ha 750m3 40m 16.25m 28.5m 7.25m 2.3m 2 0.82m 166 150mm 150mm 6.0m

2.75ha 825m3 41.75m 17.0m 30.25m 7.75m 2.3m 2 0.81m 183 150mm 150mm 6.5m

3.0ha 900m3 43.25m 17.5m 31.75m 8.25m 2.3m 3 0.80m 133 Manhole 300mm 7.25m



3.75ha 1125m3 47.5m 19m 36.25m 9.75m 2.3m 3 0.78m 166 Manhole 300mm 8.75m

4.0ha 1200m3 49m 19.25m 37.5m 10.25m 2.3m 3 0.78m 177 Manhole 300mm 9.5m


4.5ha 1350m3 51.5m 20.25m 40m 11m 2.3m 3 0.77m 200 Manhole 300mm 10.5m


5.0ha 1500m3 54m 21m 42.5m 11.75m 2.3m 3 0.76m 222 Manhole 300mm 11.75m


Device Specific Details ‐ 20 Year ARI Culvert Sizing

The minimum culvert sizes detailed in the following table have been determined based on:

A 10 minute 20 year ARI rainfall of 113mm/hr. A runoff coefficient (C) of 0.35 for clean water Culverts (Heavy Clay Soils – Bush and scrub cover) A runoff coefficient (C) of 0.70 for dirty water Culverts (Heavy Clay Soils – Bare impermeable clay) 1% Culvert Slope 500mm head A minimum culvert size of 300mm is used

Catchment Area (ha)

Peak Flow (m3/s)

Minimum Culvert Size (mm)

Clean Water Dirty Water Clean Water Dirty Water

0.5ha 0.055 0.11 300 300

1.0ha 0.11 0.22 300 375

2.0ha 0.22 0.44 375 525

3.0ha 0.33 0.66 450 600

4.0ha 0.44 0.88 525 750

5.0ha 0.55 1.10 600 750

6.0ha 0.66 1.32 600 825

7.0ha 0.77 1.54 750 900

8.0ha 0.88 1.76 750 900

9.0ha 0.99 1.98 750 1050

10.0ha 1.10 2.20 750 1050


Device Specific Details ‐ 100 Year ARI Culvert Sizing

The minimum culvert sizes detailed in the following table have been determined based on:

A 10 minute 100 year ARI rainfall of 156mm/hr. A runoff coefficient (C) of 0.35 for clean water Culverts (Heavy Clay Soils – Bush and scrub cover) A runoff coefficient (C) of 0.70 for dirty water Culverts (Heavy Clay Soils – Bare impermeable clay) 1% Culvert Slope 500mm maximum head A minimum culvert size of 300mm is used

Catchment Area (ha)

Peak Flow (m3/s)

Minimum Culvert Size (mm)

Clean Water Dirty Water Clean Water Dirty Water

0.5ha 0.076 0.152 300 375

1.0ha 0.15 0.30 375 450

2.0ha 0.30 0.61 450 600

3.0ha 0.46 0.91 525 750

4.0ha 0.61 1.21 600 825

5.0ha 0.76 1.52 750 900

6.0ha 0.91 1.82 750 1050

7.0ha 1.06 2.12 750 1050

8.0ha 1.21 2.43 825 1050

9.0ha 1.36 2.73 825 1200

10.0ha 1.52 3.03 900 1200


Device Specific Details ‐ Cleanwater Diversion Channels / Bunds

Where practical a minimum channel depth or bund height of 0.55m is to be used

The minimum depths and heights detailed in this table are those required to convey runoff from the 20 year ARI Storm Event plus 300mm freeboard, this is greater than those required to convey runoff from the 100 year ARI Storm Event.

The minimum depths and heights detailed in this table are to be used where the above minimum is impractical.

All cleanwater diversions are to be stabilised with geotextile or aggregate where existing vegetation cannot be retained.

Channel dimensions based on a trapezoidal channel with 1m base and 1:1 side slopes

Bund dimensions based on a trapezoidal bund with 0.5m crest and 2:1 side slopes, the slope above bund has been taken as 2:1.

Catchment Area (ha)

20 year ARI

Peak flow (m3/s)

Longitudinal Slope <5%

Longitudinal Slope 5% ‐ 10%



Longitudinal Slope >50%

Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height (m)

0.5ha 0.11 0.40 0.50 0.40 0.50 0.35 0.45 0.35 0.45 0.35 0.45

1.0ha 0.22 0.45 0.55 0.40 0.55 0.40 0.50 0.40 0.50 0.40 0.50

2.0ha 0.44 0.50 0.65 0.45 0.60 0.45 0.55 0.40 0.55 0.40 0.55

3.0ha 0.66 0.55 0.70 0.50 0.65 0.50 0.60 0.45 0.55 0.45 0.55

4.0ha 0.89 0.55 0.75 0.55 0.70 0.50 0.65 0.45 0.60 0.45 0.60

5.0ha 1.11 0.60 0.80 0.55 0.75 0.50 0.70 0.45 0.60 0.45 0.60

6.0ha 1.33 0.65 0.80 0.60 0.75 0.55 0.70 0.50 0.65 0.50 0.65

7.0ha 1.55 0.65 0.85 0.60 0.80 0.55 0.75 0.50 0.65 0.50 0.65

8.0ha 1.77 0.70 0.90 0.65 0.80 0.55 0.75 0.50 0.70 0.50 0.70

9.0ha 1.99 0.70 0.90 0.65 0.85 0.60 0.75 0.55 0.70 0.55 0.70

10.0ha 2.21 0.75 0.95 0.65 0.85 0.60 0.80 0.55 0.70 0.55 0.70

15.0ha 3.32 0.85 1.05 0.75 0.95 0.70 0.85 0.60 0.80 0.60 0.80

20.0ha 4.43 0.95 1.10 0.85 1.00 0.75 0.95 0.65 0.85 0.65 0.85


Catchment Area (ha)

20 year ARI

Peak flow (m3/s)






Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height (m)

25.0ha 5.53 1.00 1.20 0.90 1.10 0.80 1.00 0.70 0.90 0.70 0.90

30.0ha 6.64 1.10 1.25 0.95 1.15 0.85 1.05 0.75 0.90 0.75 0.90

35.0ha 7.74 1.15 1.30 1.00 1.20 0.90 1.10 0.75 0.95 0.75 0.95

40.0ha 8.85 1.20 1.35 1.05 1.25 0.95 1.10 0.80 1.00 0.80 1.00

45.0ha 9.96 1.25 1.40 1.10 1.30 0.95 1.15 0.85 1.00 0.85 1.00

50.0ha 11.06 1.30 1.45 1.15 1.30 1.00 1.20 0.85 1.05 0.85 1.05


Device Specific Details ‐ Dirty Water Diversion Channels / Bunds

Where practical a minimum channel depth or bund height of 0.55m is to be used

The minimum depths and heights detailed in this table are those required to convey runoff from the 20 year ARI Storm Event plus 300mm freeboard, this is greater than those required to convey runoff from the 100 year ARI Storm Event.

The minimum depths and heights detailed in this table are to be used where the above minimum is impractical.

All dirty water diversions are to be stabilised with geotextile or aggregate where erosion is observed.

Channel dimensions based on a trapezoidal channel with 0.5m base and 1:1 side slopes

Bund dimensions based on a trapezoidal bund with 0.5m crest and 2:1 side slopes, the slope above bund has been taken as 2:1.

Catchment

Area (ha)

20 year ARI

Peak flow (m3/s)


Longitudinal Slope 5% - 10%




Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height (m)

Channel Depth (m)

Bund Height

(m)

0.3ha 0.08 0.40 0.45 0.35 0.45 0.35 0.45 0.35 0.40 0.35 0.40

0.5ha 0.14 0.45 0.50 0.40 0.45 0.40 0.45 0.40 0.45 0.40 0.45

1.0ha 0.27 0.50 0.55 0.40 0.50 0.45 0.50 0.40 0.45 0.40 0.45

1.5ha 0.40 0.55 0.60 0.45 0.55 0.50 0.55 0.45 0.50 0.45 0.50

2.0ha 0.54 0.60 0.65 0.50 0.60 0.50 0.55 0.45 0.50 0.45 0.50

2.5ha 0.67 0.60 0.65 0.50 0.60 0.55 0.60 0.50 0.55 0.50 0.55

3.0ha 0.81 0.65 0.70 0.50 0.65 0.55 0.60 0.50 0.55 0.50 0.55

3.5ha 0.94 0.70 0.70 0.55 0.65 0.55 0.60 0.50 0.55 0.50 0.55

4.0ha 1.08 0.70 0.75 0.55 0.65 0.60 0.65 0.55 0.60 0.55 0.60

4.5ha 1.21 0.75 0.75 0.55 0.70 0.60 0.65 0.55 0.60 0.55 0.60

5.0ha 1.35 0.75 0.75 0.60 0.70 0.60 0.65 0.55 0.60 0.55 0.60

pūhoi to warkworth motorway ppp - auckland council · 9.3 environmental performance metrics 48...

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