river and drainage engineering report (prd … · river and drainage engineering report (prd 01 02)...

Catchment Operations Committee

10 April 2013

River and Drainage Engineering Report (PRD 01 02)

Report No. 13-66

Information Only - No Decision Required

RIVER AND DRAINAGE ENGINEERING REPORT (PRD 01 02)

1. PURPOSE

1.1. The purpose of this item is to report on progress with river and drainage activities for the period of 1 February – 31 March 2013.

2. RECOMMENDATION That the Committee recommends that Council:

a. receives the information contained in Report No. 13-66 and Annex.

3. FINANCIAL IMPACT

3.1. Funding provision for all activities reported on in this item is included in the 2012-13 Annual Plan under the River and Drainage Schemes Activity section.

4. COMMUNITY ENGAGEMENT

4.1. Various matters contained in this item either have been, or will be communicated with scheme ratepayers through their respective Scheme Liaison Committees. As necessary, other issues will be the subject of media release.

5. DISCUSSION

5.1. Continued dry conditions and low river flows have again allowed very good progress to be made with scheduled maintenance and capital works programmes. The conditions have, however dictated that particular care be taken in minimizing sediment discharges, given the very low flows in the various receiving bodies of water and the resulting significant effects of even small amounts of sediment.

5.2. A very good response has been received from property owners affected by works that were arranged within the Lower Manawatu Scheme (LMS) City Reach Project at relatively short notice, following deferral of the proposed channel realignment at Anzac Park Cliffs. In particular, residents in Buick Crescent and property owners/occupiers at the Turitea Science Campus are being very co-operative around works that are creating some significant disturbance to their activities.

5.3. The extension of the LMS City Reach Project, to include protection of the Turitea Science Campus from flooding from both the Turitea Stream and Manawatu River, was approved through the 2012-22 Long-term Plan (LTP). That approval was based on agreed contributions, in lieu of rates, from five building/property owners within the Campus. With the Turitea Stream works being brought forward into the current year’s work programme, it has been necessary to ensure that formal agreements in respect of those contributions are in place and that the contributions for the 2012-13 year have been paid. The agreements bind the organizations concerned to annual contributions for 15 years that is until project loans are fully repaid. Formal agreements have been completed and returned by all organizations. Payments totalling approximately $70,000 for the current year have been received from all five organizations.


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5.4. No appeals were received in respect of the Commissioners’ Decision on the Operations Group’s application for consent to divert additional flood waters into the Taonui Basin. A very significant milestone has therefore been reached as regards the LMS Rural Flood Protection Upgrade Project. As reported at the February meeting of the Committee, physical works, and in particular those required as a condition of the consent, are however delayed by the requirement for further consents. Issues raised by submitters to the Group’s application for those latter consents are being worked through, however there is unfortunately little prospect that the consents sought will be granted in time for any of the subject works to commence during the current construction season.

5.5. The Catchment Operations Committee Chair and the Group Manager attended a Manawatu District Council (MDC) workshop on 29 January to discuss the findings of investigations into flooding from the Makino Stream downstream of Feilding, together with options for improved flood protection. Subsequently MDC has formally advised that it remains to be convinced of the benefits of the protection options considered, given the small land area including Kitchener Park involved, the lack of proposed urban development in the area and the overall cost of the works. MDC is however interested in seeing the ‘core elements’ remaining in Horizons’ LTP. That would mean that the scope and standard of protection of the area of rural land concerned would be further considered when it is scheduled for works in Year 12 (2017-18) of the LMS Rural Flood Protection Upgrade Project. The protection of Kitchener Park is however not provided for in that project and given the absence of MDC support for some special funding approach in respect of the park, there would appear to be no justification for further pursuing that aspect. Staff propose to now meet with Gavin Scott and MDC staff with responsibility for Kitchener Park, to update them on this issue.

5.6. Following a High Court Hearing in May-June 2011, of a claim for damages against Horizons Regional Council in respect of a breach of the Moutoa Floodway stopbank at Whirikino in February 2004, a judgment was entered for the defendant (HRC). Subsequently the Plaintiffs appealed that judgment and their submissions, together with Council’s responses, were heard in the Court Of Appeal in November 2012. The judgment of the Court Of Appeal delivered, on 26 March 2013, was that the Appellants’ application for leave to adduce further evidence was dismissed; that the substantive appeal was dismissed; and that the Appellants must pay the respondents’ costs. This litigation has placed significant demands and stresses on staff, and no doubt on the Plaintiffs, during a number of periods extending over the past nine years. There is now a clear desire to move on and to ensure that Council’s future infrastructure asset management practice fully reflects lessons learnt from the experience.

5.7. Staff have completed their Annual Reports for all schemes for the 2011-12 year in a very timely fashion. These reports collate into one document, all relevant information on scheme activities and on physical, financial and environmental performance for the year and provide a valuable record for future reviews and audits. The reports are made available to the respective Liaison Committee members and in some cases are submitted to Fish and Game NZ in accordance with consent conditions.

5.8. Council resolved on 12 March, to confirm its decision to withdraw from the LAPP Fund as from 30 June 2013 – subject to an independent assessment of Council’s projected financial ratios that would impact on its ability to partly debt fund damage repairs arising from a future natural disaster. Subsequently, Aon have been engaged to undertake the required actuarial assessment and that work is underway. Managers of the LAPP Fund have been given tentative advice of Council’s decision but have also been advised that our interpretation of the LAPP Trust Deed is that Council has until 30 June this year to formally withdraw its Notice. That date will allow Council to receive and consider the actuarial report content and also to consider any submissions that may be received in relation to its intention to withdraw from the Fund, as clearly highlighted in the 2013-14 Draft Annual Plan.


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5.9. The Committee has been kept apprised over the past year or thereabouts of a civil claim against NZTA and HRC for respectively causing flooding of a property at Koputaroa and for failing to protect that property from flooding. Both of the latter parties wish to avoid further legal and court costs in relation to this matter and accordingly have now made a settlement offer to the Plaintiff. The offer involves channel improvement works on adjoining farm properties being undertaken substantially at NZTA’s cost, but with Environmental Grant funding assistance. The improved section of stream would then be included in the Koputaroa Scheme works area for ongoing maintenance, with affected properties, including that owned by the Plaintiff, to be rated for that service. A response to the offer had not been received at the time of reporting.

DESIGN AND INVESTIGATIONS

TAONUI BASIN/BURKES PUMP

5.10. Consequent on the proposed Burkes Drain enlargement and pump installation works, several stability matters at Burkes Gates were assessed including:

The effect of the excavations needed for the pump on the geotechnical stability of Burkes Gates;

Structural check of Burkes Gates reinforced concrete structure. This was found to be fine under the new design loadings, including drawdown due to pumping – where flood levels would be significantly higher in the Manawatu River than the Taonui Basin; and

Structural check of the steel gates. The lower sets of gates were found to require some strengthening for some drawdown cases.

LOWER MANAWATU SCHEME (LMS)

5.11. Design scoping briefs were completed for stopbank upgrade works in the Upper Mangaone and Benmore Avenue areas – both bordering Palmerston North City. These works will protect the city from the Mangaone Stream and other minor streams to the agreed 0.2% AEP (500 Year) standard. The substantial design work is scheduled for 2013-14.

5.12. Further design advice was provided for the works on the Moutoa Floodway stopbank buttressing. This centered particularly on ensuring the stability of the stopbank at a redundant culvert crossing, and on buttressing stopbanks where monitoring bores show high seepage pressures.

5.13. Detailed designs were completed for the section of the Turitea Stream stopbank through AgResearch. This work is difficult, as there is a very narrow area in which to locate the stopbanks in places and as a result the design includes conventional stopbanking, planter box stopbanks, timber walls and concrete walls where appropriate. The current crest level is being raised on average 800 mm to achieve the 0.5% AEP (200 Year) plus freeboard design standard. In particular, the upgrade of an existing concrete floodwall required complex design to ensure stability of the raised wall met relevant criteria.

5.14. Several miscellaneous enquiries were addressed including preparation of a spreadsheet showing LMS jobs relative to individual stopbank assets and advice on the Linton Drain stopbank extension.

LOWER WHANGANUI RIVER

5.15. A plan was produced showing the flood levels that would have existed through Kowhai Park in the 1904 (40 Year – 2.5% AEP) and 1940 (70 Year – 1.4% AEP) historic floods. This model utilised the current design model with no fine-tuning of design parameters. The levels produced at the City Bridge by the computer model were just 9 mm off an exact


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match for the 1904 flood and 9 cm for the 1940 flood. This further shows the model has a very good degree of reliability.

POHANGINA-OROUA SCHEME AUDIT

5.16. Preliminary research work and a site inspection have been undertaken with regard to the Scheme Audit. It is intended that the scope of the Audit and some preliminary findings will be discussed at the Annual Scheme meeting on 29 April. A final draft Audit report will be available for the Catchment Operations Committee meeting on 12 June.

AKITIO SCHEME AUDIT

5.17. The Akitio Scheme Audit draft is almost completed and will be discussed at the Annual Scheme meeting on 12 April 2013. A final draft Audit report will be available for the Catchment Operations Committee meeting on 12 June.

WAIKAWA GRAVEL ANALYSIS

5.18. An assessment of the Waikawa Stream gravel resource was completed. The assessment report indicates that to return the channel cross-sections to the 1995 survey position, approximately 20,000 m3 of material is needed to be removed from a 2.1 km reach below the State Highway. To then maintain the channel in that condition, on average 1,100 m3 was required to be removed annually.

KOPUTAROA STREAM INVESTIGATION

5.19. A detailed assessment of flood risk mitigation options was completed to address frequent flooding of an area adjacent to and State Highway 57. The conclusions were that the flood risk could be reduced through relatively minor channel clearance and excavation. Currently the Koputaroa Stream floods adjacent land roughly annually and the highway at slightly lesser frequency. The proposed works will roughly double the channel capacity through this congested reach and flooding frequency should be reduced to around 20% AEP (5 Year).

ASSET MANAGEMENT

5.20. The retro-modelling of floods and assessed damages to assess the Region’s total vulnerability in any one event was completed. This information was required to assist Council with its decisions in respect of future infrastructure asset risk management. New Stopbank Inspection Guidelines were drafted and a training day was held with field staff to improve uniformity and quality of assessments. Work has continued on documenting stopbank condition parameters.

5.21. The Material Damage Insurance cover for pump stations was reviewed.

REGULATORY ADVICE

5.22. There was an increased volume of regulatory work with 30 recorded substantive matters required during the reporting period.

5.23. The regulatory work involved specialist advice on flood risks and technical reports for consent applications, re-zonings and subdivisions including:

The final technical assessment of two bridges and several culverts involved in NZTA’s Otamaraho Curve passing lane works on State Highway 2. There was extensive pre-consultation advice previously provided on structures on the Otamaraho and Kumeti Streams;


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Assessment of the revised design of two culverts on the Meridian Energy Mount Munro Project. Also assessment of a culvert on a tributary of the Taringamotu River;

Assessment of four gravel consent applications. These included applications on the Whanganui River at Rangitoto Island near Jerusalem, a small quantity from the Oroua River near Apiti, Rangitikei River near Kawhatau Valley Road and Rangitikei River both upstream and downstream of Bulls in the degradation zone. This latter application was made exactly in accordance of the agreement reached in October 2010 on reduction of quantities to a total of 30,000 m3 per annum for the entire reach;

Advice on ten flood risk and related enquiries. These included detailed advice on flood risks to several sites at Linton, two sites at Wanganui and a detailed assessment at Tangimoana;

Advice on a proposed sewer pipeline rising main between Ashhurst and Palmerston North. This included increasing the cover to the pipeline at the Stoney Creek and some culvert crossings;

Assessment and advice to Councillors that effects of a stopbank at Whangaehu were not more than minor;

A Memorandum advising on structures to mitigate erosion in the Tahuna Stream at Santoft and dismissing causes and options to mitigate downstream drainage;

A site visit and further information request for the proposed WMI Pulp Mill ash disposal site extension near Tangiwai. The assessment of vulnerability to flood flow and lahars was inadequate and further work is required on safe landfill batters and capping;

Response to two information requests on coastal processes on the West Coast, including causative mechanisms for the Manawatu River Mouth positioning;

A site visit to the damaged slipway at Wharf Street to advise Wanganui District Council (WDC) on remedial bank protection works. This is a key facility launching over 150 boats per day in the summer holiday period;

Technical assessment of major riprap bank protection works to the left bank and first pier of the State Highway 1 Ohau River Bridge. The design had inadequate sizing, layer thickness and embedment; with all these points now rectified;

Advice on the installation of protection works at the Kotukutuku Bridge, Hunterville over the Porewa Stream; and

Responses to several diverse unrecorded enquiries.

DESIGN ADVICE

5.24. During this period ongoing design advice has continued to be given to Operations Group project and Scheme Management staff and other department’s staff in relation to several matters. This included:

Provision of information for the gravel section of the State of the Environment Report;

Provision of advice on flood risks, available mitigation and wise development options at Herbertville Motor Camp;

Advice on Burkes Drain No. 1 spillway raising;

Assessment of existing and proposed works for the Manawatu Power Boat clubrooms at Foxton;

Advice on a land ownership matter on the Rangitikei River; and

Advice on the validation of both the Palmerston North and Feilding 0.5% AEP (200 Year) flood maps.


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CENTRAL AREA

GENERAL

5.25. Weather conditions over the Region have been very dry with minimal rain experienced. Ground conditions for operational works have been optimal, and have allowed in-channel and river bank works to proceed without any hindrance.

5.26. The dry conditions have led to very low flows in the rivers and tributaries, with the lowest recorded flow since 1928 in the Manawatu River of 9.1 cumecs (0.29 m stage height). Low flows were recorded in the Oroua at Almadale of 683 litres per second, and the Mangaone at Milson Line 35 litres per second.

5.27. There were only two notable rain events over the reporting period; on 4 & 5 February and 18 & 19 March. These two rain events have provided all of the rain over the two months. Total rainfall for the three months: 77.5 mm at Milson Line; 140 mm at Cheltenham; and 120.5 mm at Scott’s Road.

5.28. A Lower Manawatu Scheme Liaison Committee meeting was held at Kairanga on 22 February. The meeting was well attended and discussed the river works completed this year, expenditure to date and anticipated end of year financial position.

5.29. A breakfast meeting of the Self-Help Monitoring and Response Group (SHMRG) leaders was held at Kairanga Service Depot on 7 March, where the protocols and guidelines were reviewed and updated. The SHMRG is discussed in a separate item in this agenda.

LOWER MANAWATU SCHEME

5.30. Works undertaken on the various rivers within the scheme during this period include the following:

MANAWATU RIVER

5.31. Scheduled seasonal maintenance works, including inspection of the scheme floodgates, drains and stopbanks; stopbank repairs and mowing were completed.

5.32. A total of 3 km of mowing was completed on the stopbank between Foxton Beach and Foxton Township. The stopbank crest had localised low spots that were repaired. A cumulative total of 100 m of the stopbank was reinstated to the design crest level in this reach. Mowing was also undertaken on the bank at Riverbank Road (8 km), Poplar Road (5 km), and the Foxton Shannon Road (2 km).

5.33. Stopbank repairs were also undertaken on the bank through the former golf course on Te Matai Road, now owned by Tait-Jamison, where the bank had been damaged by the former occupants. Upon completion of the repairs, Mr Tait-Jamison was advised of his obligations for stopbank maintenance in the future, and any damage caused by his stock would be his responsibility to repair.

5.34. Trees were removed from the stopbank next to the water level recording tower at Fitzherbert Bridge. The trees were preventing grass growth and increased the potential for stopbank failure. The bank is over-steep and material to strengthen the toe will be imported, and grass seed sown in autumn to repair the damage.

5.35. Willows were planted over a 35 m stretch, completing repairs at an erosion site at Funnell’s lease on Poplar Road.

5.36. The extremely low flows in the Manawatu River revealed debris, tyres, and road signs in the river channel at Fitzherbert Bridge. An excavator was used to remove that debris and the opportunity was taken to clear debris caught up on the Fitzherbert Bridge, at Palmerston North City Council’s (PNCC) cost.


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5.37. A sandy point on the inside of a bend, on Horizons lease land at the end of Poplar Road, was removed to relieve pressure on the erosion protection works on the right bank. This is part of the inside bend berm lowering programme, to reduce the ongoing cost of maintaining erosion protection works on the outside of bends, and to increase the channel flood carrying capacity and river alignment. Approximately 16,000 m3 of sand was pushed up and redistributed on the berm

5.38. Programmed stopbank mowing and associated spraying work was carried out within the Palmerston North City Reach.

5.39. The stopbank toe was repaired and strengthened at Fitzroy bend over a 120 m length providing increased security of the stopbank structure, and to allow better access for mowing of the bank.

5.40. The substantial amount of timber and debris removed from the Fitzroy Bend groynes, and stockpiled for burning in the Autumn, was set alight twice over February and March by arsonists. These fires took several days to put out. Staff were on site to carefully control the burn and to allay the public’s concerns. The Rural Fire Service monitored the situation.

5.41. Two tonnes of rock was pulled back onto the rock lining at Gasworks Drain, due to a small rock groyne being created by an individual rolling rock into the river. This is an ongoing problem, and staff are monitoring the site with the hope of catching the offender.

5.42. Staff were requested to visit the Longburn outlet channel with Fonterra’s Environmental Officer. T he channel has become overgrown with willow and discussion centered around options for removing congestion and keeping the channel open. A solution has been found and a Horizons Plant Hire Registered Contractor will undertake the work in the near future, with the cost to be borne by Fonterra.

5.43. The mapping of infrastructural assets for inclusion in the Manawatu District Plan has been completed.

5.44. Horizons staff met with Fonterra to discuss the fencing of drains and borrow pits in the Moutoa Floodway. Fonterra was insisting that all waterways in the floodway should be permanently fenced off. Horizons mapped the waterways and borrow pits in the floodway, and calculated that over 70 km of fencing would be required. It would not be practicable to take down this length of fence when the floodway was to be used therefore increasing the likelihood of these fences being swept downstream to Foxton Beach and the RAMSAR area in the estuary. The view of staff was that permanent fencing was not necessary in the floodway. The clear requirement was to ensure that stock was kept out of waterways and this could be achieved by deploying temporary fencing around grazing areas. Permanent fencing would still be required however to specified key drains in the floodway. It appears that a common sense compromise has been agreed.

5.45. As part of the Freshwater Enhancement Project, all fencing on Council lease land was mapped. Two sections of leased land were noted to have insufficient fencing and accordingly fencing of these sections has been programmed into the works schedules for completion before the end of the financial year.

5.46. The maps for the SHMRG were updated and revised to reflect changes of membership and the relocation of SHMRG depots.

5.47. The NZ Army was contacted to assist with the Manawatu clean-up initiative in the city. Warrant Officer Brent Ruruku from the 2nd Emergency Response Unit based at Linton Camp volunteered his services to cut steel re-bar from below the water level at the site of the old bridge downstream of Fitzherbert Bridge. The steel only became apparent due to the low flows in the river and visible because of the clarity of the water. Staff assisted with the operation using our inflatable boat to transport the cutting gear to site. A letter of appreciation for this community service has been sent.


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5.48. Staff met with PNCC to discuss the continuation of the city walkway past Buick Crescent and at Ashhurst. Horizons’ primary concern is to ensure that the flood and erosion protection works in the vicinity are not compromised, and that maintenance of our assets will not be made any more difficult after the pathway is constructed. Construction of the pathway at Ashhurst has just commenced with clearance operations underway behind our front edge protection works. Horizons typically maintain the willows along this reach at five yearly intervals however, to provide views of the river for users this frequency of maintenance may well have to be increased.

5.49. Staff attended a workshop hosted by Wellington Regional Council to discuss asset inspection protocols and guidelines especially with regard to stopbanks. The workshop had attendees from Regional Councils from all over New Zealand. Despite variation in methodology, Councils are assessing stopbanks to similar standards across New Zealand, based on NAMS (National Asset Management Steering Group) guidelines. Nevertheless, the workshop recognized benefits to be had from further aligning asset condition assessment and reporting methodology across all Regional Councils. The River Managers’ Forum has subsequently agreed that the workshop will be reconvened to progress this issue for reporting back to its September meeting.

5.50. Operations staff accompanied the Freshwater Team on a survey of the Manawatu River to identify Inanga spawning sites. Several sites were identified that could be enhanced to provide better spawning habitat but the surprise of the tour was finding that the river bank at the end of the Moutoa floodway, a highly modified part of the river, was probably one of the largest Inanga spawning sites in New Zealand, with an ideal combination of vegetation density, salt water wedge, and bank gradient. Options to enhance and protect this site are being drawn up.

WILLOW LAYERING PROGRAMME

5.51. Several areas on the Manawatu River have had maintenance works completed on them, in the form of willow layering and/or mulching. This work is required to maintain a good healthy coverage of willow growth on the river bank, which provides the front line erosion protection. In all 4.7 km of edge protection was layered at nine sites.

CAPITAL WORKS

5.52. A total of 650 tonnes of concrete riprap was placed over 150 m at an erosion site on Department of Conservation property at the end of Jackeytown Road. The top half of the bank was battered back to allow willows to be planted later in the year. Approximately 100 tonnes of concrete has been stockpiled on site for future repairs at this site or nearby sites as the site has all weather access.

5.53. Seventy tonnes of concrete riprap was installed in the Ruakawa Drain to repair damage to the channel bank immediately downstream of the outlet over a 20 m length. Additional concrete was placed on the bed at the outlet due to bed erosion potentially undermining the structure.

5.54. 110 tonnes of concrete riprap has been stockpiled at Cook’s Bend on Landcorp’s property near Whirokino for a 50 m erosion site in a very deep section of the Manawatu River.

VEGETATION MANAGEMENT & CLEARANCE

5.55. The vegetation management and clearance programme aims to clear vegetation from the inside of bends to optimise the flood carrying capacity of the river, and reduce the pressure on the outside of bends.

5.56. Progress was initially slow due to the windy weather conditions affecting the spraying programme and causing spay drift, but the recent calm weather has enabled the programme to be completed on the Manawatu River.


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OROUA RIVER

5.57. Concrete riprap totalling 270 tonnes was placed to repair 30 m of erosion at river distance 31.4 km on the true right bank at Patching`s. The work extends an existing asset.

5.58. Vegetation management and clearance on the Oroua River has been completed. A total of 27 properties were inspected over the reach from Rangiotu Bridge, State Highway 56 to the Mahua Road just north of Feilding. The work also included a section of river through Feilding where boom spraying was undertaken to control vegetation regrowth within the channel.

5.59. Mulching of vegetation as part of the vegetation management programme was undertaken on three inside bends; two bends on the Guy property covering 900 m opposite Timona Park in central Feilding, and 250 m on the Jones’ property located in the lower Oroua.

5.60. 3 km of the stopbank around Frecklingtons was mowed.

GRAVEL

5.61. Gravel has been extracted at two sites on the Oroua River and at three sites on the Manawatu River. The extractions on the Oroua River are from river distance 30.0 km (Awahuri Bridge) through to 31.2 km where to date 6000 m3 of gravel has been removed by Hoult`s Contracting.

5.62. A further 4,000 m3 is programmed to be extracted from below the State Highway Bridge at Awahuri by Hoult’s Contracting. Manawatu District Council and NZTA have been informed and have approved the extraction.

5.63. In the lower Oroua at 19 km on the true left bank, the Agricultural Research Farm will remove 250 m3 of gravel from an inside river bend and a further 150 m3 of river berm silts will also be taken from the same area.

5.64. On the Manawatu River at the end of Jackytown road, river distance 66.6 km true right bank, land owner Jerry Tocker has removed 3500 m3 of river berm silts. Also in the same area, 1000 m3 of gravel was taken from Howard Voss`s beach located at 65.2 km on the true right bank.

MANGAONE STREAM

5.65. Programmed stopbank mowing and associated spraying work was completed within the Palmerston North City Reach.

5.66. Longitudinal cracks of over 100 m length have appeared in the PNCC walkway along the stopbank near the racecourse. These are going to be investigated in conjunction with PNCC to see if there is any risk to the stopbank.

5.67. Trees that were in danger of falling over fences and creating issues to the toe of the stopbank were removed. There are a number of further sites that will need to be addressed, as the trees are getting larger and partially leaning towards fences and towards houses.

MAKINO STREAM

5.68. Vegetation (mainly willow) control, was undertaken in the Makino Stream from Kitchener Park through to the top end of the scheme. Some rock repair and relocation was carried out in sections of the stream bed.

5.69. The stream channel through Feilding Township was sprayed to remove any unwanted weed growth. Any overhanging vegetation was also removed from this 5 km reach.


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5.70. A length of stopbank (15 m) immediately downstream of the Queen Street Bridge, on the true right bank, was repaired and re-fenced.

MOUTOA FLOODWAY

5.71. General maintenance was undertaken around the gates structure, the gates operation was tested and 2 km of the right bank floodway bank downstream of Kerekere Road was mowed.

5.72. The six monthly inspection of the Moutoa Sluicegates electrical systems was completed. The electrical system was found to be in good shape with no components likely to require replacement in the short term. A comprehensive replacement and maintenance programme for the electrics is being drawn up by the electrician for approval by Horizons.

5.73. Approximately 15,000 m3 of silt is being removed from the berm in front of the gates, as part of the buttressing of the left bank of the Floodway below Kerekere Road.

5.74. A 30 m stretch of the stopbank was repaired and regressed. 1 km of the drainage channel in the floodway at the outlet end was chemically sprayed.

5.75. A 2 km length of the right bank crest was metalled to allow safe passage for vehicles during the winter, and to raise a low spot in the bank.

TOKOMARU STREAM, KARA STREAM, MANGAPUKATEA STREAM, STONEY CREEK and JACKS CREEK

5.76. General maintenance work was completed.

LOWER MANAWATU SCHEME (LMS) – CITY REACH PROJECT

AMENITY ENHANCEMENT – ESPLANADE VIEWING PLATFORM

5.77. Construction was completed on the cantilevered ‘pier’ structure immediately downstream of the Fitzherbert Bridge and Okatia Steps. 160 m of concrete nibbing was also completed around the new structure and linking to the Okatia steps. The nibbing defines the planted areas.

5.78. The worked areas will be re-grassed and further planting around the berm areas will be completed when suitable weather conditions arise.

5.79. Design work is underway for a permanent flood marker to be constructed close to the steps and viewing platform. This feature structure will show a history of all significant flood events on the Manawatu River.

5.80. Discussions are underway with various parties as regards improving signage in the area.

BUICK CRESCENT STOPBANK

5.81. This work includes the raising of either existing flood banks or walls, or building new structures through 22 residential properties in Buick Crescent. Site constraints dictate that a variety of structure designs are employed and wherever possible the desires of the individual property owners concerned are satisfied.

5.82. Following close consultation and obtaining formal ‘Access Agreements’ from property owners, works have been completed on six properties. Four of the properties completed have selected the double timber wall planter box system with two opting for a single concrete wall. Construction is slow due to the confined areas that have to be worked in. All materials including the fill materials have to be basically wheel barrowed to the site. Also restoration to each property is important with care taken to restore the worked areas to at least the standard existing prior to works commencing. Feedback from owners of those properties where work has been completed to date has been very positive.


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5.83. Consultation continues on the next group of properties and it is anticipated that contractors will be engaged continuously until works on all 22 properties have been completed.

TEACHERS COLLEGE RECORDER TOWER

5.84. The most recent upgrade of the stopbanks adjacent to the recorder tower to the 0.2% AEP flood standard, has necessitated raising and strengthening of the recorder tower structure and walkway to the new flood design level.

5.85. Contract works to achieve the required elevation of instrumentation; safe access to the tower during the design floods; and compliance with modern structural codes, have now been completed. A Practical Completion Certificate was issued on 8 February and the contract is now in the 12 week Defects Liability period.

TURITEA SCIENCE CENTRE

5.86. Designs and drawings for a combination of earth stopbanks and concrete and timber floodwalls have been completed in respect of protection of the Turitea Science Centre from Turitea Stream flooding. The design standard for this component of protection is the 200 Year flood. Negotiations and land entry agreements for undertaking the physical works have also been successfully completed.

5.87. Four contractors/builders have been engaged to undertake the various works. Earthworks for the embankments started on 25 March and it is anticipated that the three sections of the earthworks component will be completed by 12 April. The timber walls are also underway. The latter work is labour intensive and will extend into the middle of May. Reinforcing steel required for the concrete walls has been ordered and as soon as that arrives the concrete wall construction will commence.

LOWER MANAWATU SCHEME RURAL FLOOD PROTECTION UPGRADE PROJECT

LINTON MAIN DRAIN STOPBANK UPGRADE

5.88. Construction work is progressing on the two contracts awarded to Doug Gerrand Ltd to upgrade approximately 500 m of stopbank along both the left and right banks of the Linton Main Drain below Tane Road. Fill material is being imported from a privately owned borrow site on Scott’s Road. Due to the contractor being awarded both contracts, after Tender Award, the contractor requested an amended construction methodology be approved that would allow a temporary bridge to be installed across Linton Main Drain which would allow fill material for both contracts to be transported along Linton Drain Road. This route avoids State Highway 57 and populated areas within Tokomaru. This change was subsequently approved at no additional cost to the contractor. The alternative route negates the requirement for a 1.8 km haul route to be constructed across productive farmland on the left bank. A downside however, has been haul vehicle congestion on the one lane section of Linton Drain Road which in turn has reduced the daily volume of material that can be delivered to site. That has become the partial cause of an expected delay in contract completion.

5.89. One variation to the contract has been approved to replace an existing culvert on the left bank that has been found to be in poor condition. This work is due to commence during the week of 19 March 2013 once the bulk of stopbank upgrade works are completed.

5.90. The possibility of instructing a further variation to extend the contract works and take advantage of very attractive rates, will be reviewed once existing contract works are substantially completed.


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MOUTOA FLOODWAY STOPBANK UPGRADE

5.91. Construction work is in progress for buttressing of the Moutoa Floodway left bank stopbank below Kere Kere Road. The works consist of excavating and hauling silt material from in front of the Moutoa Floodgates to form an overlay along the landside toe of the existing stopbank. The buttressing will resist uplift pressures associated with sub-soil flows through a sand layer that is known to exist under the stopbank in this area.

5.92. The disused Langley’s Pump Station has been demolished and its culverts through the stopbank have been sealed with reinforced concrete. A low section of stopbank crest at this location has also been raised to 1% AEP plus freeboard design over a length of approximately 50 m. All of the existing toe drain that lies within the works area has been cleaned out in preparation for filling and approximately half of a relocated new drain has been constructed. The remaining drain works will be completed after a local crop of maize has been harvested towards the end of March. Delaying this drain work will not impact upon the contract completion date.

5.93. Importing of fill material from the Moutoa Floodgates is not progressing as fast as expected due to the long off-road haul distance and very low truck crawl speeds resulting in longer than expected turnaround times.

LOWER KIWITEA STREAM SCHEME

5.94. Programmed maintenance works completed over the period consisted of spraying any willow or weed growth in the channel, commencing at Reid’s Line and going right through to the Cheltenham Cross Road.

5.95. Also, a scheduled maintenance run was undertaken during March to remove wattle growth from the front line willow tree protection. The wattle is invasive and outgrows and overtakes the willow protection and accordingly requires removal from at least the 5 m to 7 m strip along the river edge.

KAHUTERAWA STREAM SCHEME

5.96. An interim Land Use Consent has been granted to undertake works over a 7 km reach of this stream from its confluence with the Manawatu River. The work mainly involves the clearing of blockages, removal of trees on the edge of the channel and some gravel redistribution in the dry areas to ease bends. Works on the 4 km reach downstream of State Highway 57 will be completed by late March and the 3 km above the highway during the first week of April.

NORTHERN AREA

GENERAL

5.97. The Northern Area has experienced an exceptionally dry start to 2013. There has been very little rainfall over the reporting period and river levels have reached their lowest in many years. The Lower Whanganui River for instance, reached its lowest flow in 35 years. Although the dry spell has been challenging for the rural community, it has provided a great opportunity to progress river works.

5.98. Staff have been busy over the last two months and have completed a significant amount of maintenance work and vegetation spraying. In addition capital projects are well advanced on the Rangitikei River; Asset Management System (AMS) updates have continued; mapping improvements progressed; and gravel extraction monitoring continues.

5.99. Preparation work has begun for the upcoming Scheme Annual General Meetings.


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5.100. The annual scheme drain maintenance programme is underway and staff have been working with many landowners to ensure the drains are in a satisfactory condition heading into winter.

RANGITIKEI RIVER CONTROL SCHEME

5.101. Staff met with the Scheme Liaison Committee on 5 March. The meeting discussed this year’s completed works and works planned up to June 2014. The meeting was well attended with members expressing general satisfaction with Scheme Management.

5.102. The last two months have seen a significant amount of spraying undertaken to control willow regrowth at sites along the river. This activity which follows up on last year’s spraying programme is important to maintain the integrity of river control structures and keep preferred river alignment channels open for flood flows.

5.103. Mechanical beach clearing work has been concentrated around the McKelvie and Flock House reaches of the river. These reaches were rated the highest priority in the scheme review for channel realignment. Staff are integrating channel management work with capital projects to achieve the desired alignment at the least cost to the scheme. In this instance the excavated area where material was sourced for the Parewanui stopbank upgrade is planned as the new river channel and targeted beach clearing will help coerce the river into this new alignment.

CAPITAL WORKS

5.104. Upgrading of the Parewanui Stopbank between 6.9 km and 7.9 km by Stringfellows Contractors is now complete. The project was delivered on time and within budget.

FLOOD DAMAGE REINSTATEMENT

5.105. Approval was received from the insurance assessors to continue with the last two flood damage reinstatement sites at the Howard and Harding properties. The Harding job is now complete leaving only the Howard work unfinished.

5.106. The original estimate for all insurance flood damage work on the Rangitikei River was $1,002,000. Detailed inspections and design has reduced this figure down to $805,000. At this time both of our insurers have capped their total payout exposure to $685,000 leaving a deficit of $120,000 to complete work. Due to this deficit in insurance funding the remaining part of the Howard project will be completed next financial year from the operational account.

POHANGINA-OROUA RIVER CONTROL SCHEME

5.107. Staff met with the Scheme Liaison Committee on 5 March. The meeting discussed this year’s completed works and works planned up to June 2014.

5.108. Work completed during the period was concentrated on beach shaping in both the Oroua and Pohangina Rivers to improve river alignment and reduce bank erosion. Tree groyne construction work continued at Totara Reserve to protect the public amenity from river bank erosion and channel realignment.

UPPER WHANGANUI RIVER MANAGEMENT SCHEME

5.109. Works included clearing willow and poplar trees along the reach of river between Cherry Grove and Victory Bridge. Staff are working closely with the Ruapehu District Council (RuDC) along this reach in developing a walking track for public use as the trees are cleared.


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5.110. A narrow section of stopbank along Taupo Quay does not meet minimum width requirements to protect against seepage. Design engineers have inspected the site and a plan has been developed to upgrade the short section of stopbank this financial year.

5.111. A section of the Ongarue River was added to the scheme through the 2012-22 Long-term Plan (LTP)process. Good progress has been made with the first stage of a three or four year programme of clearing willow and poplar trees from this new area.

TARINGAMOTU RIVER SCHEME

5.112. Good progress on clearing the river channel has been made following the endorsement of the work programme by the Liaison Committee at it’s meeting 18 January. A good half of the work planned this year is complete with debris piled in heaps to dry prior to burning. Further work will progress once a total fire ban has been lifted and burning is able to be more efficiently undertaken in conjunction with the clearance activity.

MAKIRIKIRI FLOOD CONTROL SCHEME

5.113. No work undertaken this period.

MATARAWA FLOOD CONTROL SCHEME

5.114. All preliminary work for the Blinkbonnie stopbank upgrade is complete. Contract documents were sent to contractors for pricing in February. These have now been received and the work awarded to the lowest tenderer being Roberts Contracting who will commence work before the end of the month.

5.115. The lowest price received for this work was $24,875 was very competitive but exceeded the $18,000 funding available within the operational budget. To enable work to proceed, approval has been obtained to expend an additional unbudgeted sum of $7,000, funded by an additional $1,400 of general rate and a drawdown $5,600 from reserves in the current year, to be reinstated from the works budget next year. This arrangement effectively spreads the work over two years without incurring the inefficiencies and additional costs that would result from the work being physically being completed in two stages.

TUTAENUI FLOOD CONTROL SCHEME

5.116. Staff completed a walk-through channel inspection between Calico Line and Hawkestone Road to determine channel clearance priorities. These inspections are undertaken annually during low flow conditions and are found to be invaluable in assessing the state of the stream. This year’s inspection found very few problems with only minor debris clearance and the odd tree removal required.

5.117. General maintenance and repairs were completed at a number of the scheme dam sites to ensure ongoing effective operation and maintenance of a good asset condition.

POREWA FLOOD CONTROL SCHEME

5.118. Good progress was made completing scheduled maintenance around the scheme dam sites.

WHANGAEHU - MANGAWHERO RIVER MANAGEMENT SCHEME

5.119. Aerial spraying plans for the control of willow and poplar growth in the scheme area were developed after the January inspections. These plans have been implemented and aerial spraying is now complete for the season.


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LOWER WHANGANUI SCHEME

5.120. The monthly maintenance around the Upokongaro Jetty was undertaken. Vegetation maintenance works, including spraying and mowing were completed at various sites.

5.121. Resource Consents have now been granted in respect of the construction of rock groynes at South Spit. An on-site pre-tender meeting was held in mid-March with prospective contractors to identify any construction issues before finalising the contract documentation. It is expected that work should commence on this project in early April enabling completion this financial year.

TURAKINA RIVER MANAGEMENT SCHEME

5.122. Aerial spraying plans to control willow and poplar growth in the scheme area were developed after the January inspections. These plans have subsequently been implemented and aerial spraying is now complete for the season.

EASTERN AREA

GENERAL

5.123. The Tararua District has experienced an exceptionally dry summer with a period of constantly low river levels. There has been little rainfall over the last two months and river levels at one point reached the lowest on record, a record that stretches back nearly 100 years. One particular reach of the Mangatainoka was dry for close to a kilometre. While the dry weather has been particularly conducive to completing river works, and works programmes are ahead of schedule, staff have been mindful of the effects that even small amounts of sediment have had on the low flowing rivers, as well as the stresses that landowners are under as a result of the drought.

5.124. The highest rainfall total recorded in the eastern catchment during this two month period was 170 mm. This was recorded at the Upper Mangahao hydro recording site in the Tararua Ranges.

5.125. Staff have been busy over the last two months meeting with landowners to organise scheme works, undertaking scheme works, monitoring gravel extraction, and completing paperwork such as writing contracts and consent applications, and inputting GIS data. Preparatory work has been undertaken in relation to upcoming Annual Scheme meetings.

5.126. The annual scheme drain maintenance programme is underway and staff have been working with many landowners to ensure the drains are in a satisfactory condition heading into winter.

AKITIO SCHEME

5.127. Staff continue to monitor the effectiveness of last year’s willow poisoning while also investigating and monitoring any debris build-ups. At the moment the river channel is generally clear and free from debris.

5.128. The whole scheme works area has now been sprayed and Scheme Managers plan to carry out aerial maintenance spraying on a triennial basis. This is the first year to have no planned aerial spraying; however a small works budget has been available if needed for minor spraying and debris removal.

5.129. This year the small works budget was utilised to remove some willows from the Cadmus Bridge. These willows were too close to the bridge to be sprayed by the helicopter and were causing some visibility issues for motorists.


10 April 2013


EASTERN MANAWATU SCHEME

5.130. Staff continue to monitor the effectiveness of last year’s willow poisoning while also investigating and monitoring any new debris build-ups. Large trees sprayed several years ago have started to deteriorate leaving the channel looking much tidier, however the potential for channel blockages arising from this process is well understood and will be monitored closely.

5.131. While there was a small amount of aerial spraying planned for this season staff have decided to defer this work until next year to tie in with other spraying works to ensure the efforts are cost effective.

MANGATAINOKA SCHEME

5.132. Programmed works for this season are nearing completion, due to good progress being made in the fine weather conditions. Works yet to be completed include mechanical drain cleaning, two small erosion asset maintenance jobs, and the partially completed rock lining at Ranfurly Road.

5.133. A contract has been awarded to Infracon in the sum of $608.898 for a large rock lining contract at Ranfurly Road and works are now well underway. When the contractor set out the works in mid-February it was discovered that additional erosion to the bank since the initial survey will add an estimated $20,000 to the ‘Measure and Value’ tender price. The funding arrangement is for $250,000 to come from insurance, $250,000 from Fonterra, and the remainder from the scheme. While Fonterra were initially tentative in confirming their funding they have since formally agreed to fund the full $250,000 in two instalments.

5.134. Staff have finished GIS mapping the scheme’s hard assets. This information has been entered into the Operations Asset Mapping GIS shape file and checks and updating of asset length information in Asset Management System (AMS) records have been completed for these assets. While meetings held in November and December highlighted some minor changes to be made in mapping methodologies, staff have adapted to these and plan to continue mapping planting and tree assets as time allows.

5.135. A further 4,500 m3 of gravel has been extracted from the Mangatainoka River over the past two months. This brings the total extracted under the Code of Practice to 7,000 m3; 500 m3 under the maximum allowed for a river of this size. Staff have completed a resource consent application to increase this limit to the 25,000 m3, which is much less than the 55,000 m³ specifically allowed for allocation in the Mangatainoka River under the One Plan, and hope to have this granted in the near future.

SOUTH EASTERN RUAHINE SCHEME

5.136. As mentioned in the last bi-monthly report, this season’s bank protection works are now all but finished, with drain spraying the only scheme work still outstanding.

5.137. At the October Liaison Committee meeting ratepayers made special note of the effectiveness of the willow maintenance work and strongly support further efforts to focus on mulching to complement core works. The ratepayers also asked that there be a news release to highlight the good work that is carried out by Horizons on behalf of the scheme, this was run several weeks ago.

5.138. A field trip was held in late March for the Liaison Committee to view a selection of scheme works completed during the year.

5.139. Only a small amount (1500 m³) of gravel has been extracted over the last two months.


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IHURAUA SCHEME

5.140. Channel spraying is soon to be completed and other works this season will focus on removing some channel constrictions as identified in the updated long-term programme. Once those are complete, all recommendations from the Audit will have been addressed.

TAWATAIA - MANGAONE SCHEME

5.141. Spraying of the scheme’s drainage channels was undertaken in late March, as soon as water levels receded after the brief spell of rain. Spot spraying of willows along the Mangaone Stream was also undertaken.

5.142. The cleaning of a short section of the Cattle Creek drain is programmed to be completed by the end of this works season.

UPPER MANAWATU – LOWER MANGAHAO SCHEME

5.143. River and bank protection works are all but complete with only one last river work and the drain maintenance to be completed before the end of the season.

5.144. Because most of the assets damaged during the Sep 2010 flood were repaired last season, the scheme has been able to focus on any previously unprotected sites of new erosion this season. As a result there has been a large number of capital items constructed this season.

5.145. The task of attending to several new erosion sites before they could erode into larger problems was made easier by the Committee’s approval in February to expend an additional sum of $20,000.

5.146. The only outstanding recommendation arising from the recent scheme Audit, being some relatively minor adjustments to the rating system, was attended to during the period. This involved updating the rating maps to remove the now redundant EZ category and to offset the direct benefit rating bands. This change will ensure rates are fairly collected from the landowners farming their respective river banks.

SOUTHERN AREA

GENERAL

5.147. The Manawatu and Horowhenua Districts continue to experience an exceptionally dry summer with consistently low water levels in all scheme’s drains and rivers. This has allowed good progress to be made with both scheduled maintenance programs and capital works.

5.148. Staff have been kept busy responding to landowner enquiries regarding various drainage issues including the fencing off of water courses within the scheme boundaries.

5.149. Staff attended an Inanga spawning habitat restoration workshop organised by the freshwater management team. The purpose of the workshop was to help staff identify potential spawning sites and to discuss ways of improving and protecting these sites.\

5.150. Staff have been busy negotiating with local landowners and Horowhenua District Council (HDC) to confirm the location of the new stopbank that is to be built adjacent to the Gray’s property on the Waikawa Stream. Works have commenced by contractor and is anticipated to be completed by 11 April at the latest.

5.151. As part of the Manawatu District Council (MDC) plan change process, Horizons has been given the opportunity to formally designate existing flood protection assets within the District. Staff have mapped the location of these assets and have tabulated the relevant property details. This information will be submitted for designation in the proposed Manawatu District Plan.


10 April 2013


OHAU-MANAKAU SCHEME

5.152. Tenders for the final Stage of the flood protection upgrade programme on the Ohau River were invited from selected contractors. A contract was subsequently awarded to Alan G Gibson of Levin in the sum of $158,676.70. The tendered work included the upgrading of two sections of stopbanking totalling 2.1 km in length, together with the lowering of the adjoining berm and widening of the channel to increase channel capacity.

5.153. Work commenced on 18 February and by the end of March the majority of the earthworks and shaping had been completed. This work completes all of the upgrading work proposed on the Ohau River.

5.154. In November 2011 a report was published by the Manaaki Taha Moana Research Team on the Old Ohau Loop. The report looked at the existing ecological state of the loop and provided recommendations for the ecological rehabilitation.

5.155. One of the recommendations of the report was the installation of a fish friendly floodgate at the outlet of the loop which would allow both tidal flow and fish passage back into the loop. An existing culvert installed some years ago by the scheme to provide drainage for the surrounding farm appears to have been set too high to gain the full benefit of the tide. In a joint venture with the GEM team and the local landowners the Scheme has now installed a second culvert at a lower level and has attached a new fish friendly floodgate. Planting up of the outlet channel will be completed by members of the GEM team once suitable weather conditions prevail.

5.156. Minor repairs have been carried out on the concrete groynes on the northern side of the Ohau River after several large pieces of concrete which form part of the groyne had been dislodged by whitebaiters during the whitebait season.

5.157. A large area of berm and stopbank on the Burnell’s property on the left bank of the Ohau River has been sprayed to control fescue growth.

MANAWATU DRAINAGE SCHEME

5.158. A large slump which had developed on the left bank of Whiskey Creek was repaired using concrete riprap.

5.159. Bed scour in GL Hansen Drain downstream of a private access culvert had resulted in the undermining of the end pipe and a cavity appearing in the access way. Repairs were carried out to secure the culvert pipe and to backfill the cavity in the crossing. Several loads of concrete riprap were also placed in the bed of the drain to prevent further scour. An access culvert on Wilson drain has been replaced after several pipes had collapsed.

5.160. A total of 2.0 km of scheme drains were mechanically cleaned and a further 150 km of drains were sprayed with herbicides.

BURKES DRAIN PUMP ACCESS

5.161. Works have been completed to construct the initial section of sealed access off State Highway 56 onto the Burkes Drain pump site. The access conforms with MDC requirements. The remaining access works will be undertaken as part of the pump construction works during the 2013-14 financial year.

MAKERUA DRAINAGE SCHEME

5.162. A meeting was held with the Makerua Liaison Committee and several key landowners to discuss the proposed upgrade works on Boundary Drain. The majority of those who attended the meeting were in favour of a new weedscreen being installed next year and for the replacement of the impeller on one of the existing MacEwans pumps and the construction of the link drain between Ashlea Road Drain and Boundary Drain to be


10 April 2013


completed as soon as possible. While there was some support for the installation of two additional submersibles at the Boundary Pump Station, the majority decision of the meeting was to defer a decision on the proposed new pumps until the impact of the new weed screen and impeller changes can be observed. A separate agenda item further addresses this issue.

5.163. As part of the annual pump maintenance program, the submersible pump from Ashlea Road Pump Station was withdrawn for servicing and replaced by the standby pump. At the same time a new external power socket was installed at the station which will allow for easier removal of this pump in the future.

5.164. The MacEwans pump that was withdrawn from Okuku Pump Station back in January 2012 for major servicing, including the replacement of the badly worn main shaft, has now been reinstalled.

5.165. During last winter a cavity appeared above the gravity pipe next to the Ashlea Road Pump Station. Concerns were expressed by several locals that the pipes may have parted allowing material to be washed into the pipe. Excavation around the pipes has revealed that the cavity had been caused by material falling out under the headwall. Work has now been completed to repair the gap under the headwall and to back-fill around the pipes.

5.166. Recent culvert inspections along Linton Main Drain have identified that the end pipe on Floodgate L27 had dropped resulting in a cavity appearing in the stopbank above the pipe. Due to the age and condition of the existing culvert it was decided that the entire culvert would be replaced. After discussing the proposal with the adjacent landowner it was agreed that the size of the culvert would be increased from a 600 mm diameter to a 900 mm diameter culvert with the cost difference between the options being funded by the landowner. The new 900 mm floodgated culvert has since been installed.

5.167. Blackberry along the banks of the Linton Main Drain upstream of Tane Road has been sprayed.

5.168. A total of 62.5 km of scheme drains were sprayed with herbicides.

KOPUTAROA DRAINAGE SCHEME

5.169. The MacEwans pump at Koputaroa No.2 Pump Station was withdrawn on 19 February as part of the annual pump maintenance program. In addition to carrying out the normal servicing which includes replacing all of the bearings and gland packing, a new shaft was fitted to the pump after significant wear was noted to both the upper and lower sections. The pump has since been reinstalled.

MOUTOA DRAINAGE SCHEME

5.170. In 2008 four of the six floodgates at the end of the Moutoa floodway were dewatered and inspected to determine their structural condition. This period has seen the remaining two floodgates dewatered and inspected. Dewatering of the gates, which are below mean sea level, was a major exercise and required large steel shutters to be positioned either side of each floodgate. The area behind the shutters was then dewatered using a small submersible pump so the entire gate could be inspected. The gates and substantial structure were found to be in a sound condition. New metal strips were placed along the closing edge of each gate to compensate for timber wear.

TE KAWAU DRAINAGE SCHEME

5.171. In 2009 a CCTV programme was implemented to inspect all of the significant culvert structures through stopbanks within the Te Kawau Drainage Scheme. Over a two year period, 42 floodgated culverts were inspected to determine their condition. This information was then used to determine the potential risk of failure of the structure and the


10 April 2013


consequences of such failure. The result of the risk of failure and the consequences of failure were then combined to provide a culvert priority repair program.

5.172. One of the culverts identified as being at high priority was Asset No. 877200 (S8). The existing culvert was badly deformed (squashed), indicating a failure in the surrounding backfill, particularly in the soil supporting the culvert sides. The consequence of failure was also high with a road and 300 ha of land potentially affected.

5.173. The subject culvert has now been demolished and replaced with a new 1200 mm diameter concrete culvert and floodgate.

5.174. Two new 300 mm diameter floodgated culverts have been installed in private drains which discharge into the Main Drain along Kaimatarau Road, in order to prevent flood waters spilling out of the scheme drain and onto an adjacent organic farm. A 450 mm diameter floodgated culvert was also installed on a private drain discharging into Goodwin drain from the same organic farm.

5.175. A total of 32 km of scheme drains were sprayed with herbicides.

ENVIRONMENTAL GRANT WORK

5.176. There were three applications for grant assistance approved during the period. The status of all projects that have been approved during the year to date, is indicated in the following table:

Name River Type of Work Date

Approved Work Status

Estimated/ Actual Works

Cost ($)

Value of Grant

C Sicely Hautapu Stream

Willow clearing 5/3/2012 Complete $12,093 actual

$3,628

M Fouhy Upper Mangahao River

Erosion protection 8/3/2012 Completed $11,500 actual

$3,450

Ruapehu DC & DOC

Ohura River at Matiere

Willow clearing 22/5/2012 Completed apart from burning

$45,716 estimated

$13,714

C Thomasen Makino Stream

Erosion protection/vegetation management

23/5/2012 Completed $10,300 actual

$3,090

C Taylor Upper Mangahao River

Erosion protection and planting

8/10/2012 Completed $5,000 actual

$1,500

C Whitfeild Upper Mangahao River


$720

B Hooper-Smith

Mangatoro Stream


$1,170

R Bee Wainui River Channel clearance 19/11/2012 Yet to commence

$3,000 estimated

$900

J Gunsen Manawatu River at Oringi


$3,584

Bird and Brown

Kiwitea Stream

Channel clearance 18/12/2012 Completed $5,945

$1,783.50


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6. SIGNIFICANCE

6.1. This is not a significant decision according to the Council’s Policy on Significance.

Allan Cook

GROUP MANAGER OPERATIONS

ANNEXES

A Schedule of Completed Works (Under Separate Cover)

Ashby-Palmer Matiere

Toetoe Stream

Channel clearance 8/1/2013 Completed apart from burning

$6,097 estimated

$1,830

Perry and RDC

Mangaroa Stream - Ohura

Channel clearance 8/1/2013 Completed apart from burning

$13,760 $4,130

Tunnel Hill Mangatikotoko Stream

Scour protection/grade control

28/3/2013 Works yet to commence

$23,000 $6,900

W Blakely Porewa stream

Erosion control 25/3/2013 Works yet to commence

$21,000 $6,300

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