river and drainage engineering report (prd 01 02) · 12/14/2016 · 6.5. the most substantial...

Catchment Operations Committee

14 December 2016

River and Drainage Engineering Report (PRD 01 02)

Report No. 16-239

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 31 July 2016 to 14 December 2016.

2. RECOMMENDATION

That the Committee recommends that Council:

a. receives the information contained in Report No. 16-239.

3. FINANCIAL IMPACT

3.1. Funding provision for all activities reported on in this item is either included in the River and Drainage General or River and Drainage Schemes Activity sections of the 2015-25 Long-Term Plan (LTP); is covered by an approved carry-forward of unexpended budget in 2014-15; or additional approval will be specifically sought by way of recommendation in the item.

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 Committee and / or Catchment Community Meetings. As necessary, other issues will be the subject of media releases.

5. SIGNIFICANT BUSINESS RISK IMPACT

5.1. There are no significant risks inherent in the adoption of recommendations contained in this report. As previously reported there is a risk of the drawdown of an excessive proportion of individual scheme emergency reserve funds for the purpose of flood damage reinstatement relating to the June 2015 event. Realising this risk would require Council’s application for assistance under the National Civil Defence Emergency Management Plan (the Plan) to be declined. This business risk has declined throughout 2016 and is now considered highly unlikely to be realised.

6. DISCUSSION

6.1. Weather is a recurring theme with this report, with the impacts wide ranging across all areas. Higher than average rainfall in combination with a lack of drying conditions has impacted bulk earthworks, causing delays to both the Rural Upgrade Project and the Parewanui Upgrade near Scotts Ferry. It is too early in the financial year to say whether these delays will have an impact on project delivery for 2016-17. The wet weather has also impacted operational costs in the southern area, with the operating costs of most drainage schemes ahead of where they would usually lie. Again, prevailing weather conditions over the remainder of the financial year may well see the impact on the full year result moderated.


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6.2. As an update to the commentary contained within the Chief Executive’s report to the 29 November Council meeting, MCDEM staff have advised that Council’s second claim for financial assistance associated with the June 2015 flood damage is now with acting Minister Hon. Gerry Brownlee for consideration. Clearly the Kaikoura Earthquake has placed a substantial load on central government in that area and some sensitivity will be employed with follow-ups around the outcome of this claim.

6.3. The second claim was lodged in early September, covers 100 damage sites bundled into 90 individual claims and has a total value of $1.53M. The Regional deductible has been accounted for with the first claim so provided MCDEM accepts the claim as valid the amount payable to Horizons is around $0.92M. Estimates are that the total claim will be worth $4.4M with the MCDEM payments totalling $2.1M (again provided the second and third claims are not amended by MCDEM staff). Staff are working toward lodging a third and final claim in early March 2017 with the intent of wrapping up the process within the current financial year.

6.4. Health and Safety related matters have featured strongly in Group activity over the period. In addition to organisational initiatives associated with building staff awareness around the legislative changes that came into effect this calendar year, a fresh risk assessment has been undertaken within the Group and that has been used to drive further training in high hazard areas such as water safety, use of chainsaws, safe chemical handling, electrical hazards (both overhead and underground) and safe practices with regard to confined spaces.

6.5. The most substantial physical works deliverable in the 16-17 financial year is Year 11 (the penultimate year) of the Lower Manawatu Scheme (LMS) Rural Upgrade Project. The Year 11 programme involves further work to stopbanks alongside the Oroua River, various reaches of the Manawatu River and for the Tokomaru River. Project delivery is well underway with more detail around that delivery provided in a separate report.

6.6. Deterioration in flood protection levels of service due to berm siltation continues to have a high profile within the River Management Group. From a current operational perspective this includes thinking laterally to identify disposal options for the Oroua River, encouraging adjoining landowners to assist and therefore maximise the benefit of the budgets set for this activity. Staff have also approached the New Zealand Transport Agency (NZTA) around fill-sourcing for the Whirokino Bridge project - potentially sourcing this from in front of the Moutoa Gates. Such arrangements are inherently difficult to get to the finish line but staff are persisting and endeavouring to make such an arrangement as simple as possible for NZTA.

6.7. Staff met with Horowhenua District Council (HDC) staff and representatives from engineering consultant Good Earth Matters (GEM) on 15 November to review progress GEM staff had made with the Catchment Management Plan (CMP) for Foxton. This links to the current LTP target (page 45 - investigate options for improving the level of flood protection service for Foxton Township, through improvements to Foxton East Drainage Scheme infrastructure). Although budget provision had been made for staff time to investigate this, the CMP work funded by HDC largely achieves this objective.

6.8. Like parts of Levin, stormwater management for much of Foxton relies on soakage with all of the consequential limitations, particularly in wet antecedent conditions and / or long duration storm events. As a consequence the existing reticulated network could at best be described as limited. An initial assessment suggested substantial capital investment would be required to have any meaningful impact on levels of service – technical work completed to date reinforces that. It is intended to present a summary of the CMP report to Council when it is finalised in the New Year (a concurrent presentation to both Councils).

6.9. The Foxton River Loop Working Party met on three occasions over the period; early August, early October and early December. The technical work commissioned by HDC and undertaken by engineering consultant GHD was reported to the 6 October meeting.


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The technical work considered the feasibility of reintroducing river flow to the loop and provided a seemingly realistic summary of the challenges and benefits of achieving that aim. Specifically, the report reinforced some of the points that had been previously made in relation to the challenges associated with elevating levels in the Manawatu River by way of a weir to force flow through the loop. The report recommends dispensing with a weir and only constructing the linking channel, relying on high flow / tide to force water through the loop, costed at $5.3M.

6.10. Horizons feedback on the GHD report tabled at the December meeting mainly centred on expectations around what the $5.3M option might realise in terms of flow through the loop (the rather vague language contained in the report) and the need to have a degree of confidence in (and rigour associated with) the cost estimating. Save Our River Trust (SoRT) representatives made it clear at that meeting that they view, with some importance, the next steps as being the need to take a structured approach to building a business case. This reflects their primary focus on central government as a funding source (reflecting the circumstances that saw river flow taken away from the loop) and the current emphasis in Wellington around business cases.

6.11. Nonetheless at the December meeting the GHD representative suggested (with the somewhat tacit support of HDC and SoRT attendees) that Horizons should be not only a funding partner but should also manage the project, particularly aspects around central government funding.

6.12. The potential for legal action identified previously to the Committee relating to Horizons’ managed gravel extraction from the Oroua River is now considered highly unlikely, due in part to the efforts of former Councillor Murray Guy in conveying a better understanding of the benefit that the landowner derives from the LMS.

6.13. There are two, albeit considered remote, possibilities of legal action current facing the River Management Group, both within the Manawatu Drainage district and both relating to Taonui Basin consenting. One relates to the perceived adequacy of the mitigation measures associated with Rural Upgrade Project implementation and the other claiming effects associated with Mangaone spillway operation arising from the June 2015 (landowner has constructed a bund around his property and has sent Horizons an invoice for the cost of that work). The preliminary assessment for both is that they pose little risk to Council.

6.14. The Whanganui Flood Management Review Group has met on a number of occasions over the period and the work of that Group to date (and other matters) are the subject of a separate report. Note that at the invitation of the Group’s Ngati Apa representative a meeting was held at Putiki Marae on 24 August to provide the community with an update on the Group’s progress, what previous work indicated flood protection for Putiki might look like and what it might cost.

6.15. Staff met with a group of Porewa Scheme ratepayers (largely valley floor landowners) on 30 August to answer questions around rates invoices and a range of other operational matters. Organised by Rangitikei District Council (RDC) Councillor Dean McManaway it provided a good forum to reinforce the value the scheme provides to those ratepayers.

6.16. From a staffing perspective Horizons farewells Investigations and Design Manager Peter Blackwood. Peter has been with Horizons since 2006 and has been an integral part of the many and varied investigations projects that arose from the 2004 floods. I wish Peter and his family all the best.

7. INVESTIGATIONS AND DESIGN

INVESTIGATIONS


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7.1. Over this four month period a large number of assessments were completed and design advice requests actioned. There are 36 separate tasks programmed for the 2016-17 Design & Investigations Team Programme.

7.2. From a staffing perspective, following the retirement of Senior Design Engineer Graham Doull the team welcomed the arrival of Stuart Standen to fill the position of River Management Analyst.

LOWER MANAWATU SCHEME

7.3. The oncoming 2016-17 summer construction season is Year 11 in the 12 Year Rural Upgrade Project programme. Design work is well advanced on planned upgrades in Year 11 of the upgrade to achieve the 1% AEP (100 Year) standard with 450 mm freeboard. During the reporting period designs on these works have included:

Detailed design on the proposed stopbank upgrades on the Oroua River between Awahuri and Feilding. This required a major upgrade to the existing MIKE11 computer model through this reach. The Investigations & Design Team is particularly focussed on addressing the overflows that occurred in the June 2015 flood (and also the February 2004 flood) flooding several Awahuri houses on the true right bank at a meander loop at the Makino Stream confluence and on the true left bank where overflows travelled 3 km to the State Highway;

Provision of design stopbank levels and alignments at Rangiotu and immediately downstream of Awahuri;

Further design advice on the Tokomaru and Linton Main Drain stopbank upgrades. These need to cover the increased seepage pressures on the stopbanks resulting from the increased head of the raised stopbank, potential foundation issues and any erosion threats;

Provision of design stopbank levels for the Koputaroa Stream; and

Examination of computer modelling outputs to set 1% AEP flood levels at Longburn.

7.4. Design advice was provided to address the issue of ponding of floodwaters behind the Mangaone stopbank at Richardsons Line. Options for the stopbank at Benmore Avenue were considered and a detailed design solution is being prepared.

7.5. A meeting held with the Area Engineer Central has confirmed the proposed upgrade works to be carried out in 2017-18 on the Kara Creek and Mangapuketea Stream stopbanking near Shannon. The Kara stopbanking above the highway will be raised to the new design level consistent with the already upgraded section downstream. Some set back for channel stability may be required following detailed survey and design next year. The lower Mangapuketea return banks will be levelled so that the left bank is 150 mm lower than the right bank to help ensure floodwaters overflow into the ponding area rather than across State Highway 2. Undersized floodgates will also be replaced. These works are expected to be completed within the programmed budget of $526,163.

7.6. Inspections were completed at a number of properties to confirm flood levels experienced in the Mangaone floodway during the June 2015 event. These levels will be used to calibrate the computer modelling being carried out to identify the impact of heavy local rain coincident with floodway flows.

7.7. Current team workload has necessitated outsourcing the numerical modelling to DHI Limited. The brief includes:

Adjustment of the existing Taonui Basin 2-Dimensional MIKEFLOOD computer model to assess the flooding experienced in the June 2015 flood. Assessment of the areal and depth extent of this event has shown that flood levels were close to the 1% AEP (1 in 100 year) flood generally, with levels up to 230 mm above the 0.5% AEP (1 in 200 year) level in one area. The rainfalls themselves were


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generally between 2% (1 in 50 year) and 1% AEP for various durations, on top of two months of well above average rainfall resulting in substantially more runoff than normal. The computer model, which incorporates both inflows from watercourses and spillways plus the rainfall landing in the Taonui Basin will assist in identifying the causes of the flooding;

Modelling of the 0.5% AEP design flood event; and

Assessment of proposed stopbanking options to be built to protect Cloverlea.

7.8. The results of the computer modelling were due late November and are expected shortly.

7.9. A detailed report was completed on the flooding experienced in the Taonui Basin in June 2015.

7.10. Investigations and preliminary design has been completed on proposed works to help prevent future washouts of the Manawatu Drainage Scheme stopbanking near the intersection of Whiskey Creek and Main Drain. The Main Drain stopbank was washed out by Mangaone floodway flows during the June 2015 event and unduly added to the extensive ponding in the Taonui Basin. The proposed works provide a cost effective remedy by minor works to reshape the banks and achieve a more uniform crest level so that overflows will not concentrate at low spots.

7.11. A comparison of floodgates for the ponding areas along Burkes Drain and Main Drain in the Manawatu Drainage Scheme has concluded that the existing sizes provide a reasonably consistent discharge capacity to clear ponding. The discharge capacity was assessed based on the ratio of floodgate area and ponding volume. There have been ratepayer concerns that the new floodgates installed by the LMS had increased the capacity to clear ponded floodwater from the lower Taonui Basin more than higher areas.

7.12. Ongoing design information has been supplied to the on the Foxton River Loop Working Party.

LOWER WHANGANUI RIVER

7.13. No substantive investigations have been undertaken over the period. However periodic enquiries have been answered on the findings of the major report prepared on the June 2015 flood and on information pertaining to various upgrade options.

TUTAENUI STREAM HYDRAULIC MODELLING AND AUDIT

7.14. The 1-Dimensional part of the model is completed and has produced good information on the channel capacities, with particular importance being the capacity through Marton.

7.15. The 2-Dimensional model has also been completed. There has been difficulty in coupling the 2 models in MIKEFLOOD, but this has progressively been resolved. The modelling was parked for some time while design focussed on the extensive Rural Upgrade Project works for 2016-17.

KIWITEA STREAM GRAVEL ASSESSMENT

7.16. The survey of the cross sections on the Kiwitea Stream over the 15.77 km reach between the confluence with the Oroua River at Feilding and the Cheltenham-Hunterville Road Bridge was completed. A detailed fluvial assessment was completed following the survey.

7.17. Analysis of four cross section surveys carried out during 1985, 2004, 2010 and 2016 has identified that the following is occurring in the Kiwitea Stream study area:

The stream bed is degrading in the upper half of the study area and aggrading in the lower half;

The volume of gravel under the stream bed is degrading in the upper half of the study area and aggrading in the lower half;


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The volume of gravel under the active channel is relatively stable in the upper ¾ length of the study area with a pronounced aggradation occurring in the lower quarter;

The cumulative change shows a loss of gravel under the stream bed occurred between 2010 and 2016 while aggradation occurred between 1985 and 2004; and

The cumulative change of gravel shows the volume of gravel under the active channel has built in the lower half of the study area.

7.18. Based on the results of this study it is recommended that:

1. Gravel extraction from the Lower Kiwitea Stream Scheme be only allowed downstream of cross section 8000.

2. That the maximum annual amount of gravel to be extracted and removed from the Kiwitea Stream shall not exceed 5,000 cubic metres per annum as per resource consent 103434/1.

3. The Kiwitea Stream study area is resurveyed in the year 2021.

KAWHATAU STREAM GRAVEL ASSESSMENT

7.19. The survey of the cross sections on the Kawhatau Stream completed in 2014 is now being examined as part of the process of completing the fluvial report.

HAUNUI DRAINAGE SCHEME RATING

7.20. Assistance was provided to GIS support staff carrying out an outstanding review of the rating boundary for the Haunui Drainage Scheme, a small scheme located north of Whangaehu. The review would have been carried out under the Rates Project in 2008 but a proposed new area-based rating system was expected to replace the old one instead; this did not happen. Anomalies have been identified and these are intended to be addressed as part of the LTP update.

SOUTH EAST RUAHINES – MANGA-ATUA STREAM

7.21. Investigations have started on options to mitigate flooding from the Manga-Atua Stream next to Woodville. A site visit was completed and the existing flooding problems were identified. An investigation brief was then prepared that requires the following specific problems to be addressed:

Regular flooding and wash out of the rail line adjacent to the ponding area just upstream of State Highway 2 and to the north of the stream;

Flooding of State Highway 2; and

The need to constantly extract gravel from just above Broomfield Road Bridge to keep drainage channels open.

7.22. The stream has been extensively straightened over the years and further straightening downstream in the vicinity of Troup Road is one option now being considered. It is envisaged that this would steepen the gradient and transport gravel further downstream where the channel is more incised and flooding would not be such a problem. If the straightening option is adopted it would be a rare departure from normally avoiding this technique, which can cause significant channel degradation and erosion. However, in this case it may be an appropriate technique to mitigate flooding.

SOUTH EAST RUAHINES – SINCLAIRS CREEK

7.23. A detailed investigation and report was commenced and completed on options to mitigate flooding. The current diversion scheme of Sinclairs Creek located at Harris Road has been assessed as not being adequate to prevent flooding at the house for Q2 flood events. This


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matches comments made by the house tenant and owner. Key locations were surveyed and examined at:

The diversion culvert located on Sinclairs Creek near the intersection of Range and Harris Road;

The diversion drain that flow downstream from the culvert to the oxbow drain located on the Blatchford farm;

The farm track culvert that drains the oxbow water to the Manawatu River; and

One particularly affected dwelling.

7.24. Based on an assessment of the flood carrying capacities of Sinclairs Creek and the diversion drain the following was recommended to reduce the risk of flooding at the house for up to and including the Q10 flood event:

Lower the crest of broad crest weir in front of the diversion culvert to 87.1m elevation;

Install two 1 metre diameter culverts at the Sinclairs Creek diversion site with the culvert invert lowered to 86m OR install a bridge with the soffit matching the surrounding land elevation;

Increase the flood carrying capacity of the diversion drain immediately downstream of the diversion structure;

Remove debris from the Bluff Road culvert;

Install two 1.2m diameter culverts at the farm track;

Trim the sides of the drain upstream of the farm track; and

Assess the drain downstream of the farm track for flood carrying capacity.

OHAU RIVER PROTECTION WORKS DESIGN

7.25. A site inspection and designs were completed on three sites on the Ohau River. The recommended designs were:

Seniors: Rock riprap supplemented by a rock groyne on the upstream end of the erosion on the true right bank. The stream is also far too narrow at this location. However options for widening the stream are limited by the location of a bridge midway around the bend. If this limitation can be overcome, the erosive forces on the bend can be reduced.

Kilsby: This location is ideal for construction of permeable rail-iron groynes of a very similar design to the very successful works at McKelvie’s on the left bank of the Rangitikei River. Whilst there have been previous limited attempts with rail-iron groynes at this location, they did not have the same embedment necessary to withstand scour.

Burnells: Ideally the erosion issues are best dealt with by vegetative protection, possibly with a limited amount of toe rock strategically placed.

AMS SOFTWARE ENHANCEMENTS

7.26. An updated version of our purpose built Asset Management System (AMS) PowerBuilder software is now live after more than three years of intermittent development and testing. The largely incremental improvements affect defect length data, design and structural data, financial reporting, condition rate reporting and various other issues, some of which have been longstanding bugs in the system.

7.27. Further enhancements to meet the ongoing need for increased functionality are limited by the increasingly outdated PowerBuilder software platform and a completely new AMS is now due to be introduced next year.


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7.28. Some technical support has been provided to the new AMS Project Manager so that prospective suppliers can use our existing data in their product presentations to the AMS Working Group.

UPDATED FLOOD LOSS CURVES

7.29. Flood Loss Curves in Appendix G of the Asset Management Plans (AMPs) for each scheme have been updated as required following the annual capitalisation process and update of the AMS for discoveries and disposals. The total replacement value of all our scheme infrastructural assets (including write-offs and other adjustments) at 2 July 2016 is $390M including Work in Progress of $1.3M, an increase of some $8M in 2014-15. Most schemes had only minor changes but the LMS had a relatively significant increase due to the completion of work in progress and the addition of extensive lengths of concrete riprap identified in recent floods. Total asset value of the LMS increased by $9M to $202M and this has meant the 50 year flood damage, as taken from the flood loss curves, has increased from $5.6M to $6.0M with a corresponding increase in target scheme reserves from $4.48M to $4.8M (after deducting the 20% general rate contribution). Refer to the report to Committee in February (Report 16-15).

7.30. This would not normally be updated until the 3 yearly revaluation but given the size of increase it has been highlighted at this stage to help guide budget for next year.

7.31. It also means that the LMS will contribute a somewhat greater proportion of the total asset insurance premium, which is apportioned on damage risk and asset value.

ASSET CONDITION RATINGS

7.32. Annual inspections of all scheme assets have been carried out by River Management staff over the three month period April-June 2016. The inspections involve assessing the condition rating for maintenance planning and performance reporting purposes. Condition ratings vary from 1 (as new, no maintenance required) to 5 (failure, rebuild required).

7.33. The target level of service for most assets is CR1 or CR2 (fully effective or only minor maintenance required) with most schemes aiming for no more than 10-15% below this standard to allow for programmed upgrade works or repair of flood damage - the inspections revealed that 93% of all assets successfully achieved this standard, including 91% of all stopbanks.

7.34. The overall result was an improvement on the 87% last year and slightly better than the 10 year average of 91%.

7.35. In particular, the LMS achieved 90% while the flood damaged Rangitikei Scheme was 79%.

7.36. The inspections confirmed that the Mangatainoka Schemes had relatively more outstanding flood damage than other schemes, with 6% of bank protection assets being CR4 or CR5, while the Rangitikei Scheme had 3%.

7.37. Trend Graphs in Appendix E of each individual Scheme AMP have been updated to show the proportion of flood control, erosion protection, drainage and miscellaneous assets that have a condition rating of 1 or 2. In addition, the Performance Tables in Appendix F for the various flood protection, erosion control and drainage assets have been updated to show the level of service achieved in terms of the proportion with condition rating 1 to 5. A summary of this information was used to highlight the performance of key schemes in Council’s recently completed Annual Report 2015-16.

ANNUAL REPORT – AUDIT NZ


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7.38. Information on scheme infrastructure capitalisation, valuation, write-offs, discoveries, condition ratings, work in progress and associated processes was provided on request to Audit NZ during their scrutiny of the Draft Annual Plan (DAP) early in September.

NATIONAL OVERVIEW OF RIVER AND DRAINAGE SCHEMES

7.39. Information on our river and drainage schemes was prepared and collated over a few days for Tonkin and Taylor (T&T), who have been engaged by the national River Managers Forum to carry-out an overview of the state, value and management of river control, flood protection and drainage schemes in New Zealand. Horizons, as a member of that Forum, along with other regional councils and unitary authorities, are paying part of the T&T costs.

7.40. The information included in the AMP documents for all schemes, scheme costs and rates (excerpts from our 2015-2025 LTP 30 yr financial strategy), our schedule of assets including 20, 100, 500 year estimated flood damage.

7.41. Rating categories were simplified to standardise the benefit descriptions (high, medium, low, indirect) and categories (flood protection, erosion, drainage, pumped drainage, river management) along with the standard of flood protection provided.

7.42. Other staff provided GIS data showing location maps and rating maps of all our schemes, rating data and One Plan GIS data of our biological assets at risk or protected by river and drainage schemes i.e. significant natural areas, rivers, lakes, wetlands and other waterways.

DESIGN ADVICE

7.43. During this period ongoing design advice has continued to be given to River Management project and scheme management staff and other department’s and TLAs staff in relation to several matters. They continue to be mainly focussed on the flood-related matters as outlined above. Designs completed included:

Design of an alternative and cheaper solution to protect the Hoults site on the left bank of the Manawatu River downstream of Ashhurst. This involved a rock toe lining for the upstream half of the works, with rail-iron groynes in the downstream half. This should provide a secure and cost-effective option;

Design of a small section of additional rock lining opposite the Makino Stream debris deflector structure;

Research and advice on the use of limestone rock in rock riprap environments. There are essentially two types of limestone in the Tararua District, one that meets engineering requirements for durability and one that quickly breaks down. It is important to clarify which limestone rock is durable, as it is a cost-effective rock source in certain cases;

Assessment and determination of design solutions to under-scour of a floodwall at Foxton Beach. This involved a rock riprap lining, filter rock and geotextile to prevent loss of fines from under the wall;

A presentation was prepared and delivered on River Protection Works Design to a workshop of practitioners held in Wellington;

A rock lining was designed to protect significant erosion at the Taylor Farm located on the true right of the Tokomaru Stream upstream of State Highway 57;

Calculations by Michael Ives, Structural Consultant, were peer reviewed and submitted for drafting, for the stopbank retaining wall at Rangiotu Marae, on the right bank of the Oroua River downstream of State Highway 56; and

Advice was provided on the risks of erosion near stopbanks on the right bank of the Manawatu River at Te Matai. Recommendations were also made on the upgrade of an existing rock lining at that location, should an upgrade ever prove necessary.


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REGULATORY ADVICE

7.44. A moderate amount of regulatory work was completed with recorded advice provided on 56 substantive matters during this reporting period. Additionally, there were numerous other matters quickly assessed and not recorded due to other pressing priorities.

7.45. This regulatory work involves specialist advice on flood risks and technical reports for consent applications, rezoning and subdivisions including:

Advice on 35 flood risk and related enquiries;

Included was advice on four properties in Feilding, five properties in the Rangitikei Line-Taonui Basin area and four properties in Whanganui. The remaining enquiries covered a wide range of locations;

Included was advice on a proposed 60 lot subdivision at Ratana Pa;

The stormwater mitigation calculations for a subdivision at Feilding were peer reviewed and the mitigation found to be under-estimated. A similar exercise was carried out on the significant upgrade of a retirement village complex. The additional stormwater may go to communal detention, but cannot aggravate flooding of the Makino Stream;

Further discussions were held with MDC staff on options for communal detention of stormwater. The secondary flow paths were also found to be inadequately designed and this follows a complaint on this matter on another recent subdivision;

Advice was given on several District Plan Changes including Manawatu District Plan Changes 52 (Industrial Precinct 5), 55 (District Wide Matters) and 60 (Designations). Also advice on the appeal for a private Plan Change at Pioneer West in the Palmerston North City Council (PNCC) area;

Advice was provided on seven bridges, two proposed culverts and one dam;

This included confirmation of the design support for the proposed Manawatu and Kahuterawa pedestrian bridges being constructed under the Te Ara Kotahi Project. Free design advice was provided on optimising the location and soffit level of the Kahuterawa Bridge;

Also received was the application for underpinning of Kiwirail Bridge 114 over the Tiraumea River at Ngawapurua. These vital works have been given a high priority of design and field assistance and the only issues raised were that the construction methodology did not cause adverse environmental effects;

Consents were processed expeditiously on the walkway pedestrian bridge over Stoney Creek at Te Matai, the Upokongaro Stream Bridge renewal and the Taipo Road culvert;

A site visit was held with MDC staff, and Mr Brian Kouvelis, Consultant, to help resolve site difficulties in the replacement of the Nannestad Line Bridge, damaged in the June 2015 floods;

Advice was provided on applications for five renewed gravel extraction consents. These were at Parikino on the Lower Whanganui River, Hohotaka Road on the Upper Whanganui River, Upper Whangaehu River, upstream of Rewa on the Rangitikei River and the area bounded by the degradation zone on the Rangitikei River. This latter application was voluntarily put on hold pending the findings of the Rangitikei River gravel survey and fluvial report this coming summer. A site visit was necessary for the Whangaehu application, which was for large gravel boulders in an extended upstream reach on the lower slopes of Mount Ruapehu. The rehabilitation of the previous extraction of boulders was inspected and found to be well completed to a natural state;

Evidence was prepared and presented to the Environment Court supporting why Horizons declined the Certificate of Compliance for the dam constructed by PFDL Ltd (Les Fugle). The Court upheld Horizons’ decision and questioned the


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need for the Hearing. The basis of which the dam did not have a spillway located off the dam crest that was capable of passing the 0.5% AEP flood; and

Several other compliance matters and diverse unrecorded enquiries.

8. CENTRAL AREA

GENERAL

LOWER MANAWATU SCHEME RURAL UPGRADE PROJECT

8.1. Consistent rainfall was spread across the reporting period with October, in particular, being best described as changeable and November being wetter than average. This saw a gradual increase in base flow of scheme rivers and moderate in scheme streams.

8.2. The total rainfall for this period (1 August 2016 to 23 November 2016) has been recorded as: 378.5 mm at Milson Line, Mangaone, 336 mm at Cheltenham, Makino, 683.5 mm at Scotts Road Kahuterawa (296.5 mm Aug / Sept, 387 mm Oct / Nov), and 617.5 mm at Rangiwahia (Oroua). Typically, Oct / Nov was a third wetter than the Aug / Sept period in the central area.

8.3. The Manawatu River experienced several flow peaks at Manawatu Teachers’ College during this reporting period. These peak flows decreased as time progressed, the last recorded peak flow being an exception, with the base flow of the river also decreasing. The first ‘event’ being 669.87 m3 s-1 (a stage of 3.506 m) on 7 August, this triggered the 3.5 m stage warning level but did not trigger the 4.9 m required to notify the Emergency Management Duty Officer (EMDO).

8.4. The Oroua River had inconsistent residual flows over the reporting period. The largest flow of the period occurred on 27 August and saw a flow of 98.013 m3 s-1 (with a stage height of 2.381 m) but again this did not trigger EMDO notification (threshold being 3.2 m river height).

8.5. The Mangaone Stream had four significant peaks, from August through to November. The second of these peaks was the largest where flow reached a maximum of 46.098 m3 s-1 (stage height of 3.040 m). This again did not warrant an EMDO notification which is triggered by a river height of 3.75 m.

8.6. The Makino Stream had two significant peak flows in August and a reasonably consistent flow throughout September before again peaking in October and November. The residual flow of the Makino Stream remained reasonably steady despite the peak flows. At 12 pm on 7 October a flow of 24.092 m3 s-1 (stage height 2.788 m) was recorded at Boness Road. This event did trigger a EMDO notification, sent at 8 am; it also necessitated the closing of the Makino floodgates. The event generated sizeable stormwater discharge from Feilding creating relatively minor operational issues.

8.7. The Tokomaru Stream had five peak flows and a reasonably consistent base flow throughout the period, with the flow peaks progressively reducing before increasing slightly in October and then significantly again mid-November. The largest flow occurred on 10 November with a flow of 86.064 m3 s-1 shown (stage height of 3.160 m).

8.8. The Kiwitea Stream had two significant flow peaks in August, and a gradually decreasing residual flow throughout September through to November. The largest flow was recorded on 29 August and measured 25.547 m3 s-1 (1.711 m stage height).

8.9. Scheme engineers continue to assist with the delivery of the Rural Upgrade Project. Consultation between the project delivery team and LMS staff in regard to project work for the 2016-2017 Rural Upgrade Project works has begun, with site visits to programmed work areas undertaken and meetings with landowners completed. Scheme staff have also assisted the Survey Team in completing levelling surveys of stopbanks programmed for


14 December 2016


upgrade. Closed Circuit Television (CCTV) inspections will be continuing for all culverts located within a Rural Upgrade Project work programme area, to identify any repairs or renewals that can be done by the scheme during the upgrade works.

8.10. During this period, scheme staff continued to provide advice to ratepayers and other authorities with regard to the One Plan. These have included giving advice to property owners concerning how to deal with the adverse effects of activities undertaken by their neighbours, erosion advice for streams outside of the scheme, and consenting issues for activities adjacent to our stopbanks including house extensions and new builds.

8.11. GIS asset maps were updated to reflect asset alterations or the creation of new assets over the 2015-2016 year. Changes to scheme assets are recorded in the AMS during inspections and works, and the maps revised accordingly at the end of the financial year. Hard copies of the maps are then approved by the area engineer and printed to be used in the field for the forthcoming year.

8.12. Representatives from specialist property consultant, The Property Group, facilitated a workshop at the Kairanga Service Centre covering legislation around accretion claims and possible solutions with regards to river management. The speakers were invited following an influx of accretion related queries to scheme engineers.

8.13. Scheme staff attended a River Management Forum on 29 and 30 September. This was held by Greater Wellington Regional Council (GWRC) and was facilitated by Manakau- based river engineering consultant Gary Williams. The first day involved a series of short presentations on a variety of river management issues followed by a day in the field visiting a number of GWRC river works sites to discuss the practical aspects of river engineering. River Management staff from a number of regional councils attended enabling discussion and idea sharing between representatives.

8.14. Other training attended by scheme staff included: a Site Safety Supervisor course and Refresher Site Safety Supervisor course; a Chainsaw course; changes to Contract Law course and First Aid courses.

8.15. The third of four Horizons’ Staff Hazard and Risk Management Training workshops took place at service centres during November. These courses have been designed to help staff understand updated regulations and legislation, including ensuring effective management of Health and Safety when engaging with contractors.

8.16. Friday October 21 saw members of the public and the recently elected Councillors attend the Horizons Expo held at Te Manawa. This event is primarily held as new Councillor’s introduction to the organisation, with each Horizons’ team putting together a stand to showcase their business.

8.17. Following the 14 November magnitude 7.8 Kaikoura Earthquake all major structures were inspected for damage, with none being identified. The Moutoa Gates, the Makino diversion structure and the Mangaone spillway gates were all run and checked for serviceability, along with the major floodgates on the scheme. No damage has been reported by landowners regarding other assets, including stopbanks, nor has any damage been found during inspections completed so far. Structures will be re-checked following any significant aftershocks felt in the Region.

LOWER MANAWATU SCHEME

8.18. The LMS Liaison Committee meeting was held at Kairanga on 28 October. Minutes are available on request.

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

MANAWATU RIVER


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8.19. Maintenance work throughout the city reach is continuing and has included weed spraying, graffiti removal, mowing, mulching and layering, planting of native plants and freeing of existing plantings, along with debris removal and disposal. It is often quiet at this time of the year but with improving weather, vegetation growth rates have increased, along with required maintenance works.

8.20. The most significant activity undertaken in the city is the mulching of the willows along the shared pathway. Mulching is typically undertaken when the willows, that provide the majority of our erosion protection, mature. Mature willows are less effective and mulching has been proven to encourage vigorous root growth and therefore improve bank protection. Mulching in the rural areas usually occurs every 5 years while in the city, due to the amenity value of the river, mulching is undertaken every 2-3 years. There have been a number of calls querying this activity from city residents both on site and on social media, and officers have done a great job in explaining what was happening and why, taking this opportunity to educate the public with respect to river management practices (we are not killing the trees) and also listen to how residents use and interact with the river. One such enquiry concerned the spiritual connection some members of the community attach to certain liminal spaces along the river, and how these types of public spaces are utilised by different groups of users. This has led us to incorporate “natural doorways” to the river and “native grottos” in amongst our erosion protection works. While there will always be enquires regarding work in such a public space, a good level of signage will accompany future willow mulching within the city reach.

8.21. Waitoetoe Park has been a topic of discussion and development for several years. Scheme staff are continuing to work with Iwi, PNCC, members of Horizon’ Natural Resources and Partnerships Team and interested local community groups to assist in the development of an overall management plan for the area. Horizons’ River Management staff have an interest in the development of the area due to the importance of managing berm flows to avoid erosion and vegetation potentially adversely impacting on flood carrying capacity. Scheme staff have participated in PNCC’s planning and community development meetings and the Active and Sport and Recreation Focus Group regarding the development.

8.22. As part of the City Reach Project, Horizons are proposing to construct a further recreational access / amenity enhancement element in the form of a river access and launching ramp for Waka and Kayak / Canoe users. The preferred location of the ramp is in Waitoetoe Park at the end of Maxwells Line. Horizons’ engineers have been working with iwi representatives and PNCC officers to ensure that the ramp is optimally configured. Ideally, the ramp will incorporate mooring points and swimming platforms, but this will be subject to budget, practicality and any health and safety considerations (a structured risk assessment).

8.23. Works to enable safe jet boat mooring at the Okatia Steps are almost complete. Staff met with the Vice President of Jet Boating New Zealand to consult on what would be required to make the area safer to use, and become a more useable attraction in the area. Timber has been affixed to the front of the two lowest steps to act as a bumper for vessels. These have been constructed to allow replacement at a future date when required. A taut tethering rope will soon be affixed under the lip of the third step to avoid introducing a non lineal element to the structure.

8.24. A small amount of shaping has been undertaken downstream of the Okatia Steps where a windrow of soil had been left behind the willow bank protection in the area. The windrow had resulted in storm water concentrating at low spots and causing erosion into the berm area, which posed a risk to public users of the area. Plastic drainage pipes have been installed at the lowest points to prevent future scouring. The windrow has been removed to allow storm water to flow over the bank more evenly, while the soil was used to top up nearby low spots that had been prone to ponding. Further work is required along the bank


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above the Esplanade rock lining, which will require greater planning and resources due the confined nature of much of the area by the walkway and nearby underground services.

8.25. Willow mulching was undertaken between Albert Street and Gasworks Drain. A small amount of layering was required at the upstream end of this section where the high bank and large macrocarpa trees hindered access for the long reach excavator being used for these works. During this process, PNCC’s floodgate assets within the area were cleared of any debris which could restrict them from opening, and the culvert outlet near Waterloo Park was cleaned.

8.26. The Fitzroy groynes, near Roxburgh Crescent, have had the build up of driftwood and trees removed. The debris was stacked on the river berm and disposed of by burning. Flood debris that had earlier been deposited on the berm, then stacked into piles during winter, was also burned. Any remaining debris was buried. Palmerston North City Council and the New Zealand Fire Service were notified prior to the fires being lit and no fires were left unattended.

8.27. A new track has been constructed upstream of ANZAC Cliffs to enable vehicular and plant access to the new rock lining for maintenance and repairs. The current ramp down the cliff face is not a permanent feature. Once construction is completed the ramp will be removed and replaced with steps and a narrow walking track, unsuitable for access to the rock for maintenance activities. Spraying of the rock was undertaken soon after completion of the track, along with additional willow pole planting where the gravel cofferdam was located during construction of the rock lining.

8.28. Officers have continued maintenance tasks along the Manawatu River, floodway and around the Moutoa sluice gates and tower. These included inspecting and clearing floodgates and apron area; spraying the lime caps of the gate piers; planting; mowing; new fencing and maintenance; cleaning drains; minor stopbank repairs; rebuilding of a double ramp; and wave lap damage repairs at Foxton Beach.

8.29. The June 2015 event caused significant damage along the banks at Hoults yard in Aokautere, where a slip caused recently constructed bank protection works to be taken out by the flood. The contract for repair works was awarded in the autumn however, due to rock supply issues and weather conditions, work has been delayed and is programmed for this summer. In the interim, all projects undertaken in the LMS have been reviewed to ensure that the works at any given location accurately reflect an appropriate level of service. The proposed bank protection at Hoults yard is, by a large margin, the highest single cost item in the scheme, post the June 2015 flood event. The review concluded that the works proposed substantially overstated what would constitute an adequate level of service at this location and accordingly the design was modified to a form considered more appropriate in this context. Officers recently met with the landowners to explain the revised scope of works and give the landowners the option of contributing to the higher standard design initially proposed.

8.30. The construction of a wake boarding park close to the base of the Foxton Loop stopbanks, at the south end of Foxton Township has triggered an assessment as to whether the excavation has impacted on the integrity of the stopbank at this location.

8.31. Wave lap damage at Foxton Beach has resulted in the stopbank and concrete wall that provides protection against storm surges being compromised. It appears that the mouth of the Foxton estuary may have shifted slightly exposing this area to recent strong westerlies. The concrete riprap that did offer erosion protection has disappeared in places leaving the foundation of the wall and stopbank exposed to continuing wave lap damage. Concrete riprap has been placed to prevent further erosion of the stopbank and a rock lining that will protect the concrete wall will be constructed in the first quarter of next year. It is anticipated that rock will be stockpiled between the Sailing Club and the concrete wall in January. Given the vulnerability of the asset, a contingency plan has been implemented and the area is inspected weekly by officers until the works are complete.


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8.32. A stockpile of rock has been assembled at AgResearch ready for use in the Turitea Stream adjacent to the Kindergarten. Placement is scheduled for January.

8.33. Site investigations and cost estimates have been provided to our Freshwater Team for proposed works to undertake clearance of vegetation on Massey Farms No’s.1 and 4.

8.34. Bank stabilisation works that threatened an Urupa on the Manawatu River has been undertaken after consultation with landowners, local iwi and Tanenuiarangi Manawatu Incorporated (TMI). This involved the re-battering of a cliff followed by planting of willow poles and native species. Officers involved all affected parties in the planning stages and during the works, to ensure that everything was executed as intended.

8.35. A drone flyover was completed above Ashhurst Domain to generate an up-to-date picture of the movement of the river which is occurring in this area. The aerial mosaic was then compared to a series of historical aerial photographs dating back to 1942. Looking back at past river channel locations can assist in planning and design decision making, as it shows how meanders have oscillated in a particular reach. Of particular interest here is that the river has eroded accretion land that has built up over the last 70 years, returning to an alignment last seen in 1942. Officers are awaiting confirmation from PNCC regarding how they wish to proceed.

8.36. Scheme engineers have been assisting PNCC with He Ara Kotahi, the shared path that will run along the Manawatu River, and the Kahuterawa and Turitea Streams. The working party, chaired by PNCC to undertake this project, involves New Zealand Defence Force, Massey Farms, Rangitāne, NZTA, PowerCo and Horizons. Much of the current pathway stage is now complete, with only a few weeks of work remaining for the transition section from Fitzherbert Bridge down to the river side path.

8.37. Officers have also been working with PNCC to design a suitable shared pathway crossing of the Kahuterawa Stream at Bells Road in Linton Army Camp. This is particularly problematic as a cost effective low level bridge has associated risks of use due to the probability of it being submerged during medium freshes.

8.38. On 21 October, tenders closed for the contract to replace the Whirokino Trestle Bridge over the Manawatu River and Moutoa floodway. The contract is managed by the NZTA, and it is anticipated that the contract will be awarded in the first quarter of next year with significant works starting next summer, which will have an effect on river users at this location. The project is expected to require over 200,000 m3 of fill; taking this from river berm sites would clearly constitute a win-win. Staff have continued to make both NZTA staff and their agents aware of this option and the community benefits it would provide.

OROUA RIVER

8.39. Wet ground conditions and high river levels have delayed the start of programmed repair works on the Oroua. These works include programmed maintenance and the completion of all remaining flood damage sites from the June 2015 flood.

8.40. The raising of the stopbank at Saunders property in the Glen Oroua region has re-commenced. Started in the last financial year, the work was suspended over the winter period. Approximately 1,000 m of stopbank has been raised to height, with the remaining 300 m scheduled to be completed by late November.

8.41. Given the higher than expected flood levels in the June 2015 event, willow mulching has been prioritised on the Oroua River, with the programme completed for the 2016-2017 season. This has formed an integral part of vegetation management ensuring that willow vegetation provides adequate bank protection with strong root structure, while ensuring that the willow trees do not form an obstacle for flow paths. Work was first undertaken at Saunders on the right bank of the river to ensure willow restriction did not direct flows onto the newly constructed stopbank. Work was then undertaken from 2 km to 4 km on the right


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bank and 2 km to 7 km on the left bank, which connected to the mulching work done in the 2015-2016 season.

8.42. Following on from repair work done during the June 2015 flood, willow planting was undertaken to reinforce concrete riprap assets which had been placed in the summer of 2015-2016. This work forms a part of the MCDEM insurance claim.

8.43. Staff are continuing to explore a range of options to address the build up of silt on the berms of the Oroua River between Kopane Bridge and Hoihere Road (the reduction in flood flow conveyance and the consequent diminishment of levels of service). One option involves re-battering the stopbank sides from a 1 in 2 batter slope to a 1 in 7 batter slope and the second re-contouring of paddocks adjacent to the river. Initial feedback from landowners has seen two main issues raised; the transportation of the noxious weed field horsetail (Equisetum Arvense) from the river channel to farmland, and the potential decrease in fertility of land as a result of the silt spreading. Silt relocation aims to remove 72,900 m3 of silt from within the channel within four years, with just over 11,000 m3 used as part of Saunders stopbank upgrade. Consultation with landowners is progressing well and it is expected that agreements with landowners will be finalised mid-November with a contract going to tender late November for works to commence early next year.

8.44. Scheme engineers are assisting the Rural Upgrade Project upgrade of the Oroua River stopbanks, including introducing the project delivery team to some of our well known landowners. The involvement of River Management staff is important in ensuring that the works are carried out in a manner that compliments ongoing organisational and management activity.

8.45. In preparation for rural upgrade works, significant work has been undertaken downstream of the Rangiotu Bridge. This has involved the filling of a large erosion hole with concrete and the mulching of willows to alleviate flow pressure. The upgrade work in this area has seen Horizons purchase land from Turks Poultry to enable the demolition of an existing building, and allow a better stopbank alignment. The concrete received from the demolished building has been repurposed directly downstream of the site to ensure that a scour hole parallel to the Rangiotu Marae is rectified.

8.46. Lighting installations at the Hoihere Road barrier are almost completed. Solar powered floodlights will provide lighting to barrier installers if an event occurs during the hours of darkness. The lights are turned on via a switch located inside the storage bunker onsite. During the LMS Liaison Committee meeting, it was suggested that an ‘Open Day’ style event should be held at the Hoihere Road barrier. The purpose of this would be to provide an opportunity to inform members of the surrounding community how the barrier is installed and show how quickly this can be done when required. The meeting date has not yet been finalised, but is planned to take place before March next year.

8.47. Staff have been dealing with accretion claims on the Oroua River, one located downstream of State Highway 3 towards Awahuri, with a second regarding the land parcels of MDC’s water treatment plant, which will tidy up the area significantly. In some areas it would be preferable to retain an esplanade strip or reserve to allow room for future river channel migration to occur. This would reduce the confinement of a river and the potential for significant protection works in the future. Currently there is no general policy for this kind of land reservation to occur.

MANGAONE STREAM

8.48. The Mangaone Stream city reach is frequently inspected by scheme engineers and, overall, is in a good condition with regards to flood protection. Any areas where risk to stopbanks becomes imminent, works are undertaken immediately.

8.49. A drone fly-by to record the channel condition from Flygers Line to the confluence with the Manawatu River has been undertaken. A frequent problem when inspecting assets is that


14 December 2016


defects may be hidden under long grass or by high river levels. Inspection by drone is no different, and although this task has been ready to go for several weeks, it was delayed due to sodden ground conditions which made mowing difficult and water levels remaining relatively high. The drone videography is planned to be completed by the end of November. The advantage of a drone is to be able to spot river alignment problems that are not readily apparent from the ground, and also to have a record of the condition of channel that can be compared to future fly-bys.

8.50. Scheme engineers continue to check the Flygers Line spill gates at least once a week to make sure they will perform as designed in a flood event. This is necessary as the land around the gates is often grazed, occasionally resulting in gates being pushed over unintentionally. Additional inspections are undertaken prior to forecast severe weather events, especially if cattle have been seen in the area. It is likely the CCTV camera will be added at some point in the future as a more robust and cost-effective monitoring solution.

8.51. Investigations into the replacement of the gabion baskets downstream of the Tremaine Avenue Bridge have started. Clearly, PNCC take responsibility for erosion protection of their bridges; the gabion walls that extend downstream of the Tremaine Avenue Bridge are also identified as their assets. The walls are in very poor condition and their failure is likely to result in a stopbank breach. Repeated requests to PNCC staff to urgently replace the structures have so far prompted no action. In any event, the assets more logically lie with Horizons; provision has been made in the draft AP to replace the structures as an addendum to the City Reach Project.

8.52. Mowing of the Mangaone Stream city reaches has been completed twice this reporting period. Due to prolonged wet ground conditions and significant vegetation growth, both mows were very difficult. During the November mow, the right bank downstream of Flygers Line was also mown as the grass in the area had grown so long that the usual grazing efforts would not be effective.

8.53. After the stopbanks and berm areas are mown, manual trimming with a weed-eater is undertaken around structures such as sign posts and areas which are too wet for the tractor. Officers monitor and undertake when possible, additional vegetation maintenance behind fence lines where fly tipping or hidden hazards are not an issue. This work includes weed spraying, grass trimming and removing saplings before they grow to become an issue. A total of four medium to large trees have been removed by arborists from within the stream reserve this reporting period.

8.54. The recently cleared old dog pound site on Botanical Road will likely be used as a stock pile area for works to be undertaken by PNCC in the coming months. PNCC have resource consent to construct walkway / cycleway underpasses at bridges throughout the city, and have recently put out to tender the projects located at Botanical Road and Highbury Avenue. It is understood that works will not commence until early next year. Scheme officers have been working with PNCC and have been fully involved in the process.

8.55. Scheme officers also assisted PNCC in undertaking mulching and spraying of considerable areas of blackberry and vegetation on the left bank below Pioneer Highway. The Mangaone Stream at this location has been inaccessible, and this clearance work will open up the stream for recreational use and the construction of a lime pathway, which will extend behind the Awapuni Race Course to Totara Road. The work was undertaken by an approved Horizons’ contractor and supervised by Horizons on behalf of PNCC, who funded the work. While on site, several log jams were removed from within the channel which had previously been very difficult to access.

8.56. Our staff continue to manage enquiries and requests from the public and neighbouring residents regarding the Mangaone Reserve, and work hard to respond to any concerns in a timely manner. It is also appreciated when members of the public alert staff when they see something new suddenly appear. One such alert was received the morning after a


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large fresh had deposited a very bulky tree stump on the Railway Bridge. Because of this early warning, staff were able to mobilise an excavator the same day to remove the trunk before the water levels rose again the following evening.

8.57. The stopbanks are continuing to be monitored for excessive vehicular movements and any damage repaired as necessary. New access gates and fencing are in the process of being installed across several points within the city where vehicular access is easy. Underground services have been marked by the associated utility companies, and any new fence lines will be constructed outside these areas to avoid possible damage. A recent example highlighting the need for these barriers occurred in November when a stolen van was driven along a stopbank and was abandoned.

8.58. Vegetation was removed from the Mangaone West Stream, immediately upstream and downstream of the Feilding–Awahuri Road, on behalf of the MDC.

MAKINO STREAM

8.59. Investigations were undertaken on the Makino Stream upstream of the diversion structure to assess the condition of the channel in light of the debris that collects on the diversion structure in a flood, and the effect that the urbanisation of the surrounding countryside may have on the flood carrying capacity of the stream. The scheme ends just upstream of the structure, and therefore the only works that have been undertaken on this reach of the Makino is by way of environmental grants.

8.60. Flood damage repairs were completed on the stream edge timber wall in the Palmer Reserve, Feilding Township.

8.61. A stockpile of 200 kg grade rock, plus another of concrete interlocking blocks, was assembled ready for use in the summer construction period.

8.62. Two webcams have now been successfully installed on the Makino Stream. The two cameras live stream images of the Makino diversion structure and the stream at the Duke Street Bridge breakout point. These cameras have been installed as part of the Makino diversion structure upgrade works which are intended to decrease the response time required to lower the Makino diversion gates and operate the spillway.

8.63. On 7 October, the Makino Stream experienced a flood of 33 cumecs. Staff were on standby to operate the diversion gates. Fortunately, it was not required.

8.64. This flood created two erosion problems which required urgent repairs. Both sites were below Feilding Township and rock was used to secure both sites.

8.65. A local contractor has been engaged as a ‘backup’ for operating the Makino diversion gates in future.

8.66. At the Pharazyn Road floodgates, a lockable storage box has been permanently set up on site in which to store sand bags.

8.67. Windblown trees blocking the stream were removed from two separate sites.

KIWITEA STREAM

8.68. A programme of machine planting of willow poles has been completed in the lower reach of the Kiwitea Stream as part of the LMS i.e. Kimbolton Road Bridge downstream to the confluence with the Oroua River.

DERBY CREEK

8.69. No works have been undertaken on Derby Creek this reporting period.

STONEY CREEK


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8.70. No works have been undertaken in this reporting period.

MANGAORE STREAM

8.71. All floodgates have been inspected, with no other works undertaken in this reporting period.

MOUTOA FLOODWAY

8.72. Inspection of all floodways, stopbanks and floodgates has been completed. Maintenance tasks have included spraying of lime on the tops of the piers, spraying on pier concrete, minor removal of silt and debris from the apron, general maintenance around the control tower, stopbank mowing and floodgate inspections.

8.73. The sluice gates are run every six weeks and the six monthly electrical testing of the gates was completed in November.

8.74. A culvert pipe was also replaced over the gas line in Whirikino in conjunction with FirstGas.

TOKOMARU RIVER

8.75. General inspections of all assets, including floodgates, have been undertaken. The winch was repaired on the floodgate located on Woods’ property.

LOWER KIWITEA STREAM SCHEME

8.76. The Lower Kiwitea Scheme Liaison Committee meeting was held at Mr Wilkins (Chair) property on 10 November.

8.77. A programme of willow planting has been completed on the Lower Kiwitea Stream. Approximately 5000 poles have been machine planted to date.

8.78. Channel clearing of flood debris and the relocating of gravel point-bars which were causing erosion problems, were completed as the machinery moved up the stream.

8.79. Several existing erosion repair sites have had extra work completed on them as a result of the smaller flood events over the winter period.

8.80. Gravel extraction was completed on several sites.

8.81. A gravel study has been completed on the Kiwitea Stream by Investigations and Design staff and was presented at the Lower Kiwitea Scheme Liaison Committee meeting. The study was completed to identify if the stream bed is aggrading or degrading and to check if the annual consented gravel extraction volume matches the available gravel resources.

8.82. At present there is no gravel extraction allowed in the lower reach of the stream i.e. 0 km to 1.0 km, and extraction allowable on the balance i.e. 1.0 km to 14 km (5000 m3 annually). Recommendation from the study is that the gravel extraction volume remains at 5000 m3 annually, and that the location is reversed i.e. extraction allowable in the lower half of the scheme and not in the upper reaches.

8.83. A new run of aerial photographs covering the scheme area was flown on 23 October 2016.

KAHUTERAWA STREAM SCHEME

8.84. A large Macrocarpa tree fell across the stream in the upper reach of the scheme. Under the current resource consent, this time of year is within the exclusion period for work in the stream. Therefore, permission / notification was applied for and the works to remove the tree was completed. The tree was used to finish a permeable rope and rail deflector groyne at the same site.


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8.85. A landowner required urgent assistance after a recent fresh, when his bridge was washed out and he was stranded at home. Officers arranged for a contractor to undertake emergency repairs to assist the landowner.

ASHHURST STREAM SCHEME

8.86. A full inspection of the stream channel was completed. Maintenance work was completed at the flood wall immediately upstream of North Street i.e. cut and spray of rank grass.

LOWER MANAWATU SCHEME RURAL FLOOD PROTECTION UPGRADE PROJECT

8.87. The following table schedules all current Rural Upgrade Project works and provides commentary on 2016-17 project status.

Project Title Description Status

Manawatu River Right Bank Stopbank Upgrade, Te Matai Rd

Upgrade 4,700 m of stopbank on the right bank of the Manawatu River adjoining Te Matai Rd, Whakarongo.

Due to landowner concerns, a section of the proposed stopbank upgrade and alignment through a farm in this location has been postponed until 2017-18. A tender for the remaining section through Higgins Aggregates has been awarded to M&M Earthmovers Ltd and works are currently in progress.

Manawatu River Right Bank Stopbank Upgrade, Longburn Railway

Upgrade 1,600 m of stopbank on the right bank of the Manawatu River along the railway line and adjoining farmland east of Longburn.

This project is currently out to tender with a closing date of 12 Dec 2016. Land entry negotiations with KiwiRail cannot be finalized until the preferred tenderer has been appointed and trained.

Manawatu River Right Bank Stopbank Upgrade, DOC Reserve, Springs Rd, Whirokino

Upgrade 930 m of the Manawatu River right bank stopbank on Department of Conservation reserve land at two locations in the vicinity of Whirokino Rd and Springs Rd, Whirokino.

This contract was awarded to Paranui Contractors Ltd during the 2015-16 financial year and was suspended in May 2016 due to the onset of wet weather. The contractor has since re-established on site and works are continuing as weather and ground conditions permit.

Manawatu River Left Bank Stopbank Upgrade, Koputaroa

Upgrade 200 m of the Manawatu River left bank stopbank at Koputaroa.

Survey and design work will be undertaken for this work along with land entry negotiations in January 2017.

Manawatu River Right Bank Concrete Floodwall, Ervine Property, Rangiotu

Construct 35 m of concrete floodwall on the Manawatu River right bank at the Ervine property, Rangiotu.

Survey and design work is complete. A contract has been awarded to ABC Contractors Ltd. Work will commence on site when weather and ground conditions permit.

Oroua River Left & Right Bank Stopbank Upgrade, Downstream of Awahuri Bridge

Upgrade 3,300 m of existing stopbank and construct 1,300 m of new stopbank on the left and right banks of the Oroua River immediately downstream of the SH3 Bridge at Awahuri.

This project is currently out to tender with a closing date of 12 Dec 2016. The land entry agreement with Livestock Improvement Corporation (LIC) is currently being finalised.

Oroua River Left & Right Bank Stopbank Upgrade, Upstream of Awahuri Bridge to Feilding.

Construct new stopbanks on the left & right banks of the Oroua River from the Makino Stream confluence upstream of the SH3 Bridge at Awahuri. This project will extend over a

Survey and design work will continue through into January. This project involves a number of difficult design issues due to the complex river terrace alignment as well as there being no pre-existing stopbanks in this area.


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river distance of approximately 6,000m to Feilding.

Oroua River Left and Right Bank Stopbank Upgrade, Rangiotu

Upgrade existing stopbanks on the left and right banks of the Oroua River from the Rangiotu Rd bridge to the Manawatu River confluence. Works will extend over a river distance of 3,000 m.

A tender for this work has been awarded to M&M Earthmovers Ltd and works are currently in progress at this site. Demolition works and site clearance of the pre-existing Turks Poultry building have been completed.

Oroua River Right Bank, Te Rangimarae Marae Concrete Floodwall, Rangiotu

Construction of a 45 m long by 2.6 m high concrete floodwall on the Oroua River right bank adjoining the Te Rangimarae Marae.

An engineer has completed design work for this concrete wall. The marae building and narrow berm width at this location prevent the continuation of the upgraded stopbank past this point. Drawings will be completed and works commence upon completion of the adjoining stopbank upgrade project.

Linton Main Drain Left and Right Bank Stopbank Upgrade, Tane Rd

Upgrade existing stopbanks on the left and right banks of the Linton Main Drain downstream of Tane Road. Works will extend over a river distance of 1,000 m. The right bank involves undertaking road re-construction along the crest of the upgraded stopbank.

This project will be released for tender by 1 Dec with a closing date of 9 Jan 2016. Agreement has been reached with right bank landowners and Horowhenua District Council to permit Linton Drain Rd to be raised.

Tokomaru River Left and Right Bank Stopbank Upgrade, Okuku Rd

Upgrade existing stopbanks on the left and right banks of the Tokomaru River from Okuku Pumpstation upstream to Opiki Road. Works will extend over a river distance of 4,300 m.

Investigations into existing stopbank and foundation material integrity have been completed. Design work is expected to be completed by 5 Dec 2016. The contract tender is expected to have a closing date of 9 Jan 2017. LEA negotiations will be finalised during December.

Mangaore Stream Left and Right Bank Stopbank Upgrade, Shannon

Upgrade existing stopbanks on the left and right banks of the Mangaore Stream downstream of Otauru Road, Shannon. Works will extend over a river distance of 2,700 m.

Tenders for this project have closed and a contract has been awarded to Graeme Bagrie Contracts Ltd. A contract start date of 1 February has been agreed to.

Protect Individual Property, J.Mason, Lockwood Rd

Lift the Mason house at 943 Lockwood Rd by 300 mm to a height of RL 10.19 m

This landowner has confirmed they want the house to be raised. Alpha Group Ltd have been engaged to complete drawings and resolve a number of structural complications around raising this house as well as obtaining Building Code ‘Section 112’ approval from Manawatu District Council.

Protect Individual Property, Taonui Farms, Main Drain Rd

Provide flood protection to the Taonui Farms dairy shed to a height of RL 10.19 m.

An agreement has been reached with the landowner and design work is expected to be completed by late-December.

Protect Individual Property, Rangiotu Estates, Highway 56

Provide flood protection to the Rangiotu Estates dairy shed to a height of RL 10.19 m.

An agreement has been reached with the landowner and design work is expected to be completed by late January.

Protect Individual Property, P. Sales, Rangiotu Rd.

Construct a flood protection bund around the motorcycle workshop on this property

Although this property protection work is programmed for 2017-18, it is more cost-effective to complete the works


14 December 2016


where it adjoins the Oroua River left bank stopbank, Rangiotu.

during the current construction season and forming part of the adjoining Oroua River left bank stopbank upgrade.

Foxton Storm Surge Repair Stabilise erosion areas of the concrete floodwall where coastal erosion has been undermining the wall.

A rock supply contract is currently out to tender with a closing date of 9 Dec 2016. The subsequent rock placement contract will be put out to tender by 5 Dec 2016 with a closing date of 9 Jan 2017.

Oroua River Right Bank Stopbank Upgrade, Saunders Property, Kopane.

Raise a section of right bank stopbank and widen a localized area of river channel.

A contract was awarded to John Ray Ltd in 2016-17 which was suspended in May due to the onset of wet weather. The contractor has since re-established on site and works are continuing as weather and ground conditions permit. Works are expected to be complete by 5 Dec 2016.

Feilding Golf Club Repay Feilding Golf Course $75,000 for work advanced ahead of programme and paid for by them in 2013-14.

Repayment was made on 18 Oct 2016.

City Reach Project: Benmore Ave Stopbank Upgrade

Upgrade a section of the Flygers Line Spillway stopbank adjoining Benmore Ave, Palmerston North.

The design work for this project has been outsourced. Land entry negotiations will be undertaken during December and a tender is expected to be advertised by mid-January 2017.

9. NORTHERN AREA

GENERAL

9.1. The reporting period has seen the weather conditions move from the cold, wet environment of winter to the rapid plant growing warmer spring period. In general terms, the work programme has followed the seasons where asset data processing and work programming occurs during the cold months, willow and native vegetation planting takes place in the autumn before conditions warm, through to the commencement of our construction season in late spring. We now have a wide range of work activities underway and look forward to a productive summer.

TRAINING AND FORUMS

9.2. Staff have been involved in several training opportunities this period including:

The Area Engineer Northern attended a two day tour of Environment Canterbury river schemes on 4 and 5 August looking at a variety of river management techniques.

Three staff attended the IPENZ Rivers Group workshop in Wellington on 29 and 30 September.

A number of staff have attended a range of Chainsaw courses. The need for good proficient training in this field is emphasised by the number of injuries and deaths that occur annually in the forestry sector.

COMMUNITY INVOLVEMENT

9.3. This period a northern staff member has attended two Bulls Community River Group meetings where discussions focused around future planting following the completion of


14 December 2016


370 m of rock lining upgrade on the right bank of the Rangitikei River at Bulls Bridge. Along with clearing and contouring the adjacent river berm, the contractor’s completed rock lining is of a very high standard.

9.4. Northern area staff are actively involved in the Ruapehu District Council (RUDC) Wai Group that meets regularly in Ohakune which has the aim to better holistically manage the waterways in the district. Recent meetings were held on 10 October and 17 November.

9.5. Staff attended the Rangitikei Environment Group Meeting hosted by the RDC on 19 October.

9.6. Scheme Liaison meetings have been held for all the larger schemes in the northern area. These are also noted in the individual scheme reports.

RANGITIKEI RIVER CONTROL SCHEME

RANGITIKEI MAINTENANCE WORKS

9.7. Now that winter is behind us there is a challenging work programme ahead of us to not only achieve the scheme’s regular maintenance works, but to also complete nearly $600,000 of June 2015 flood damage.

9.8. One area of particular interest is the repairs to the Wilson Rock riprap toe lining. This asset has received repetitive damage in large floods and a more integrated approach is to be followed in this repair process. In addition to the rock lining repair identified and supported by MCDEM there will be incorporated extensive beach clearing, willow planting, and river realignment works to help lessen the impact of future flood flows on the site. Close consultation has been maintained with adjacent landowners who now fully support this initiative.

9.9. The Opus project for Transit New Zealand upgrading the rock lining on the right bank upstream of the Bulls Bridge is now complete. This work was completed in a very professional and efficient programme that was able to continue construction through a range of winter water levels. Site re-instatement was completed to a high standard that now gives community groups a selection of options available to them to further enhance the site for public enjoyment.

9.10. Currently staff have commenced investigations for preparing an application for a global resource gravel extraction consent for the Rangitikei River Scheme. The approval of this consent will greatly assist scheme engineers manage the build up of gravel in the system to the betterment of river management. Staff are getting quotes from an engineering consultant for the preparation of these consent applications.

RANGITIKEI CAPEX WORKS

PAREWANUI STOP BANK UPGRADE FOR 2016-17

9.11. Tenders for this work closed on 6 October with four tenders received. The tender documents called for contractors to submit two tenders as MCDEM funding for the project was still to be confirmed. Option A tender, was for 750 m of stopbank upgrade and Option B tender was for 1300 m of stopbank upgrade. The Parewanui stopbank upgrade work is located on the Walmac Farm near Scotts Ferry from river distance 5 km to 6 km. Each tenderer submitted two tenders each, but during the tender assessment process Option A was confirmed as the preferred option. The successful tenderer was Graeme Bagrie Contracts Ltd of Waitarere with a tender price of $168,001.25. An acceptance letter was issued on 21 October 2016 with possession of site being given on Monday 7 November 2016. Unfortunately, due to very wet weather patterns work was not able to commence until 21 November.


14 December 2016


WILSON ROCK RIPRAP TOE LINING

9.12. Last financial year the rock lining flood damage at the Wilson Rock site at river distance 27.4 km (right bank) of the Rangitikei River was postponed due to poor weather conditions, high river flows and awaiting MCDEM funding approval. Eight shortened rope and rail groynes were installed along with placement of 300 tonnes of rock at the head of the groynes to protect against further bank erosion. This period tender documents were prepared to complete these rope and rail groynes along with the rock riprap toe lining to be constructed this coming summer.

9.13. The contract was advertised via TenderLink; a pre-tender meeting was held on 27 October 2016 with two contractors attending. Two tenders were received at the contract closing date on 10 November with the successful tenderer being John Ray Ltd with a tender price of $399,167.50. The acceptance letter was issued on 18 November 2016. The inaugural site meeting is planned for Monday 28 November 2016. An Entry Agreement was signed up with the property owner in late October.

RANGITIKEI RIVER ENHANCEMENT

9.14. No enhancement work undertaken this period.

GRAVEL EXTRACTION

9.15. No gravel extraction has taken place from Council’s consents in the reporting period.

POHANGINA-OROUA RIVER CONTROL SCHEME

9.16. A Scheme Liaison Committee meeting was held on 18 November at Country Fayre in Pohangina. Following the meeting a field trip was organised to give the committee an opportunity to inspect river works completed on the Andrew MacDonald and Ian Passey properties. This was greatly appreciated by those attending and stimulated some lively discussion between members.

POHANGINA RIVER

9.17. Pole planting is now complete for the season with some 5,400 poles installed. It is pleasing to see this trend in increased planting as Horizons has been looking to the farmers on this river to support a greater rate of willow installation to provide future stock for river protection work.

9.18. On the negative side however, the plan to establish a field nursery on the Bolton property downstream of the Saddle Road Bridge has been cancelled. Following a feasibility investigation by an experienced willow nurseryman the site has been deemed too dark with insufficient drainage and limited security to exclude four wheel drive vehicles to guarantee good willow growth. While this is regrettable, there are better options for willow plantings in the catchment and staff continue to explore other sites.

9.19. Other work on the Pohangina has included a short section of channel maintenance along the right bank below the Edwards property where the river was starting to undermine protection works already in place. At this location we have cleared the site of blackberry and unwanted trees then followed through with the planting of approximately 200 new willow poles. We are also in discussions with a gravel merchant about removing the local built up beach that is narrowing the channel and forcing water towards the river bank.

GRAVEL EXTRACTION

9.20. A total of 510 m3 of gravel was extracted in the August to November period.


14 December 2016


OROUA RIVER

9.21. Pole planting is now complete for the season with some 4,235 poles installed. The largest single planting of 1,500 poles was on the McDougal property at the top end of the scheme. This area had a large number of mature pine trees that have been a nuisance to the scheme when they frequently fell into the river and required removal. The owner has recently decided to harvest them and this left the river bank area vulnerable to erosion. Several holes had been steadily developing along the reach and a repair using rope and rail groyne structures is soon to commence. In addition, minor channel maintenance is also planned. These willows were planted in late October and the warmish, wet conditions experienced since then have allowed the area to rejuvenate quite well.

9.22. Other work is planned at the Pettigrew property on Londons Ford Road and involves a short length of tree bank protection work, starting late November.

GRAVEL EXTRACTION

9.23. A total of 10,932 m3 of gravel was extracted in the August to November period.

TOTARA RESERVE

9.24. As soon as the spring weather stabilises and the river levels drop work is planned to start on the rope and rail groyne at Totara Reserve on the left bank north of the Old Coach Road. There are several erosion spots along this section of the Pohangina and contractors are currently pricing up this work to start late November to early December. An additional 280 willow poles were planted in the reserve at the two repair sites recently completed in August and September. This brings the total willow poles planted in the reserve to 1280.

RAUMAI BRIDGE EROSION PROTECTION

9.25. For several years now concern has been expressed about the deterioration of the channel alignment in the Pohangina River immediately upstream of the Raumai Bridge. Following the June 2015 flood event, serious bank erosion on the right bank of the Pohangina River had encroached and was threatening to potentially sever the road access to the Raumai Bridge.

9.26. Designs were prepared and discussions were held with MDC as to the impact of a flood event that could detrimentally affect their assets. Consequently financial approval was given by MDC for Horizons’ staff to manage the proposed contract. Contract documentation was completed, tenders were called and the successful tenderer, John Ray Ltd, was awarded the contract for a sum of $179,150. Work on the 12 week contract commenced on the 15 August 2016 to construct a major rock groyne and associated rope and rail groynes to mitigate future flood erosion to the right bank of the Pohangina River. This lengthy contract period was allowed for to mitigate the expected difficulties expected in the supply of rock.

9.27. As it was, the supply of rock was excellent and the placement of 1840 tonnes of rock was completed on the 27 September. On the 19 October work commenced on installing four rope and rail tree groynes and these were completed on 11 November 2016.

UPPER WHANGANUI RIVER MANAGEMENT SCHEME

9.28. The Scheme Liaison meeting was held on 10 November in Taumarunui.

9.29. There were no issues with the proposed works programme for this current year, although there was some discussion on whether it was necessary to continue with the current level of funding for next years’ works programme. When the Ongarue River was bought into the Upper Whanganui Scheme it was envisaged that it would take six years to complete the


14 December 2016


removal of the old crop poplars through the urban township. Due to operational efficiencies this is now likely to be completed in five years.

9.30. Staff will look at the schemes’ long-term objectives to assess the feasibility of reducing the operational budget one year early from $99,000 to $60,000 in next years’ AP.

TARINGAMOTU RIVER MANAGEMENT SCHEME

9.31. The Scheme Liaison Committee meeting was held on 10 November in Taumarunui.

9.32. There were no issues with the proposed works programme for this current year that would see the completion of stage one, debris blockage clearance work, and the commencement of stage two works that focused more on riparian vegetation management.

9.33. A proposed format to accelerate and complete stage two works over a two year programme funded by a loan drawdown would be put to the Liaison Committee for them to approve before it was presented at the 2017 Catchment Community meeting.

9.34. No work undertaken this period.

MATARAWA FLOOD CONTROL SCHEME

9.35. The Scheme Liaison Committee meeting was held on 19 October in Whanganui.

9.36. Work on this scheme has been limited to dam inspection and minor maintenance as wet ground conditions have limited access to many sites.

9.37. Some negotiations with Mateongaonga Stream landowners is currently underway to gain waterway access to machinery for much needed vegetation maintenance. Flood waters are diverted to the Mateongaonga Stream via a diversion channel from the Matarawa Stream during high flows to help protect the Whanganui East area from flooding. To date these landowner negotiations have been unsuccessful which may then result in higher scheme costs as work will need to be undertaken manually.

9.38. A proposal to extend the Matarawa Scheme to include the urban reaches through Whanganui East is being prepared by staff. Over many years this section of the waterway has been ignored and unmaintained by property owners. The channel is congested with overgrown weeds, unwanted trees, and debris blockages. The magnitude of the work is now greater than what most landowners can handle and a managed approach by Horizons is required to return flow capacity to the system. Consultation with the community on this proposal is planned for early 2017 and if supported a recommendation to Council will follow for inclusion in next years’ AP.

TUTAENUI FLOOD CONTROL SCHEME

9.39. The Scheme Liaison Committee meeting was held on 17 October in Marton.

9.40. Only minor maintenance has been undertaken to date this year. This scheme operates on a very small operational budget and it has been found more efficient to delay non urgent work until mid summer when the stream dries up and access conditions improve.

9.41. Progress on the two significant studies currently underway for the Tutaenui Scheme are near completion and will be presented to Committee in December. The first being a scheme audit that will review performance objectives against those delivered and also investigate the potential to increase the flood protection standard to the community. The second is an exercise looking at flood plain modelling, with a particular interest in flood mitigation options for Marton and Bulls.

9.42. Work has begun on obtaining a global gravel extraction consent for the scheme. Several property owners in the lower reaches of the river below Curls Bridge have conveyed their concerns about gravel build up since the June 2015 flood. In some areas this build up has


14 December 2016


had a detrimental effect on channel shape and flow carrying capacities resulting in more frequent flow over the berms. By obtaining this consent staff will be better able to manage this problem and meet the expectation of the landowners.

MAKIRIKIRI FLOOD CONTROL SCHEME

9.43. No scheme work undertaken in this period.

9.44. An upgrade of culverts to 750 mm diameter through the stopbank on either side of the Makirikiri Stream road bridge was completed by RDC in November. The increased culvert size will greatly improve the drainage of water back to the stream following floods reducing the time that productive land is submerged.

MAKIRIKIRI EGRESS GATE

9.45. Resulting from significant flood events in the Turakina River in October 2013 and again in June 2015, the need to construct a flood egress gate through the Makirikiri Scheme stopbank become a high priority. The flooding on these occasions closed the Turakina Beach Road for several days isolating the Koitiata community. Floodwater from the Turakina River overflowed the surrounding farmland, causing extensive ponding against the outside of the Makirikiri Stream stopbanks. With no natural drainage options the rising flood level closed Turakina Beach Road. To mitigate extended road closures the Makirikiri Stream stopbank was mechanically breached to quickly lower the flood levels to ensure the Koitiata community was not isolated and subjected to an unacceptable risk to their wellbeing.

9.46. The installation of the flood egress structure was seen as a good solution to mitigate these risks by allowing drainage to occur immediately if there is a water level difference between the Makirikiri Stream and the ponded floodwater. This will reduce road closure times to hours rather than days. At the same time the scheme’s flood protection capability is not compromised.

9.47. The funding for this project is estimated at $125k with the largest share of nearly 60% being funded by the NZTA through RDC. Horizons Regional Council will then fund a further 30% of the cost by way of environmental grant with the remaining balance being met by the landowner. The high level of financial support from NZTA reflects the importance of providing a largely retired and aged community with access to community services outside of their township.

9.48. Tenders were called in March 2016 and the contract was let to ABC Contractors Ltd for a sum of $124,550 with an agreed start date for construction of 9 January 2017. The contract documents have now been signed by both Horizons and the contractor. By providing a lead in time and constructing the egress structure during the summer months considerable savings have been made. The contract period is six weeks. When finished the flood egress gate will become a depreciable Makirikiri Scheme asset, inspected and maintained by Horizons staff.

9.49. It must be noted that a high level of collaboration was achieved between both councils and the property owner throughout initial project discussions. The outcome being a design that will greatly benefit the local community.

POREWA FLOOD CONTROL SCHEME

9.50. A Scheme Liaison Committee meeting was held on 26 October at the Hunterville Town Hall. No issues were raised and the few attending enjoyed a general discussion on the scheme’s operation.

9.51. An accumulation of flood debris around the Hunterville sewer pipe stream crossing is being investigated by staff. Local landowners are being asked to remove flood gates from


14 December 2016


around the road bridge and sewer pipe that collect debris putting the security of the sewer pipe at risk.

9.52. Work replacing the temporary Bailey Bridge at Te Hou Hou Road by RDC is now complete. Some site reinstatement work still remains to be done before Christmas including the removal of a large pine tree and smaller Macrocarpa tree that are threatening to fall into the waterway.

WHANGAEHU MANGAWHERO RIVER MANAGEMENT SCHEME

9.53. The Scheme Liaison Committee meeting was held on 19 October in Whanganui and endorsed the proposed works programme which will be centred around maintenance aerial spraying operation.

TURAKINA RIVER MANAGEMENT SCHEME

9.54. The Scheme Liaison Committee meeting was held in Marton on 28 October.

9.55. The committee endorsed the aerial spraying programme proposed by the scheme engineer and further approved the use of funds held in reserve if deemed necessary to extend this work for efficiency reasons.

LOWER WHANGANUI VEGETATION MANAGEMENT AND FLOOD PROTECTION PROGRAMME

9.56. The Scheme Liaison Committee meeting was held in Whanganui on 27 October.

9.57. After the 2015 stopbank upgrade in Kowhai Park it has been difficult to keep vehicles off the Shellrock walking track. In the last month staff have focused on eliminating the numerous access points by installing kneebreaker fencing, bollards and ditching. Repair work has been carried out to fill in wheel ruts both up the batter slope and across the crest.

9.58. During the winter there was an almost complete breakdown of the riprap walls downstream of the Q West shipbuilders. 70 m has been replaced together with a 30 m extension funded by the District Council.

9.59. There will be a focus in December on removing large areas of bamboo from both banks of the Matarawa as it flows through Kowhai Park. Bamboo increases the likelihood of ‘piping’ within a stopbank but it is a dreadful plant to eradicate and takes many years of persistent effort to get any measure of control. It is made more difficult in this type of riparian / park environment where the efficiency of some chemicals is questionable.

9.60. On 15 September staff were advised that an investigational borehole being drilled in Karoro Road had passed through a Whanganui District Council (WDC) 1600 mm diameter gravity sewer line close to the main WDC pumping station. Karoro Road is located beside Horizons’ Balgownie stopbank; the depth of the sewer line (located in the order of 7 to 8 m below ground level) and the sandy nature of the soils led to the rapid formation of a sinkhole in Karoro Road. As per a previous report to Council repairs will begin in the New Year when the sewer has been repaired.

9.61. Work has begun on preparations for the round of community consultation that is programmed for early next year where Horizons will talk to Whanganui residents on the level of flood protection they desire. Cost estimating associated with some of the more challenging / complex components of the earlier technical work are currently being revisited.

9.62. Staff have attended two meetings of the Whanganui Navigation and River Safety Group meetings held on 13 September and 15 November.


14 December 2016


9.63. Early in the New Year the NZ Secondary School Triathlon Series is being held in Whanganui. Sports Whanganui have experienced some challenges in obtaining river access for the swim leg starts and staff have been providing advice in this respect.

PAKIHI SCHEME

9.64. The scheme will now have a biennial works programme commencing 2017-18.

FOREST ROAD DRAINAGE SCHEME

9.65. The Scheme Liaison Committee meeting was held at Forest Road on 11 October.

9.66. The fencing of drains throughout this scheme has increased the need for two weed sprays a year as the waterway banks are no longer being grazed. This unfortunately comes at a higher cost leaving less funding for other maintenance work. A re-adjustment of budget is required in the next LTP round.

HAUNUI DRAINAGE SCHEME

9.67. A Scheme Liaison Committee meeting was held on 11 October. No issues were raised at the meeting and a general discussion took place on scheme management. Staff are to look at getting a light mechanical clean of the open drain between the Bebarfald and Sainsbury’s properties before Christmas along with some drain spraying.

OTHER WORKS

NORTHERN ANNUAL SCHEME REPORT

9.68. Each year an Annual Report is prepared outlining the activities, and financial standing of the 14 schemes in the northern area for the previous financial year. Work has now commenced on the 2015-2016 report.

THE BIG FIVE

9.69. Currently one staff member is representing the Marton Service Centre on the Big 5 Strategy Group. Following a recent meeting all staff have been updated on some of those initiatives. They include the Creativity Group, who have been blown away by the number of ideas to create efficiencies for staff to help deliver the business needs of our customers, Service Centre Open Days, the ‘Good Sorts’ award which is to encourage staff to recognise those staff who embody the Big 5 in their work or who have gone the extra mile for someone in need.

PROPOSED OHAKUNE SCHEME

9.70. The Ohakune Township is seriously affected by flooding as waterways through the community are congested with vegetation, blocked by urban development, and in many locations under sized for the flow required of them.

9.71. Horizons has completed a flood modelling exercise for the town and prepared an upgrade proposal that will be taken to the community for feedback next year. The concept and feedback received will be brought to Council ahead of the process of beginning the update of the LTP.

ENGINEERING ADVICE

9.72. During the last four months there have been continued requests for advice on a variety of issues including rural flooding in non scheme areas, involving clearing blocked culverts,


14 December 2016


clearing stream channels of vegetation and fallen trees, drainage issues and flood damage work.

9.73. Another request involved a joint consultation by River Management and Natural Resources and Partnership staff working with a local iwi group from the Kai Iwi Marae regarding stream channel clearing work. In addition, requests have been made for checking rating areas on a farm and some survey assistance regarding an irrigation system.

9.74. Staff met with Transpower staff at Rangitatou East Road in Kai Iwi and provided advice on river management options to protect a power pylon at risk of being undermined by river erosion.

OTHER PROJECTS

MOAWHANGO RIVER

9.75. The works programme is most likely to be centred around the control of regrowth willow between Maunganui Station and the confluence with the Aorangi Stream, but this is subject to a ground inspection to determine the extent of the problem.

MISCELLANEOUS

9.76. During August staff completed inputting all the scheme asset inspection data into the AMS.

9.77. A further Health and Safety meeting was held at the Marton Service Centre for staff from Whanganui, Taihape and Marton.

9.78. Over the past 18 months the Horizons Rural Advice Team have requested assistance from the River Management Team to assess the actual catchment boundaries pertaining to specific farms as it affects the resource consent conditions applicable to a particular farming operation. During the last four months northern staff have assessed seven separate farm properties located mainly in the coastal corridor from Wylie Road, Himitangi through to Parewanui Road, Bulls.

9.79. In early August 2016 letters were sent out to all properties with detention dams requesting invoices to pay property owners the annual licence agreement fee. To date 80% of property owners have responded and annual fees have been paid out. The licence agreement fee paid by Horizons acknowledges that the Council has rights under statute to enter the owner’s land at reasonable times with vehicles and other machinery or equipment in order to examine, clean, repair or otherwise maintain the existing dam and if necessary to reconstruct the dam and the works on the owner’s land. A recent change in land ownership for Porewa Scheme detention dam 75 has required the completing of a new Licence Agreement with the new landowners.

10. EASTERN AREA

GENERAL

10.1. The weather over the last four months has been fairly unsettled. As so often happens, spring tends to deliver more rain with greater intensities than we receive during winter. Fortunately, while this weather has caused the bigger rivers to fluctuate, they have not risen to the point of causing severe flooding.

10.2. The highest total rainfall recorded in the eastern catchment during the last four months was close to 1,400 mm and this was recorded at the Upper Mangahao hydro recording site in the Tararua Ranges, and while this was much the same as what fell during the same period last year, November has been particularly wet with over 500 mm falling this month alone.


14 December 2016


10.3. Work efforts this period have seen the planting programmes for all schemes completed and the start of river maintenance works are well underway for most. The schemes that are a little behind are the Mangatainoka and Manawatu, and this is largely because these rivers have been too high and the paddocks have been too wet for machinery.

10.4. This period staff have also been busy introducing our new staff member (Matt Kilsby-Halliday) to the ratepayers, inspecting the rivers - post freshes, whilst also preparing for and undertaking Scheme Liaison Committee meetings. The Mangatainoka and South Eastern Ruahine Scheme meetings were held on 26 October, and the Upper Manawatu-Lower Mangahao and Eastern Manawatu meetings were held on 27 October. These meetings were well attended and there was good discussion, generally in regard to the seasons programmed works.

10.5. With the summer roading season for the District Council (Tararua) and NZTA starting to kick off, contractors have been busy sourcing gravel for this work. So far 10,000 m³ has been allocated from each of the Manawatu reaches as well as the full 14,000 m³ from the Mangatainoka.

10.6. A recent inspection of the eastern areas willow plantings have shown that the Giant Willow Aphid has, as it usually does, disappeared over winter. However, our expectation is that while the pest will return it is unlikely to be any worse than last year. This season staff have planted bigger poles to combat mortalities caused by the pest (last season the smaller poles were often overcome by the infestation) and tried to plant a greater percentage of other varieties, varieties that appeared to be less desirable. Staff continue to work with the Willow and Poplar Collective to learn more about the problem.

AKITIO SCHEME

10.7. Again, the Akitio catchment has remained fairly settled over the last four months. Like the rest of the eastern area, this catchment has had an increased level of rainfall but this has been fairly well spread out. The only period to note was during early September when close to 40 mm fell over several days. There have been no incidences of flooding so far this season and the rain has been welcomed by the landowners.

10.8. Because this season is again, a season of reduced works, there are no programmed works going forward. However, staff will be undertaking an inspection of the channel in preparation for next season’s maintenance spraying. There is also $1,000 available for minor works if needed.

10.9. Current inspections indicate that the channel is currently in a good condition, and as such, staff will continue to monitor the river for willow debris going forward. This will be completed while monitoring the debris accumulation at the river mouth which will be done in accordance with the agreement made with the local landowners last season. To date, inspections of the beach show that this material continues to do a good job of protecting the vulnerable foreshore from sea erosion.

EASTERN MANAWATU SCHEME

10.10. Like the Akitio, the Manawatu has again been settled over the last four months, in actual fact, records show that the Manawatu at Weber Road has so far been more settled than it has been in any other year in recent history. This has meant that there have been no significant debris dams forming that require clearing enabling staff to work on clearing minor blockages where one or two trees have fallen.

10.11. Over the last two months staff have also undertaken a small amount of planting and have been updating works programmes preparing for the season’s programmed works.

IHURAUA SCHEME


14 December 2016


10.12. Ongoing inspections show that the Ihuraua Stream has remained clear and free flowing throughout winter and spring and as such, staff will continue to monitor its condition over the coming months while also planning the season’s programmed works. These include some substantial works to widen the channel in several locations and work identified in the last audit report which was postponed in order to allow a sufficient accumulation of funds to become available.

MANGATAINOKA SCHEME

10.13. As mentioned earlier, the planting programmed for the season has been completed, but unfortunately the wet weather, while good for watering plantings, has made it hard to start river bank protection works due to the higher flows and unpredictable water levels.

10.14. During this period staff have also been undertaking inspections. Staff have just begun bank protection works and the focus of these efforts will include catching up on any maintenance that had to be deferred from last season. There is a small amount of claimable work, still outstanding following the June 2015 flood event to be undertaken this season; however this can be undertaken utilising the emergency reserves that were approved last season. The total is only $22,000 worth and this will largely be covered by the pay out to come from the MCDEM.

10.15. Recently there has been a high level of interest in gravel for local roading projects and staff have been able to organise the material to be extracted from sites where it will benefit the river and scheme. The scheme is able to allocate 14,000 m³ annually, this has already been allocated and so far 11,000 m³ has already been taken. Most of this is being taken by the District Council for local road works.

SOUTH EASTERN RUAHINE SCHEME

10.16. The South Eastern Ruahine Scheme is ahead of the eight ball and has made good progress in undertaking not only its planting programme but also its bank protection works. Although river / stream levels have fluctuated recently this early start has been possible because these steep, small waterways quickly settle down to a workable water level. Fortunately this means two things; that the trees used in tree works are ready for a full season of growing and that once complete, the scheme manager can focus on undertaking work in the other rivers that are currently a little high.

10.17. During this period the Investigations & Design Team have been helping to investigate a flooding issue on Sinclairs Creek. This is a situation where there are multiple factors effecting the water level near the State Highway just south of Woodville and this has caused ponding around a house. Survey work has also been carried out and staff are looking at programming a combination of channel clearance and the lowering of a diversion structure.

10.18. Going forward, staff will be busy undertaking the remainder of the scheme works while inspecting the scheme for any new damage or maintenance to consider.

TAWATAIA - MANGAONE SCHEME

10.19. As with the Ihuraua, ongoing inspections indicate that the scheme is in a good position and that the drainage systems have worked well over the recent wetter months.

10.20. Going forward staff will continue to monitor channel performance and plan to undertake the seasons’ programmed works.

UPPER MANAWATU – LOWER MANGAHAO SCHEME


14 December 2016


10.21. Like the Mangatainoka, the season’s programmed planting is complete, but higher river levels have meant that bank protection works are having to wait.

10.22. Again, like the Mangatainoka, the works programme will involve catching up on any maintenance that was deferred from last season, while also undertaking the still outstanding small amount of claimable work that was caused by the June 2015 flood event. These works are to be undertaken utilising emergency reserve funds that were approved last season. This totals $29,000, and is to be reimbursed by the pay out to come from MCDEM later in the season.

10.23. As mentioned earlier, there has been a large interest in gravel. So far 20,000 m³ of the consented 40,000 m³ has been allocated and this is for the district councils local roading works. So far 10,000 m³ has been extracted and this was taken from the upper reach of the upper Manawatu.

10.24. Going forward, staff will be busy carrying out inspections while planning the upcoming works.

ENVIRONMENTAL GRANT WORKS AND ENGINEERING ADVICE

10.25. Following the higher flows of winter and spring there have been several enquiries for engineering advice and a number of these are likely to result in applications for environmental grant assistance.

11. SOUTHERN AREA

GENERAL

11.1. Weather for the last four months has been very unsettled. Extended periods of rain on already saturated ground conditions have seen many of the streams, rivers and drains levels fluctuate over the period.

11.2. Increasing temperatures during October saw weed growth in drains take off. October and November have also seen some strong winds and rain which have kept the spray contractor at home putting our maintenance programs behind schedule. Strong weed growth over this latter part of the period has seen a number of weed blockages form and weed growth keeping up water levels in the drains. This has resulted in the need to put machinery into these drains which otherwise would have been sprayed.

11.3. The persistent rainfall and fluctuating river and drain levels have kept staff and contractors busy running around the various scheme pumpstations in order to keep the screens and platforms clean of weed.

11.4. The 14 November Kaikoura Earthquake caused major disruption across the schemes with many of the pumpstations losing power for a period of time. Follow-up inspections were undertaken by our on call electrician to reset the soft starters. A majority of the stations were up and running within two days. Staff have also carried out external inspections of all the pumpstations for signs of earthquake damage. More detailed inspections of the pump chambers and discharge pipes will be undertaken over the next few months as weather conditions improve and drain levels drop.

11.5. During this period staff have attended three workshops for the Levin Northern Connection Otaki to North of Levin, part of the Roads of National Significance project. The meetings involve various groups including NZTA and their consultants, representatives from HDC and Horizons and a number of other cultural and environmental advisors. The workshops are aimed at looking at the various alternative routes and intersections and reviewing them through a Multi-Criteria Analysis process.


14 December 2016


11.6. Staff have attended several meetings in regards to progressing the works around Lake Horowhenua.

11.7. Staff attended a meeting with various other groups from within Horizons to look at the potential impact of the weir failure at the downstream end of Lake Kaikokopu. Further monitoring of the impact of the weir failure on the lake over the summer period will be undertaken by consents monitoring staff before a decision is made on whether to replace the weir or not.

11.8. Staff hosted consultants and staff from Waikato Regional Council who were interested in discussing and visiting Burkes Pumpstation. The visit was part of a fact finding trip to guide capex Waikato Regional Council have planned for their land drainage infrastructure.

11.9. Staff have meet with representatives from HDC to discuss a number of issues including the proposed Koputaroa Stream discharge consent, responsibilities of the different councils in regards to rural stormwater management, and the stormwater modelling being undertaken both in and around the Foxton Township.

OHAU-MANAKAU SCHEME

11.10. Ongoing rainfall over this period has seen the rivers and streams in this area respond quickly to any rainfall in the headwaters. While there have been no significant events in the rivers the largest flows in the channels were: Ohau – 2 m (156 m³) on 11 November, Waikawa – 1.3 m (38 m³/s) on 11 November, Manakau – 1.9 m (14 m³/s) on 15 November.

11.11. This time of year normally sees maintenance and planting of willows along the edges of the rivers and streams in this scheme. This period is no exception with 3250 willows and 500 natives being planted and 3 km of willows along the Waikawa Stream and Ohau River being either mulched or layered.

11.12. In 2013, a new Fish-Friendly Floodgate (FFFG) supplied by ATS Environmental Solutions was installed on the old loop outlet on the Ta Hamata farm block. Not long after the gate was installed staff noticed several of the welds on the steel gate had failed. The supplier of the gate was informed and they subsequently repaired the welds. During a recent inspection of the gate staff again noticed that a number of the welds had again failed, however this time the actual gate had also been damaged. Due to the extent of the damage and the lack of confidence in this type of gate a decision was made to replace the gate with a different type. As the new gate will take some time to be constructed, temporary repairs have been carried out to the old gate in order to provide a level of protection for the upstream properties. The new gate is expected to be installed before the end of January.

11.13. Repairs were carried out to the floodgate hinges on the Takapau Drain outlet.

11.14. A total of 3 km of drain machine cleaning occurred during this reporting period.

MANAWATU DRAINAGE SCHEME

11.15. During this period the spring spray programme has been put together, detailing the work required to be carried out on the scheme drains. Both mechanical and spray work is required of the drains.

11.16. During the June 2015 event a section of Mitchells Creek was over topped resulting in the flooding of several properties. Some minor topping up of the bank was done following the event at the request of the landowners however ,heavy rainfall in August again saw water spilling out of Mitchells Creek and flowing around adjacent properties. Further discussions with the landowners have revealed that this has been a regular occurrence during heavy rainfall events. As a result, staff have agreed to review the performance of the creek and to discuss options to improve the performance of Mitchells Creek with the landowners. As


14 December 2016


part of this review a 1.6 km section of Mitchells Creek has been surveyed to determine the current capacity of the creek. This information will be used to identify restrictions within the channel and what options are available to provide additional protection to the surrounding properties.

11.17. Along the Lockwood Road Drain a culvert became blocked with weed so this was cleared.

11.18. Along the Rongotea Road Drain a collapsed culvert that ran along the side of the road and into Whiskey Creek has been replaced with a new 600 mm pipe. Also a second culvert upstream of this was also replaced to a larger culvert size.

11.19. Due to the high amount of rainfall during this period the Burkes gate outlet has been clogged with weed. This has meant regular removal of weed from the gate structure.

11.20. A 0.3 km section of Walls Drain has been machine cleaned.

11.21. Rutledge Drain has been machine cleaned through the Fleming’s property.

11.22. A new floodgate (225 mm) has been fitted on K4 to prevent water flowing back up the pipe into the adjoining property. Also a new 450 mm floodgate had been fitted to K6 to replace a broken concrete gate causing flooding at the property.

11.23. A large number of willows and other invasive plants have been removed from a section of the Taonui Stream down stream of Waughs Road as part of a joint project with both the Fresh Water and Environmental Education Teams’. The area of land from which the trees were removed from will be planted up with natives by students from the local Taonui Primary School.

11.24. A 100 m section of Wilsons Drain has been machine cleaned due to a large build up of weed.

MAKERUA DRAINAGE SCHEME

11.25. During this period the spring spray programme has been compiled, detailing the work required to be carried out on the scheme drains. Both mechanical and spray work is required of the drains.

11.26. Large weed blocks that were holding up the water in Funnels property along Akers Drain, have been removed.

11.27. Due to the high amount of rainfall this period Okuku Pumpstation has been running and the weed screen grills have required regular mechanical cleaning. Electrical contractors were also called into this station to replace one of the soft starter units after the old unit failed.

11.28. A 1 km section of Sieferts Drain North has been machine cleaned.

11.29. A culvert on the intersecting channel has been replaced with new pipes and a new floodgate.

11.30. A 1.2 km section of Donnelly’s Drain was machine cleaned.

11.31. Old Main South Drain a retaining wall was constructed to repair slumping that was occurring on the Taylors property.

11.32. A rotten roof beam has seen the roof replaced on Ashlea Road Pumpstation, at the same time the builder undertook some minor maintenance on the main door which tended to stick during the winter period.

KOPUTAROA DRAINAGE SCHEME

11.33. Spring drain maintenance inspections are underway and the work will be completed during the next reporting period.


14 December 2016


11.34. While undertaking inspections at Koputaroa No.4 Pumpstation following the November earthquake, staff observed water piping from the back of the pumpstation. Material had to be removed from behind the station in order for preliminary inspections of the pipe to be undertaken. High water levels in the drain prevented staff from entering the pump chamber to inspect the pipe. Closer inspections revealed a crack at the base of the surge chamber along with a crack around the outlet pipe. Earth blocks were installed both upstream and downstream of the pumpstation so the site could be dewatered. Once this was completed work was undertaken to fill the cracks in both the chamber and pipe after which concrete was poured into the floor of the chamber and around the pipe to reinforce the repairs and provide a good watertight seal.

11.35. While the station was switched off and dewatered for the work to be undertaken, the gravity pipe and the station outlet pipe had a CCTV camera inspection to record their condition. Apart from the crack at the surge chamber end the outlet pipe was in good condition. The gravity pipe was in good condition also apart from the first pipe on the upstream end which had disconnected from the rest. This pipe was dug out and relayed.

11.36. An inspection was also conducted on the weed fence and a possible gap was found that could let weed through. Staff used fencing materials to minimise any weed being sucked through.

11.37. As part of the renewal program the culvert on Kanes Spillway No.2 was replaced. This culvert had high headwalls made of concrete sandbags which were leaning out. A gap was growing behind the headwalls where material was being washed away due to pipes in the culvert separating. New collared pipes were installed and the culvert was extended so that the headwalls did not require being so high.

11.38. A tree was removed that had fallen onto the outlet of Koputaroa No.3 Pumpstation.

11.39. Council surveyors have completed a crest survey on both the left and right stopbank on the Koputaroa Stream from the floodgates up to the Railway Bridge. This information will be used to identify any remedial works that may be required to ensure that the banks are up to design height.

MOUTOA - WHIROKINO DRAINAGE SCHEME

11.40. Work is underway at both the Cooks and Diagonal Pumpstations to improve the safety of the sites, part of an initiative reported to Committee earlier in the calendar year. New handrails have been installed at the weed screens and around the tops of the surge chambers. New and improved walkways are also being installed in the pump chambers to ensure working around the pumps are safe. Lifting beams have also been installed above the manholes to the pump chambers so that extraction of personnel can be achieved.

11.41. With the work at these stations expected to be completed by the end of November, members of the Moutoa, Makerua, Koputaroa, Manawatu and Te Kawau Scheme Liaison Committees have been invited to attend an Open Day at Cooks Pumpstation on 14 December to inspect the improvements that have been made at this station.

TE KAWAU DRAINAGE SCHEME

11.42. During this period the spring spray programme has been compiled, detailing the work required to be carried out on the scheme drains. Both mechanical and spray work is required of the drains.

11.43. Several drains have been mechanically cleaned to remove weed build up and blockages. In total 3.7 km of scheme drains have been machined cleaned.

11.44. Council surveyors have commenced a crest survey on both the left and right stopbank on the Sluggish Main Drain from the floodgates up to Saunders Road and on Johnsons Drain from Kaimatarau Road to Longburn Rongotea Road. This information will be used to


14 December 2016


identify any remedial works that may be required to ensure that the banks are up to design height.

11.45. High water levels in Johnsons Drain resulted in some localised over topping of the right bank downstream of Leens Drain outlet. Material was excavated from a nearby paddock to stem the over topping.

HOKIO CATCHMENT DRAINAGE SCHEME

11.46. This period saw some more work carried out under the drainage upgrade program. A culvert under CD Farm Road was completed and the drain leading into a culvert under Bruce Road was re-graded to align it with the new culvert recently installed.

11.47. An existing drain was regraded to provide better drainage to a property on Hokio Beach Road and a culvert was installed at the end to ensure water did not flow back up it. The drain and the culvert were added to the scheme’s asset list

HIMATANGI DRAINAGE SCHEME

11.48. During this period the spring spray programme has been compiled detailing the work required to be carried out on the scheme drains. Both mechanical and spray is required of the drains.

11.49. During this period a total of 1 km of scheme drains have been mechanically cleaned and 2 km have been sprayed.

FOXTON EAST DRAINAGE SCHEME

11.50. Rapid weed growth in some of the scheme drains have resulted in the early spraying of Kings Canal from Purcell Street up to Avenue Road.

11.51. A collapse culvert at the top end of Howan Street has been replaced with a larger sized culvert.

12. ENVIRONMENTAL GRANT WORK

12.1. Environmental Grant works to date for 2016-17 are noted in the below table.

Name River Description Application Status

Estimated Cost

Expected Subsidy Cost

Work Status

N Randell Tutaenui Stream Bank Protection Works

Approved

$7,000 $2,100 In progress

Carried over from 2015-16

Rangitikei DC & Redmayne

Makirikiri Stream Construct Flood Gate Egress Structure

Approved

$125,000 $37,500 Work to commence in Jan 2017

Carried over from 2015-16

Whenuatupu Ohinemoa Trust

Ohinemoa Stream

Willow Clearing Work

Approved $33,000 $9,900 Yet to commence

Ruapehu DC Makotuku River Remove lf Willow Congestion


Hooper-Smith Mangatoro TBPW, Approved $8,000 $2,400 In progress


14 December 2016


Stream Mulching Carried over from

2015-16

PNCC Ashhurst Domain

Bank Protection – Rock Riprap / Rail Groynes & Tied Tree Work


Robb Mangamaiti & Mangaetoroa Streams

Removal of Willow Congestions

Awaiting Approval

$23,650 $7,095 Awaiting Approval

N Kelland Ongarue River Remove Poplars from River Banks

Application being Prepared

$10,000 $3,000 Application being Prepared

I McKean Mangawharariki Stream

Bank Erosion Repair Work



B Walker Mangawharariki Stream

Bank Erosion Repairs & Clearing Vegetation off Beaches



D Smith Tutaenui Stream Bank Protection Work


$12,000 $3,600 Property Owner has put Work On Hold

R Redmayne Mangatikotoko Stream

Construct Concrete Weir & Timber Retaining Wall at Tunnel Hill Flume


$18,000 $5,400

J Patel Tutaenui Stream Rock Lining Bank Protection Work


$45,000 $13,500 Discussing Design with Consultants

R Lee Urban Drain Repair Flood Damage Bank Erosion


$10,000 $3,000

J Allen – Kauangaroa Marae

Whangaehu River

Ring Bank Flood Protection


$90,175 $27,053 Iwi Funding – Highly Possible

Marton Motel Tutaenui Stream Rock Lining Bank Protection Work


$20,000 $6,000 Client to get Independent Design

K Norman Mangahao River R&R Groynes, Planting


$5,000 $1,500 To be Investigated

Riding for the Disabled

Mangaramarama Stream

Stopbank Work

Application being

$5,000 $1,500 To be Investigated

Carried over from


14 December 2016


Prepared

2015-16

C McConachy Tributary of Porewa Stream

Bank Protection & Channel Clearing

Completed & Paid

$4,000 $1,046.25 Completed & Paid

G Waller Taringamotu River

Bank Protection & Diversion

Completed & Paid

$27,000 $7,471.20 Completed & Paid

M Short Tapuata Stream Rock Lining Completed & Paid

$8,000 $2,088 Completed & Paid

K Black Oroua River Repair Bank Erosion

Work Not Proceeding

$13,000 $3,900 Work Not Proceeding

M Carte Mangataua Stream

Removal of Willow Congestion

Work Not Proceeding


S Glasgow Kahurauponga Creek

Channel Willow Clearing

Work Not Proceeding


TOTAL $776,325 $231,803

13. SIGNIFICANCE

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

Ramon Strong GROUP MANAGER RIVER MANAGEMENT

ANNEXES

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