Catchment Operations Committee 16 September 2015
Report No. 15-182 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 17 July to 31 August 2015.
2. RECOMMENDATION
That the Committee recommends that Council: a. receives the information contained in Report No. 15-182 and annexure.
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; 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 Committees. As necessary, other issues will be the subject of media release.
5. DISCUSSION
5.1. As weather, river and site conditions have allowed, progress has been made with the reinstatement of damage arising from the June floods. The initial focus has been on reinstating critical pieces of infrastructure, followed by clearance of debris blockages from river and drainage channels. Those items have been substantially completed and works have commenced on the higher priority asset repairs within many schemes.
5.2. Estimates for damage repairs have been progressively refined. As part of the Annual Report process, it was necessary to separately identify damage to assets as opposed to channel blockages and ‘new’ erosion, such that provision could be made in the Profit and Loss Statement for asset impairment. The number arrived at for that purpose was $3.039 million. If the damage repair cost incurred over the last two weeks of 2014-15, that is $0.527 million, is added to that, the total of $3.56 million gives a good indication of the maximum amount that could be claimed for 60% assistance through the National Civil Defence and Emergency Management Plan, which applies only to ‘essential infrastructure’.
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Catchment Operations Committee 16 September 2015
5.3. Initial discussions have been held with Ministry of Civil Defence and Emergency Management (MCDEM) officers around the framework and timing of a claim. MCDEM understands that it will be some time before a detailed claim is lodged and is satisfied with the indicative numbers provided at this stage. It is expected that we will be in a position to lodge a formal claim by mid October.
5.4. The Chief Executive and GMO met with the Chief Executive of Wanganui District Council (WDC) in early August to discuss various flood related matters. It was accepted that there are a number of issues arising from the floods within the Wanganui District that will require some investigation, consultation and decisions over the next year or so. It was decided that those issues would be best managed through the establishment of a joint flood risk management technical advisory group, comprising CEO’s and Executive Officers from each Council. Draft Terms of Reference for such a group are presently being prepared.
5.5. Staff have attended to a number of public meetings arranged by WDC to provide affected property owners with an opportunity to convey their experiences and concerns with regard to the flood event. The two meetings attended specifically addressed Matarawa Stream and Putiki flooding issues. One issue that could be considered at an early stage by the Advisory Group, is the possible inclusion of that section of the Matarawa Stream that flows through Wanganui East, within the Matarawa Scheme for maintenance purposes.
5.6. Letters have been sent to each of the three ratepayers who were given public speaking rights at the July Catchment Operations Committee meeting, providing responses to each of the key issues raised.
5.7. HRC staff have met with engineering staff from Horowhenua District Council (HDC) to discuss flooding issues in Foxton, associated with channel overflows within the Foxton East Drainage Scheme. The main drainage channels in this scheme contain only 5 to 10 year flood flows, so not surprisingly the runoff resulting from the extreme rainfall event in June easily overtaxed the system. While the most recent review undertaken in 2012 did not identify a demand for an increased level of service, there are indications that the extensive flooding experienced on this occasion may lead to such a request. It is understood that the issue will be discussed at the next meeting of the Foxton Community Board and staff will be attending that meeting.
5.8. Individual letters were sent to 69 ratepayers on 28 July, that is in advance of them receiving rates invoices, explaining the inclusion of properties within the Lower Manawatu Scheme (LMS) HF rating category for the first time. Those letters have generated a number of queries and staff are working their way through those.
5.9. During the operation of the Mangaone Spillway on 20-21 June, at least one house within the spillway in the Rongotea Road, Kerekere Road area was seriously flooded. That has not occurred during previous spillway operations and is thought to result from a large overland flow contribution to the spillway in that lower area. The issue requires careful investigation and there may be justification for the provision of localised protection through the LMS.
5.10. The Operations Group undertook its annual strategic planning exercise in early August. A substantial number of investigation, design and construction projects have been identified and programmed for completion over the next 12 months. In order to accommodate a particularly large number of construction works this year, it will be necessary to award the first contracts very early in the season and planning is in place in that regard.
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Catchment Operations Committee 16 September 2015 6. DESIGN SECTION
INVESTIGATIONS
6.1. Following the 19-21 June 2015 floods there has been an intensive demand on design resources in regard to both scheme and public matters related to the flood, whilst also carrying out the programmed design projects.
TAONUI BASIN
6.2. Work has again continued on completing the consenting requirements for this project, which involves the enlargement of the waterways and completion of ring banks.
6.3. Detailed advice has been provided to a landowner in Basin ‘D’, on his request, for over- sized culverts.
6.4. Investigations also show that the capacity of the drain involved is more effectively addressed by regrading the lower reaches. This will significantly improve drainage in Basin ‘D’ in the final phase of draining after a major flood.
LOWER MANAWATU SCHEME
6.5. This period further design work has been provided on the lodged Lower Manawatu Scheme (LMS) Rural Upgrade earthworks consent application. This application covers all the remaining earthworks on the Manawatu River, Tokomaru Stream, Mangaore Stream and Kara Creek and partly this has involved forming formal responses to the Consents team while also being involved with further public consultation. It is important to note, that consent is already held for outstanding works on the Linton Main Drain and Oroua River.
6.6. We are now in year 10 of the 12-year Rural Upgrade programme and so far design has been provided for most of the stopbank raising work planned for this season between Hoihere Road and the Rangiotu reach of the Oroua River. These designs have included stopbank upgrades for the whole reach, minor upgrading of the Rangiotu Spillway, protection to an adjacent milking shed and works to the Main Drain gates.
6.7. Survey is also well underway for the several remaining sections of the Lower Manawatu River stopbank upgrade project. Designs for this will be provided through September.
6.8. Survey is also well underway, with designs nearing completion, for the upgrade to 0.2% AEP on three sections of the Mangaone Stream. These are located adjacent to the Palmerston North Airport, at Flygers Line and Benmore Avenue.
ANZAC CLIFFS
6.9. An assessment was completed of the optimal strategy for completing outstanding works on the bed armouring of the Manawatu River alongside the substantive rock riprap riverbank protection works.
LOWER WHANGANUI RIVER
6.10. Preliminary modelling of the June flood has been continued, with calculations showing a 1.2% AEP (1 in 85 year return period) at the Te Rewa gauge. This is the largest recorded flood for this location since records began. It is indeed a flood of major consequence. Very high rainfalls in the lower catchment may have boosted the flow in the lower reaches. Normally in a river of this nature, the flood wave spreads out as it moves through the lower
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Catchment Operations Committee 16 September 2015 river and often this approximately cancels the downstream tributary flows. However, the tributary flows were high in this flood.
6.11. It is important to recognise that further assessment of the flood size and any design ramifications at this stage are premature and require further complex professional processing. This will require a resurvey of the cross sections in the first instance. However, the following general points are clear:
1. Levels in the river downstream of Putiki were relatively low. This was due to the peak not coinciding with high tide, the tidal range being small (it was 0.5 m higher earlier in the month of June and the design case is a further 0.4 m higher again with minor storm surge) and the mouth very likely was scouring. As the sea levels offshore were low, the ability of the mouth to scour was enhanced. To date, modelling has been able to reproduce the recorded flood levels using sensible parameters. This scouring process is not included in the design levels, as the amount of scouring may be small with a higher tide. 2. Levels at Aramoho were above expected levels, particularly on the right bank. Interestingly on the left bank, near the Aramoho Railway Bridge, the levels were close to the 1.2% AEP flood level. There are a variety of possible reasons for this variation which include; the strong swash affecting levels on the right bank (particularly in the vicinity of the rowing clubs and motor camp, which were close to the main flow of the river); changes in riverbed levels; formation of dunes (these increased levels in the Rangitaiki River downstream of the Township of Edgecumbe by almost a metre in a flood in 1998); and higher flows than measured.
6.12. The higher levels at Aramoho reinforce the need for freeboard to be included in design flood levels, not only for rivers, but also houses where a different set of phenomenon may come into play (as accurately described in NZ Standard 4404).
ARAWHATA SEDIMENT TRAP
6.13. Additional design information was provided this period for the design and operation of the Arawhata sediment trap required for the Lake Horowhenua resource consents application.
TE KAWAU SCHEME AUDIT
6.14. The programmed audit of the Te Kawau Drainage Scheme is complete and the outcomes are presented separately in this Agenda. This scheme was formed in 2004 by the amalgamation of the Sluggish River Drainage Scheme and the Oroua Drainage Scheme, following a review of the two schemes in 2001.
ADDITIONAL DESIGN ADVICE FOLLOWING THE JUNE FLOOD
6.15. Continued design advice is being provided to the Flood Recovery Group on predictions and risks on most of the flooding rivers.
6.16. Following the flood numerous matters continue to arise, with the principal matters as follow:
A significant amount of modelling and onsite assessment has been carried out to analyse the high flood levels in the Oroua River. Mitigation of these levels is currently well underway. Causes are diverse but include restrictions due to vegetation and access ramps and sediment build-ups. A planned programme of sediment removal was due to commence in earnest following the completion of the 12-year Rural Upgrade programme. However, there has been an abnormally high succession of floods over the past decade, commencing with the February 2004 0.4% AEP (1 in 250
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Catchment Operations Committee 16 September 2015 year) flood and continuing on to the 2% AEP (1 in 50 year) in June 2015. Staff are now investigating accelerating the priority this programme has. An investigation has been carried out into the failure of one of the “summer stopbanks” on the Oroua River. This is located slightly downstream of Awahuri. These stopbanks are designed to focus the river flow so that silt deposition in the adjacent reach is minimised. They are generally perched close to the main channel and cannot be expected to withstand major floods. Hard edged protection works would generally be unaffordable, though rail iron works may well be cost-effective and are being trialled – using the same design parameters that have made these successful on the Rangitikei and Mangahao Rivers. The conclusion of this study is to slightly retreat these banks and reinstate them in the failed location. A detailed assessment has been made of the outflows of the Oroua River at Awahuri and the Camerons Line area. In particular, outflows travelled 2.7 km east of the State Highway 3 Bridge to flood the houses and Triple R factory. Assessments have also been made of the cause of the flooding on the right bank of the Oroua River at Awahuri. This is due to the very large flows in the Makino Stream that entered an old meander loop near these houses. This was clearly an over-design event with the likely coincidence of 1% AEP flows at both the Makino at Rata Street site and West Mangaone catchment. Stopbanking planned for 2016-17 under the Rural Upgrade programme will protect these areas from the Oroua River and Makino Stream. Warning flood levels were determined for flood actions at the Whitelock’s stopbank on the Manawatu River. Damage to the McAloon stopbank on the Rangitikei River was assessed and remedial recommendations made. An investigation has commenced into flooding of land adjacent to Napier Road caused by Stoney Creek outflows. In the June 2015 floods, Stoney Creek outflowed over the stopbank on the true right bank downstream of Napier Road and travelled to the east before re-crossing Napier Road through a culvert. The overflows continued to the west crossing Roberts Line and flooding several properties and a house. This was an extreme flood with the 48-hour rainfalls of approximately 1.7% AEP (60 year) magnitude. Due to the high rainfalls preceding the event, the flood flows would likely have been between 2% AEP and 1% AEP. There are several component parts to an option to prevent a recurrence. The brief for the study is due for mid September and study completion is due end of October. An initial assessment was carried out on the very high flood levels in the Whanganui River. Future detailed investigations will assess the elevated flood levels in several other areas including Hunterville, Makowhai Stream, Tangimoana and Marton, though these are yet to be programmed or, are programmed for later investigation. Again, it appears that, whilst flows in the Tutaenui, at Marton, were significant at around 1.7% AEP (60 year), they were significantly greater near the confluence with the Rangitikei River and particularly in the Brandon Hall Road area. The Tutaenui modelling is included in the Horizons Regional Council long-term Flood Hazard Modelling project for 2015-16 and Makowhai 2016-17.
ASSET MANAGEMENT
6.17. Updates to the Asset Management System (AMS) software are pending action by Datacom. It is understood that higher priorities at Datacom have delayed progress.
6.18. The annual capitalisation of scheme assets was completed in one week instead of the two weeks allowed in previous years. Staff have worked extra time to meet this timeframe agreed in order to provide a buffer against any later contingencies in the Annual Report process. As a result, the required AMS Depreciation Run was able to be carried out for the
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Catchment Operations Committee 16 September 2015 Finance team on 28 July. A snapshot of the AMS data was taken immediately afterwards to provide a consistent basis for future reference, particularly for Audit in September.
6.19. The capitalisation process first involved the allocation of almost $11m of capital expenditure for projects completed in 2014-15, including some $4m of works begun in previous years (i.e. work in progress). Most notable projects involved the stopbanking of Kowhai Park/Anzac Ave in Wanganui, Burkes Pumpstation and LMS upgrade works in the Taonui Basin. This expenditure was allocated to approximately 100 new or existing assets, with input from the area engineers to provide dimension and location data for the AMS.
6.20. Of the $7.89m of expenditure this year, there was $3.3m of LMS work in progress that will be allocated next year, mostly on the Anzac Cliffs Project and Turitea Upgrade.
6.21. As result of the $7.89m of capital expenditure this year, the value of all the schemes managed by Horizons is now $382m (on 30 June 2015), an increase of 2%.
6.22. The annual capitalisation process also involved adjustments in asset values (Additions and Disposals) to account for over 240 dimension changes identified during GIS mapping, as well as Write-offs for redundant assets. GIS mapping has been progressively carried out across the Region over recent years and the data used to update existing AMS dimensions. The value of assets with dimension changes have been adjusted using the unit rates derived for the revaluation of scheme assets on 1 July 2014. These unit rates are an average for the type of work in each scheme. For example, the unit rate for tied tree work is $117 per metre in the South East Ruahine Scheme but $179 per metre in the Mangatainoka Scheme. This reflects the relative river sizes and intensity of vegetative protection works required. This year largely involved mapping of the South East Ruahine Scheme, with changes to approximately 150 assets resulting in an increase in value of $3.6m, mostly from increases in the area of protection planting. An additional $1.3m of tied tree work assets was inadvertently omitted and has been input as Additions and Disposals for 2015-16.
6.23. The most significant changes in other schemes were a reduction of $1.1m in the LMS value, largely due to writing-off concrete riprap that was previously replaced with rock lining at Dittmer Drive in Palmerston North, plus changes in miscellaneous stopbank and drain dimensions.
6.24. None of the Additions and Disposals has included damage from the flooding on 20 June 2015. This flood event occurred after most of the annual end of the year inspections had been completed and it was considered impracticable and misleading to treat the damage as Additions and Disposals for individual assets, especially as major repairs were completed soon after the 30 June 2015 cut-off date for the reporting year. Separate bulk provision has therefore been made in the Annual Report accounts for the “impairment” of scheme assets at 30 June 2015.
Total Asset Value 01/07/2014 $372,443,830 Additions and disposals + $2,245,283 CAPEX 2014-15 + $7,892,184 Total Asset Value 30/06/2015 $382,581,297 Note 1. The Total Asset Value 30/06/2015 includes approximately $4.9m of work in progress that is yet to be allocated to specific assets.
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Catchment Operations Committee 16 September 2015
6.25. A SQL-based excel spreadsheet has been developed by Jesse Singson, Operations Management Accountant as a new reporting tool to help track and report 2014-15 changes in scheme value. It provides a “snap-shot” of the AMS data at the time of the Depreciation Run and allows 2014-15 AMS data to be readily accessed by Accounts staff for Annual Report and Audit purposes.
6.26. As a result of the capitalisation process, there were changes in the asset value of some schemes, particularly the LMS, Lower Whanganui River, South East Ruahine and Manawatu Drainage Schemes. For completeness, the Flood Loss Curves for all schemes have been updated in Appendix G of the respective Asset Management Plans (AMPs) Part B. The updates have been based on the asset values at 1 July 2015 to allow for significant write-offs such as the transformer upgrade required for Burkes Pumpstation (a scheme cost but not a scheme asset).
6.27. Changes were also made to the Target Reserves for the most affected schemes. In particular, the South East Ruahine Scheme increased from $2.2m to $2.8m, however it is noted that the estimated flood loss should be based on damage to the “front line” portion of the substantial areas of protection planting and therefore the loss factor needs to be revised. This anomaly will need to be addressed during the review of Target Reserves, programmed for later this year.
6.28. Allocation of the Annual Infrastructural Asset Insurance premium has also been adjusted in line with the change in asset values. The updated allocation also corrects the Earthquake Damage Factors that had been applied erroneously to several schemes by GNS under the LAPP regime.
6.29. Condition ratings for all assets have been analysed and the results for each asset type have been used to update the Level of Service and Performance Measures in Appendix E and F of the current AMP for each scheme. The condition data was put into the AMS by Operations staff following annual inspections in the three month period from 1 April to 30 June 2015. The data included the results of inspections to assets most affected by the flood on 20 June 2015. As a result, the Performance Measures, at 30 June 2015, may be less than the targeted Level of Service. For example, only 80% of scheme stopbanks meet their level of service when the target is generally 90% or more.
REGULATORY ADVICE
6.30. The amount of regulatory work completed was down on the previous reporting period with recorded advice provided on 25 substantive matters. However, there were numerous other matters quickly assessed and not recorded due to other pressing priorities.
6.31. This regulatory work involves specialist advice on flood risks and technical reports for consent applications, re-zonings and subdivisions including:
Advice on 12 flood risk and related enquiries. These included three requiring assessments of the required raise of houses to mitigate flooding experienced in June. Two of these houses may need to be raised around 1.5 m, as there are no robust flood protection options; the third will be protected by the proposed year 11 works for the LMS Rural Upgrade Project. A careful assessment was required for a proposed 13 lot rural residential subdivision in Awatea Place, Ohakune. Several of these lots are vulnerable from overflows to the NNE from Miro Street Drain and other watercourses. Unless mitigation works proceed, this risk will always exist. Consequentially, advice was provided to Ruapehu District Council (RuDC), that flood risks must be taken account of so that the proposal
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Catchment Operations Committee 16 September 2015 does not aggravate flooding either within the subdivision or adjoining land (for example from proposed inadequate piping of stormwater). Advice was also provided on a proposed house in Shannon Street, Ohakune near the Korokoio Stream. This assessment had to take account of the turbulence and super- elevation of the rugged mountain stream and also to ensure erosion was not a threat. Flood risk advice was provided to a prospective buyer of yet another lot in Tangimoana. The detailed minimum floor level assessment for a proposed house in Godley Street, Halcombe was reviewed following the June flood. Part of the property is vulnerable to flooding from a tributary of the Rangitawa Stream. The outcome was a recommendation to further increase the minimum floor level by 150 mm – though this fell well within the 500 mm freeboard of the original assessment. Detailed calculations were prepared to ensure proposed works at a Powerco substation are unlikely to flood in the 0.5% AEP flood. These are critical to the substation operation. Powerco provided detailed survey information. A detailed technical assessment was completed for the proposed replacement bridges at the Whirikino Trestle and Manawatu River Bridges. These bridges will have significantly longer spans, be higher, and pass the 1% AEP flood with forecast climate change and freeboard. This follows numerous meetings with the consultant and New Zealand Transport Authority (NZTA) staff during the formative stages, resulting in a very favourable outcome. Further detailed advice was provided to Palmerston North City Council (PNCC) on options for upgrading/replacing a bridge over the Turitea Stream. This includes a site visit with PNCC staff and hydraulic modelling. Advice was provided on new culverts over the Waimutu Stream and at the State Highway 57 and Turitea Road intersection – as part of a road safety upgrade. Advice was provided firstly on a proposed stormwater drain realignment and subsequently a piping option at a subdivision in Reids Line West. Advice was provided on two fords in the Makowhai Stream and a further ford in the West Mangaone. This latter site is better suited by a bridge and that appears to be the favoured option. A technical review was completed on the proposal by the sole gravel extractor on the Kawhatau River to combine their consents into a single site delineated global consent. This will require conditions on regularly riverbed surveys and controls on extraction to avoid degradation. Evidence was requested on matters relating to a ‘so-called’ modern midden at Hokio Beach. However, this has been declared by the NZ Historic Places Trust archaeologist as not being a historic midden. The June 2015 flood caused significant damage to some of the drop structures constructed on the Glasgow Farm at Santoft. The 48 hour rainfall at the nearby Forest Road site was of 1.4% AEP (1 in 70 year) magnitude, with a belt of rain providing a sting in the tail of the storm. Thus likely, the flow was well beyond design standards, at around 1% AEP. Though this is disputed by the landowner, they do agree that the prolonged rainfall was exceptional. Remedial options are being assessed for this difficult job in sand country. Several other compliance matters and diverse unrecorded enquiries.
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Catchment Operations Committee 16 September 2015
7. CENTRAL AREA
GENERAL
7.1. Over the last six weeks the Central area has received a high number of small rainfall events and this has caused the water table to remain high and ground conditions to be saturated. As a result, staff have had to focus their work efforts on only undertaking the most important emergency and temporary repair works within the schemes.
7.2. All annual asset inspections have been completed and staff are continuing to monitor flood damage while developing a works schedule for other less urgent repairs and maintenance which will be undertaken as conditions allow.
7.3. The total rainfall for this period (17 July 2015 to 27 August 2015) was: 107.5 mm at Milson Line (Mangaone); 120.5 mm at Cheltenham (Makino); 183.5 mm at Scotts Road (Kahuterawa); 209.0 mm at Delaware Ridge (Pohangina); 304.5 mm at Makawakawa Divide (Pohangina); and 158.0 mm at Rangiwahia (Oroua).
7.4. During this reporting period, the following peak flows and stage heights were recorded at the locations listed below:
7.4.1. On the Manawatu River, the peak flow at the Teachers’ College recorder site for the period was 417.4 cumecs (2.487m stage), which was recorded on 8 August 2015. With an additional peak, of just over 2 m, recorded on 26 August.
7.4.2. The highest peak on the Oroua River was, 45.98 cumecs (1.852 m stage), and this was recorded at the Almadale Slackline on 26 August. However, two other minor freshes did occur, these were on 19 July and 16 August and reached stage heights of 1.669 m and 1.775 m respectively.
7.4.3. Flow rates in the Mangaone Stream reached a peak of 32.595 cumecs (2.457 m stage) on 8 August, with one other peak above 2 m occurring on 25 July (reaching 26.6 cumecs and 2.229 m stage).
7.4.4. The Makino Stream at Reids Line reached 10.118 cumecs (1.341 m stage) on 8 August. With a further peak of 9.818 cumecs (1.33 m stage) occurring on 25 August.
7.4.5. The Tokomaru Stream experienced a peak flow of 18.78 cumecs (1.972 m stage) on 25 August.
7.4.6. There were relatively high flows maintained in the Kiwitea Stream during this reporting period, compared to the same period in the previous few years. The peak event during this period was 22.98 cumecs (1.649 m stage) on 19 July.
7.5. During this reporting period, scheme engineers have continued to assist in the delivery of the Rural Upgrade and City Reach Upgrade programmes. Staff attended to a large amount of non-scheme engineering advice and Environmental Grant enquiries (as a result of the floods). whilst also fielding a large number of rates enquiries, largely in regard to the recent HF UAC rate amendment.
7.6. The HF UAC rate amendments were made following a recent audit of this rating category, in which it was found that a number of houses, which should have been paying this rate, were not. A letter advising the affected ratepayers of this amendment was sent on 28 July and as a result, Central engineers have received a large number of calls from aggrieved
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Catchment Operations Committee 16 September 2015 ratepayers demanding to know why Horizons were increasing their rates for flood protection by $512.65, given that they were flooded in the 20 June event, and have spent two months out of their properties while repairs were being undertaken. In these instances, an enquiry has had to be made as to why they were flooded and the ratepayer satisfied as to why they still have to pay the HF UAC rate even though they were flooded. In most instances, it was because of localised rainfall exceeding the drainage scheme’s designed capacity rather than from the river. It has been an enormous help in dealing with these issues to be able to advise ratepayers that they can apply for rate relief.
7.7. Staff have also attended a Walkways Development Committee meeting which was held at the Landcorp offices in which the Horowhenua District Council (HDC), interested members of the community, the Police and DoC also attended to discuss the construction of a cycleway along the berm and stopbank from Whirokino Trestle Bridge to the Foxton- Shannon River Bridge. It was decided that HDC would develop a Strategy Plan with links to next year’s Annual Plan. There was comment about the length of grass on the Foxton- Whirokino stopbank walkway making it difficult to walk. The scheme already mows this bank once a month during the summer, a cost of $3,500 a year. To meet the communities desired level of service for this walkway, and stay within our budget, the scheme will place some hard-facing on the bank this year to reduce the frequency of mowing while maintaining a good walking experience.
LOWER MANAWATU SCHEME
7.8. Works undertaken on the various rivers within the scheme during this period include the following:
MANAWATU RIVER
7.9. The annual jet boat inspection was undertaken by scheme staff in July. This was timely to occur after the June flood event and allowed difficult to access stretches of the Manawatu River to be inspected for flood damage. Scheme engineers continue to monitor flood damage and update works programs for the coming construction season.
7.10. Clean-up and repair works throughout the City Reaches are continuing, and are planned to be completed by the next bi-monthly reporting period. The clean-up includes; flood- damage repairs to Fitzroy groynes; debris removal and disposal at Fitzroy bend; drain clearing and reshaping; bank shaping and planting. Compost is also planned to be spread around new and existing natives between Fitzherbert Bridge and Buick Crescent to boost plant growth.
7.11. Staff have also undertaken other maintenance tasks along the river and around the Moutoa Sluice Gates and these include; edge protection works and channel maintenance, inspecting and clearing floodgates, spraying gorse near stopbanks; small stopbank and ramp repairs and maintenance; cleaning drains, grass seeding and 2280 m of fencing work. Willow poles and wands are also being harvested for the planting season which commences in the coming weeks. However, given that stock exclusion periods are currently still in place, there has been no mowing of rural stopbanks.
7.12. Both Higgins and Landcorp have damaged stopbanks along the Manawatu River, either by uncontrolled grazing by stock or by ramps cut into the bank. It is extremely disappointing that such large companies do not understand the importance of maintaining stopbanks on their properties. Meetings with senior management have occurred and we have their assurance that the damage will be repaired as soon as conditions allow, and that processes will be improved to prevent any further damage.
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Catchment Operations Committee 16 September 2015 7.13. Willow mulching and willow clearance on the upper bank of the Manawatu was undertaken upstream of the Foxton-Shannon Road Bridge. This was done to enable the area to be planted with natives by Whakawehi Marae on 12 September, during their annual riparian planting day. Engineers and officers from the Freshwater team worked together to prepare for the day. Over 1,000 natives will be planted over a 300 m length of river bank. Engineers have checked, and this planting will not affect the flood carrying capacity of the river. To ensure there is no loss of protection as a result of the work, the planting was undertaken on a straight. However, as a precaution, willows have been retained at the toe of the bank to provide extra erosion protection. It is really encouraging to see the community take an interest in the river environment and adopt sections of the river.
7.14. Palmerston North City Council (PNCC) have approached scheme engineers with a proposal to site a natural burial ground in the flood plain. Engineers have discussed this with our Consents team and before approval can be granted, there needs to be certainty about the effect on groundwater and proper cultural consultation with Iwi, as the Manawatu River is a Site of Significance – Cultural.
7.15. Engineers have also been involved in several legal issues regarding easements on subdivisions alongside stopbanks and accretion claims.
7.16. A total of 5,980 m3 of gravel was extracted from the Manawatu River in this reporting period. The extractions were at two sites; the first at Akers Bend, located 1200 m upstream of the Opiki Bridge on the true left bank. The other site is at Jackeytown Road on Jerry Tocker’s property on the true right bank. Longburn Shingle has expressed interest to extract up to 20,000 m3 of gravel from this beach. This would take the pressure off the opposite river bank on Braeden Whitelock’s property. This bend is prone to lateral erosion in flood events.
OROUA RIVER
7.17. Flood damage repairs are nearing completion at Livestock Improvement Co-operation’s property (LIC) downstream of Awahuri Bridge on the true right bank. At this location, approximately 250 m of tied tree works and supporting summer bank had eroded in the June flood. New works consisting of 100 m of concrete riprap; and 5 x 15 m permeable wire rope groynes have been put in place to protect the river bank. The supporting summer bank of 200 m in length is under construction at the moment.
7.18. 133 t (35 m) of concrete riprap have been placed to protect the recent repair of Kuhne’s summer bank on the true left bank at 29.9 km.
7.19. At a site opposite Awa Street in Feilding, and located directly below the AFFCO meat processing plant on the true left bank, an existing concrete riprap asset has had 120 t of concrete riprap put into an erosion hole.
7.20. Fencing repairs are underway on the Kopane Spillway properties owned by Mike Edwards, Trevor and Daphne Dahl, Marie Pearce, Collis Properties on the Kairanga-Rongotea Road, and Pauline Gorton’s block. These damaged fence lines are in the spillway flow path and were significantly damaged in the June 2015 flood. LMS staff have used a small excavator to clear large amounts of trees and debris scattered about in the spillway, which were piled up and then burnt.
7.21. A large scour hole has been filled with river gravel at Mike Harnett’s property on the true left bank. The hole was filled because of its close proximity to the Kopane Spillway, and also for being within 10 m of the toe of the stopbank. 4,124 m3 of river gravel was extracted from Bruce Macaulay’s Beach and carted downstream to the hole.
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Catchment Operations Committee 16 September 2015 7.22. The 20 June flood event showed some variation in the freeboard on the Oroua River. This may be attributed to several large trees in the berm area and large willows that provide bank protection that could be mulched. Thirteen large macrocarpa trees have therefore been removed at the Kaimatarau Road end on the Oroua River on the true right bank. This was done at no cost to the scheme by a local firewood contractor. The same exercise is planned for the true left bank where there are more macrocarpa and poplar trees.
7.23. Mulching has also been carried out from Kaimatarau Road, upstream and downstream for 500 m to clear willow growth on both sides of the river and was also completed at Bryan Saunders property to help maintain a consistent freeboard along the Oroua.
7.24. Vegetation spraying in the Oroua River is expected to recommence in October.
MANGAONE STREAM
7.25. Mowing of the Mangaone Stream and City Reaches, has now been completed. The mowing contractor reported that this was quite difficult due to interrupting weather conditions, and flood debris (including silt. It may take several mows to get the area back to normal.
7.26. Emergency flood damage repair works have been undertaken in two locations along the Mangaone Stream Reserve within the City. The first was in the right bank adjacent to the access point from Cecil Place. A minor hole had developed in the toe of the stopbank which posed a risk of greater damage or failure in a future flood event. Initial emergency works consisted of building-up the hole with filled fadges. When conditions allowed, rock was placed in the toe from the opposite bank to temporarily prevent slumping and further erosion. Bank shaping of the opposite berm was undertaken at the same time to help realign the channel and ease the pressure on the repair. Rock is planned for this area as a more permanent solution.
7.27. The second location was on the left bank, downstream of the Botanical Road Bridge. The area had eroded to the point where the stopbank ramp was in danger of slumping due to the high berm. The area was shaped and rock placed to prevent further erosion until a more permanent fix can be undertaken. The opportunity was taken to shape the berm on the next downstream inside bend to alleviate pressure on the opposite bank.
7.28. Scheme staff also met with staff from PNCC to inspect and initiate discussions regarding repair requirements around City assets. When conditions allow, Horizons will undertake the more urgent repairs with contributions from PNCC. In other locations, where repairs are less urgent, and the walkway is planned be constructed under the bridge, protection works will be combined where possible.
7.29. Most vegetated beaches within the channel were removed during the June flood events. Excessive vegetation growth within the channel needs to be controlled to maintain channel capacity and is usually controlled with spraying or mechanical beach removal.
7.30. A very large poplar tree has been removed from the Mangaone Stream at Allan McKlean’s property on the true left bank.
7.31. Scheme engineers are continuing to monitor flood damage, especially within the City Reaches. Any areas where risk to stopbanks becomes imminent, emergency works will be completed. Non-urgent works are planned for the coming construction season.
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Catchment Operations Committee 16 September 2015
MAKINO STREAM
7.32. Operations staff are currently working with a landowner along the Makino Spillway to remove a culvert through the spillway stopbank. This will reduce the number of slide gates that need to be closed in a large flood event and remove the potential of a culvert failure under the access road to the Makino structure. The landowner will be contributing to these works.
7.33. The flood on June 20 has resulted in significant asset damage. The long reaches of stopbank overtopping caused several breaches in the area between Rata Street and Kitchener Park i.e. three sites on the true left bank and another site on the true right bank. These four sites have all been repaired. However, other than the sites which were damaged during the flood event, there are close to 30 other sites which are programmed to be repaired over the coming months.
7.34. Engineers have been involved with a Makino swimming pool extension that runs alongside the Makino Stream in Feilding.
MANGAORE STREAM, MOUTOA FLOODWAY AND TOKOMARU
7.35. Assets have been inspected and are performing well, with little damage following the June flood event.
7.36. Transpower have been working with scheme engineers and leaseholders to replace a farm bridge in the Moutoa Floodway.
STONEY CREEK / JACK’S CREEK
7.37. Preparation is underway to repair 50 m of lateral erosion on Gary Teague’s property at Stoney Creek. The site is immediately downstream of the State Highway Bridge at Whakarongo. Repairing this site will involve the redistribution of stream gravels from around the bridge which will be placed in the erosion site as back fill. Concrete riprap will then be placed in front to act as the bank protection.
7.38. Two channel blockages have been removed from Jacks Creek. They were mainly tree laden banks slumping into the channel. The slumps were too big to be moved on by the stream so they had to be mechanically removed by an excavator. The erosion sustained onsite at Colin Jürgen’s boundary amounted to 65 m of concrete riprap being placed against the true right bank to protect against lateral erosion.
KARA STREAM and MANGAPUKATEA STREAM
7.39. Stream assets have been inspected and are performing well, with little damage following the June flood event.
ASHHURST STREAM SCHEME
7.40. Scheme assets have been inspected and are performing well, with little damage following the June flood event.
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Catchment Operations Committee 16 September 2015
LOWER KIWITEA STREAM SCHEME
7.41. The 20 June flood was the largest experienced since the Lower Kiwitea Scheme was established, post the 2004 floods. Significant damage was recorded at 25 sites throughout the scheme area and the estimated cost of repair is $400,000.
7.42. Multiple tree/flood debris blockages have had to be cleared to avoid further flood damage and river realignment works were required at 11 sites to gain control prior to undertaking permanent repairs and to avoid further flood damage. The realignment works were completed at the same time as the channel clearance works.
7.43. Permanent repairs have been completed at 10 erosion sites. Six of these, that have been repaired, used tied tree bank protection works, and the other four using rope and rail permeable groynes and a further five sites have had major planting works completed.
7.44. Gravel extraction has also been undertaken to help with the river realignment and in many cases has been done to allow permanent repairs.
KAHUTERAWA STREAM SCHEME
7.45. Engineers are providing advice to NZDF Linton Camp as a result of significant flood damage incurred on their property during the June event. The river bank has retreated by over 10 m in places, undermining the camps explosive store on one bend which caused some consternation in June. Any works undertaken will be fully funded by the NZDF, but will require a consent.
ENVIRONMENTAL GRANT WORK
7.46. Three Environmental Grant Applications are being prepared for the following landowners situated outside the LMS.
Mr Derrick Woods, 100 Te Ngaio Road, Bunnythorpe. Mr Wood’s property borders the top end of Derby Creek. Smaller flood events have recently flooded the back section of Derrick’s land around his workshop. In a 200 year flood event the main house on the property is surrounded by water. Derrick has approached Horizons for advice on remedying his situation, with the suggestion being vegetation removal from the stream channel. A Grant Application is being prepared. Mr Steve Dalley, Reids Line West. The damage is downstream of the bridge over the Mangaone Stream on his property. The work will include vegetation clearance, gravel redistribution and some concrete riprap placement. A Grant Application is currently being prepared. Chris Hill, Spur Road. Mr Hill’s property borders the Mangaone Stream. Mr Hill has concerns over large trees on the channel edge and some erosion at the top end of his property. His property is outside of the LMS. A Grant Application is currently being prepared.
LOWER MANAWATU SCHEME RURAL FLOOD PROTECTION UPGRADE PROJECT
7.47. Preparation is well underway for the very full programme of works for the upcoming construction season. The following table schedules all programmed works and provides commentary on present project status.
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Catchment Operations Committee 16 September 2015
Project Title Description Status Oroua River Left Bank Stopbank Upgrade, Hoihere Upgrade 5,200 m of stopbank on Survey work is complete and Road to Rangiotu the left bank of the Oroua River tender documents are downstream from the Hoihere programmed for completion in Road Bridge to Highway 56, early September. Meetings have Rangiotu been held with all affected landowners on site to discuss the works. All Land Entry Agreements have been posted out. Oroua River Right Bank Stopbank Upgrade, Hoihere Upgrading 5,300 m of stopbank on Survey work is complete and Road to Rangiotu the Oroua River right bank tender documents are downstream from the Hoihere programmed for completion in Road Bridge to Highway 56, early September. Meetings have Rangiotu been held with all affected landowners on site to discuss the works. All Land Entry Agreements have been posted out. Oroua River Right Bank Stopbank Transition at Construct retaining wall, upgrade Affected landowners have been Hoihere Road Bridge stopbank and install road stoplog contacted and Land Entry on the right bank Negotiations will progress during September. Design work is programmed for completion in mid October. Oroua River Left Bank Road Raising at Hoihere Road Raise Hoihere Road to the Affected landowners have been Bridge upgraded stopbank height on the contacted and Land Entry left bank. Negotiations will progress during September. Design work is substantially complete and works are programmed to commence during September. Protect Individual Properties, Hopkins Farming Group, Construct bunds around two The Farm Manager has been 1591 & 1601 State Highway houses owned by Hopkins contacted to discuss details of the 56 Farming Group on State Highway protection works and a Land Entry 56, Tiakitahuna Agreement posted out. Works are programmed to commence in October depending on suitable ground conditions.
Protect Individual Property, S. Bond, 767 Lockwood Protect the Bond house at 767 Two recent meetings have been Road Lockwood Road held with the landowner. A solution has been agreed in principle and negotiations over construction detail are continuing. Protect Individual Property, R. Astwood, 802 Lockwood Raise the Astwood house at 802 Meetings have been held with the Road Lockwood Road landowner and agreement reached. Building consent is currently being sought and works are programmed to be undertaken during October. Discussions have been held with Protect Individual Property, Protect the Muncey house at 821 the landowner. Investigation work V. Muncey, 821 Lockwood Lockwood Road is currently in progress to raise this Road house if feasible.
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Catchment Operations Committee 16 September 2015 Protect Individual Property, G. Lynch, 892 Lockwood Raise the Lynch’s Farm Manager’s Agreement reached with the Road house at 892 Lockwood Road landowner in principle. Some engineering difficulties have been encountered but a contract for this work is expected to be awarded in mid September. Protect Individual Property, Van Oostveen, 691 Construct a bund around the Van This property is on the market and Lockwood Road Oostveen house at 691 Lockwood further consultation will be delayed Road pending the outcome of a sale offer. Protect Individual Property, Strahan Property, Rangiotu Construction 65 m of concrete Documentation is complete. The Road floodwall on Strahan farm to landowner has requested that protect dairy buildings works be undertaken in May 2016. Manawatu River Right Bank Stopbank Upgrade, Karere Upgrade 5,100 m of the Manawatu Meetings have been held with all Road, Longburn River right bank stopbank in the affected landowners on site to vicinity of Karere Road, Longburn discuss the works. Land Entry Agreements have been posted out with half having been returned to date. Survey and design work is scheduled for completion in early October. Manawatu River Right Bank Stopbank Upgrade, Ervine Upgrade 3,600 m of the Manawatu Meetings have been held with all Property & Funnell Lease, River right bank stopbank affected landowners on site to Rangiotu immediately downstream of the discuss the works. Land Entry and Opiki Bridge and through the Rent Relief Agreements have been Ervine property into Taonui Basin posted out. Survey and design D. work is scheduled for completion in late October. Manawatu River Left Bank Stopbank Upgrade, BM 486, Upgrade 1,600 m of the Manawatu Works have been discussed with Funnell Lease, Poplar Road River left bank stopbank on the leasee to discuss the scope Council-owned land currently and potential impacts on his leased by Mr Funnell adjoining farming operation. Survey and Poplar Road, Opiki design work is scheduled for completion in mid November. Manawatu River Right Bank Stopbank Upgrade, Upgrading 17 individual sections of Landowners will be contacted Whirokino Road stopbank on the Manawatu River during September to discuss the right bank in proximity to scope of works and potential Whirokino Road upstream of State impacts on their farming Highway 1. operations. Survey and design work is scheduled for completion in early December.
Manawatu River Left Bank Stopbank Upgrade, Akers Upgrade 550 m of the Manawatu A meeting has been held with the Property, Linton River left bank stopbank at the affected landowner to discuss the Akers property immediately works. A Land Entry Agreement upstream of Akers Road, Linton has been posted. Survey and design work is scheduled for completion in mid December. Manawatu River Right Bank Stopbank Upgrade, Higgins Upgrade 4,880 m of the Manawatu Landowners have been contacted & Tait-Jamison, Whakarongo River right bank stopbank at to discuss the potential works Whakarongo however this project may not be undertaken this financial year.
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Catchment Operations Committee 16 September 2015 8. NORTHERN AREA
GENERAL
8.1. Since the June flood staff have focused on inspecting the channels and assets of the Northern River and Drainage Schemes. This has been done by, air, boat, or ground and the inspection data shows that there has been significant damage throughout the works areas. The inspection information has been used to update the AMS and this will provide the mechanism for staff to programme the coming seasons work efforts.
8.2. Of this damage, temporary repairs have been made in some locations such as the planned stopbank breach at Kowhai Park, however other works will be discussed below in each schemes respective sections of this report.
8.3. Requests for engineering advice has also increased significantly following the June floods as landowners are now recovering from the initial flood event and looking for assistance with damage repairs and advice on longer-term mitigation solutions. Staff have been kept busy visiting and providing help to these ratepayers.
8.4. In addition to flood related issues, there continues to be ongoing requests for advice on verifying catchment boundaries for dairy farm units seeking new or amended consents. Staff have been busy attending; Operations Duty Officers training for the Makino Floodgates; IPad training for asset inspections (using newly developed inspection forms); and First Aid training.
8.5. Letters to all property owners who have a scheme detention dam located on their property have been sent out during this period. These request that property owners submit an invoice for the Licence Agreement fee. The Licence Agreement 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 fee is paid to acknowledge that the owner’s land has been injuriously affected by the dam and the works that may be required.
8.6. Recently Northern staff were heavily involved with the “BIG FIVE” group organising and participating in the Kowhai Park planting and clean-up project in Wanganui. This was a very positive experience for team building with fellow staff members but, more importantly, showing Wanganui community that we care and support them during flood recovery.
8.7. Other tasks going forward include, a meeting which is to be held in the Moawhango Community Hall on 17 September (convened by Genesis Energy) and work on the 2014- 15 Annual Report. Items to be discussed at the Genesis meeting are to include; ecological monitoring and consent appliance; Fish and Game drift dive results; willow management; and flushing flow dates and sediment assessments. The 2013-2014 Northern Area Annual Report is complete and with administration staff for final formatting. Preparation for the 2014-2015 Report has commenced with a completion date expected before Christmas.
RANGITIKEI RIVER CONTROL SCHEME
8.8. Over the past two months extensive inspections by air, land and jet boat have helped staff collate a more accurate assessment of flood damaged sites and areas requiring general maintenance. This will be further enhanced in September when aerial photography is completed showing the changes in river alignment. The floods have left many reaches of the river stripped of vegetation and many hectares lost to bank erosion. Landowners have shown concern at the latest loss and staff are working closely with them to find economic solutions and to action work as soon as possible.
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Catchment Operations Committee 16 September 2015 8.9. Ongoing wet conditions are delaying the start of many flood repairs as river levels remain high and access to sites with machinery is impossible. Since June, the river has experienced five flow events over the Mangaweka 4.0 m alarm level with one exceeding the 4.5 m alarm.
8.10. Where possible, work is continuing with channel clearance on inside bends completed at major erosion sites, drains have been de-silted in flooded areas, repairs undertaken on several stopbank ramps, and a concrete post cleared from the Amon Drain water channel that prevented the floodgate working during the June flood.
8.11. An area of particular concern has been the capital works at Parewanui Stopbanks. Following the completion of the stopbank upgrade contract, the Rangitikei River experienced a significant flood event on 15 May 2015. The flood waters flowed 1 m high against the new stopbank upgrade causing a 400 m length of erosion to the stopbank toe. The estimated cost to repair the flood damage was $30,000. Then, a month later, on 20-22 June, the Rangitikei River recorded a further flood event. This time the stage height readings at the Mangaweka and McKelvie hydrological sites, recorded 6.26 m and 7.05 m respectively. The flood damage to the stopbank batter toe was further exacerbated and the repair cost now estimated at $100,000. However, with weather and ground conditions being very wet, it is not currently possible to complete this repair work.
8.12. As a result, survey design and drawings are currently being prepared to allow a contract to be prepared for physical works to commence in early November. In the meantime, should another flood event occur before remedial work can be completed, a Contingency Plan has been prepared to minimize the effects of any further flooding. The Plan outlines measures, actions, resources and the contact details of property owners.
8.13. There has been no gravel extraction from Horizons consents during this period.
POHANGINA-OROUA RIVER CONTROL SCHEME
8.14. Fortunately, both the Pohangina and Oroua Rivers suffered relatively minor damage during the June floods. Also, because there has been little disruption to most farming operations as a result of the flood, staff have been able to liaise quickly with property owners and gain approval to undertake required bank protection repairs.
8.15. On the Oroua River, repairs have been completed at Mr. Christie’s property and he has expressed his thanks to Horizons for prompt action after the flood. This attitude has been present with many other property owners and they do genuinely appreciate Horizons’ assistance to repair the damage quickly before costs increase as erosion holes enlarge. In addition, tree bank protection work is now approved and will begin over the coming weeks at the Hoggard, Manville, Malcolm and Nesdale properties along with pole planting at multiple sites.
8.16. On the Pohangina River, work has been completed at the Ward property where 750 poles where planted to improve bank stability and is shortly to begin on the Carroll and Aker’s properties.
TOTARA RESERVE
8.17. A substantial area within the reserve has been set aside for native tree planting over the next few weeks and this is to be funded by the He Tina Awa Trust program, an initiative which is viewed upon very favorable by the local community who has expressed their thanks to Horizons.
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Catchment Operations Committee 16 September 2015 8.18. Several sites within the reserve have also been identified for willow planting to improve localised river bank protection. Work is scheduled to begin in September.
8.19. No gravel returns have been received for extraction in the reserve this period.
UPPER WHANGANUI RIVER MANAGEMENT SCHEME
8.20. Work activities in the Taumarunui area remain very quiet with field inspections confirming only minor damage from the June flood. The only item of work as a result of the flood thus far, has been work to repair a section of fence near Turaki Street. Other than that, there was also some vegetation management in the same area.
TARINGAMOTU RIVER MANAGEMENT SCHEME
8.21. While there has been no work undertaken during this period, staff continue to monitor the scheme works area.
MATARAWA FLOOD CONTROL SCHEME
8.22. Following the June flood staff are now busy in the clean-up phase with damage repair tasks being implemented. Flow conditions through the diversion channel exceeded the channel capacity and left extensive areas of bank slumping requiring repair. This is particularly severe around the diversion structure where Horizons are investigating bank stability options at Gudsell’s farm between the Rail Bridge and No.1 Line.
8.23. With the soil completely saturated, the land can no longer soak up water and the area is experiencing high levels of surface run-off with each rain event and the catchment has experienced five significant flows since June, making access for flood repairs impossible. Staff have completed 2 rounds of dam inspections in response to these events, and have prepared a list of work to be undertaken when conditions allow.
8.24. Water ponding behind the Blinkbonnie stopbank is now becoming a problem for the landowner. Staff are currently looking at the issues associated with this problem and working closely with the farmer on a possible solution.
8.25. As time progresses, a number of reports are being received of trees blocking the channel. This is particularly so in the Long Acre and Matarawa Valley area and staff are having these removed as access allows.
TUTAENUI FLOOD CONTROL SCHEME
8.26. Wet weather throughout July and August continues to delay flood clean-up throughout the scheme. Paddocks in many areas remain too wet to allow heavy machinery access so work priories have concentrated on ensuring dam assets remain in good working order and to clear channel blockages where access allows.
8.27. Two rounds of dam inspections were completed following smaller high flow events on 19 July and 8 August. On both visits, there was evidence of some water being retained in the pond and staff removed debris from culvert inlet grills. On a positive note, there was no further sign of damage to the structures.
MAKIRIKIRI FLOOD CONTROL SCHEME
8.28. Following the 20 June flood event there has been ongoing investigations and discussions regarding a proposed floodgate structure, to allow trapped floodwaters to drain. Currently, Horizons has approved an Environment Grant of $27,500 towards the installment of a flood
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Catchment Operations Committee 16 September 2015 egress gate in the Makirikiri Stream stopbank. The property owner has also indicated that he would make a contribution toward the project while the Rangitikei District Council (RDC) are still deliberating on possible funding options to alleviate flooding to Turakina Beach Road and the Redmayne property.
8.29. In the meantime, a decision was made with the property owner not to reinstate the breached stopbank until a decision on the future of the egress structure was known. There are significant savings to the scheme with this decision, as it would not be prudent to repair and then remove the same section of stopbank to enable construction of the egress gate.
POREWA FLOOD CONTROL SCHEME
8.30. Extensive river bank damage occurred throughout the lower reaches of this scheme in June and although it is not up to the scheme to repair, staff have been busy advising landowners on their repair options. This service is valued greatly and helps build a positive relationship with the community.
8.31. A second round of dam inspections has now been completed since the June floods and no further damage has been identified. However, the planned repair work is now awaiting a change in weather conditions and a subsequent drying-out of soil to allow machinery to access the sites without causing excessive damage.
WHANGAEHU MANGAWHERO RIVER MANAGEMENT SCHEME
8.32. The June floods created problems for two dairy sheds which are sited within the immediate vicinity of the bank. In one case, the dairy shed will have to be relocated further away but, hopefully the other will avoid the same fate with extensive plantings on the river bank.
8.33. Discussions are taking place with Kaungaroa Iwi over the viability of retaining the marae in its current location. The site has been flooded on several occasions placing significant clean-up costs on the occupants. One flood protection option being considered is to encircle the marae with a stopbank. Kiwifruit orchardists have also said that they may pull out of the industry as the cost of de-silting their orchards after each major flood event is becoming too costly.
8.34. Maintenance work throughout the scheme this year will focus on the removal of flood debris along the river banks as there is a risk of this becoming mobile in smaller flow events and lodging against downstream bridges. Engineers are waiting on dryer conditions before commencing this task.
TURAKINA RIVER MANAGEMENT SCHEME
8.35. A meeting was held at the Makohau Hall on 7 July to answer questions from the farming community on where they could go for practical, financial and emotional assistance in the wake of the June flood. Although the meeting was instigated by RDC, Horizons and Federated Farmers were present with offers of assistance.
8.36. Like the Whangaehu, maintenance works in the Turakina will concentrate on removing debris from the river bank as a result of the flood when conditions allow.
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Catchment Operations Committee 16 September 2015
LOWER WHANGANUI VEGETATION MANAGEMENT AND FLOOD PROTECTION PROGRAMME
8.37. As mentioned previously, and through other means, there was an overtopping at Kowhai Park during the June floods and as a result, the stopbank had to be opened. At the present moment ground conditions within Kowhai Park remain too wet to allow stopbank repairs to commence. Until conditions improve, staff are keeping a close watch on the temporary sandbag repair implemented after the June floods when protection works were breached to allow the Anzac Parade area to drain. A close collaboration continues with WDC staff around work planned in this area.
8.38. The 20 June flood event has underlined the need for post-planting management of poplars especially if the combined biomass weight is not to become unstable after long periods of ground saturation. However on the whole, vegetation with a high root/branch ratio fared well (native shrubs, flax, willow and alder) whilst hundreds of metres of poplars, oaks and podocarp have been lost from the riparian corridor. There have been a large number of enquiries around riverbank stability in Wanganui and the variability of different vegetation types to secure the banks from slumping.
8.39. Inspections show that while siltation at the Upokongaro Jetty site needs a more extensive clean-up, this work will have to wait until the banks can bear the weight of heavy machinery and that slumping on Papaiti Road (which is not a responsibility of the scheme) may result in the need for Environmental Grant assistance next year.
8.40. Of interest, the considerable silt loading in Whanganui flood waters has created some unusual problems. Sand bars have appeared in places where they have never been before and upstream of the Dublin Street Bridge the boat ramp will only be useable once the access channel is dredged. Again, this is a non-scheme issue.
PAKIHI SCHEME
8.41. Inspections of the dam following the June flood have confirmed that there has been no damage to the scheme assets.
FOREST ROAD DRAINAGE SCHEME
8.42. Inspections have not identified any flood damage to this scheme and staff continue to monitor the situation.
HAUNUI DRAINAGE SCHEME
8.43. Inspections have not identified any flood damage to this scheme and staff continue to monitor the situation.
TAHUNA STREAM (NON-SCHEME).
8.44. Two bed control structures on Alex Glasgow’s property suffered damage when an estimated 100-year return period event hit the catchment in June. Staff have inspected the damage with Alex and are now looking at repair options for him.
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Catchment Operations Committee 16 September 2015
9. EASTERN AREA
GENERAL
9.1. The weather over the last six weeks has been fairly typical for this time of the year and while, fortunately, the consistent rainfall has not been heavy enough to cause any further flooding it has made the paddocks wet, making it hard to complete some urgent works.
9.2. The highest total rainfall recorded in the Eastern catchment over the last six week period was close to 400 mm and this was recorded at the Upper Mangahao hydro recording site in the Tararuas. This is slightly more than was recorded at the same location for the same period last year.
9.3. Since the June floods staff have been busy inspecting scheme rivers, reprioritising works programmes and undertaking emergency repair works. In locations with trout spawning value, emergency works have been undertaken with official notification given to the Compliance team. This period staff have also made a start on the seasons various scheme planting programmes, followed-up general enquiries and managed several Environmental Grant assisted works.
9.4. Looking forward, staff are busy preparing for, and undertaking scheme works which now includes an extra $965,700 worth of flood damage repairs. This extra work is to be funded by a reprioritisation of $249,955 worth of existing budgets and $715,745 of Emergency Reserve funds.
9.5. Once again, a fair amount of gravel has been extracted from scheme rivers this period under scheme consent. Over the last 2 months, 9,400 m³ of gravel in total was taken from various locations in the Mangatainoka, South Eastern Ruahine and Upper Manawatu/Lower Mangahao Schemes. A lot of this material has been taken for the various roading and Fonterra projects which are currently underway within the Tararua District.
AKITIO SCHEME
9.6. So far this season, the Akitio has flowed freely with little interruption and the scheme continues to be in a good position in regard to meeting both its short and long-term works programmes and financial aims. As mentioned previously, the whole works area has been completely treated for willow and regrowth, the channel is in a good condition with the instances of flooding now greatly diminished. There is very little debris left in the channel with most of the woody tree material now either burned, decomposed or washed out to sea.
9.7. However, while the channel is in a good condition and the scheme has achieved its aims, there have been some queries raised regarding the portion of the dead material that has been washed out to sea. Akitio residents are concerned that this material is ending up on the beach and in an extreme event on the road.
9.8. While this issue was raised at the last Annual General Meeting, in March 2015, and the consensus was that the debris wasn’t really causing a big enough issue to warrant the expense of removing it, other residents have canvased the district council to address the problem.
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Catchment Operations Committee 16 September 2015 9.9. Estimates to remove the material are estimated to be tens of thousands of dollars based on the need to gain a consent to allow a weeks worth of digger time to pile the debris, burn it, stoke it and load the ashes on to a truck for removal to a clean fill site.
9.10. There is also the belief that the debris may be doing some good by protecting the vulnerable road from the current foreshore erosion.
9.11. In order to try and address the issue, Horizons’ Councillor (John Barrow), the Area Engineer and the Liaison Committee have organised to meet on 3 September to discuss the matter.
EASTERN MANAWATU SCHEME
9.12. Since the June flood the full channel has now been inspected and with little in the way of damage or debris blockages found, the works programme has been left largely unchanged. The only debris that was found has been cleared and the channel is again clear from blockages and flowing well.
9.13. In essence, the Eastern Manawatu Scheme is in a very similar position to the Akitio Scheme, it is also ahead of its long-term works and financial programmes, and this season will be focused on maintaining the capital works which were completed last season.
9.14. Looking ahead, a small amount of planting has been programmed for the coming weeks. This is in accordance with discussions had at the last Annual General Meeting. Liaison Committee members felt that there was benefit to be had in identifying any vulnerable outside bends that could benefit from planting now that the priority capital works are complete. It is important to note that these are outside bends that were not cleared as part of the works but historically have had little cover.
MANGATAINOKA SCHEME
9.15. The majority of the emergency works required as a result of the June flood have now been completed, with the only site still requiring some completion being the Hamua stopbank. Unfortunately, this work had to be suspended due to damp ground conditions which were preventing fill material from compacting to an acceptable level. However, most of the establishment work has been completed and it is estimated that once the area has dried out, it will take approximately one week to complete. Channel realignment and bank protection work at the site is complete, and a bund has been erected in the hole in the bank, however until the full reinstatement work can be completed the site remains particularly vulnerable.
9.16. The scheme planting programme was also completed this period and saw approximately 4000 willows and 4500 natives planted throughout the scheme. As well as this 1500 large willow logs have also been cut for driving into more difficult sites in the coming weeks. These large logs are much hardier and become established much faster than the traditional stakes. As such, they are used in places where good willow growth is required quickly.
9.17. Going forward, staff are busy preparing for scheme works which now include $389,000 worth of extra flood damage repairs. Funding this will require the reprioritisation of $159,000 worth of budgeted funds and the addition of $230,000 worth of Emergency Reserve funds.
9.18. Gravel extraction on the Mangatainoka Scheme this period has been limited to only four takes, with the total amount extracted 4,400 m³. 4,000 m of this was extracted from one
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Catchment Operations Committee 16 September 2015 site at Halls Road. Staff have been working with extractors to ensure compliance with the scheme’s resource consent conditions.
SOUTH EASTERN RUAHINE SCHEME
9.19. Management’s main focus over the last six weeks has been to complete the emergency flood damage repairs that were needed following the June flood. Generally this has involved clearing a large number of sites that were blocked with debris and gravel by the flood waters. Often these blockages were so severe that the streams were not able to flow in the original channel at all.
9.20. Inspections have also shown that a large amount of gravel has entered the channels (most likely from the headwaters) which is not only causing the blockages described above, but has filled the established extraction sites, especially those in the Kumeti, Raparapawai, Tamaki and Mang-Atua Streams. Given that the extraction sites are designed to fill first and prevent blockages, the situation confirms the need for managed extraction to prevent any further blockages occurring. As such, a small amount of gravel extraction has already taken place and staff are working to direct any enquiries to those locations which will benefit the scheme the greatest. 2,700 m³ was extracted under the scheme’s consent this bi-monthly period.
9.21. Going forward, staff will be busy preparing for scheme works which now include $397,500 worth of flood damage repairs. Funding this will require the reprioritisation of $40,000 worth of budgeted funds and the addition of $357,900 worth of Emergency Reserve funds.
IHURAUA SCHEME
9.22. Recent inspections show that while the Ihuraua is flowing at a normal winter level, last seasons works have ensured that the channel is clear and free flowing. Work to clear several blockages and small constrictions, as identified in the 2011 Scheme Audit, have clearly been of benefit.
9.23. Over the coming months staff will continue to monitor the stream and prepare for works later in the season.
TAWATAIA - MANGAONE SCHEME
9.24. As with the Ihuraua, the water levels in the Tawataia and Mangaone Streams have risen to winter levels and last seasons works are ensuring that the channels flow as freely as possible.
9.25. Inspections also show that the detention dam filled to a considerable level in the June flood and that while the spillway did not flow in this event, it does remind us of the relevance of the Ministry of Business, Innovation and Employment’s recent decision to revoke the Dam Safety Regulations which were planned to finally come into force in July 2015.
9.26. Under this regulation the Tawataia Dam, which had been classed as a ‘Referable’ dam with a medium ‘Potential Impact’, was likely to need a further upgrading of the spillway. While a partial upgrade has been undertaken in the aim to achieve a 1 in 100 year capacity, further works would have been required if the draft legislation was finalised. As such, the scheme can only continue to prepare financially for this requirement in the supposition it will be needed.
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Catchment Operations Committee 16 September 2015
UPPER MANAWATU – LOWER MANGAHAO SCHEME
9.27. Following the June flood, damage repair works are underway, however these are progressing slowly due to the wet paddocks and constantly high river levels. Maintenance works in the form of planting have been completed over the last two weeks with a total of 2,500 willow poles planted in ten locations throughout the schemes two works areas.
9.28. Going forward, staff are busy preparing to undertake scheme works which now include $179,200 worth of flood damage repairs. Funding this will require the reprioritisation of $50,995 worth of budgeted funds and the addition of $128,245 worth of Emergency Reserve funds.
9.29. A reasonable amount of gravel extraction has taken place over the last 2 months. 2,300 m³ was again extracted from the Mangahao for use at the Fonterra factory upgrade at Pahiatua. Fortunately, due to the sites close proximity to the factory, the metal has been extracted from a location which has long needed the relief of gravel extraction. While the consent allows for a total of 8,000 m³ to be extracted from the Mangahao, there are few sites that are actually suitable for extracting from.
ENVIRONMENTAL GRANT WORKS AND ENGINEERING ADVICE
9.30. With the increase in rain and higher river levels there has been continues to be a marked increase in general river and drainage enquiry with some likely to qualify for Environmental Grant assistance.
9.31. In the last two months the works of two previously approved Environmental Grant Applications have been completed, these were at the Bennett’s and Norman’s properties on the Mangahao (above the works area) and consisted of tied tree work, two rope and rails and a substantial amount of planting.
9.32. The status of all Environmental Grant works will be further reported on in a separate item in the agenda document.
10. SOUTHERN AREA
GENERAL
10.1. As with much of the Region, the weather over the last six weeks has been fairly typical for this time of the year. While there have been no significant rainfall events, the consistent rainfall on already saturated ground conditions has been sufficient to cause surface flooding and to keep most drains up for long periods of time.
10.2. Both drainage and flood related enquiries, continue to consume a significant amount of staff time. Generally, landowners are seeking advice on how to remove ponded water or, are wanting to report damage.
10.3. Several enquires have also been received regarding the flooding of buildings, with landowners seeking options to provide long-term protection. In most cases, these properties are within the Manawatu Drainage Scheme and have flooded as a result of the extreme localised rainfall event and/or overland flows of flood waters from spillway operations or riverbank overtopping. Current drain design capacities are based on a 2-5 year rainfall event, with stopbanking only in place in the lower reaches of the scheme around Burkes and Main Drains. Clearly, any change to the existing levels of service will need to be investigated and consulted on.
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Catchment Operations Committee 16 September 2015 10.4. New hazard signs have been installed at all scheme pumpstations with the purpose of producing a comprehensive report which covers the following aspects of the pumpstations:
full and detailed visual inspection of the pumpstation and all its components; to asses the pumpstations components, such as the electrical work, building, pumps, and mechanical parts, commenting on the remaining useful life, and items due for renewal; to discuss whether the pumpstation is continuing to provide the required level of service for the drainage scheme; to produce a comprehensive list of all improvements that need to be made to the operational and maintenance efficiency of the pumpstation; and to asses weather the pumpstation meets the current health and safety requirements, and if not, how will these issues be mitigated.
10.5. A safety inspector from Site Safe has now completed three health and safety site audits at three scheme pumpstations. Site Safe is a nationwide team of health and safety professionals that offer safety systems, training, consultancy, and audits. The results of the audits will be included in a comprehensive report which is currently being undertaken by Council staff.
10.6. New EDAC systems have been installed at Koputaroa No. 2, Donnelly’s and Dixon’s Pumpstations. This EDAC is a new text messaging system allowing staff to determine the current status of the pumpstation, as well as allowing the system to generate and send alarm notifications to Council staff regarding issues at each station. This now brings the number of stations with this system to 11.
OHAU-MANAKAU SCHEME
10.7. Recent periods of heavy rainfall have seen numerous freshes within the various river channels mentioned below. Although these flows have not caused any further damage to river edge protection, they have caused delays in getting the flood damage remedial works underway. River heights of note were: 1.39 m, 81 m³/s on the Ohau on 25 August, and 1.2 m (33 m³/s) on the Waikawa; with the Manakau reaching 1.7 m (8.4 m³/s) on 28 July.
10.8. During this period programmed maintenance of edge protection was completed along seven different sites on the Ohau and two sites on the Waikawa. This maintenance, which involved layering and mulching, ensures that existing willow trees on the channel bank maintain a healthy coverage, which provides front line protection against floods.
10.9. Historically, tied tree protection has been used extensively along the Ohau River to repair damage and provide edge protection. Following the June flood, four sites have required attention to reinstate the edge protection provided by these assets. This work has involved either the layering of the existing trees, placement of additional trees (to bolster the works), or the replacement of damaged or lost railway irons. The most notable of these repairs was on Bishops Bend, which required 16 new irons and additional trees to repair the asset.
10.10. Other works on the Ohau-Manakau include the construction of several large tree groynes at four sites on the Ohau River, and the placement of, concrete riprap at six sites on the Ohau River and Waikawa Stream to repair, or extend, existing works and work needed as part of channel realignment.
10.11. Sections of the Takapau Drain and the lower section of the Manakau Stream was machine cleaned to remove weed and silt build-up.
10.12. Large amounts of debris were removed from the Ohau River, Waikawa and Manakau Streams following the June floods. The majority of this debris was moved to the outside of
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Catchment Operations Committee 16 September 2015 the channel flood-flow areas to ensure that it does not cause any issues further downstream.
MANAWATU DRAINAGE SCHEME
10.13. Since the June floods, staff have been busy inspecting scheme drains to identify damage and to prioritise repairs if required. In most cases the channels have remained in good condition allowing the free flowing operation of the drain. Some damage has occurred as a result of slumping or erosion and these sites have been identified and prioritised, with works already underway at several of these sites.
10.14. Heavy localised rainfall and over-flows from the Oroua River caused significant overtopping and damage to the drains along Oroua Road. Due to significant structural damage, three access-way culverts, off Oroua Road, that cross the Upper Aorangi Drain, were replaced. Headwalls on two additional culvert crossings off Oroua Road were replaced with new sand bag walls and the top re-gravelled.
10.15. Bank protection work was carried out along four stretches of the Upper Aorangi Drain along Oroua Road due to significant slumping. Power poles and railway irons were used to stabilise the toe of the slump then it was back filled.
10.16. A drain that runs down the middle of five Campbell Road properties was machine cleaned and re-dug in order to improve the water flow.
10.17. Meetings have been held with several landowners regarding the length of time that water was ponded on their properties following the June flood event. In most cases the issue stems from the ability of water trapped behind stopbanks to get back into Burkes and Main Drains through existing floodgated culverts. Further design investigation will be required to determine an appropriate design standard of any potential future upgrades. Any changes in design standards will have an impact on the current level of service and will require consultation with the wider scheme ratepayers.
10.18. Staff have met with representatives from PNCC to discuss the slumping that is occurring on Whiskey Creek alongside Flygers Line. At several locations, the slumping has encroached onto the road and has forced PNCC to close the road down to a single lane. Further meetings with PNCC staff will be arranged once they have had an opportunity to review their options regarding the maintenance or future use of the road.
10.19. On 15 May, Burkes Pumpstation was fired up for the first time in response to heavy rainfall. While running two mains supplied pumps faulted as a result of moisture being detected in the junction box. The tests, undertaken by both Max Tarr and Flygt, confirm the fault and a decision was made to withdraw the two affected units so they could be inspected. Subsequent inspections identified damage to the casing of the main power cables which allowed water to seep down the cable and into the junction box. Both pumps have since been repaired and were installed back into the station on 3 August.
10.20. Heavy rainfall on 7 August resulted in levels across the Manawatu on the raise again and by early Saturday morning the levels in Burkes Drain were such that the pumps were again fired up. By mid morning all four pumps were operating without issue and they continued to operate until late Sunday afternoon when a decision was made to switch off the two diesel generator pumps once gravity drainage was operating. The two mains-supplied pumps remained in operation until the early hours of Monday morning.
10.21. Also to occur during this reporting period, has been the scheduled maintenance inspection of the Burkes Pumpstation generator, this was carried out by Goughs Power System.
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Catchment Operations Committee 16 September 2015 10.22. Grassed areas around Burkes Pumpstation have been sprayed in preparation for the site to be planted with selected native plants. The organising and supervision of the planting has been done in conjunction with Aaron Madden, Environmental Programme Coordinator.
MAKERUA DRAINAGE SCHEME
10.23. During this reporting period submersible pumps form both Boundary and Birnie Coombes Pumpstations have been overhauled and reinstalled after problems were identified during the June event. Also during this period, a pump at Donnelly’s Pumpstation has had to be switched off after staff discovered the pump was vibrating during its operation. The pump will be pulled and serviced once ground conditions improve. In the meantime, the remaining pump at the site is fully operational.
10.24. Both, Council machinery and staff have been kept busy clearing weed build-up from in front of the various pumpstation weedscreens. Unfortunately, dead livestock has had to be removed from Okuku and Boundary Pumpstations.
10.25. Staff have met with representatives from HDC to discuss proposed improvements to the intersection of Linton Main Drain Road and Tane Road. The proposed improvements will require several floodgated culverts to be extended to enable the proposed changes.
KOPUTAROA DRAINAGE SCHEME
10.26. The electrical upgrade at Koputaroa No. 2 Pumpstation is now complete following delays to the installation due to the June floods. The upgrade has replaced the existing switch/control board, which was identified during a recent condition report, as being outdated and containing components which were no longer available. The upgrade is part of a renewal program which aims to standardise the electrical components across the various scheme pumpstations making it easier for future maintenance.
10.27. A new culvert was installed adjacent to Aratangata No. 1 Drain outlet. This extra gate will assist the existing gate with the egress of water from the surrounding paddocks.
MOUTOA - WHIROKINO DRAINAGE SCHEME
10.28. Repairs have been completed on a culvert crossing on Drain No. 5 after the headwall had partially collapsed blocking the drain and restricting access across the culvert. As the culvert is used by both the scheme and the landowner, repair costs were shared.
TE KAWAU DRAINAGE SCHEME
10.29. During the flood event in June, Dixon’s Pumpstation was completely submerged under flood waters saturating all of the electrics, causing damage to the pump and the building. New electrics have since been installed and the pump fully refurbished. Repairs to the building have also been completed with the inside of the building being relined, sheet iron put on the door, the door rehung and base course placed and compacted around the outside of the pumpstation.
10.30. The outlet from Dixon’s Pumpstation had also significantly undermined, so repair work involving the headwall concrete being cut back, and rock placed to stabilise the outlet pipe has also had to be completed.
10.31. Three culverts that cross scheme drains, within Willy Duncan’s property, have been repaired due to undermining and suffering structural damage during the June flood event.
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Catchment Operations Committee 16 September 2015 10.32. Scouring on the right bank of Drain No. 1, which feeds into the Te Kawau Main Drain, was discovered during the flood damage inspections. This has since been repaired.
10.33. Along Drain No.6, on Dawn’s property, a culvert pipe had slumped into the drain allowing water to backflow in to his property. The pipe was lifted back in place and concreted over to secure it in place.
10.34. At Reesby’s property, in the Kopane Basin, pumping was carried out after significant rain fell in August resulting in substantial ponding. At the request of Fonterra and the landowner, two tractor pumps were used to pump the water from the paddocks into Kopane Drain No.3.
FOXTON EAST DRAINAGE SCHEME
10.35. Following the heavy rainfall in June which resulted in overtopping occurring along Kings Canal at the back off the Foxton Township, and flooding along the full length of Purcell Street Drain, staff have completed a full inspection of the drain and have identified several issues. The issues identified include:
the build-up of sand in the invert of the canal from Nye Street through to Union Street; bank slumping and dumping of household rubbish in Purcell Street Drain; and erosion and damage to the outlet culvert at the end of Purcell Street as a result of pumping undertaken during the June event.
10.36. However, all of these issues have since been resolved and the canal is fully operational.
10.37. Staff were invited to attended a meeting of the Foxton Community Board on 17 August, at the Manawatu College Library, along with a representative from HDC to discuss the flooding issues that occurred during the June event. While the Board and several attendees expressed concerns about the level of flooding that occurred during that event, staff from both Horizons and HDC explained that the current scheme is not capable of dealing with events of that magnitude and without significant upgrading of the schemes infrastructure this would be unlikely to change. Any changes to the level of service would require the full support of both the Community Board and HDC and would require significant design investigation and consultation before these changes could be implemented.
HOKIO CATCHMENT DRAINAGE SCHEME
10.38. Debris that had caught on overhanging vegetation during the recent flood have been pulled out of Arawhata. In addition to the removal of the debris, a number of trees were also cut back and some minor channel work completed along the side of the channel to improve channel capacity.
10.39. A meeting was held with the HDC to progress discussions around the funding and impacts of the coming seasons works programme to upgrade various drainage channels and culverts this season.
HIMATANGI DRAINAGE SCHEME
10.40. Over the last six weeks staff have met with representatives of the Koputara 382 and 383 Trust to discuss their concerns regarding the construction of a new link drain between Lake Koputara and the two lower lakes.
10.41. The new link drain was constructed after the existing link channels had become blocked by Raupo, restricting the flow between the lakes and causing surface flooding on surrounding
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Catchment Operations Committee 16 September 2015 farms. Accessing the existing channels would have resulted in significant damage to existing lake edge vegetation, so after discussions with representatives from Horizons’ Science and Environmental teams, it was agreed that the best solution was to construct a new channel. While the new channel has resulted in the free flow of water between the lakes, the Trust members are concerned that this has impacted on their ability to access the lake and it has lowered the level in Lake Koputara. After several meetings with Trust members, staff have agreed to investigate options to improve access to the lake, to restrict the outflow from Lake Koputara and to enhance the lake environment. A further meeting to discuss options and to continue to work on the relationship with the Trust members is scheduled for 11 September.
11. ENVIRONMENTAL GRANT WORK
11.1. One new project was approved for Environmental Grants during the reporting period. The status of grants approved during the 2015-16 year to date, together with those approved last year but deferred, is as shown in the table below:
Name River Type of Work Date Work Estimated/ Value of Approved Status Actual Grant Works Cost ($) Blackfern Ongarue River Tree removal, 12/8/2015 Yet to $1,800 $540 estimated Lodge cut up and commence estimated stack. N Tripe and Mangatipona Grade control 30/4/2015 Yet to $15,440 $4,632 estimated T Mathews Stream commence estimated
G Bennett Upper Erosion 12/6/2015 Yet to $22,370 $6,710 estimated Mangahao protection commence estimated River K Norman Upper Erosion 17/7/2015 Yet to $7,360 $2,208 Mangahao protection commence estimated estimated River
12. SIGNIFICANCE
12.1. This is not a significant decision according to the Council’s Policy on Significance.
Richard Apthorp Allan Cook AREA ENGINEER EASTERN GROUP MANAGER OPERATIONS
ANNEXES A Schedule of Completed Works
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