CONTENTS INTRODUCTION. 3 OVERVIEW. 3 CARTERTON S WASTEWATER STRATEGY. 5 THE CARTERTON WASTEWATER CATCHMENT. 8 FUTURE GROWTH

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1 CONTENTS 1. INTRODUCTION OVERVIEW CARTERTON S WASTEWATER STRATEGY THE CARTERTON WASTEWATER CATCHMENT FUTURE GROWTH THE EXISTING CARTERTON WASTEWATER SYSTEM RECENT TREATMENT UPGRADES PLANNED FUTURE UPGRADING TO SUPPORT THE CONSENTS APPLIED FOR STAGING OF PROPOSED UPGRADING WORKS PROPOSED DISCHARGE REGIME SHORT-TERM LONG-TERM COMMUNITY ENGAGEMENT REGIONAL CONTEXT EXISTING CONSENTS EXPIRY OF GWRC CONSENTS AND CONTINUED OPERATION OPERATIONAL PERFORMANCE OF WWTP OPERATIONAL PERFORMANCE OF THE EXISTING LAND IRRIGATION ACTIVITIES OPERATIONAL PERFORMANCE OF RETICULATION NETWORK PROPOSED MANAGEMENT PLANS CONSENT STATUS EFFECTS ON THE ENVIRONMENT: DESCRIPTION OF RECEIVING ENVIRONMENTS EFFECTS OF DISCHARGES TO GROUND FROM WWTP PONDS, SEQUENTIAL BATCH RESERVOIRS AND WETLANDS EFFECTS OF EXPANDED LAND IRRIGATION EFFECTS OF PROPOSED NEW DISCHARGE OUTFALL STRUCTURE EFFECTS OF DISCHARGE TO MANGATĀRERE STREAM EFFECTS ON DOWNSTREAM CATCHMENT MASS LOADS EFFECTS OF CONSTRUCTION OF SEQUENTIAL BATCH RESERVOIRS EFFECTS OF RE-CONTOURING EARTHWORKS FOR CREATE SECOND CENTRE PIVOT RELEVANT RMA DECISION-MAKING FRAMEWORK PART SECTION 104 (1) SECTION 104 (1) (2A)... 58

2 2 32. SECTION 104B DISCRETIONARY ACTIVITIES SECTION 104D THRESHOLD TESTS FOR NON-COMPLYING ACTIVITIES SECTION 105 ADDITIONAL CONSIDERATIONS FOR APPLICATIONS FOR DISCHARGE PERMITS SECTION 107 ADDITIONAL REQUIREMENTS FOR DISCHARGE TO WATER SECTION 168A PARTICULAR REQUIREMENTS FOR DESIGNATIONS CONSIDERATION OF ALTERNATIVE SITES, ROUTES AND METHODS AND BEST PRACTICABLE OPTION NECESSITY FOR THE WORK AND DESIGNATION SECTION 176A OUTLINE PLAN REQUIREMENTS ASSESSMENT AGAINST PART 2 MATTERS AND RELEVANT POLICY PROVISIONS CONDITIONS CONCLUSION HYPER-LINK REFERENCE MATERIAL... 73

3 3 1. Introduction This Assessment of Effects on the Environment supports the notice of requirement and applications for discharge permits and land use consent for Carterton District Council s proposed wastewater treatment, management and disposal facilities. The notice of requirement is lodged with Carterton District Council (in its regulatory capacity). The applications for discharge permit and land use consents affecting stream bed are lodged with Greater Wellington Regional Council. For completeness and transparency, the notice of requirement and applications are presented together. The proposals will operate as an integrated, whole system and the assessment of effects is made on that basis. Different provisions of the Act pertain to the notice of requirement and the applications for consent and the requirements for evaluation of them differ. Those evaluation requirements are discussed in Sections 30 to 35 of this assessment. 2. Overview Carterton District Council has a long-term aim to improve water quality in the Mangatārere Stream by removing urban wastewater. This aim will take a great deal of planning and investment over many decades. The Council has made good progress towards the long term aim since purchasing the Daleton Farm, adjacent to the wastewater treatment plant, in The Council has established centre-pivot and drip-line irrigation of treated wastewater to approximately 20 hectares of land within Daleton Farm. This has meant that there has been nil discharge of treated wastewater to the Mangatārere Stream during the 2014/2015, 2015/2016 and 2016/2017 summers when stream flows were at their lowest. The Council has also invested in treatment process upgrades, such as the installation of ultra-violet disinfection to enhance the tertiary treatment of wastewater. The Council s objective, for the next 35 years is to minimise the number of occasions and the total volume of treated wastewater discharged to the stream. This will be achieved by: a. Earthworks on the lower terrace of Daleton Farm: including filling and levelling and relocation of the existing ephemeral channel to the western boundary of the site; b. Constructing three sequential batch reservoirs (SBRs): the SBRs will have a combined storage capacity of 200,000 cubic metres and will provide additional treatment. The SBRs will allow the Council to hold treated wastewater within the site, to irrigate treated wastewater to land when soil conditions allow, and to only discharge to the stream when stream flows are high; c. Re-locating the point of discharge into the Mangatārere Stream: the current outfall discharges into an unnamed tributary of the Mangatārere Stream adjacent to the wastewater treatment plant. It is proposed to re-locate the point of discharge downstream to the true left bank of the main stem Mangatārere Stream just upstream from the State Highway 2 bridge. The new discharge structure is to comprise a series of diffuser ports set into a 2-metre-high gabion rock basket wall set at a water level appropriate to enable discharge during flows above 2x median flow in the stream. The structure will have rock rip-rap placed on the stream face to protect it from erosion. Construction of the outfall will occur during a dry period, clear of the flowing stream, and potential earthworks construction effects are expected to be contained without affecting the stream;

4 4 d. Installing a second centre-pivot irrigator and additional non-pivot irrigation equipment: this will enable irrigation of treated wastewater to an additional 30 hectares of land within Daleton Farm; e. Discharging to the stream in high stream flow events: it is proposed that tertiary treated wastewater will discharge to the mainstem Mangatārere Stream only in stream flows at or above 3x median flow and in stream flows above 2x median flow during times of exceptionally high inflows to the WWTP which are unable to be irrigated to land or stored in the reservoirs. Three times median stream flows are known to have high ambient levels of contamination already and have sufficient velocity to mobilise the stream substrate. This means that nutrient-rich treated wastewater will not accumulate in the near downstream environment. This will ensure treated wastewater contaminants will not cause increased periphyton growth or chronic ecological effects in the downstream environment. The features described above are illustrated in Figure 1 (in Attachment 1). A period of 3 to 5 years is needed to implement the above improvements. During this time, the Council has no option but to continue the existing discharge of tertiary treated wastewater to the unnamed tributary. Compared with the current discharge regime, the future combination of a higher standard of tertiary treatment, on-site storage, re-located discharge point and high-flow-only discharge will mean improved water quality in the downstream Mangatārere Stream receiving environment (as measured by chemical composition, periphyton growth and macroinvertebrate health). Carterton District Council has considered a range of alternative treatment and disposal methods and has concluded that its proposed treatment standard and combination land and water discharge regime represents the best practicable option for the foreseeable future, having regard to: a. the nature of the discharge and the sensitivity of the receiving environment; b. the financial implications compared to other alternatives and the affordability of the proposed system; and c. the achievability of the proposed system and certainty that it can be successfully and sustainably applied. The land use consents and discharge permits applied for will enable the proposed treatment, storage, land irrigation and stream discharge regime. Whilst acknowledging that the proposed periodic discharge of treated wastewater to the Mangatārere Stream during high flows will contribute to potential contamination of downstream Ruamāhanga River receiving environment, the proposal represents significant reduction in adverse instream effects compared with historical discharges from the Carterton wastewater treatment plant. The effects of the discharge on the receiving environment are expected to be no more than minor. Accordingly, a 35-year duration is sought for all consents (except the 5-year duration for the interim consent for continued discharge to the unnamed tributary). Condition 44 of the current discharge permit (WAR090120) requires the Council to investigate alternatives for the discharge of treated wastewater from the Carterton WWTP so as to minimise the discharge to and its effects on the Mangatārere Stream. This must include long term options for avoiding discharges during stream flows below half median. The discharge regime proposed

5 5 by these applications achieves that aim (nil discharge is proposed during stream flows below half median) and goes considerably further. Apart from emergency discharges to flows above twice median in extreme conditions, it is proposed that all treated effluent will be either irrigated to land or discharged to stream only in flows above 3x median. Consent is also sought, for a maximum 5-year interim period, to allow the current discharge regime from the existing discharge outfall to continue while the infrastructure to support the 35- year discharge regime is installed and commissioned. The effects of this temporary continued discharge are not expected to differ from those currently experienced. The ecological assessment is that the effects on the stream of the existing discharge are measurable but not significantly adverse. These effects, and continuation of them for the interim 5-year period applied for, are assessed as minor and will not give rise to any of the unacceptable outcomes listed in section 107 of the Act. Beyond the installation and commissioning period for the proposed upgrading works, consent is also sought for retention of the existing discharge outfall for emergency and unforeseen discharges of treated wastewater to the unnamed tributary during periods of urgent maintenance. These are expected to be infrequent. The effects of any infrequent and shortduration discharges are assessed as minor. Since 2014, the Council has been developing amenity wetlands and planting parts of Daleton Farm with indigenous plants. In addition to the treatment and land irrigation purposes, the notice of requirement lodged with Carterton District Council also includes this amenity planting and the future recreational uses of these areas by the public. 3. Carterton s Wastewater Strategy CDC confirmed in 2015 its Infrastructure Strategy addressing Council s wastewater, water supply, stormwater drainage and roading assets. The Strategy covers the 30-year period until The Strategy identifies the significant issues facing the Council s infrastructure assets and the principal options for managing those issues. For the purposes of planning, the Council has assumed that, for the foreseeable future, any future local government reorganisation proposals will not alter the need for the continuing operation of the Carterton wastewater treatment and disposal facility. The Council s long-term (35-year plus) aim is to remove the discharge of treated wastewater effluent from the Mangatārere Stream all year round, other than in exceptional circumstances (such as extreme rain events that temporarily overwhelm the treatment plant s capacity). Whilst the intention is to review the Strategy 3-yearly (next due in 2018), the current intention for wastewater assets involves three stages over the Strategy s forecast 30-year period. The Strategy recognises that, while outright ownership by CDC of the total land requirement (250 ha gross to achieve 160 ha net usable area 1 ) for irrigation to achieve its aim is likely to be beyond its financial means, a public/private land ownership arrangement is possible. Within this mix, ownership of the land required for bulk storage infrastructure upstream of land discharge distribution points would logically be held by CDC because of the strategic significance of the storage asset(s). The Strategy is summarised below: 1 It is estimated that approximately 160 hectares of net usable land is required for land irrigation of all treated wastewater. Accounting for gullies, steep areas and other unsuitable areas the total gross land area requirement is likely to be in the order of 250 hectares.

6 6 Stage 1 = Continue inflow & infiltration investigations; Continue network condition assessment, rehabilitation & replacement; More tightly manage trade wastes; Implement the 2014 consent for Stage 1 irrigation to land on Daleton Farm (completed); Install UV disinfection (completed); Operate and monitor the environmental effects of land irrigation Prepare application for replacement consents informed by monitoring data (these applications); Develop sustainable land use practices on Daleton Farm (under way); Pilot scale test and design Sequential Batch Reservoirs (completed); Line the treatment wetland inlet and outlet channels and replant the wetland cells (scheduled for April 2017). Stage 2 = Complete earthworks on Daleton Farm in preparation for the second irrigator, including levelling of the site and relocation of the existing ephemeral channel; Construct on-site Sequential Batch Reservoirs on Daleton Farm; Relocate existing stream discharge to the lower reach of Mangatārere Stream immediately above the State Highway two bridge and close to the confluence with the Waiohine River; Install second centre pivot and extend on-site irrigation area; Discharge to stream during high stream flows (except in rare events when extreme weather conditions overwhelm on-site storage capacity); Further develop amenity wetlands; Continue inflow & infiltration investigations including interception and lowering of shallow groundwater; Continue network condition assessment, rehabilitation & replacement; Continue to tightly manage trade wastes; Progressively investigate opportunities for supplementary land for additional storage and irrigation; Develop sustainable arrangements that facilitate long term security of tenure over privately owned land available and suitable for irrigation. Stage 3 = Progressively expand supplementary bulk storage capacity for treated wastewater off-site as land becomes available and is affordable (land additional to Daleton Farm); Extend irrigation to land additional to Daleton Farm as suitable private and/or Council-owned land becomes available and is affordable; Continue irrigating treated wastewater to Daleton Farm; Continue high-flow stream discharge; Continue inflow & infiltration investigations. Continue network condition assessment, rehabilitation & replacement; Continue tightly managing trade wastes.

7 7 The Strategy seeks to address six issues: Groundwater infiltration entering the sewer pipe network, necessitating an ongoing programme of investigations, assessment, interception of groundwater and/or repair and replacement to reduce unwanted inflows to the wastewater treatment plant; Forecast future increased wastewater generated by residential growth; The impact of trade wastes on treated effluent quality; A tightening of environmental standards signalled in the GWRC Proposed Natural Resources Plan and early outputs from the Whaitua planning process; The importance of using existing wastewater facilities as efficiently as practicable by optimising the capacity of the existing WWTP and Daleton Farm; and The importance of achieving a high degree of certainty in giving effect to the Strategy. The Council has made a significant investment in land and treatment and discharge systems recently (including the purchase of the Daleton Farm property in 2012) to enable achievement of Stage 1. The Council has also included substantial funds in the current LTP and Annual Plan to achieve Stage 2. The Council has demonstrated its commitment to reducing discharge to the Mangatārere Stream and improving the discharge quality including by installing a UV light irradiation disinfection plant in 2013 and by establishing the 20ha irrigation system on Daleton Farm in These current applications represent the Council s commitment to significantly further reducing the frequency, volume and effects of treated wastewater discharge to the stream by installing the SBRs, second centre pivot irrigation area and replacement discharge outfall. For a local authority of Carterton s size, the financial commitment is significant. In addition, the Council has continued to fund improvements in environmental outcomes associated with its wastewater management generally. In its most recent, draft 2017/2018, Annual Plan the Council proposes the following staged implementation of the wastewater management upgrade: 2017/2018: Re-contouring the proposed second centre pivot irrigation area and construction of the substitute ephemeral channel 2017/2018; SBR design finalised 2017/2018; 2018/2019: Construction of the SBRs; 2019/2020: Construction of the replacement discharge outfall and pipeline; 2020/2021: Installation of the second centre pivot irrigation system. The proposed implementation programme will enable improvement in stream water quality at the earliest practicable opportunity whilst being financially sustainable for the community. These current applications seek the consents that are necessary to allow the core treatment and disposal activities relied upon during Stages 2 and 3. Those core activities are: tertiary treatment, storage, land irrigation and high-flow stream discharge. These activities will continue to be required during and beyond Stage 3 whilst the supplementary land irrigation areas are identified and secured. That is the reason why the maximum consent duration is sought (35 years) for these

8 8 activities. The applications also seek the continuation of the current discharge regime from the current discharge outfall to the unnamed tributary whilst the infrastructure necessary to support the long-term high-flow discharge regime is installed and commissioned. Thereafter, the application seeks consents for retention of the existing discharge outfall for discharge during emergency and unforeseen periods when urgent maintenance is required. It was signalled in CDC s 2015 Infrastructure Strategy that the stream discharge may be shifted to the Waiohine River. However, further investigation of treatment systems and potential environmental effects since the preparation of the Strategy suggest that it is not necessary to shift the stream discharge point from the Mangatārere Stream to the Waiohine River. The Strategy had assumed that, at some point, the greater dilution achievable in the Waiohine River receiving environment would be necessary. However, current analysis confirms that in-stream effects in the Mangatārere Stream receiving environment can be minimised to an acceptable level over the proposed 35-year consent term by adopting the proposed combination of additional land irrigation, sequential batch reservoir treatment, storage and high-flow stream discharge. Relocation of the discharge point to the main stem Mangatārere Stream, just above its confluence with Waiohine River near the SH2 road bridge, achieves increased dilution. This, combined with the additional treatment provided by the SBRs and managed high-flow stream discharge, represents the best practicable option. Importantly, even if the Council is able to secure additional land for land irrigation or storage in Stage 3 of the Strategy, it expects that these improvements will still need to be supported by occasions of high-flow discharge to the stream. Consent for stream discharge is therefore required during Stage 3 and beyond, for the 35-year consent term sought. 4. The Carterton Wastewater Catchment Carterton is a small district, encompassing predominantly rural land on the eastern side of the lower Tararua Ranges. The District is one of three Wairarapa local authorities, located between Masterton District to the north and South Wairarapa District to the south. The reticulated network catchment comprises the urban area of Carterton. The usually-resident population of this area was recorded as 4,686 at the 2013 Census. Council s 2015 Wastewater Asset Management Plan records approximately 2,400 properties connected to the system. The predominant land use in the district is pastoral agriculture, principally beef and sheep and dairy farming, with a significant amount of forestry in the eastern hill country. The main employment sectors are agriculture, forestry, and fishing. There is a small industrial precinct located at Waingawa at the northern end of the district near the Masterton District boundary. However, that industrial precinct s wastewater is, by agreement, reticulated for treatment and disposal at the Masterton wastewater treatment facility. There is a moderately-sized food processing factory 2 located in the south-eastern sector of Carterton s wastewater network. The factory s trade wastes are reticulated to the Carterton wastewater treatment facility. After discussion with the Council, the factory in 2015 installed the first stage of an on-site package treatment plant comprising a dissolved air flotation unit, which substantially reduces the phosphorus concentrations of the trade waste discharged to the 2 The Premier Beehive factory imports dressed pork and produces cured smallgoods but does not incorporate any abattoir facilities.

9 9 Council s treatment facility. A second stage biological nutrient removal pre-treatment facility has been designed for the factory s pre-treatment system but is not yet constructed. When commissioned, it will substantially reduce the organic load from the plant, which is currently approximately the equivalent of that from the full domestic population of Carterton. The factory is understood to be planning a significant increase in production capacity over the foreseeable future. The second stage biological nutrient removal plant and a duplicate dissolved air flotation unit is planned to coincide with the production expansion. The Council is maintaining dialogue with the factory operations manager to ensure that the expanded factory does not create an unacceptable increase in nutrient load for the Council s wastewater treatment plant. The Council will continue to limit the load discharged from the factory through a trade waste agreement under its Trade Wastes Bylaw. There are, otherwise, no significant trade waste sources within the catchment of the Carterton wastewater treatment plant. 5. Future Growth Carterton District has experienced relatively high population growth since The district-wide usually resident, population increased from 6,849 in 2001 to 8,235 in 2013 (an overall increase of 20% and an average annual increase of 1.7% per annum). The Carterton district population is distributed across four census area units. The largest area unit population is the urban area of Carterton which coincides with the area served by the wastewater network. This area unit experienced an increase in population from 4,104 in 2001 to 4,686 in 2013 (an average annual increase of 1.2%). Of particular relevance to CDC s wastewater infrastructure is the number of new urban dwellings constructed since These have increased by 333 between 2006 and 2013 (including new dwellings and relocated dwellings). This represents an annual average urban increase of 41.6 new dwellings over the 8-year period ( inclusive). In 2007, Boffa Miskell prepared an assessment of the remaining capacity for future residential parcels within Carterton s zoned residential area. It was estimated that there were between 1012 and 1,460 potential allotments available for future residential growth based on typical lot sizes between the minimum permissible and actual historical subdivision density for urban residential units. CDC records show that there have been 268 new or relocated houses constructed in the residential zone over the period That leaves between 744 and 1,192 allotments potentially available for residential development. Assuming a continuation of recent housebuilding rates at approximately 42 per annum, this suggests the capacity of the available zoned residential land could be fully developed by 2034 (with low density development) or 2044 (with higher density development). The Council has recently commenced preparation of an urban growth strategy which will determine the location and density of future urban development and the infrastructure services required to support growth. Changes to the operative Combined Wairarapa District Plan may follow the urban growth strategy. The estimated future population of the Carterton area unit at the end of the planning period is estimated to be approximately 8,500 based on the long-run average population growth rate, the annual number of new houses and continuation of the current occupancy rate. A key assumption is that there is sufficient residential zoned land available to accommodate future demand. The extent of land availability or additional serviced land will only be known once the urban growth strategy is completed.

10 10 For the purposes of the current applications, and assuming there are no land availability constraints, a future domestic population of approximately 8,500 is expected to be able to be accommodated without compromising the planned land irrigation and high-flow discharge regime. There are three components to consider: i. hydraulic capacity of the wastewater treatment processes and pipes (how much influent can pass through the plant); ii. nutrient and organic loading (how well the treatment processes will treat the influent at any given inflow rate); and iii. the management of the SBRs and land irrigation areas. Assuming a continuation of the current approximate 640L/person/day flow rate, the resulting annual average dry weather flows (AADW) would be in the order of approximately 5,500m³/day towards the end of the consent duration. However, there are good reasons why the per capita future flows can be expected to reduce. These are: - better supervision of new waste water reticulation infrastructure and of new domestic property development so that inflow and infiltration is minimised, - Continuation of the successful inflow and infiltration reduction and mains replacement programme, - Anticipated future building recommendations for low water use fixtures and organic waste reuse. Therefore, it is anticipated that increases in hydraulic load will be matched by reductions in per capita discharge until the reticulated population reaches approximately 7,000. The annual average daily flow will then continue to grow but at the reduced per capita rate (including inflow and infiltration) of 630L/person/day and will be reduced to 430L/person/day over the period until a population of 7,000 is reached, primarily by tackling inflow and infiltration. For the 35-year design population of 8,500, the annual average daily flow is estimated to be of 3,700 m³ per day which is well within the hydraulic capacity of the proposed wastewater management system. The anticipated flow increases are readily able to be accommodated hydraulically. It is also anticipated that this volume will be able to be treated to a consistent standard throughout the consent period by modest incremental improvements to the treatment process (for example, additional clarifier capacity or additional oxidation pond aeration). It is not anticipated that the treatment process will require change or significant additional capital and it is not proposed to programme expenditure on additional unnecessary treatment facilities before they are required. Importantly, once the Premier Beehive food processing factory s second stage biological nutrient removal system is operational, it will result in a net reduction in organic and nutrient loads in the WWTP catchment which is expected to compensate for any gradual increase in nutrient load arising from population increase. A substantial proportion of the influent flow, particularly during peak wet weather events, is sourced from inflow and infiltration. Continued commitment to identifying and addressing inflow and infiltration sources will provide a capacity buffer over the consent term. Historical and current I&I issues are associated with the condition of existing pipe reticulation. It is reasonable to assume that future servicing of urban land will adopt best practice methods to reduce water demand and reduce future I&I. These matters will be relevant considerations in the urban growth strategy.

11 11 6. The Existing Carterton Wastewater System Reticulation network: The Carterton wastewater reticulation network comprises approximately 30.8 km of sewer pipe ranging in size from 80mm to 380mm diameter. Approximately half of the pipe material is asbestos cement and earthenware which tend to be brittle. Some of these pipes are approaching the end of their useful lives and CDC has established an annual survey and replacement programme to address deterioration of its older sewerage network. Approximately 2.9km of sewer pipelines have been replaced or repaired since 2008 (for example the major pipe replacement undertaken recently in Lincoln Road). In addition to the pipe reticulation, the network includes 15 pump stations (including 2 pump stations at the treatment plant) servicing various sub catchments within the reticulated area. Wastewater is gravity-fed (with supplementary pumping in parts) via the network to the Dalefield Road treatment plant. Figure 4 Extent of Carterton Reticulation System (pump stations are shown in blue) Existing Wastewater Treatment Plant and Discharge Facilities: The existing wastewater treatment plant is a three-stage tertiary treatment plant featuring the following treatment steps:

12 12 1. Inlet fine screen and grit removal; 2. Flow measurement flume; 3. Pumping chamber (which transfers the wastewater to the following treatment stages); 4. Primary clarifier; 5. Sludge removal from clarifier to heated digester followed by drying beds; 6. Secondary oxidation ponds; 7. Tertiary oxidation pond; 8. Constructed surface flow wetlands; 9. Screen filtering and UV treatment (prior to both land irrigation and stream discharge); 10. Irrigation to land via centre pivot irrigator and drip-lines within Daleton Farm (when soil and wind speed conditions allow); or 11. Discharge via an outlet weir into a tributary of the lower reach of Mangatārere Stream in accordance with a discharge regime specified in the current discharge permit. The screenings from step 1 are deposited into a thick-walled plastic liner at the site. The liner is then sealed and transported for disposal at Bonny Glen landfill. From the pumping chamber, the effluent is pumped up to the clarifier, where the sludge is settled and drawn off to the digester, and the liquor is discharged to the oxidation ponds for secondary treatment. Sludge from the digester is transferred to drying beds and dried to a moisture content of less than 60% before being lifted. Currently the dried digestive sludge is being stockpiled on a spare drying bed. In future once the new landfill consent is issued it is proposed that this material will be removed to the lined cell at the adjacent CDC landfill. Leachate from the landfill is currently collected in the liner and is pumped back to the head of the WWTP. Oxidation ponds 1 and 3 act in parallel as secondary treatment ponds. Pond 2 provides a polishing function as a tertiary pond. Treated effluent from the tertiary pond discharges into a constructed wetland, and from there either: through the filtration and UV plant before discharge to a small unnamed tributary of the Mangatārere Stream (typically in spring and winter conditions); or through the filtration and UV plant before irrigation to land within Daleton Farm (typically in summer and early Autumn conditions). In 2012, the Council purchased the 65.7-hectare Daleton Farm next to the treatment plant explicitly for the purpose of undertaking land irrigation of treated wastewater effluent. The first irrigator was designed, implemented and commissioned in late 2014.Subsequently, a dripline was installed for irrigating a native shelter belt on the eastern (SH2) boundary. These irrigated areas are shown on Figure 1 in Attachment 1. The consent holder manages the irrigation and farm operation through a Land Irrigation Management Plan in accordance with the requirements of the current land discharge permit WAR [27251]. Land irrigation has been implemented over the summer periods of 2014/15, 2015/16 and 2016/17. For the 2015/2016 summer, all treated wastewater during the period 19 December to 4 May (138 days) was either held within the wastewater treatment plant ponds or discharged to land. For part of both summer periods, there was insufficient influent wastewater to promote crop growth within the irrigated area. Although both irrigation seasons are acknowledged to have been dry summers, the experience suggests that summer time wastewater inflows can be managed by a combination of land irrigation and storage. For the 2016/2017 land irrigation season, stream discharge ceased on 21 December and there have been no discharges of treated wastewater to the stream since then. Land irrigation commenced on 22 December 2016 and had not ceased at the time of writing this AEE (30 March 2017). A full summary of the effluent volume and quality parameters achieved for the 2014/2015 and 2015/2016 land irrigation seasons is

13 13 provided in the Compliance Reports that have been lodged separately with Greater Wellington Regional Council in accordance with the current permit conditions. No compliance report is available yet for 2016/2017 as the irrigation season has only just concluded. 7. Recent Treatment Upgrades In addition to the recent installation of the UV treatment and land irrigation facilities, CDC has also invested recently in upgrading of the treatment plant and site. Upgrading has included: design and installation of supplementary mechanical aeration in Ponds 1 and 3; covering the anaerobic digester and collection and diversion of digester gases to a soil filter; the planting of shelter belts of native plants and pine trees to prevent any fugitive spray drift from land irrigation; excavation of an amenity wetland area and initial planting with wetland species in partnership with the Mangatārere Restoration Society and GWRC; installation of monitoring bores, anemometers, leaf sensors, soil moisture probes, and rain gauges. In addition, as earlier noted, the trade wastes from the Premier Beehive food processing factory are now being partially treated at source before reticulation to the WWTP so as to reduce contaminant concentrations (predominantly phosphorus) at the WWTP. Previously, concentrations of dissolved reactive phosphorus in the treated effluent had been non-compliant with the limits specified in conditions. Since the Premier Beehive pre-treatment installation was commissioned in early 2016, DRP concentrations have reduced to compliant levels and this is expected to continue. 8. Planned Future Upgrading to Support the Consents Applied for The Council plans to undertake the following works to support the consents now applied for: a) Lining the inflow and outflow channels to and from the existing constructed (treatment) wetland with impervious material to prevent leakage to ground (the intention is to pipe these channels and the work is scheduled to commence in April 2017); b) Rehabilitation and re-planting of the existing treatment wetland cells to optimise their treatment capability; c) Earthworks to level the topography of the lower farm terrace and render it more suitable for central pivot irrigation; d) Excavation of a substitute ephemeral channel to replace the existing ephemeral channel that is to be filled in re-contouring the lower terrace to create the proposed second centre pivot irrigation area. e) Construction of three sequential batch reservoirs which will provide a further treatment step and which will have a combined storage of 200,000 cubic metres; f) Incorporation within the SBR structures of low height netting, similar to that used in fruit orchards, to deter birds from landing on the surfaces of the reservoirs; Re-location of the existing discharge outfall to a point downstream on the true left bank of the mainstem Mangatārere Stream and construction there of a gabion rock diffuser structure set at a height to allow pumped discharge during elevated stream flows;

14 14 g) Installation of a second central pivot to irrigate approximately 20 additional hectares of Daleton Farm with the potential for irrigation of an additional 10 hectares using non-pivot irrigation equipment (approximately 50 hectares total); h) Installation of pipelines to supply treated effluent to and from the sequential batch reservoirs to the expanded land irrigation area and to the re-located stream outfall; i) Further development and planting of amenity wetlands located at the south-eastern corner of Daleton Farm and riparian planting, in partnership with the Mangatārere Restoration Society and GWRC, including the development of walking tracks suitable for use by the public; Detail describing these proposals can be found in the Attachments referenced below: The location of the proposed upgrading works is shown on Figure 1 in Attachment 1; The re-located stream discharge structure is detailed in Attachment 2; and The proposed scheme design for construction of the sequential batch reservoirs is included in Attachment 4; A description of the options for management of the proposed SBRs and an assessment of their expected treatment performance is contained in Attachment 5); The proposed wetland amenity planting is shown schematically in Attachment Staging of Proposed Upgrading Works All components of the Stage 2 upgrading works are scheduled to be in place by late 2020: a) Re-contouring earthworks to prepare the land for irrigation, and substitution of the existing ephemeral channel will be completed in 2017/2018 so as to be ready for installation of the second irrigator in 2020/21. b) Construction of the Sequential Batch Reservoirs is planned for summer 2018/2019 (to provide additional storage from late 2019 to be used in conjunction with the existing land irrigation area); c) Construction of the re-located discharge outfall and pipeline is scheduled to be completed by the end of the 2019/2020 summer (ready for use for high-flow discharge in the autumn and winter of 2020); d) Installation of the second centre pivot land irrigation area is scheduled for completion in September-November 2020 (ready for commissioning of expanded land irrigation over the 2020/2021 summer. Until then, the hydraulic capacity of the existing irrigation area will allow irrigation of a greater volume than actually experienced to date and this will be supplied from the sequential batch reservoirs from late 2019); The above staging will achieve the benefits of the proposed land irrigation and high-flow discharge regime at the earliest practicable opportunity and is affordable alongside the community s other significant capital investment demands. However, aspects of the current discharge regime will be required to continue for a short period until all of the components are in place. For example: e) Until the re-located Mangatārere Stream discharge outfall and pipeline are operational, winter time discharge from the wastewater treatment plant will continue to be from the existing treatment wetland via the existing outfall into the unnamed tributary of the Mangatārere Stream (i.e. until the end of the 2019/2020 summer);

15 15 f) Until the second centre pivot is installed, treated wastewater can only be irrigated to the existing 20-hectare irrigation area which will increase volumes required to be treated and held within the Sequential Batch Reservoirs compared with the ultimate design intention. This means that, for a short period, it will be necessary to manage volumes held within the site by discharge via the existing outfall to the unnamed tributary (as currently). Accordingly, the applicant seeks consent to continue the current discharge to the unnamed tributary of the Mangatārere Stream via the existing outfall until construction of the re-located stream outfall and supply pipeline are operational. 10. Proposed Discharge Regime Preferential discharge by irrigation to the existing land irrigation area will continue until the second land irrigation area is operational. Experience during 2014/15 and 2015/16 with the 20- hectare irrigation area has been that there is insufficient wastewater inflow in a dry summer period, when land discharge is achievable, to fully meet crop needs. The existing land discharge area is therefore capable of absorbing a greater treated wastewater flow during a dry summer. Once the sequential batch reservoirs are completed, treated wastewater will be able to be stored so that greater volumes will be able to be irrigated to the existing irrigation area. Increased land irrigation is therefore achievable even before the second centre pivot irrigator is installed. Preferential discharge to land will continue, once the second centre pivot irrigator is installed, and will be to the expanded land irrigation area. The proposed discharge regime is expected, short term and long term, to achieve the discharge quality and receiving water quality outcomes specified in Policies P66 and P71 of the proposed Natural Resources Plan. These outcomes are discussed in further detail in the ecological assessment in Attachment 6 and in the policy analysis contained in Attachment 21. Short-Term Discharge Regime for Short Term Discharge Permit (Maximum 5 Years) The same regime for stream discharge will apply in the short term as currently. That is: a) Ponds will be operated at their lowest practicable operational level at all times; b) Discharges to the stream will be avoided wherever practicable, with preferential irrigation to land whenever practicable; c) Wastewater levels in oxidation ponds and wetlands will not overtop the pond or wetland walls; d) An annual average daily discharge flow of 3,500m³/day; e) A maximum daily discharge rate of 30,000m³/day. f) All flows up to 10,000m³/day will be treated by UV disinfection; g) Allow for higher irrigation rates to avoid discharges to water in extreme circumstances; h) The system will be maintained in an efficient operating condition at all times to avoid deterioration in the quality of discharged effluent; i) There will be no discharge to the Mangatārere Stream tributary when flow in the Mangatārere Stream is below half median;

16 16 j) When the flow in the Mangatārere Stream at SH2 is between the estimated half median (1,140 litres/second) and estimated three times median (6,840 litres/second), the Consent Holder shall ensure that the dilution ratio of stream flow to discharged treated wastewater is not less than 50:1; k) When the flow in the Mangatārere Stream at SH2 is above three times estimated median flow (6,840 litres/second), the Consent Holder shall ensure that the dilution ratio of stream flow to discharged treated wastewater is not less than 30:1, unless the treatment ponds are at full capacity. Treated Wastewater Quality for Short Term Discharge Permit (Maximum 5 Years) The conclusion of the ecological assessment undertaken by EIA (Attachment 6) is that, since commencement of the 20-hectare summer/autumn land discharge regime, the discharge to water has had a measurable but not significantly adverse effect on downstream water quality. The applicant proposes treated effluent quality standards ( end-of-pipe standards) that will ensure there is no further deterioration in downstream water quality for the duration of the short-term discharge to the unnamed tributary. EIA s advice is that the following end-of-pipe compliance limits will achieve this: Proposed Maximum Contaminant Concentrations Median Compliance Value 95 th Percentile Compliance Value BOD 5 50 g/m³ 80 g/m³ Total Suspended Sediment TSS 85 g/m³ 140 g/m³ Total Ammonia Nitrogen NH 4-N 35 g/m³ 55 g/m³ Dissolved Reactive Phosphorus 8 g/m³ 15 g/m³ DRP E. coli For discharges up to 5,000m³ per day, the median of 10 consecutive E. coli values shall not exceed 100 per 100 mls and no more than 2 out of 10 shall exceed 1,400 per 100 mls; For discharges between 5,000m³ and 10,000m³ per day, the median of 10 consecutive E. coli values shall not exceed 10,000 per 100 mls; For discharges over 10,000m³ per day, UV treatment shall be applied to a minimum of 10,000m³ per day for which the median of 10 consecutive E. coli values shall not exceed 10,000 per 100 mls (and the remaining flow shall have no UV treatment). The above median and 95 th percentile compliance values can be converted into the number of permitted exceedances of the value and the number of required compliant samples to achieve compliance in accordance with the methodology set out in Section 13 and Table 13.2 of the New Zealand Municipal Wastewater Monitoring Guidelines (2002) for the purposes of consent conditions. Receiving Water Quality for Short Term Discharge Permit (Maximum 5 Years) After consideration of instream water quality sampling results for the current stream discharge and discussion with GWRC s water quality adviser, the applicant proposes to adopt

17 17 the instream water quality compliance limits set by the current discharge permit but with some amendments and deletions as noted below: a) No conspicuous oil, grease, films, scums, foams or floatable or suspended material (none recorded to date); b) No emission of objectionable odour (none reported to date); c) No freshwater to be rendered unsuitable for consumption by farm animals (water quality is currently suitable for consumption by animals, there is no reason to expect this to deteriorate, and the E. coli compliance standard is a sufficient proxy for animal consumption); d) No significant adverse effect on aquatic life (although there have been measurable impacts on macroinvertebrates, there is no consistent evidence of significant adverse effects on aquatic life caused by the discharge via the weir outlet to the unnamed tributary and this standard remains appropriate); e) Maximum cover of the bed by periphyton as filamentous growths (more than 2cm long) not to exceed 30% (consistent compliance achieved); f) Maximum cover of the bed by periphyton as diatom or cyanobacteria mats (more than 0.3cm thick) not to exceed 60% (consistent compliance achieved); g) Biomass of periphyton as filamentous growths or mats on the bed not to exceed 120mg chlorophyll a per square metre over a representative reach (consistent compliance achieved); h) Dissolved oxygen to be above 80% saturation (EIA s analysis of recent water quality data confirms that there has been no material effect on DO); i) Concentration of total ammonia-nitrogen to not exceed 0.9g/m³ (CDC s treated wastewater discharge is not the only contributor of ammonia nitrogen. It is more appropriate to set an end-of-pipe standard for ammonia nitrogen, as proposed above); and Compared with upstream: j) No conspicuous change in colour or visual clarity (the wording of this standard is vague. The below condition setting a maximum upstream/downstream change in horizontal visibility is a more appropriate indicator of visual clarity); k) No greater than 20% change in horizontal visibility (measured as the horizontal sighting range of a 200mm black disc or similar method for paired upstream/downstream samples); l) No greater than 20% reduction in QMCI; m) No greater than 10% increase in percentage deposited sediment (deposited sediment has not been observed as an adverse effect of the treated wastewater discharge the standard is not required to address an actual or potential adverse effect); n) No greater than 2 C increase in temperature (the water quality sampling data confirm that the treated wastewater discharge consistently reduces stream temperature the standard is not required to address an actual or potential adverse effect; o) No greater than 0.5 change in ph (the water quality sampling data confirms that the treated wastewater does not adversely affect ph the standard is not required to address an actual or potential adverse effect). CDC acknowledges that there is evidence of diffuse contamination from an unknown source during times when all treated wastewater is being discharged to land. The presence of diffuse contamination is not, however, evidence of adverse effects of the discharge to water via the weir outlet. CDC proposes an intensive sampling programme at the next achievable

18 18 opportunity (the effects will be most reliably observed during summer low flows, if present). This requirement, and any adaptive management response that is found to be necessary, will be addressed by conditions of consent on the discharge permit for discharge to land beneath the WWTP facilities (not as a condition of consent of the permit for discharge to water via the weir outlet). The proposed treatment quality and receiving water quality listed above relate to the permit sought to discharge to water, via the existing weir outlet. Long-Term Discharge Regime for 35-Year Discharge-to-Stream Permit All wastewater inflows will be treated in the WWTP and either stored in the SBRs and/or directed to land irrigation, or discharged from the SBRs to stream. Treated wastewater will be preferentially discharged from the sequential batch reservoirs to the land irrigation areas when soil and wind conditions allow. Treated wastewater will be piped from the sequential batch reservoirs to the relocated discharge outfall into the main stem Mangatārere Stream only in stream flows above 3x median (at all times of the year) except where a combination of climatic factors and storage capacity necessitate discharge to the Mangatārere Stream in flows no lower than twice-median flows. The only other exception to the high-flow-only discharge regime is that treated wastewater will not be discharged to the Mangatārere Stream at times when the discharge is likely to coincide with flood flows in the Ruamāhanga River that could cause flood flows to spill into Lake Wairarapa. No treated wastewater will be discharged to the Mangatārere Stream in flows below half median flow (at any time of year). Land irrigation of treated wastewater will be by deficit irrigation. The operating regime will be: a) Ponds will be operated at their lowest practicable operational level at all times; b) Discharges to the stream will be avoided wherever practicable, with preferential irrigation to land whenever practicable; c) Wastewater levels in oxidation ponds and wetlands will not overtop the pond or wetland walls; d) All flows up to 10,000m³/day will be treated by UV disinfection; e) Target minimum Sequential Batch Reservoir retention time will be a minimum of 14 days before discharge; f) Higher irrigation rates will be adopted to avoid discharges to water in extreme inflow circumstances (CDC has modelled the relative impacts of higher land irrigation rates versus discharge direct to stream and concludes that increasing irrigation rates for shortduration periods will be beneficial for stream ecosystem health and will not cause adverse effects on long-term soil properties or groundwater quality refer to the report on irrigation and land use effects in Attachment 8); g) The system will be maintained in an efficient operating condition at all times to avoid deterioration in the quality of discharged effluent; h) There will be no discharge to the Mangatārere Stream tributary when flow in the Mangatārere Stream is below half median; i) Discharge to the stream will target periods of stream flow above 3x median flow and may occur at any time of year; j) When treated wastewater is discharged to the Mangatārere Stream tributary during times when flow in the Mangatārere Stream at SH2 is above 3x median, the discharge of treated

19 19 wastewater shall not exceed 60,000m³/day and shall achieve a minimum discharge dilution of 30:1; k) When flows in the Mangatārere Stream are above twice median flow, discharge to the Mangatārere Stream tributary will only be permitted when soil conditions prevent land irrigation and there is no remaining storage capacity in the WWTP and SBRs; l) When treated wastewater is discharged to the Mangatārere Stream tributary during times when flow in the Mangatārere Stream is above estimated half median and below 3x median, a minimum discharge dilution ratio of 50:1 will be achieved. Treated Wastewater Quality for 35-Year Discharge-to-Stream Permit CDC estimates that, once the SBRs are operational, contaminant concentrations in the treated wastewater will be improved by the SBR storage system to the following extent: Table 1 Assumed Wastewater Treatment Quality Analyte Current Actual Treatment Standards Achieved (Minimum Maximum) Post - SBR Target Treatment Quality (Minimum Maximum) Total Ammoniacal Nitrogen (TAN g/m³) Total Nitrogen (TN g/m³) Total Phosphorus (TP g/m³) Total Suspended Solids (TSS g/m³) 5-Day Carbonaceous Oxygen Demand (BOD 5 g/m³) E.coli On this basis, CDC has assumed the following minimum treated wastewater quality standards in assessing the potential impacts of the proposed stream discharge regime: 3 Note: The treated wastewater quality data set records one sampling result of 7,200 cfu/100mls taken on However, that sample was taken at the wetland outflow, prior to UV treatment, and is not representative of the treatment quality achieved post-uv. All other samples were sampled post-uv. Since installation of UV treatment, the highest sampled monthly post-uv E. coli result has been less than 300 cfu/100mls. Given that wastewater flows over 10,000m³/day may receive less effective UV disinfection, a realistic range of E. coli treatment quality may be in the order of cfu/100 mls.

20 20 Table 2 Minimum Treated Wastewater Quality (based on minimum 14-day retention in the SBRs) TAN g/m³ TN g/m³ DRP g/m³ TSS g/m³ BOD 5 g/m³ E-coli c.f.u./100 mls Maximum Contaminant Concentration <100 Receiving Water Quality for 35-Year Discharge Permit The assessment of ecological impacts (Attachment 6) concludes that the potential effects on ecosystem health of the proposed discharge regime from the upgraded wastewater management system will be negligible. Reproduced below are the receiving water standards from the current discharge permit (WAR090120). The deletions represent the parameters EIA recommends should be deleted, with an explanation of why they should be deleted. Full compliance is expected with the remaining proposed water quality standards: a) No conspicuous oil, grease, films, scums, foams or floatable or suspended material (none have been recorded to date and there is no reason to expect any would be discernible, compared to background conditions, in flows above 2x or 3x median given the higher standards of treatment proposed in the SBRs); b) No emission of objectionable odour (none reported to date and none is expected given the higher standard of treatment in the SBRs however this standard may provide some reassurance about amenity concerns); c) No freshwater to be rendered unsuitable for consumption by farm animals (water quality is currently suitable for consumption by animals, there is no reason to expect this to deteriorate, and the E. coli compliance standard is a sufficient proxy for animal consumption); d) No significant adverse effect on aquatic life (the ecological assessment is that adverse effects on the downstream environment will be minor however this condition is a usual condition, derived from section of the RMA and is accepted as reasonable); e) Maximum cover of the bed by periphyton as filamentous growths (more than 2cm long) not to exceed 30% (this standard is additional to those specified Policy P71 of the proposed Natural Resources Plan but is consistent with MfE guidelines and general practice. Consistent compliance achieved has been achieved recently with the existing level of treatment and the proposed SBR treatment and discharge regime are expected to also comply); f) Maximum cover of the bed by periphyton as diatom or cyanobacteria mats (more than 0.3cm thick) not to exceed 60% (as above - consistent compliance achieved); g) Biomass of periphyton as filamentous growths or mats on the bed not to exceed 120mg chlorophyll a per square metre over a representative reach (as above - consistent compliance achieved);

21 21 h) Dissolved oxygen to be above 80% saturation (EIA s analysis of recent water quality data confirms that there has been no material effect on DO and none is expected with a higher standard of SBR treatment); i) Concentration of total ammonia-nitrogen to not exceed 0.9g/m³ (CDC s treated wastewater discharge is not the only contributor of ammonia nitrogen. The EIA report concludes that historic non-compliance has not correlated with significant adverse effects in the stream and EIA s recommendation is to dispense with a receiving water standard for total ammoniacal nitrogen and, instead, to set an end-of-pipe treatment quality standard for ammonia nitrogen, as proposed above); and Compared with upstream: j) No conspicuous change in colour or visual clarity (the wording of this standard is vague. The below condition setting a maximum upstream/downstream change in horizontal visibility is a more appropriate indicator of visual clarity); k) No greater than 20% change in horizontal visibility (measured as the horizontal sighting range of a 200mm black disc or similar method for paired upstream/downstream samples); l) No greater than 20% reduction in QMCI; m) No greater than 10% increase in percentage deposited sediment (deposited sediment has not been observed as an adverse effect of the treated wastewater discharge the standard is not required to address an actual or potential adverse effect and EIA concludes it is not necessary); n) No greater than 2 C increase in temperature (the water quality sampling data confirm that the treated wastewater discharge consistently reduces stream temperature the standard is not required to address an actual or potential adverse effect and EIA has agreed with GWRC s water quality adviser that this standard is not necessary; o) No greater than 0.5 change in ph (the water quality sampling data confirms that the treated wastewater does not adversely affect ph the standard is not required to address an actual or potential adverse effect EIA s recommendation is to not include a receiving water standard for ph). Treated Wastewater Quality for 35-Year Discharge-to-Land Permit The current consent authorising land irrigation of treated wastewater (WAR150068) sets three treated wastewater quality standards: Median E. coli shall not exceed 100 per 100 mls; The median concentration of BOD 5 shall not exceed 70g/m³ and 600 kg/ha/year; and Dissolved oxygen shall have a median concentration greater than 2g/m³. CDC s experience to date is that the first two standards can be consistently met. However, depending on time of day, the treated DO concentration can range from below 0.5 to above 1.5. The median concentration recorded for the 2015/2016 irrigation season was 1.5g/m³. The current compliance limit of 2g/m³ is not achievable. The purpose of the DO limit is understood to be the control of potential odour. However, the operation of the irrigator has not been the subject of any complaints about odour. In other words, regardless of non-compliant DO levels in the oxidation ponds, the treated wastewater discharging via the centre pivot is not causing any known adverse odour effects. CDC proposes that either the current 2g/m³ compliance limit be reduced to 1g/m³, or deleted altogether. CDC also proposes a condition requiring avoidance of anaerobic conditions in the ponds and avoidance of objectionable or offensive odour beyond the boundary.

22 Community Engagement CDC has been working closely with its neighbours and communities of interest in developing and implementing its Wastewater Strategy. The Council has engaged with known, interested stakeholders and with the wider community using a variety of media and fora including running an open day at the WWTP and through formal consultation on the draft 2016/2017 Annual Plan. The process was initiated by the formation of a Community Liaison Group in 2014 comprising Iwi, the Mangatārere Restoration Society and stakeholders representing community, environmental, business and public health interests. All submitters to the previous discharge permit applications were invited to attend Community Liaison Group meetings. The process and timeline for community engagement are summarised in Attachment 9. The Council has distributed regular newsletters to those registering an interest in the project (the latest copy is included in Attachment 10. Conversations at the open day and various meetings indicates overall support for the Council s long term wastewater strategy and for the upgrading project and discharge regime proposed by these current applications. Examples of the feedback received are included in Attachment 10. The community engagement has been integral to the Council s process of considering alternative sites and methods. The evolution of the strategy for wastewater management and identification of alternatives are described in Attachment Regional Context There are seven urban wastewater treatment and disposal facilities in the Wairarapa part of Greater Wellington Regional Council: Masterton (the largest), Riversdale, Carterton, Greytown, Featherston, Martinborough and Lake Ferry. The following summarises the wastewater discharge consents granted or proposed recently for municipal urban wastewater treatment and disposal facilities in other Wairarapa towns. Table 3 Other Authorised Municipal Wastewater Discharges in Wairarapa Treatment technology Masterton Greytown Martinborough Featherston Oxidation ponds and 6 Oxidation ponds, UV Facultative ponds, Oxidation ponds, with maturation cells instead of disinfection maturation ponds, UV High Rate Treatment UV disinfection proposed no later than 2025 Decision Date 2009 February 2016 February 2016 No decision yet; lodged & submissions closed September 2014 Authorised Discharge to Papawai Discharge to Proposed discharge Discharge Regime Stream; Ruamāhanga River to Donald s Stream Discharge to Ruamāhanga River via automated penstocks from final maturation pond when River conditions permit; When River conditions unsuitable = land based border dyke. Restrictions & Requirements No summer discharge below median flow; No winter discharge below half median flow; Staged upgrading: 1A pond optimisation; 1B 21% of effluent flows to land by Staged upgrading to commence: 1A minor WWTP upgrades (2 ½ years); No decision yet

23 23 Masterton Greytown Martinborough Featherston 1:30 dilution. irrigation to 1B 24% effluent flows commence 2022 to discharge to land avoid discharge below half median; during low flows (no later than November 2A additional 68% 2017); effluent flows to land by 2035; 2A 42% effluent flows to land except when 2B construction of capacity is storage to enable land treatment to no less than 100 ha by end 2040; Plus provision for high-flow river discharge where onsite capacity is compromised; Review & report on efficacy of storage & land treatment by compromised + must be above 3x median (no later than 2030); 2B additional storage to be provided to contain all treated wastewater other than in extreme events (no later than 2035); Review & report on efficacy of additional storage & land treatment by Consent Duration 25 years 35 years 35 years Seeking 35 years In comparison with the recent experience of other Wairarapa municipal wastewater schemes, Carterton s wastewater management proposal has: already optimised its oxidation pond treatment process to minimise contaminant concentrations; established and demonstrated the efficacy of its 20-hectare land irrigation system; Council owned land available for additional irrigation; Council owned land available for large-volume storage of treated wastewater the ability to provide on-site storage and an expanded land irrigation area within a short time frame (by 2020/2021); identified and addressed the most significant inflow and infiltration sources; and committed funds to continue identifying and addressing I & I, through the consent period. The period before Carterton s fully-integrated low-impact discharge regime is able to be fully established is brief (a maximum of 5 years to 2022) and can be considered to be temporary for the purposes of section 107 of the Act. Within that short period, the SBRs and relocated discharge point will be commissioned first so as to enable the low-impact stream discharge regime as early as practicable. The potential adverse effects on the downstream river environments during that temporary period are assessed in the report in Attachment 6 as minor. Following completion of the planned upgrading work, the combination of the high-capacity UV plant, the capture and filtration of gas emitted from the anaerobic digester, the additional treatment provided by the proposed SBRs, the ability to store large volumes of treated wastewater on-site, the expanded land irrigation area, the additional dilution available at the relocated point of discharge and proposed high-flow stream discharge regime will ensure that any adverse effects on the downstream receiving environments are no more than minor for the 35- year duration sought. In these respects, Carterton s proposed 35-year wastewater treatment and disposal proposal is achievable and compares favourably with other 35-year consents recently

24 24 granted in the Wairarapa. Compared with historical levels of contamination in the downstream environment, the discharge regime applied for is expected to substantially improve instream ecosystem health. 13. Existing Consents District Plan Land Use Consents The Carterton wastewater treatment plant site is designated under the Wairarapa Combined District Plan (reference DC 007 stated purpose Sewage Treatment Plant ). The Daleton Farm irrigation area is not currently included within that designation. Rule (m) of the Wairarapa Combined District Plan permits the disposal of wastewater from a municipal wastewater treatment plant subject to compliance with standards specifying minimum setbacks from boundaries, maximum E. coli concentrations and maximum wind speeds for spray irrigation. CDC holds a certificate of compliance, granted in 2014, confirming that the land irrigation activities currently undertaken on Daleton Farm comply with the District Plan standards and are authorised permitted activities. In addition, CDC secured land use consent (Consent No ) in 2014 to allow location of the drip-line closer than the standard minimum of 5m to the site boundaries. In November 2015, CDC obtained land use consent to irrigate treated effluent at sustained wind gusts of up to 12m/s (Consent No ). CDC also secured land use consent in 2014 to complete earthworks to re-contour the upper terrace of Daleton Farm in preparation for installing the first pivot. Copies of the certificate of compliance and all District Council land use consents are contained in Attachment 11. GWRC Consents CDC holds GWRC discharge permits authorising the operation of the existing treatment plant, granted in October 2013 by consent order issued by the Environment Court following appeal by CDC. Those permits authorise the following activities and the expiry date for all permits is 14 October 2017: WAR [27251] WAR [27252] WAR [27253] WAR [30652] The discharge of treated wastewater to land via an irrigation system (in a different location and smaller in area than the centre pivot irrigation area described below this irrigation system has been removed and is no longer in use) The discharge of treated wastewater to (a tributary of) the Mangatārere Stream The discharge of odours to air from the oxidation ponds and other operational activities The discharge of partially treated wastewater to land and groundwater through the base of the existing oxidation ponds

25 25 WAR [30653] The discharge of partially treated wastewater to land and groundwater through the base of the constructed wetland system. CDC also holds discharge permits granted in 2014 authorising the discharge of treated effluent to air and to an area of approximately 20 hectares of land via a low pressure central pivot irrigator and subsurface dripline within Daleton Farm. These permits (WAR [33168] and [33169]) also expire on 14 October 2017). Some of the conditions of these GWRC consents include requirements intended to protect adjoining land and protect people on nearby properties. Although they are imposed on discharge permits, those conditions address matters typically also associated with the land use activity of treated wastewater irrigation. For example, Condition 16 of discharge permit [33168] requires that the activity not result in the discharge of treated wastewater to any surface water draining from the irrigation area onto adjoining land. Condition 16 also requires that the activity not result in spray drift beyond the boundary or objectionable of offensive odour detectable beyond the site boundary. Condition 17 prevents drip-line irrigation within 1.5 metres of any site boundary. Condition 18 prevents centre pivot irrigation within 25 metres of any site boundary. Condition 21 limits centre pivot operation to wind speeds up to 12m/s. Condition 22 requires the centre pivot lines to be fully flushed if they have not been irrigating for a continuous period of 48 hours (to prevent potential bursts of odour at start-up after a period of non-irrigation). Condition 23 of discharge permit [33169] requires adoption of best practicable measures to avoid objectionable or offensive odour beyond the site boundary. CDC proposes inclusion of some of these conditions as restrictions on the proposed designation. However, it is not necessary to replicate all conditions in both the designation and GWRC discharge permits sought. 14. Expiry of GWRC Consents and Continued Operation As noted above, consents for the operation and maintenance of the WWTP and for the land irrigation and stream discharge activities, will expire on 14 October CDC will lodge the applications for consent included in this document no later than 14 April This will allow CDC to continue to operate under the authority of the existing GWRC discharge permits as provided for by section 124 of the RMA 4 : 124 Exercise of resource consent while applying for new consent (1) Subsection (3) applies when (a) a resource consent is due to expire; and (b) the holder of the consent applies for a new consent for the same activity; and (c) the application is made to the appropriate consent authority; and (d) the application is made at least 6 months before the expiry of the existing consent. (2) Subsection (3) also applies when (a) a resource consent is due to expire; and (b) the holder of the consent applies for a new consent for the same activity; and (c) the application is made to the appropriate consent authority; and (d) the application is made in the period that (i) begins 6 months before the expiry of the existing consent; and (ii) ends 3 months before the expiry of the existing consent; and 4 For these purposes, CDC s application will be made no later than 6 months before the date of expiry of the consents.

26 26 (e) the authority, in its discretion, allows the holder to continue to operate. (3) The holder may continue to operate under the existing consent until (a) a new consent is granted and all appeals are determined; or (b) a new consent is declined and all appeals are determined. 15. Operational Performance of WWTP Inflows Inflows to the system have historically averaged approximately 3,500 m³ per day annual average with peak wet weather inflows estimated in the order of 20,000 m³ per day. Following an inflow and infiltration control programme over the last five years, in conjunction with additional buffer storage within the oxidation ponds, these flows have been reduced to approximately 3,000 m³ per day annual average inflow and in the order of 15,000 m³ per day peak wet weather flow against a background of modest population growth. The inflow and infiltration program, described below, has been relatively successful and although traditional remediation methods have diminishing returns as time goes on it is anticipated that the programmed future expenditure on both replacement of old wastewater mains and innovative inflow and infiltration methods will achieve ongoing reductions which will at least offset short-term population growth. Trade Wastes Currently the Carterton wastewater system receives three discharges from what could be termed unusual commercial and industrial premises. Unusual is considered to be more than the usual shops, restaurants, hotels, cafeterias, retirement villages, automotive garages, dentists, and doctor s surgeries which are typical for a small town. The three unusual discharges are: Premier Beehive, which processes frozen pork carcasses; Ranchman s pet foods, which produces products for the pet food industry including dried animal parts and dog rolls; A Paua shell factory, which processes Paua shells to produce jewellery type products. While Premier Beehive s trade waste discharge is monitored intensively, the other two are monitored on an intermittent basis for wastewater volume production and quality. Due to its significance, Premier Beehive is monitored with an effluent flow meter located on the outlet pipe from Premier s DAF unit and 24-hour composite sampling undertaken several times a week and analysed for a range of relevant parameters. Current upgrade work being carried out by Premier will relocate the effluent meter (Magflow) to the trade waste discharge pipeline immediately inside Premier s property boundary from where a continuous signal will be sent to CDC s telemetry system.. As described earlier, Premier Beehive s recently-installed dissolved air flotation (DAF) plant, which is used in conjunction with a chemical coagulant, has resulted in a substantial reduction in phosphorus concentrations since early This in turn has meant that the phosphorus concentrations in the treated wastewater discharge from the Carterton plant have been compliant since March 2016, compared with previous frequent non-compliance. Also, as earlier discussed, Premier Beehive s planned second-stage upgrade is proposed to include biological nutrient removal which will achieve substantial reduction in nitrogen, particulate material, and dissolved

27 27 organics. CDC understands that Premier Beehive plans to install the second stage in concert with an intended plant expansion. The combination of the two should achieve an overall net reduction in loading rates of key parameters discharged to the Carterton wastewater system. Treated Effluent Quality The current consent authorising discharge to water requires compliance with five end-of-pipe standards: BOD 5, TSS, TAN, DRP and E. coli. The current consent authorising land irrigation requires compliance with three standards: E. coli, BOD 5 and DO. Achievability of these standards for the duration of the 5-year and 35-year consents sought is discussed earlier in Section 10 of this document. Since the UV irradiation plant was installed in November 2014, full compliance has been achieved with the indicator bacteria criteria, with typical levels being well below 100 E. coli per hundred millilitres. It should be noted that this is against a background of significant upstream concentrations in the Mangatārere Stream, often in excess of the CDC WWTP discharge limit. Concentrations of suspended solids, BOD, and ammoniacal nitrogen compliance have been variable and are, to a significant degree, related to the performance of the surface flow wetlands. Currently the wetlands suffer from poor flow distribution, have inherent potential for discharge to ground from the inlet and outlet channels, and very poor plant growth. A major planting program which was undertaken in late 2015 early 2016 had a limited strike rate primarily due to the new plants being submerged before they had become established. As part of the proposed upgrade, it is intended that the wetlands will be reconstructed including lining of the inlet channels and flow distribution to the individual wetland cells. This work is expected to facilitate full compliance with the current discharge permit limits for all end-of-pipe parameters. Emerging contaminants, (EC s), is an area which requires some consideration as it represents potential contaminants of concern, the environmental and public health impacts from which have not been well or fully characterised. As part of the preparation for this consent application, a literature review and current best practice guidelines for EC s have been considered. Emerging contaminants include; pharmaceuticals, hormones, personal care products, illicit drugs, antibiotics, plasticisers, sunscreen constituents, fire retardants, and preservatives. The processes, other than conventional biological secondary treatment, which have been found to be generally effective in the transformation and reduction of many emerging contaminants include: ponds, wetlands, UV irradiation, and land irrigation. The proposed treatment regime incorporates all of these steps. It is not possible to definitively predict the concentrations of emerging contaminants in the final treated effluent, or residual discharges to the environment. However, it is contended that the proposed treatment combination, along with recommendations for residents on appropriate substances to purchase and use and especially to dispose of via sewer, represents best practicable option for a small community with limited resources, accepting that influent concentrations of emerging contaminants would be typical of other New Zealand municipal wastewater catchments. Potential Improvement in Treated Effluent Quality Following Upgrading Following construction and operation of the sequential batch reservoirs it is expected that there will be a significant improvement in the 6 compliance parameters mentioned above. Whilst the improved wastewater quality is not required for land irrigation, it will have benefits for the occasions of discharge to the stream. The extent of the improvement in treatment quality will be a function of: the time of year, ambient conditions such as temperature, and the duration that the

28 28 current effluent is able to be held within the reservoirs. The estimated degree of improvement, based on trials of the SBRs, is discussed in Section 10 of this document. The improved treated wastewater quality, in combination with the high dilution rates and high stream flows proposed when discharge occurs, is expected to result in a substantial reduction in the current impact on the receiving waters. In order to address increased organic loading that occurs as a result of increasing population during the term of the consent, it is proposed that the following measures will be implemented as necessary: a. additional and more effective aeration will be added to the current oxidation ponds; b. the ponds will be progressively de-sludged leading to a lower potential for re-entrainment of solids; c. an additional heated cell will be added to the current digester, to accommodate the increased sludge loading from the SBR pond operation; and the progressive desludging of the existing ponds, and d. the sludge drying beds will be extended and have movable covers installed to make solar sludge drying achievable over a longer period of the year. Continued disposal of dried sludge to the adjacent landfill is also proposed under a separate landfill operating consent application. These ongoing improvements are expected to match and address any increased organic load resulting from population growth. 16. Operational Performance of the Existing Land Irrigation Activities Description of Equipment The existing land treatment system was commissioned in late It comprises central pivot irrigation of the effluent from the wastewater treatment plant wetlands which has then been fine screened and UV irradiated. Discharge is over an area of approximately 20 ha comprising a 300- metre radius central pivot sweep through approximately 253. The irrigator therefore travels in alternate directions as it runs backwards and forwards through this part circle sweep. Application rate is typically approximately 2 to 10 mm per day. The irrigator can operate at various speeds and discharge rates through the individual nozzles in order to achieve the required application rate. The nozzles are suspended on dropper lines, which place the discharge nozzle at less than 1.5 m above ground surface. There are a total of 83 dropper lines and nozzles providing a spacing of approximately 3.5m between nozzles. The spray from each nozzle achieves a slight overlap with the adjacent nozzle however this is compensated by the reduced flow spread at the extreme edge of the spray pattern. Each dropper line has an individual solenoid valve controlling its action and the loading intensity throughout the irrigator sweep can be modulated using the IQ controller which has a GPS tracker on the irrigator location. For example, this function is currently used to prevent irrigation closer than 25m from site boundaries (required by Condition 18 of the land irrigation permit WAR [33168]). This function could also be used if it was found that a given area of the site should be irrigated at a lower rate than the rest of the site.

29 29 Automation The irrigation system has automated controls which will prevent operation in situations where ground moisture content is too high, wind speed is too high, rainfall is too high, or spray drift is experienced outside the area of the predicted spray pattern. Once programmed for a given application rate, the irrigator will apply this over a maximum 24-hour period, automatically stopping and starting as required and potentially constrained by the above sensors. Monitoring of the irrigation area is undertaken with a weather station located adjacent to the central pivot point in conjunction with nine remote sensors, spread representatively throughout the irrigated area; three for soil moisture, three leaf sensors for spray drift, and three anemometers for wind speed. Compliance with Consent Conditions During the last reported 12 months of operation and over its operational life to date, operation of the centre pivot irrigator and its discharge to land consent has been generally compliant with the consent conditions. For example, full compliance was achieved for the 2015/2016 irrigation season except for some technical and minor non-compliances relating to trade waste bylaw, DO concentration, irrigation rate and the omission of some herbage testing. Since the commencement of operation of the central pivot irrigator, there have been no complaints of any nature regarding the effects of the land irrigation activity. Groundwater monitoring associated with the discharge to land consent for the central pivot irrigator has shown a slight increase in nutrient concentrations in downstream wells however because of the limited monitoring period it is uncertain whether this is an ongoing trend or just part of the typical variation which would naturally occur between different times and different years. Integration with Farming Activities Experience to date confirms the importance of integrating the land irrigation with farm operations. The intention is to continue to monitor and collaboratively manage, with the farmer leaseholder, the farming activities including the timing, type and location of stock grazing and fertiliser application to ensure achievement of the overall Daleton Farm nutrient budget. 17. Operational Performance of Reticulation Network Description The reticulation system (Figure 4) consists of domestic pipes on private land approximately 2,300 connections, the pipes and manholes of the municipal system; pipes range in diameter from 80mm to 380mm and the network consists of 30.8 km of underground piping. There are 15 pump stations at strategic locations through throughout the town to lift sewage from low lying areas up into the gravity network. The system reticulates flows to the southern end of Carterton to the municipal wastewater treatment plant in Dalefield Road. The reticulation system is generally sized well for the population, and there are no storm overflows.

30 30 Flows, Inflow and Infiltration Elevated flows are typically related to significant rainfall events which can be a mixture of inflow and infiltration. Regular smoke testing, typically performed on a two-year cycle, identifies inflow locations, which are then rapidly fixed. Smoke testing was first carried out in Work on I/I started in earnest in 2009 with a sewer main renewal in Kent Street from Tasman Crescent to Tavernier Street and in Garrison Street between Victoria and Redwood Street. Flow monitoring over 2011/2012 combined with survey work identified flows/dwelling at strategic locations within the system, and subsequently identified catchments where flows were proportionally higher than in other areas. By June 2012, western catchments had been identified as dominant infiltration areas (Figure 5). Planned 2016/17 work 2015 sewer 2014 sewer replacement 2012 grouting work Figure 5 Inflow & Infiltration Priority Areas June 2012 Major repair works in 2012 saw a significant drop in infiltration into some of the deeper pipes in the western catchments, by grouting pipe joints in Lincoln road. Following from the 2012 work, the northern catchments then became the priority areas. In early 2014, pipe bursting of mains & laterals and manhole replacement work was carried out in Wyndham Street from Kent to Belvedere Road and Rhodes from the railway to Wyndham Street. The grouting of pipe to the Timber Spec s factory off Kent Street was carried out in June Two manholes were also replaced. The replacement of three manholes in Kenwyn Drive took place in July Between April and July 2014 smoke testing was carried out on all the eastern suburbs. Whilst some remedial works on private property were identified and repaired following rectification notices, inflow in the eastern suburbs can be classed as minor.

31 31 Replacement of the Garrison St main was finished in June Smoke testing in the western suburbs was completed in early 2016, with only minor remediation necessary. Following routine flow measurements, CCTV work 2015/2016 confirmed High St North as the current highest priority in terms of infiltration, and replacement work is scheduled for the summer of 2016/17. More recent work has focussed on the bigger picture for infiltration to better understand potential options and alternative strategies for combating infiltration in Carterton s wastewater reticulation system. Further details are contained in Attachment 12. Survey findings suggest that the dominant infiltration pattern is from a perched water table in the north end of Carterton, particularly around Kent St. Investigations are underway to assess the implications of this and formulate mitigation strategies. Overall the I/I remediation programme to date has had wins and losses as pipes fail and are repaired (Figure 6), but the overall trend since 2006 has been a decrease in yearly flows. Figure 6 Carterton Population and Wastewater Flow Estimates Continued Funding Commitment Given the significance of reducing overall flows, both in terms of cost and environmental effects, there is strong argument that investigations into infiltration reduction are equally as important, or more important than, land acquisition and irrigation. $2.5M dollars is budgeted for mains

32 32 renewals over the next ten years. Priority is assessed each year based on flow measurement, CCTV, and observations by experienced operational staff. 18. Proposed Management Plans CDC has developed a number of operational management plans, as required by the current consents. CDC intends to rationalise these into one whole-system operational management plan. Time has not permitted completion of that management plan. CDC proposes to complete the management plan, in discussion with GWRC, following lodgement of these applications. 19. Consent Status Regional Plan Discharge Permits and Land Use Consents Attachment 13 includes a detailed analysis of the applicable regional plan rules. Most of the activities applied for are discretionary activities. However, the proposed discharge to water is classified as a non-complying activity under the proposed Natural Resources Plan. On a bundled basis, the applications must therefore be considered as a non-complying activity. Under the proposed Natural Resources Plan, the discharge to water of wastewater that is an existing discharge is a discretionary activity under Rule R61. The continued discharge to the unnamed tributary is an existing discharge and, therefore, a discretionary activity. However, the proposal to relocate the discharge outfall to a new location downstream introduces differences compared with the existing discharge that mean that the long-term discharge falls within the proposed Natural Resources Plan definition of new discharge and is a non-complying activity under Rule R62. Although the long-term discharge proposal represents an improvement upon the existing discharge, due to the proposed Plan s definitions, it has a more stringent consent status. District Plan The pipeline conveying treated wastewater to the discharge outfall structure and the outfall structure are part of a reticulated wastewater network. Accordingly, they fall within the District Plan definition of network utility and are provided for as a permitted activity under Rule Effects on the Environment: Description of Receiving Environments The proposed activities involve discharges to the land, (indirectly to) groundwater, to the Mangatārere Stream and to air. This section provides a brief description of the environment in which land use and discharge activities are proposed. The descriptions here are summaries. More comprehensive detail is included in the individual assessment reports contained in the attachments to this document. Land and Soils Daleton Farm is currently in permanent pasture. It is currently leased to a farmer and has been farmed as a dairy support block. Baleage is grown and cut during spring and summer. The existing and proposed land application areas consist of largely flat terrain of relatively recently formed river terraces associated with the Mangatārere Stream. The site is bounded at the northwest

33 33 corner by the Mangatārere Stream, and is separated from the stream along its western boundary by a parcel of grazing land under private ownership. Daleton Farm has a fall of nearly 12 metres from its north-eastern tip to the southern corner, with a distinct change in elevation along a terrace scarp which also corresponds with a change in soil type. Figure 7 Daleton Farm Soil Types The current irrigation area is largely located on a slightly elevated area of river terrace that offers protection from flood events. The upper terrace slopes gradually in an east to southwesterly direction. The proposed second centre pivot irrigation area is largely located on a low terrace. The area is interspersed with an ephemeral channel and abandoned river channels, all part of the Mangatārere Stream system. As shown in Figure 7, there are two soil types at Daleton Farm: Opaki soils (also known as Kohinui) and Ahikouka soils (also known as Prebbleton). The inferred boundary of these soils is evident by the change in elevation that is visible in the field and confirmed by an EM survey undertaken by CDC (included in Attachment 15. Key features of the soil groupings which occur on the site include:

34 34 Opaki soils Ahikouka soils mainly on upper terrace (current irrigation area) mainly on lower terrace (proposed irrigation area) typic Firm Brown Soil (S-Map) weathered Fluvial Recent soil (S-Map) intermediate in texture predominantly silty or loamy intermediate in texture predominantly silty or loamy shallow, moderately stony top soil on stones, top soil is stoneless on silty alluvium gravels or sand well drained and the most freely draining soils on the property moderately well drained surface compaction from animal treading N leaching vulnerability is potentially high N leaching vulnerability is low topsoil P retention medium (43%) topsoil P retention low (19%) The drainage limitations of the Ahikouka soils mean these soils can become saturated under winter and spring wet conditions with the potential for ponding, and surface compaction from animal treading (pugging). The well drained and moderately well drained Opaki soils are more suited to (year-round) irrigation. The proposal includes removal of stock from the existing and proposed second irrigated areas. There are soil monitoring probes in place that are connected to the centre pivot irrigation system and the applicant is able to fine-tune the operation of the irrigators to ensure that irrigation will cease before soil moisture reaches field capacity levels. More detail describing soil properties are included in the soils assessment report contained in Attachment 15. Groundwater The geology beneath the site is underlain by interbedded silty gravels, silts and gravelly silts. The site stratigraphy can be generalised to be underlain by 4-5m thick silty gravels, underlain by a 3 4m thick silt layer. Beneath the silt layer are further gravels and silty gravels under which a positive pressure aquifer is encountered. There are currently nine groundwater monitoring bores providing information on the shallow aquifer beneath the farm. In conjunction with Greater Wellington s recommended staff hydrologist, four new monitoring bores have been installed for monitoring the shallow aquifer downstream of the SBR reservoirs and CPI 2 irrigation site. There are also two existing monitoring bores to the north of the SBR reservoirs, and 3 geotechnical boreholes with piezometers for water level monitoring that may be converted into monitoring bores located in the vicinity of the SBR pond area. The general direction of groundwater flow is towards the southwest (towards the Mangatārere Stream). The groundwater flow pattern reflects a hydrogeological system in which rivers interact closely with adjacent shallow aquifers, and therefore, connect the groundwater system to the surface water system of the Mangatārere Stream. The assessment and pump test results provided by Greg Butcher (Professional Ground Water and Environmental Services) describes the connectivity in more detail. Groundwater monitoring results indicate: higher and varying levels of conductivity in bores downstream of Daleton Farm (with peak values during winter); generally static levels of DRP and Total Phosphorus;

35 35 winter peaks in nitrate nitrogen and total nitrogen (with highest values being in an upstream bore with lowest values in bores immediately downstream from the oxidation ponds; ph values relatively consistently in the range 5.5 to 6.5; and no E. coli present in samples. More detail is contained in the two assessment reports contained in Attachment 14 (assessment of groundwater connectivity and assessment of potential impacts of land irrigation on groundwater quality). Mangatārere Stream The Mangatārere Stream is the main tributary of the Waiohine River in the middle Wairarapa Valley, draining a catchment of 157 km². Rising in the foothills of the Tararua Range, the stream flows for approximately 31 km before its confluence with the Waiohine River to the east of at State Highway 2, south of Carterton Township. Three main tributaries discharge into the Mangatārere Stream: Enaki Stream, Kaipaitangata Stream and Beef Creek. Of these three tributaries, the Enaki Stream is located well above the CDC wastewater treatment plant. The Kaipaitangata Stream and Beef Creek are located below the current discharge point. When the discharge point is relocated downstream, upstream of the State Highway 2 bridge, then only Beef Creek will be below the discharge point. The Mangatārere Stream at SH 2 has been sampled at monthly intervals since 1998 as part of Greater Wellington s Rivers State of the Environment (RSoE) monitoring programme. The lower Enaki Stream (near the Mangatārere confluence) has been sampled monthly since early 2002 as part of Greater Wellington s riparian rehabilitation monitoring programme. It is important to note that the furthest downstream monitoring site located on the Mangatārere Stream (at SH 2) is above its confluence with Beef Creek. Therefore, the results of sampling in Beef Creek at SH 2 must be added to the contaminant load when assessing the impact of the quality of the water entering the Waiohine River from the Mangatārere catchment. Mangatārere Stream flow is continuously monitored by Greater Wellington Regional Council (GWRC) at the sites; Mangatārere Stream at Gorge (just upstream from where the stream emerges onto the plains from the foothills) and at SH2. At the Gorge, the stream has a mean flow of 1,830 L/s, a median flow of 900 L/s and a mean annual low flow of 133 L/s. At SH2 the streams mean flow is 3,974 L/s, median flow 2,000 L/s and mean annual low flow 217 L/s (based on data from ). GWRC undertook a Mangatārere Stream catchment water quality investigation commencing in Its findings confirmed that degradation of water quality in the Mangatārere Stream begins generally downstream of the Gorge, where the stream opens onto the more intensively farmed plains. Carterton s municipal wastewater discharge has historically had a profound impact on water quality in the nearest downstream reaches of the mainstem Mangatārere Stream. Beef Creek was also found to have very poor water quality. Overall, elevated dissolved nutrient concentrations together with a lack of riparian vegetation cover and periods of low or stable stream flows were found to be contributing to nuisance periphyton growth and reduced invertebrate health, particularly in the lower reaches of the Mangatārere Stream. The Mangatārere Restoration Society, landowners, GWRC and CDC have been attempting to rehabilitate the riparian margins of the lower stream reaches in recent years.

36 36 There is community support for improving water quality in the Mangatārere catchment generally including in the reaches affected by the CDC wastewater discharge. Notwithstanding the acknowledged degraded water quality, the Mangatārere Stream is identified as having important habitat values under the operative Regional Freshwater Plan and proposed Natural Resources Plan, including: significant indigenous ecosystems (Brown mudfish, common bully, Cran s bully, dwarf galaxias, giant kokopu, inanga, lamprey, longfin eel, redfin bully, shortfin eel, torrentfish and upland bully); and being an important trout fishery and spawning waters. The Mangatārere Stream is also one of the waterways identified in the operative and proposed plans as a priority for water quality improvement for contact recreation and Māori customary use. Downstream Catchment The Mangatārere Stream is a tributary of the Waiohine River (the confluence is to the east of SH2 south of Carterton). The Waiohine River joins the Ruamāhanga River approximately 4.5 kilometres downstream of the Mangatārere confluence. The Ruamāhanga River flows to Lake Onoke and, ultimately, to Palliser Bay. Although the Ruamāhanga River has been diverted so that its usual flows no longer enter Lake Wairarapa, some flows can cause water to spill from Lake Onoke and from floodways along the lower Ruamāhanga River into Lake Wairarapa. Ultimately, therefore, any discharges of contaminants in the upper catchments (including to the Mangatārere Stream) have the potential to contribute to cumulative contamination in Lake Wairarapa. It is understood that this risk is predominantly confined to very high flood flows in the Ruamāhanga River. Lake Wairarapa is identified in the proposed Natural Resources Plan as an outstanding water body. The Ruamāhanga River is identified as having significant indigenous ecosystem values associated with indigenous fish as well as being a taonga for, and having sites of significance to, Ngāti Kahungunu ki Wairarapa and Rangitāne o Wairarapa. The Waiohine River is also identified as having significant indigenous ecosystem values and values for primary contact recreation. All values identified have been assessed on the basis of known historical catchment-wide water. All parts of the wider downstream catchment are potentially sensitive to the effects of contaminant discharge. Air Dalefield Farm is surrounded to the west, south and east by farmed land. The Carterton urban area extends to Dalefield Road, to the immediate north-east of the site. There is a group of residential houses on both sides of Dalefield Road near SH2. There are also dwellings on the rural residential properties to the immediate west of the site, along Gallon/Hodders Road. The existing irrigation area is immediately adjacent to the WWTP. The proposed second centre pivot irrigation area is on land south of the WWTP and north of the rural residential properties on Gallon Road. SH2 passes the site s eastern boundary and is not considered to be a sensitive receiving environment. The nearest residential dwellings are considered to be potentially sensitive to effects of aerosol sprays and odour not contained within the site. The nearest residential dwellings are on:

37 37 1 Dalefield Road (Lot 1 DP TARATAHI DIST BLK X TIFFIN) 27 Gallon Road (Lot 1 DP BLK X TIFFIN SD) 35 Gallon Road (Lot 7 DP and LOT 1 DP ) 36 Gallon Road (Lot 6 DP , LOT 1 DP and Lot 2 DP Daleton Farm farmhand s dwelling (there is a residential dwelling on the same title as the irrigation area which is leased by the same tenant who leases the irrigation land); Lot 1 DP (now owned by CDC) however the intention is to remove this dwelling to construct the SBRs and SBR support infrastructure (see Figure 1 in Attachment 1). There are also residential dwellings on the northern side of Dalefield Road. Farmhand s dwelling (Carterton District Council No. 1 Dalefield Rd Gallon Road Dwellings Figure 8 Nearest Residential Dwellings The dwelling on the corner of SH2 and Dalefield Road is currently 200 metres from the Council landfill boundary and approximately 375m from the nearest of the existing WWTP treatment facilities. This property s nearest boundary will be 50 m from the existing pivot irrigation area and 20 m from the drip-line irrigation area (a continuation of the current situation which is understood to have been operating successfully without odour or spray drift issues). The dwelling itself is 80m from the nearest arc of the pivot and 365m distance to the average overall sprinkler location (i.e. the pivot arm is pointing away from the property for roughly 2/3 rds of the time). It is separated from the pivot irrigation area and the dripline irrigation area by a mature macrocarpa hedge along the boundary, and young native plantings on the southern side of the macrocarpas. Dwellings on the eastern side of SH2 (opposite Daleton Farm) are more than m from the closest pivot point, and the closest farm building is approximately 125m distant. Dwellings on the north-eastern side of Dalefield Road are separated by the new boundary planting (amidst the existing mature but open-spaced silver birch trees) as well as Dalefield Road, and existing vegetation on the individual properties. The nearest dwelling is approximately 75m from the extreme point of the pivot arc and an average distance of 355m from sprinklers.

38 38 The outermost extent of the proposed second centre pivot irrigator will be approximately: 65m from the dwelling on 27 Gallon Road; 95m from the dwelling on 35 Gallon Road; and 200m from the dwelling on 36 Gallon Road. A native plant buffer has already been planted along the eastern boundary (in2014) and southern boundary (in 2016) in anticipation of a future pivot irrigator in this vicinity and in order to mitigate potential spray drift risk. Dwellings on the western side of the Daleton Farm boundary are upwind of the proposed second irrigator and more than 400m from the closest pivot point. The closest farm building is approximately 340m distant. Local ambient air quality is characterised as typical of working rural environment. Although there are sensitive receivers located nearby, experience of the existing centre pivot irrigation to date indicates that ambient air quality enjoyed on nearby downwind residential properties is not compromised by the centre pivot irrigation of tertiary treated wastewater. Experience to date has confirmed that the irrigation equipment can be fine-tuned to confine the extent of aerosol drift. No end guns have been used on the existing irrigation area and none are proposed for the second land irrigation area. Ephemeral Channel There is an ephemeral channel occupying part of the area that is to be developed as the second land irrigation area as shown in Figure 9 below:

39 39 Proposed Replacement Ephemeral Channel Existing Ephemeral Channel Figure 9 Existing and Proposed Replacement Ephemeral Channels