EVIDENCE OF DAVID JOHN CARLSON McCOLL

Transcription

1 BEFORE THE TASMAN DISTRICT COUNCIL IN THE MATTER OF The Resource Management Act 1991 AND IN THE MATTER OF Resource Consent Applications RM and others BY Harakeke 2015 Limited Applicant EVIDENCE OF DAVID JOHN CARLSON McCOLL McFadden McMeeken Phillips Solicitor acting: Nigel McFadden PO Box 656, Nelson 7020 Phone (03)

2 Introduction 1. My full name is David John Carlson-McColl. I am a Water and Wastewater Engineer employed by CGW Consulting Engineers. 2. I hold the qualifications BE (Chemical) from The University of Melbourne and a Diploma in Conservation and Land Management from the Riverina Institute of TAFE. I am a Chartered Professional Engineer and a Member of the Institution of Professional Engineers of New Zealand. In my employment at CGW Consulting Engineers I specialise in the design of water and wastewater infrastructure. 3. I have read the Code of Conduct for Expert Witnesses in the Environment Court Practice Note (2014) and agree to comply with it. My evidence is within my area of expertise, however where I make statements on issues that are not in my area of expertise, I will state whose evidence I have relied upon. I have not omitted to consider material facts known to me that might alter or detract from the opinions expressed in my evidence. 4. CGW Consulting Engineers were engaged to undertake the following tasks in relation to the development proposed by Harakeke 2015 Limited: 5. Wastewater Management a. Identify the volume of wastewater generated by the proposed development b. Identify areas within the proposed development that are suitable/unsuitable for land application of treated effluent c. Prepare a conceptual design for the treatment of wastewater generated by the proposed development 6. Water Supply a. Assess the likely water demand from the proposed development b. Assess the adequacy of current bores on site to meet water demand for the proposed development c. Develop a conceptual design for water supply for the proposed development 7. The proposed development is understood to be as follows a. 116 House Lots b. 54 two bedroom apartments c. 6 commercial buildings 8. I investigated these issues and prepared the report RPT-004-F Wastewater and Water Supply Assessment Harakeke 2015 Limited, included in the application. This evidence is based on my investigation and findings. Wastewater 9. I completed a site evaluation on the 29th of September 2014 in accordance with the site assessment factors detailed in AS/NZS1547:2012 Onsite Domestic Wastewater Management. Outcomes of this assessment included: a. Identifying areas suitable for effluent disposal, or only suitable for effluent disposal at a low rate, for example the low lying area to the south of Aporo Road. b. Identifying existing bores, gullies and water courses. c. Observing test pits dug as part of geotechnical evaluation. Medium to heavy clay was observed in the test pits. 10. The preliminary design has been completed based on Category 5-6 soil observed in accordance with AS/NZS1547:2012. This site is included in the Tasman Resource Management Plan (TRMP) Wastewater Management Area which mandates a maximum

3 effluent disposal rate of 2mm/day. This is consistent with an appropriate, conservative disposal rate for the observed soil conditions. 11. An onsite soil assessment in accordance with Appendix E of AS/NZS 1547:2012 was not undertaken because: a. The soil observed in geotechnical test pits was consistent with previous soil investigations undertaken by CGW in this locality. b. The TRMP specified maximum disposal rate is considered appropriate for this type of soil. c. The site will be subject to disturbance as part of proposed development. It was not possible to view any site specific issues at the time of inspection. Site specific assessments in accordance with AS/NZS1547:2012 should be required as a condition of consent to ensure site conditions match those observed during the site investigation undertaken as part of this work. 12. The volume of wastewater generated by the proposed development as assessed in accordance with the method outlined in AS/NZS1547:2012 making the following assumptions a. Houses have 5 bedrooms with 10 occupants in accordance with TRMP Section Rural Zones, and a reticulated water supply. It is noted that a reticulated water supply is unavailable at present. Wastewater flow rates have been assessed assuming reticulated water supply is available to ensure the lots remain appropriate for effluent disposal if conditions change in the future, so this is conservative for the proposed rainwater supply. The size of effluent fields has been calculated assuming peak wastewater production is 2000L/day per house in accordance with AS/NZS1547:2012 for a 10 person occupancy. b. Apartments have 2 occupants and a reticulated water supply. Total wastewater production is 400L/day per apartment. c. Commercial building use is unknown at this point. It is expected that use could include a café/restaurant, professional offices or a craft brewery or winery. I understand that there is no intention for onsite production from a brewery/winery, nor any other wet industry. The assessment was completed assuming all commercial buildings are equivalent to a public bar with 100 patrons per day, or a restaurant with 80 patrons per day. Total wastewater production is 2000L/day per commercial building. 13. The TRMP (clause r (j)) requires the following effluent quality for onsite wastewater treatment in the Wastewater Management Area a. Biochemical Oxygen Demand: 90% of samples < 20g/m3 absolute maximum 30g/m3 b. Total Suspended Solids: 90% of samples < 30g/m3 absolute maximum 45g/m3 The TRMP specified effluent quality standards are considered appropriate for this development. Secondary effluent treatment will be required for all properties within the proposed development in order to meet the effluent quality standards specified by the TRMP 14. I concluded that all effluent disposal should utilise shallow subsurface pressure compensated drip irrigation with an irrigation rate not exceeding 2mm/day. This rate should be reduced in accordance with AS/NZS 1547:2012 for any areas where the ground slope exceeds 10%. Dripline should either be buried by mm or installed on the surface and covered with 100mm of mulch. 15. All systems require detailed design in accordance with AS/NZS1547:2012 and the specifications outlined in the CGW report RPT-004-F.

4 House Lots 16. The suitability of house lots for onsite effluent disposal was determined by considering the setback and buffer distances specified in the TRMP clause All specified criteria were complied with, with the following exceptions a. A reserve disposal area equal to 100% of the required primary disposal area. A 50% reserve area was provided b. A 20m offset from any adjoining disposal field. A 10m offset was provided I considered these changes appropriate as all adjacent effluent treatment systems will be distributing secondary treated effluent at a suitably low rate. 17. A map was prepared identifying remaining areas suitable for effluent disposal taking into account buffer distances from waterways, bores, roads and property boundaries. The locations for house lots were adjusted as required so that effluent disposal would not occur in the areas identified as unsuitable or marginal. 18. The available area for effluent disposal on each house lot was calculated by Canopy Landscape Architects, based on a house and shed size assumed by Canopy and the buffer distances specified by CGW. An additional 100m 2 was allowed for paved and hardstand areas, giving a total of m 2 per lot occupied by buildings and hardstand area. All of this area was conservatively assumed to be within area which would otherwise be suitable for onsite effluent disposal. 19. In cases where individual house lots were found to be too small, lot boundaries were adjusted, in consultation with the Applicant. 20. The boundary of one house lot (Lot 206) could not be adjusted to provide adequate area for effluent disposal from a 5 bedroom house. Provided this Lot is restricted to a 3 bedroom home, it is considered suitable for onsite effluent disposal. 21. All other house lots were assessed to be suitable for onsite effluent disposal for up to a 5 bedroom/10 occupant home. Commercial and Apartment Buildings 22. Individual treatment and disposal systems were assessed to be inappropriate for apartment and commercial buildings due to a requirement for multiple systems and easements within public open space and productive land. 23. A centralised wastewater treatment system was considered more appropriate for effluent from the commercial and apartment buildings 24. The total treatment capacity of this system should be 33,600L/day. The system should be a modular design which can be progressively expanded as the apartments and commercial area are developed. 25. A total of 1.7Ha was identified as required for effluent disposal from the centralised treatment system. Again, a 50% reserve area was recommended giving a total required area of 2.5Ha. 26. A suitable location for effluent treatment and disposal from the centralised wastewater treatment system was identified on the eastern side of Aporo Road in consultation with the Applicant

5 27. The nominated site varies in slope from 9-28%. Once slope reduction factors are taken into account, in accordance with AS/NZS1547:2012, the total area for effluent disposal from the centralised treatment system is 3.2Ha. 28. The conceptual design includes the treatment of effluent on the western side of Aporo Road prior to pumping it across to the proposed disposal area. Water Supply 29. Water demand for the proposed development was calculated as follows a. House lots: A range of sources were considered to assess potable water demand for house lots as tabulated below: Water Demand House Lots Information Source Average Use Peak Use Reference NCC Land 1,000L/day L/hr 1 NCC LDM Development Manual NZS 4404:2010 Land Development Standard 1,000L/day L/day 2 NZS 4404:2010 Land Development and Subdivision Infrastructure Richmond Average Use 758L/day 1093L/day 3 MWH International, 2010 NCC Average Use 420 L/day CGW, 2014 Appleby Hills 623 L/day 4 Up to 2,800L/day 5 CGW, 2013 Subdivision Notes 1) Assumes 2.5 occupants per house 2) Assumes 4 occupants per house and a peaking factor of 2 for populations less than 2,000 3) Average use in peak demand week between 2007 and ) Average May December 2012 use (i.e. likely to be minimal irrigation) 5) Understood to include a significant amount of irrigation use (no water use restrictions enforced) Water use figures from the TDC Engineering Standards have been omitted. These standards specify a peak water use of 16,800L/day per connection. TDC have previously confirmed to CGW that these figures are in error. Following a review recorded average use as presented above, an average water demand for house lots of 700L/day has been adopted. It is noted that this figure is different to the assumed wastewater calculation flow rate detailed in item 12(a). AS/NZS1547:2012 requires the wastewater system to be designed based on the maximum wastewater production rate with 10 occupants. The water consumption rate has been calculated assuming typical average values. b. The potable water supply requirements for apartments were assessed in accordance with NZS4404:2010 Land Development and Subdivision Infrastructure assuming 2 occupants per apartment, the total average use per apartment is calculated to be 500L/connection per day.

6 c. The potable water supply requirements for commercial premises has been assumed to be consistent with the wastewater production flow rates detailed in Item above at 2000L/day per connection. 30. Firefighting requirements for all properties in the development have been assessed in accordance with SNZ PAS 4509:2008 New Zealand Fire Service Firefighting Water Supplies Code of Practice, assuming a. Houses are single family homes without a sprinkler system b. Apartments are not classed as multi story apartment blocks c. Commercial buildings are i. Used for crowd activities with less than 100 people ii. Have a maximum fire cell area of less than 399m2 iii. Are considered a light fire load, for example restaurants or hairdressers iv. Are not fitted with a sprinkler system On this basis, the firefighting water requirements are as follows House lots and apartment buildings: Water supply classification FW2 - Two hydrants within 270m, capable of delivering a total of 25L/s Commercial buildings: Water supply classification FW3 - Three hydrants within 270m, capable of delivering a total of 50L/s 31. The available groundwater supplies for potable water within the proposed development area are tabulated below: Harakeke Groundwater Bores Bore Identification Number Consented Take (m 3 /day) (irrigation) None Take of 5m 3 /day as a permitted activity None Take of 5m 3 /day as a permitted activity None Take of 5m 3 /day as a permitted activity None Take of 5m 3 /day as a permitted activity 32. In accordance with TRMP Rule , Table 31.1A, the extraction of up to 5m 3 /day per point of take is a Permitted Activity in this aquifer. 33. Bore is presently consented for irrigation use. From discussions with Joseph Thomas, TDC Resource Scientist/Water, I understand that it is likely the present consented irrigation take of 29m 3 /day for 181 days will be reduced to 14.4m 3 /day if the use is changed to the supply of the community scheme for 365 days per year. 34. The TRMP Section states that bores deeper than 120m deep must be separated from existing bores by a minimum of 600m. It is possible to install an additional bore within the proposed development area, adjacent to Lot 505, in compliance with this rule. An allowance of 5m 3 /day being taken from this bore has been made, consistent with the permitted activity in accordance with TRMP Section The total assumed consented and permitted take from bores within the development has been calculated as: (5 x 5) = 39.4m 3 /day 36. Based on the water demand presented at item 29 above, total average water demand for the development is as follows: a. House Lots 81.2m 3 /day

7 b. Apartments 27m 3 /day c. Commercial buildings 12m 3 /day 37. Available bore water supplies are inadequate for the entire development, therefore I determined that apartments and commercial buildings should be serviced with water from centralised reticulation and house lots should be serviced with rainwater. Detail is as follows: a. Apartments and Commercial Buildings Firefighting Demand: Met through a reticulated supply designed in accordance with SNZ PAS 4509:2008. It is proposed that groundwater bores will pump to common storage tanks to supply the reticulation via gravity. Potable water demand: Met through a community reticulated supply. It is proposed that all groundwater bores within the proposed development area will pump to two 500m3 storage tanks. In the conceptual design, the proposed location for tanks is to the east of Lot 311. Tanks will supply the reticulation via gravity. It is expected that the security of bores and hence the required treatment will be determined as part of detailed design. b. House Lots Firefighting Demand: Met through a reticulated supply designed in accordance with SNZ PAS 4509:2008. It is proposed that groundwater bores will pump to common storage tanks to supply the reticulation via gravity as follows: i. One 500m3 storage tank will be located between Lots 128 and 1231 to service the 100 zone lots ii. Two 500m3 storage tanks will be located to the east of Lot 311 to service the 300, 400 and 500 zone lots. These tanks also service the community system described in item above. iii. One 500m3 storage tank located adjacent Lot 228 to service the 200 zone lots Potable water demand: Met through rainwater with onsite storage tanks. Initially a minimum of 45,000L of storage was specified by CGW. Following discussion with the Applicant; this has been revised to 70,000L. 38. I have recommended that house lots are provided with a tapping point to connect to the reticulation network. Under normal circumstances, this will not be connected to the house lots water supply, it will provide two functions: a. In the event of unforeseen circumstances, such as a plumbing failure leading to emptying of rainwater tanks, it could be used to top up rainwater tanks. This would be at the discretion of the management entity and subject to available water within the limits of the consented water take and storage requirements for firefighting. b. In the event that an alternative water supply ever became available, it could allow simple connection of house lots to a reticulated water supply. All water supply calculations for house lots have been completed assuming no alternative supply is available. 39. In developing the conceptual design, it has been assumed that any bore can pump to any tank within the development to ensure both firefighting and potable water requirements will be met. The actual pipework configuration will be determined as part of detailed design depending on the staging of the development. 40. Reticulated supply intended for potable use will require detailed design and management in compliance with the New Zealand Drinking Water Standards, the Health Act and relevant sections of the TDC Engineering Standards.

8 41. Onsite water supplies for house lots will be required to comply with Potable Water Supply requirements under the Building Code Section G12 Water Supplies Response to Submissions - Wastewater 42. A number of submitters raised concerns with the impact of effluent disposal on adjacent wetlands, specifically: a. Concerns regarding disposal of effluent from septic tanks b. Concerns that the proposed discharge will cause nutrient or microbial contamination of adjacent waterways 43. Effluent disposal will not be directly from septic tanks. As required by the TRMP for this region, secondary effluent treatment will be used. The difference in effluent quality between a secondary treatment system and a typical septic system is presented below, values are taken from Auckland Regional Council Technical Publication 58 On-site Wastewater Management Systems (ARC TP58) Effluent Treatment Septic Tank only ( good operation ) Secondary Treatment 30 (TDC mandated requirements) Biochemical Oxygen Total Suspended Total Nitrogen (g/m3) Demand (BOD g/m3) Solids (TSS g/m3) (TDC mandated requirements) (TP 58 Typical for secondary treatment) Historically, effluent from septic tanks has commonly been disposed of via soakage pits, beds or trenches. This is typically done at very high rates which can lead to surface ponding and nutrient run-off when poorly designed or maintained. Effluent disposal for this proposed development will be irrigated via drip line at a maximum rate of 2mm/day, average rates will be closer to 0.5mm/day. This is times lower than typical rates for traditional septic and soakage field type systems. A picture illustrating the difference between the two systems is shown in Figures 1-3 below. Figure 1: Conventional Septic and soakage field (taken from Pima County DEQ)

9 Figure 2: Secondary treatment and dripline typical installation schematic (taken from HR Complete Septic Service) Figure 3: Dripline installation (taken from Rodenhiser Excavations Inc) 44. The irrigation of treated effluent will add nutrients to the disposal field area. The primary nutrient for consideration from domestic wastewater is nitrogen. The TRMP does not specify the maximum amount of nitrogen that may be applied to land from an onsite effluent system. Auckland Regional Council Technical Publication 58 On-site Wastewater Systems (ARC TP 58, 2004) refers to the Auckland Regional Plan: Farm Dairy Discharges when considering nutrient application from onsite domestic effluent systems. The maximum permitted nitrogen application rate on low permeability clayey soils in the Auckland Regional Plan clause (b) is 200 kg/ha/year. This limit is considered to pose a minimum risk to groundwater quality (ARC, 2004 Section ). This is consistent with Section of the TRMP. Nitrogen application of up to 200kg/ha/year is a Permitted Activity for a dairy farm in Tasman.

10 45. Work done for Environment Waikato estimates that average nitrogen application for average pastoral (non-dairy) farming to be approximately 14 kg/ha/year (Environment Waikato, 2007). 46. From TP 58, the expected nitrogen concentration in secondary treated effluent typically varies from g/m 3. Assuming an average of 37.5 g/m 3, the average nitrogen application rate over the total 72.4 Ha of house lots is about 10.5 kg/ha/year. For the centralised system serving the apartments and commercial buildings, conservatively assuming that the commercial wastewater has similar nitrogen content to domestic wastewater, the average nitrogen application rate over the area of the disposal field alone is about 131 kg/ha/year. These values are well below the 200 kg/ha/year limit noted above. As an average application rate over the whole property it would be substantially less. 47. The potential for microbial contamination of surface or groundwater from the proposed effluent discharge has been considered. A 20m offset from a disposal field to any bore or surface water body has been specified in accordance with the TRMP. Effluent disposal will be approximately 100mm below ground surface to minimise the possibility of a direct pathway between treated effluent and surface or groundwater. To assess the impact of the proposed discharge, CGW have considered research work into horizontal setback distances from septic tanks completed by the Institute of Environmental Science and Research Ltd (Pang, L. et al). This work found that in sand aquifers, a 5 log reduction in virus concentrations is typically achieved within 23-33m of a contamination source. The aquifer in this area is separated from the proposed effluent discharge zone by clay and silty clay. There is a high probability that the lower hydraulic conductivity in this soil type will increase the log reduction in virus concentration, such that the 20m setback is a reasonable criteria in these soils. 48. The TDC Co-ordinator Natural Resources Consents (Section of Officers Report) has agreed with the CGW conclusion that the risk of nitrate or microbial contamination from the proposed effluent discharge is low, subject to the recommended conditions. 49. Submitters raised concerns regarding the management of the onsite effluent systems, in particular the nature of the management entity and adequacy of management. 50. The exact legal nature of the management entity is not within my area of expertise. I understand that these details will be provided by others. 51. TRMP requirements specified under rule should be imposed as a condition of consent, with the proposed variations as identified in CGW report RPT-004-F. This should include effluent quality requirements, the requirement for no surface ponding of effluent and no discharge of effluent to water bodies. If a consent holder breaches conditions of their consent, TDC may take enforcement action. 52. The centralised treatment system will be a modular design that can be progressively added to as the development is built. The failure of an individual module will restrict treatment capacity, it will not cause the failure of the entire system. 53. It is recommended that service agreements should be implemented for all onsite waste water systems. For a secondary treatment system this typically involves 6 monthly inspections, but is generally defined by the manufacturer. This should be imposed as a condition of consent. 54. A number of submissions stated that no changes to the reserve areas or buffer distances specified in the TRMP should be permitted

11 55. The TRMP must allow for a wide range of situations and cannot be specific to every design case. Variations to the Restricted Discretionary activity requirements can be approved, subject to the discretion of TDC. A setback of 20m may be reasonable where the adjacent system is an existing septic tank and soakage bed in some soil conditions. All systems within this development will be discharging secondary treated effluent at a low rate. Recommended drip emitter spacing is specified by manufacturers based on the wetted area per emitter. For clay soil, an emitter spacing of 0.6m is recommended (Rainbird, 2014). This means that there is a very low probability that a drip line effluent distribution field will impact upon an adjacent dripline field located 10m away. For any area in Tasman District not within the Wastewater Management Area, a 1.5m buffer to a boundary, therefore a 3m buffer to an adjacent field is required. 56. Clause Item f(iv) requires a 20m setback from any adjacent domestic wastewater disposal field, but clause Item f(iii)requires a setback of only 5m from a boundary. If this approach is followed it would mean that the first landowner to build could install a disposal field within 5m of the boundary and the next would need to be 15m from that boundary The conceptual design recommends a buffer of 10m from any adjacent disposal field, which agrees with the 5m setback on each property, and in my opinion is ample setback for the proposed development. 57. TRMP section Item k specifies that where a disposal system services a single household, 100% of the design land disposal field is available as a reserve disposal area. The conceptual design recommends a reserve area equal to 50% of the primary disposal area. There are two reasons why use of the reserve area is likely to be required; either because the original system is undersized, or because the disposal system fails over time. a. Systems will require design and construction in compliance with AS/NZS1547:2012 in order to obtain Resource and Building Consent, therefore it is unlikely the original design will be undersized. A 50% reserve area allows for a substantially reduced application rate in the event that there are issues with a system. b. If the entire disposal system fails, it is possible to install new drip irrigation line in the same location as the old line, hence minimal reserve area is required. 58. A number of submitters were concerned that wetlands and gullies have not been considered, and that this would impact upon adjacent wetlands. 59. The TRMP (Section item f) requires effluent disposal fields to be located a minimum of 20m from any surface water body. This offset has been allowed for when determining the available area for effluent disposal on each lot. 60. The wetland on the western side of Horton Road, noted by a number of submitters, is approximately 40-50m from the nearest proposed disposal fields for lots 320 and 305 Response to Submissions Water 61. A number of submitters noted that calculated water use is different to TDC Standards 62. It is recognised that the assumed water use is different to that specified in the TDC Engineering Standards. The calculated average use of 700L/day per house and 500L/day per apartment is considered a realistic estimate of actual average use. A number of examples were cited in Item 29 to demonstrate that actual average use in similar communities was between L/day per house for reticulated water supplies. Residents reliant on rainwater supplies are typically aware of the need for water conservation and use less water

12 than residents serviced with reticulated supplies. This is recognised in AS/NZS1547:2012 where residents relying on rainwater supplies are assumed to use 10% less water than those on a reticulated supply. 63. It is acknowledged that higher water users will use more water than average. Based on the above statistics, the calculated average use of 700L/day per house is considered appropriate for normal residential use with some irrigation. The implications of high water use are discussed further at Item 68 below. 64. The calculated average use of 2000L/day per commercial building is considered a realistic estimate for the following reasons: a. Average non-residential water use in Christchurch, Tauranga and New Plymouth was approximately 2000L/day per connection (CGWL, 2014). These records include any non-residential customer; they do not make a distinction between commercial and industrial customers. Non-residential water use in Nelson was higher at approximately 3300L/day per connection. These figures will include high use customers such as fish and meat processing and other wet industries. b. I understand commercial operations for the site could include a café, winery or professional offices. Any winery or brewery would not include processing. A commercial use including processing has not been considered in this assessment. c. Additional surface water allocation of 1139m 3 /day is available within the development, therefore it is assumed that irrigation requirements within the commercial area or public open space will be met with untreated surface water. 65. Submitters raised concerns that there is insufficient water available for rainwater supply for house lots 66. The TRMP (Section ) requires a minimum of 23,000L of rainwater storage in addition to firefighting water storage for the construction of a dwelling in the Rural 3 Zone. The Applicant has volunteered a condition of a minimum of 70,000L storage for house lots in this development. This is in addition to firefighting storage, which is to be provided by the reticulation network. 67. To determine if the proposed water storage was adequate, I completed calculations for water use for house lots using a number of different scenarios based on assumptions as follows: a. Rainwater catchment area of 350m 2 per house, consistent with the estimate provided by Canopy Landscape Architects b. Water storage capacity of 70,000L per house c. Rainfall data for Mapua from , sourced from The National Climate Database produced by NIWA Scenarios have been considered as follows: a. Scenario A 700L/day, 70,000L storage. b. Scenario B 700L/day, 100,000L storage. A graph is presented as Figure 4 showing the amount of rainwater stored in tanks under these scenarios.

13 Volume in Tank (L) Figure 4: Harakeke - Rainwater Storage /07/ /04/ /01/ /10/ /07/ /04/ /12/ /09/2017 Date Scenario A (70 kl Storage) Scenario B (100kL Storage) Under Scenario A, additional water approximately equal to 20,000L would have been required once during the past 15 years. Under Scenario B with additional storage capacity, no additional water would have been required at any time over the past 15 years. 68. It is recognised that residents undertaking a significant amount of irrigation may run out of water during summer. Residents likely to have higher irrigation demand should be advised to implement additional storage capacity. As an example, typical water use for a higher water demand resident has been considered as follows: a. 100,000L storage b. 1500L/day in January and February c. 600L/day in June-August d. 1000L/day at all other times unless tank is below 10,000L in stored volume. In which case use drops to 600L/day Under this scenario, 1 tanker load equivalent to 20,000L would be required 12 times over the past 15 years. 69. Water available from rainwater is considered adequate for the proposed house lots based on typical use in accordance with the information sources presented in Item 29 above. Residents should be made aware that for higher irrigation demand, tanker water supply may be required more frequently. 70. Submitters raised concerns that the proposed groundwater extraction will impact upon adjacent wetlands 71. CGW have reviewed work done by others investigating the hydrology of the Moutere Aquifer (Stewart M. K., and Thomas, J. T. (2002)). Based on information presented in this report, there are three aquifers in vertical succession in this area. A schematic diagram of this arrangement is shown in Figure 5 below. There is limited connectivity between the Shallow, Middle and Deep Moutere Aquifers. Deep bores are defined in that report as 30-50m deep.

14 Figure 5: Moutere Aquifer. Taken from Thomas, J. (2001) 72. Of the bores proposed to be included in the water supply for this development, bore has a consented take of 29m 3 /day for irrigation use. This bore has a screen set at 20-88m below ground surface. Actual take from this bore will be consistent with present use. For the remaining bores, the depth to the top of the screen is at least 60m. These latter bores will not be drawing surface water therefore there will be negligible effect of the proposed groundwater extraction on adjacent wetlands. 73. The TDC Officers Report has concluded that the existing conditions for groundwater use are sufficient to address the potential adverse effects of the change in take on the environment. (Section 12.23) 74. Submitters raised concerns that the proposed groundwater extraction will impact upon adjacent bores 75. Results of pump testing completed at the construction of bores within the development area are as follows: Harakeke Bore Pump Test Details Bore ID Depth (m) 2 Hour Pump Test Drawdown (m) Flow (m 3 /day) The proposed annual extraction rate from bore is unchanged from the presently consented take. From all other bores, the proposed extraction is 5m 3 /day per bore. This is a

15 very low rate compared to the rates achieved during pump testing and it is a rate permitted by the TRMP. 77. The TDC Officers Report has concluded that the effect of the proposed groundwater take on the groundwater resource is no more than minor (Section 12.13) 78. A number of submitters have raised concerns regarding the visual impact of water tanks from the community system /firefighting supply. Specifically, submitters have queried if they will they be fully or partially buried. 79. The tank design including the exact levels will only be set following the detailed design process. At this point in the design process, the design of tanks has not been specified however the applicant has volunteered a condition that water tanks shall be incorporated into the structure of a building or buried Officers Report 80. Section of the Officers Report queries the justification and possible environmental effect of a reserve area which is 50% of the minimum required disposal area for the centralised effluent treatment system, rather than 100% as required by the TRMP. 81. There are two possible reasons for failure in a drip irrigation effluent disposal field; either the original field is undersized or drip line fails and requires replacement. There is a low probability that the centralised disposal area will be undersized because water use will be restricted to meet the consented limits on bore water supply. If sections of drip line fail it is possible to install new drip line in between the existing lines. Therefore a 50% reserve area is considered adequate. 82. Section of the Officers Report suggests that the Applicant provides a trigger water level for the consented bore where pumping ceases to protect the bore and further mitigate the risk of salt water intrusion (Section 12.14). 83. This is a reasonable suggestion and should CGW be engaged to progress the design of a water supply for this development, I would recommend this work is done as part of the preliminary design process. Conditions The draft conditions specified in the TDC Officers Report have been reviewed and are generally consistent with those identified in CGW Report RPT-004-F. Recommended amendments are as follows: Draft Subdivision Consent Conditions for RM Condition 37 (h) requires water tanks to be either buried or incorporated into the structure of a building. This may not be practical for house lots, where typical water tanks are not suitable for fully burying. It is recommended that screening of water tanks with an earthen bund, densely planted screening vegetation or fencing consistent with the building cladding requirements is considered as an acceptable solution. 85. Condition 61 recommends restricting water use to 0.5m 3 /day for apartments and 2m 3 /day for commercial buildings. There are existing consented/permitted takes for bores which will

16 restrict total water use to 39.4m 3 /day. It is recommended that this requirement is removed and it is the responsibility of the management entity to manage demand to meet the overall consented/permitted water take and effluent discharge flow limitations specified in proposed condition 7 of RM As an example, the management entity could permit higher water use from one commercial occupant if the remaining occupants are low water users such as professional offices. RM Recommended conditions of consent for the cluster wastewater system 86. Conditions 14 (ii) and 21 require the avoidance of effluent disposal on slopes exceeding 15 degrees. It is requested that this condition is changed to effluent disposal on slopes exceeding 30% is avoided unless it is identified as acceptable by a suitably qualified and experienced person. This is consistent with AS/NZS1547:2012 where reductions in design irrigation rates for slopes are presented as a percentage, not degrees. References American Manufacturing Company, 2016, Drip Systems, accessed via website 4/4/ Auckland Regional Council (ARC), 2004, Technical Publication 58 (TP 58) On-site Wastewater Systems: Design and Management Manual, ARC, Auckland CGW Consulting Engineers, Water Use and Loss Report , 2014, CGW Consulting Engineers Nelson Environment Waikato, 2007, Proposed Waikato Regional Plan Variation 5 Lake Taupo Catchment MWH International, 2010, Richmond and Brightwater/Hope Water Demand Management Plan, Richmond Netafim USA, 2014, Subsurface Dripline, Netafim USA, California Guide, Oasis Clearwater Environmental Systems, 2012, Oasis Texass Owner Operation and Installation Manual, Christchurch HR Complete Septic Service, 2016, Jet Septic Systems, Accessed via Website 4/4/2014, Pima County Department of Environmental Quality, 2013, Water at Pima County DEQ, accessed via website 4/4/16 Rainbird, 2014, XF Series Dripline, Design, Installation and Maintenance Guide, California, USA Rodenhiser Excavations Inc., 2015, Septic Systems, accessed via website, 4/4/16, Standards New Zealand, 2012, AS/NZS1547:2012 Onsite Domestic Wastewater Management, Standards New Zealand, Wellington

17 Standards New Zealand, 2010, NZS 4404:2010 Land Development and Subdivision Infrastructure, Standards New Zealand, Wellington Standards New Zealand, 2008, SNZ PAS 4509 New Zealand Fire Service Firefighting Water Supplies Code of Practice, Standards New Zealand, Wellington Statistics New Zealand 2016, Quickstats About a Place: Mapua, accessed via website 12/02/ Stewart M. K., and Thomas, J. T., 2002, Moutere Valley Groundwater: Nature and Recharge from Isotopes and Chemistry, Institute of Geological and Nuclear Science, Lower Hutt Tasman District Council Staff Report Assessment of Potential Groundwater Availability in the Moutere Aquifers, 2006 Thomas, J. T., 2001, Groundwater Resources of the Tasman Region in Groundwaters of New Zealand, M.R. Rosen and P.A. White (eds). New Zealand Hydrogeological Society Inc. Wellington Water New Zealand, 2012, On-site Waste Water Systems Maintenance Guidelines for Home Owners, SWANS-SIG, Wellington