1/83 HEATON DRIVE, TAI TAPU, SELWYN DISTRICT
LOT 14 DP 425016
WASTEWATER DESIGN REPORT
ISSUE 1: May 18 SUBMITTED BY MARC JENSEN
EXECUTIVE SUMMARY
TM Consultants Limited was commissioned by Shannon Rugg to produce a wastewater design report for 1/83 Heaton Drive, Tai Tapu, Selwyn District. TM Consultants Limited completed site and soils assessments in May 18 to determine the suitability of a wastewater system to adequately treat and dispose onto land and the expected waste flow from this property. The existing site has a current resource consent (CRC063492.2) that shall be terminated and replaced once this resource consent has been awarded. The existing dripperlines shall be decommissioned and replaced with the land application system as detailed in this report.
This application is to apply for replacement resource consent to install a suitable wastewater treatment system for the multiple dwellings with a total of six bedrooms at 1/83 Heaton Drive, Tai Tapu, Selwyn District.
DWELLING DETAILS: 1/83 Heaton Drive, Tai Tapu, Selwyn District. PROPERTY AREA: 4.84 ha LEGAL DESCRIPTION: Lot 14 DP 425016 MAP REFERENCE: NZMS 260 M36:76156-28420 DISTRICT COUNCIL: Selwyn District Council REGIONAL COUNCIL: Canterbury TYPE OF DWELLING(S): House and sleep out with a total of 6 bedrooms BUILDING CONSENT NUMBER: Unknown SLOPE: Gentle/steep WATER SUPPLY: Public Supply SOIL CATEGORY: Light Clays (Cat 5) USAGE PROFILE: Steady NUMBER OF PEOPLE: 10 WASTEWATER LOADS L/person/day: 200 WASTEWATER LOADS: 2,000 l/day (Existing Consent 1,600L/day) TYPE OF SEPTIC TANK: Existing Oasis S2000 TYPE OF DISCHARGE FIELD: EcoTrench APPLICATION RATE mm/day: 24 REQUIRED FIELD SIZE: 17x5m Table 1. Site details
GW flow
Figure 1. Site map
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COVER SHEET FOR WASTEWATER APPLICATIONS
PLANNING ASSESSMENT
Canterbury Land and Water Regional Plan
Rule 5.8 – The discharge of wastewater from a new, modified or upgraded on-site domestic wastewater treatment system onto or into land in circumstances where a contaminant may enter water
Does your activity Explanation where Condition comply with this relevant condition?
1. The discharge volume does not exceed 2 m 3 per day; and Y N 2,000L/day
2. The discharge is onto or into a site that is equal to or greater than 4 hectares in area; and Y N 4.8 ha
2a. The discharge is not located within an area where residential density exceeds 1.5 Y N dwellings per hectare and the total population is greater than 1000 persons; and
3. The discharge is not onto or into land: Y N (a) where there is an available sewerage network; or Y N (b) that is contaminated or potentially contaminated; or Y N (c) that is listed as an archaeological site; or Y N (d) in circumstances where the discharge would enter any surface water
body; or (e) within 20 m of any surface water body or the Coastal Marine Area; or Y N Mounded EcoTrench (f) within 50 m of a bore used for water abstraction; or Y N discharges 10m from (g) within a Group or Community Drinking-water supply Protection Zone watercourse. Refer to Y N area as set out in Schedule 1; or Attenuation calculations.
(h) where there is, at any time, less than 1 m of vertical separation between Refer to section 2.5 for the Y N the discharge point and groundwater; and groundwater assessment.
5. The treatment and disposal system is designed and installed in accordance with Sections Y N 5 and 6 of New Zealand Standard AS/NZS 1547:2012 – On-site Domestic Wastewater Management; and
6. The discharge does not result in wastewater being visible on the ground surface; and Y N
7. The discharge does not contain any hazardous substance. Y N
Plan Change 1 to the Canterbury Land and Water Regional Plan
Regional Rules 5.7, 5.8 and 5.9 apply in the Selwyn Waihora catchment. Rules 11.5.1 and 11.5.2 apply as additions to Regional Rules 5.8 and 5.9.
Rule 11.5.1 – Within the Selwyn Waihora catchment Regional Rule 5.8 shall include the following additional condition:
1. The discharge of wastewater from a new on-site domestic wastewater treatment system is Y N not within the Cultural Landscape/Values Management Area.
Other Plans
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Please note that if the activity is covered by the Opihi River Regional Plan or Waimakariri River Regional Plan , you will need to assess the activity against the rules in these plans below.
Objectives And Policies Please indicate which regulations, objectives and policies are relevant to your proposal and provide brief comments (where relevant) to demonstrate why it is relevant and whether your proposal is consistent with it.
NATIONAL ENVIRONMENTAL STANDARD FOR SOURCES OF HUMAN DRINKING WATER The National Environmental Standard for Sources of Human Drinking Water is intended to reduce the risk of contaminating drinking water sources such as rivers and groundwater. It does this by requiring regional councils to consider the effects of activities on drinking water sources in their decision making. Regulations 7 and 8 apply to water and discharge permits issued by regional councils. The resource consent requirements under these regulations apply only to water permits and discharge permits that have the potential to affect registered drinking water supplies that provide 501 or more people with drinking water for 60 or more calendar days each year. Regulation 12 is relevant to activities that have the potential to affect a registered drinking-water supply that provides no fewer than 25 people with drinking water for not less than 60 days each calendar year. See the Draft Users’ Guide for the National Environmental Standard for Sources of Human Drinking Water for further information. Please indicate whether your proposal is consistent with the regulation, objective or policy and provide comments where relevant. Y N N/A Regulation, objective or policy Comment where relevant
Regulation 7 – A Regional Council must not grant a water permit or discharge permit for an activity upstream of abstraction point where drinking water meets health quality criteria if the activity is likely to introduce or increase determinands in the drinking water so that it no longer meets the health quality criteria or aesthetic guideline values
Regulation 8 – A Regional Council must not grant a water permit or discharge permit for an activity upstream of abstraction point where drinking water has not been tested or already does not meet health quality criteria if the activity is likely to introduce or increase determinands in the drinking water by more than a minor amount or so that it no longer meets the health quality criteria or aesthetic guideline values
Regulation 12 – Requires conditions on resource consent if activity may significantly adversely affect registered drinking- water supply
Regional Policy Statement 2013 Y N N/A Objective 7.2.1 – (Sustainable management of fresh water) – ensure water resources are sustainably managed, while safeguarding the life-supporting capacity of ecosystems and the mauri of fresh water; the natural character of surface water bodies Policy 7.3.6 – (Fresh water quality) – establish minimum water quality standards, manage activities which may affect water quality singularly and cumulatively to maintain water quality, and where water quality is below the minimum standard to avoid any additional discharge of contaminants Policy 7.3.7 – (Water quality and land uses) - to avoid remedy or mitigate adverse effects of changes land uses on the quality of freshwater
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Canterbury Land and Water Regional Plan Objectives Y N N/A Objective 3.1 – Recognise and enable Ngāi Tahu culture, traditions, Access to the watercourse will not be customary uses and relationships with land and water impeded or impacted by this activity.
Objective 3.2 – Ki uta ki tai – recognising the connectivity between surface water, groundwater, fresh water, land and the coast
Objective 3.5 – Land uses develop and change in response to socio-economic and community demand Objective 3.6 – Water is recognised as essential to all life and is respected for its intrinsic values Objective 3.7 – Fresh water is managed prudently as a shared resource with many in-stream and out-of-stream values Objective 3.8 – Safeguard the life-supporting capacity of ecosystems
Objective 3.8A – High quality fresh water is available to meet actual and reasonable foreseeable needs for community drinking water supplies
Objective 3.12 – When setting and managing within limits, regard is had to community outcomes for water quality and quantity
Objective 3.14 – High quality fresh water is available for community drinking water supplies
Objective 3.15 – Valued parts of rivers/lakes are suitable for contact recreation Objective 3.16 – Freshwater bodies and their catchments are maintained in a healthy state, including through hydrological and geomorphic processes such as flushing and opening hāpua,
flushing algal and weed
Objective 3.17 – Significant indigenous biodiversity values of rivers, wetlands. Objective 3.18 – Maintain Wetlands that contribute to cultural/ community values, biodiversity, water quality, mahinga kai, water cleansing & flood mitigation
Objective 3.23 – Soils are healthy and productive, and human induced erosion and contamination are minimised LAS located away from unstable slopes causing under-runners and gulley erosion. Objective 3.24 – Activities operate at good environmental practice or Areas of high interflow are avoided. better to optimise efficient resource use and protect freshwater resources
Policies Y N N/A Policy 4.1 – Lakes, rivers, wetlands and aquifers should meet freshwater outcomes Policy 4.2 – The management of freshwater will take account of the fresh water outcomes, water quantity limits and the individual and cumulative effects of land uses, discharges… Policy 4.4 – Groundwater is managed so that (e) overall water quality in Significant treatment through the LAS is aquifers does not decline expected with suitable separation distances maintained. Policy 4.5 – Water is managed through the setting of limits to safeguard the life-supporting capacity of ecosystems, support customary uses, and provide for group of community drinking water…
Policy 4.7 – Resource consents not granted where quality limit breaches or will be breached
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Activity and resource policies Y N N/A Policy 4.12 – There are no direct discharges to surface water bodies or groundwater of: (a) untreated sewage, wastewater (except as a result of extreme weather related overflows or system failures) or bio-solids; (b) solid or hazardous waste or solid animal waste; (c) animal effluent from an effluent storage facility or a stock holding area; (d) organic waste or leachate from storage of organic material; and (e) untreated industrial or trade waste Policy 4.13 – For other discharges of contaminants into or onto land where it may enter water or to surface water bodies or groundwater (excluding those passive discharges to which Policy 4.26 applies), the effects of any discharge are minimised by the use of measures that: (a) first, avoids the production of the contaminant; (b) secondly, reuses, recovers or recycles the contaminant; (c) thirdly, reduce minimise the volume or amount of the discharge; or (d) finally, wherever practical utilise land-based treatment, a wetland constructed to treat contaminants or a designed treatment system prior to discharge; and (e) in the case of surface water, results in a discharge that after reasonable mixing meets the receiving water standards in Schedule 5
Policy 4.14 – Any discharge of a contaminant into or onto land where it may enter groundwater (excluding those passive discharges to which Policy 4.26 applies): (a) will not exceed the natural capacity of the soil to treat or remove the contaminant; and (b) will not exceed available water storage capacity of the soil; and (c) where meeting (a) and (b) this is not practicable, the discharge will: i. meet any nutrient limits allowance in Schedule 8 or Sections 6 to 15 of this Plan; and ii. utilise the best practicable option to ensure the size of any contaminant plume is as small as is reasonably practicable; and iii. ensure there is sufficient distance between the point of discharge, any other discharge and drinking-water supplies to allow for the natural decay or attenuation of pathogenic micro-organisms in the contaminant plume; and iv. not result in the accumulation of pathogens, or a persistent or toxic contaminant that would render the land unsuitable for agriculture, commercial, domestic, cultural or recreational use or water unsuitable as a source of potable water or for agriculture; and v. not raise groundwater levels so that land drainage is impeded
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Policy 4.14A – The disposal of domestic effluent and wastewater shall be managed so as to avoid any adverse effect that is more than minimal on surface and ground waters. Where residential density exceeds 1.5 dwellings per hectare and the total population is greater than 1000 persons, community reticulated systems should be promoted. Alternatively, other measures should be promoted to reduce adverse effects on water bodies from effluent disposal systems, including secondary treatment systems and septic tank warrants of fitness Policy 4.23 – Any water source used for drinking-water supply is protected from any discharge of contaminants that may have any actual or potential adverse effect on the quality of the drinking-water supply including its taste, clarity and smell and group and community drinking water supplies are protected so that they align with the CWMS drinking-water targets and meet the drinking-water standards for New Zealand Policy 4.81 – (Discharge does not adversely affect the significant values of wetlands, hapua, coastal lakes and lagoons) Policy 9.4.1 – (Protect the high quality, untreated groundwater sources available to Christchurch City as a potable water supply in the area shown on Planning Maps)
Other plans: The following plans, if relevant should be included in your overall planning assessment The following sub -regional plans may apply to your activity
. Hurunui and Waiau River Regional Plan . Waitaki Catchment Water Allocation Regional Plan . Waimakariri River Regional Plan . Waipara Catchment Environmental Flow and Allocation Regional Plan . Pareora Catchment Environmental Flow and Water Allocation Regional Plan . Opihi River Regional Plan . Selwyn – Te Waihora Plan Change (Plan Change 1) . Hinds Plan Change (Plan Change 2) . South Canterbury Plan Change (Plan Change 3) . Wairewa Plan Change (Plan Change 6) The following Regional Plan may apply to your activity
. Omnibus Plan Change (Plan Change 4) Y N N/A Policy of Regional Plan
Policy of Regional Plan
Policy of Regional Plan
Policy of Regional Plan
Policy of Regional Plan
Policy of Regional Plan
Other Matters
Section 105 – Matters relevant to certain applications
Please provide an assessment of: (a) the nature of the discharge and the sensitivity of the receiving environment to adverse effects; and
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(b) the applicant’s reasons for the proposed choice; and (c) any possible alternative methods of discharge including discharge into any other environment
If this has been discussed in the Consideration of alternatives section in the application form, please indicate below. Otherwise, please provide an assessment below.
2. ASSESSMENT OF INVESTMENT VALUES (RENEWAL OF EXISTING CONSENTS ONLY)
Please complete this section only if your application is to renew an existing consent.
Important: you must complete this question if your application is intended to replace a current resource consent, and this application will be lodged with Environment Canterbury at least 3 months before that consent expires.
• Provide an assessment of the value of your investment. You need to:
Specify the value of investment of the activities/infrastructure that are reliant on the resource consent/s you are applying for here. This must be the ‘book value’ of the investment (not the replacement value).
< $10,000 $10,000 to $50,000 $50,000 to $250,000
$250,000 to $1,000,000 $1 Million to $5 Million $5 Million to $50 Million
> $50 Million
• Include evidence that supports the assessment.
http://www.selwyn.govt.nz/my-property/rates/search-properties/property-details?val-id=2356413337
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CONTENTS
CONTENTS ...... 8 1. INTRODUCTION ...... 9
2. BUILDING AND SITE INFORMATION ...... 10 2.1 SITE PLAN ...... 10 2.2 SITE DETAILS ...... 10 2.3 LASE LOCATIONS ...... 11 2.4 SOILS ASSESSMENT ...... 12 2.5 GROUND WATER ASSESSMENT ...... 12 2.6 GROUND WATER QUALITY ...... 13 2.7 CONSENTED ACTIVITIES ...... 13 3. DESIGN FLOWS CALCULATION ...... 15 3.1 EXISTING WASTEWATER MANAGEMENT SYSTEM ...... 15 3.2 DISCHARGE FIELD DETAILS - ECOTRENCH ...... 16 3.3 ECOTRENCH DESIGN CRITERIA ...... 16 3.4 ITEMS TO AVOID IN WASTEWATER SYSTEM ...... 17 3.5 PATHOGEN ATTENUATION ...... 18 3.6 NITROGEN ATTENUATION ...... 19 3.7 RISK ASSESSMENT ...... 20 3.8 CULTURAL IMPACT ...... 21 3.9 CONSIDERATION OF ALTERNATIVES ...... 21 4. RESULTS SUMMARY ...... 22 4.1 LWRP RULE 5.8 CRITERIA ...... 22 5. FURTHER DISCUSSION & MOVING FORWARD ...... 22 6. APPENDIX ...... 23 6.1 LOADING CERTIFICATE ...... 23 6.2 LAND CARE RESEARCH SOIL REPORT ...... 24 6.3 LAS DRAWINGS ...... 25
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1. INTRODUCTION
TM Consultants Limited was commissioned by Shannon Rugg to produce a wastewater design report for the multiple dwellings with a total of six bedrooms at 1/83 Heaton Drive, Tai Tapu, Selwyn District. This report presents the outcome of the site assessment as well as results of the desktop study based on available knowledge incorporating aspects of building location, orientation, occupancy and usage, slopes, soils, wells and cultural Ngai Tahu impacts. Analysis was carried out to validate the proposed solution and deliver support for the replacement resource consent application.
GLOSSARY
DIR: Design irrigation rate (AS/NZS1547:2012 Table M1) LAS: Land application system LASE: Land application system envelope LWRP: Land and Water Regional Plan NRRP: Natural Resources Regional Plan OWMS: On-site wastewater management system GW: Ground water BGL: Below ground level STD: Standard FC: Faecal coliforms MAV: Maximum Accepted Value (TN 11.3g/L)
DISCLAIMER
This report is based upon the information supplied by the Client regarding proposed activities on the site. The Client is responsible for disclosing all relevant information on existing and proposed activities on the site that may influence daily wastewater quantity and quality (for instance; existing onsite wastewater systems, chemical use, medication, irregular loadings). This report is also based on the as-built plans, site usage and expected occupancy provided by Shannon Rugg. TM Consultants Ltd have not taken steps to verify this information on site and do not take responsibility for inaccurate information supplied to TM Consultants Ltd. Changes to the site that could alter the slope/topography/planting and soil compositions are to be notified to TM Consultants Ltd.
The installer shall install servicing connections, drainage, fencing, landscaping and or other site specific requirements to ensure reliable operation for the life of the OWMS and LAS. Written approval is to be obtained from TM Consultants Ltd for any variations to the specification, drawing(s) and consent conditions. Failure to correctly service, maintain and operate the OWMS and LAS will invalidate the Design Producer Statement and TM Consultants Ltd will no longer take responsibility for the design.
This document has been prepared solely for the benefit of our client. No liability is accepted by this firm or by any principal, or director, or any servant or agent of this firm, in respect of its use by any other person. Any other person who relies upon any matter contained in this report does so entirely at their own risk.
Some information provided in this report have been reproduced with the express permission of EcoEng Limited. No liability is accepted for inaccuracies in this information, graphics or estimated calculations.
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2. BUILDING AND SITE INFORMATION
2.1 SITE PLAN
Existing House Location 5m Stormwater N Drain and Interflow Existing Sleep Out Separation
Existing Failed LAS Water Easement
Existing Oasis S2000
LASE 1 - EcoTrench
LASE 2 – EcoTrench with Runanga 200m 2 of earthworks Power Easement Sensitive Area
10m Surface Water Separation 20m Surface Water Separ ation
Figure 2. Proposed site with land application system envelope
2.2 SITE DETAILS
The following section details the site conditions and soil type.
LASE 2 – EcoTrench with LASE 1 - EcoTrench 200m 2 of earthworks
Figure 3. Site area
The house has been located at the base of a steep linear convergent slope. This results in significant overland flow and interflow after rainfall events. This rainfall saturates the lawns for long periods and displaced sediment and silt flow down the slope from tunnel and gulley erosion. The existing surface mounted dripperlines have failed and were far too small for six bedrooms. An existing cut off drain has been installed, however significant earthworks would be required to rectify this issue.
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2.3 LASE LOCATIONS
Due to the linear convergent slope, soil type and location; the existing discharge field has failed. The existing lawn is boggy with visible groundwater seepage days after rainfall events. As such the feasibility of this location has been discarded.
Therefore, two locations have been proposed for the LASE:
LASE 1 is the ideal location for wastewater dispersal on site and is located on the flat grass beside the driveway and river. This is the only feasible location near by the treatment system that can be easily constructed. Some buried services exist in this area, however there is suitable space for an EcoTrench as shown. This location is partly within the 20m separation to the stream and Runanga Sensitive Area. Most if not all of the LAS shall be located more than 10m away from the water course. Refer to Section 3.5 for attenuation calculations.
LASE 2 is located beside the poplar trees on the 35° slope. This location is not protected by the existing stormwater diversion system and channels. Significant earthworks would be required in this area to obtain a level EcoTrench base as shown in Figure 1. A large unstable area of ground exists above LASE 2 and eroded material flows down the slope in storm events. It is expected that the natural gully above this location would funnel the stormwater (interflow and overland flow) directly into the stormwater cut off drains.
Figure 4. View from up steep hill in natural gully
LASE 1 - EcoTrench
Figure 5. Soils profile and existing Oasis S2000
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• The site receives relatively interrupted sunlight due to the large trees and other shading. • Ground water was not encountered. • The site one usable reserve area, however significant earthworks would be required to locate the field in this location.
Figure 6. Landcare Research soils summary
2.4 SOILS ASSESSMENT
The following section details the soil conditions as shown in Table 2.
SOILS TEST DETAIL BORE LOCATION: Nearby hill cutting. Top soil: Topsoil Thickness of layer: 400 mm Subsoil 1: Sandy Clay Thickness of layer: 100 mm Subsoil 2: Light Clay Thickness of layer: 700 mm BORE DEPTH: 1.2m CATEGORY (Table E1, 1547) Light Clays (Cat 5) Table 2. Soils test
2.5 GROUND WATER ASSESSMENT
The following section details the ground water conditions.
Well Distance Highest Water Start End Depth Readings Number from LAS Reading Readings Readings BX24/1373 890m NW 89.5 1 -6.64 7/28/2016 7/28/2016 BX24/1589 600m W 63.0 1 -5.30 11/02/2017 11/02/2017 Table 3. Well Assessment
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Table 3 details that the minimum GWL is approximately -5.3 mBGL for the site in question, this has been averaged and calculated from the elevation profiles and LiDAR information for the surrounding area. There are no community supply wells within 1km of the site. The closest water body is the drain 10m S as shown on Figure 1.
2.6 GROUND WATER QUALITY
The following section details the ground water quality within 1,000m.
Highest Well Distance Highest FC Depth Readings Nitrate Date Number from LAS Reading Reading M36/4915 690m NW 20.7 2 1 0.6 2013 M37/0103 545m NW 8.4 3 3 0.05 1989-2013 Table 4. Ground water quality
Please refer to section 3 for the pathogen and nitrate attenuation calculations.
2.7 CONSENTED ACTIVITIES
The following section details the consented activities within 1,000m of the property.
Consent Feature EC Consent No Permit Type RMA Section Activity Text Location Holder Name File No Status Type Number 611 Old Tai Tapu Road & 2120 Christchurch Issued - RMA s9(2) Use Andrew David CRC182961 Farm Farming Akaroa EC167055 CRC182961 Active Authorisation Land Florance Road, Taitapu & Gebbies Pass Discharge s15(1)(b) Old Tai Tapu Issued - RMA Human Contaminant CRC031469 Discharge to Road, TAI David Florance EC197820 CO6C/00637 Active Authorisation Effluent into Land to Land TAPU Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant Merrilies Margaret CRC146463 Discharge to Road, TAI EC148825 CRC146463 Active Authorisation Effluent into Land to Rebbeck Land TAPU Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant Mr & Mrs A C & J M CRC063496.2 Discharge to Road, TAI EC277246 CO6C/31194 Active Authorisation Effluent into Land to Marshall Land TAPU Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant Mr & Mrs B A & D T CRC060700.3 Discharge to Road, TAI EC277854 CO6C/31240 Active Authorisation Effluent into Land to Wilson Land TAPU Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant Mr & Mrs D W & E J CRC053534 Discharge to Road, TAI EC116793 RESC/PER/WWPA010048 Active Authorisation Effluent into Land to Livesey Land TAPU Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant Mr A M Laurenson & CRC063481.2 Discharge to Road, TAI EC286211 CO6C/31776 Active Authorisation Effluent into Land to Ms M Baars Land TAPU Water Discharge s15(1)(b) 4/83 Heaton Issued - RMA Human Contaminant Mr B G & Mrs S L CRC168339 Discharge to Drive, TAI EC370025 CRC168339 Active Authorisation Effluent into Land to Williams Land TAPU Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant Mr C W & Mrs P J CRC063488.2 Discharge to Road, TAI EC297166 CO6C/32691 Active Authorisation Effluent into Land to O'Dell Land TAPU Water Discharge Mr D F & Mrs J H De s15(1)(b) Rhodes Issued - RMA Human Contaminant Bont & Michaels CRC063487.2 Discharge to Road, TAI EC305654 CO6C/33484 Active Authorisation Effluent into Land to Trustee Company Land TAPU Water Limited Discharge s15(1)(b) 21 Heaton Mr D W Johnston & Issued - RMA Human Contaminant CRC063515.2 Discharge to Drive, TAI MJO Trustee EC280720 CO6C/31505 Active Authorisation Effluent into Land to Land TAPU Company Limited Water
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Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant CRC135957 Discharge to Road, TAI Mr I & Mrs Y C Grant EC315753 CRC135957 Active Authorisation Effluent into Land to Land TAPU Water Discharge 4182 Mr J C & Mrs M s15(1)(b) Issued - RMA Human Contaminant Heaton Wood & Canterbury CRC063486.3 Discharge to EC308400 CO6C/31926 Active Authorisation Effluent into Land to Drive, TAI Trustees (2006) Land Water TAPU Limited Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant CRC063492.2 Discharge to Road, TAI Mr J J & Mrs C J Ward EC101602 CO6C/32736 Active Authorisation Effluent into Land to Land TAPU Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant CRC063491.2 Discharge to Road, TAI Mr J P & Mrs T J Weir EC307476 CO6C/33620 Active Authorisation Effluent into Land to Land TAPU Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant Mr K B & Mrs D A CRC063484.2 Discharge to Road, TAI EC286199 CO6C/31775 Active Authorisation Effluent into Land to McFetridge Land TAPU Water Discharge s15(1)(b) 4/42 Hayton Mr R M & Mrs H S Issued - RMA Human Contaminant CRC167272 Discharge to Drive, TAI Williamson & Mr G C EC369028 CRC167272 Active Authorisation Effluent into Land to Land TAPU Saunders Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant Mr RM & Mrs CL CRC181322 Discharge to Road, TAI EC310177 CRC181322 Inactive Authorisation Effluent into Land to Spenceley Land TAPU Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant Mr S J & Mrs E K CRC141404 Discharge to Road, TAI EC299962 CRC141404 Active Authorisation Effluent into Land to Nicholl Land TAPU Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant Mr S J & Mrs E K CRC063494.2 Discharge to Road, TAI EC299962 CO6C/32989 Inactive Authorisation Effluent into Land to Nicholl Land TAPU Water Discharge s15(1)(b) Rhodes Mr S R & Mrs B E Issued - RMA Human Contaminant CRC063516.2 Discharge to Road, TAI Moffatt & Ms M M C EC301204 CO6C/33115 Active Authorisation Effluent into Land to Land TAPU Ryan Water Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant Otahuna Holdings CRC063507.2 Discharge to Road, TAI EC284568 CO6C/31934 Inactive Authorisation Effluent into Land to Limited Land TAPU Water Discharge Rhodes s15(1)(b) Issued - RMA Human Contaminant Road, CRC053652 Discharge to Otahuna Nuts Ltd EC104369 RESC/PER/WWPA030035 Active Authorisation Effluent into Land to OTAHUNA Land Water VALLEY Discharge s15(1)(b) Rhodes Issued - RMA Human Contaminant RD Consultants CRC063482.1 Discharge to Road, TAI EC265662 CO6C/30375 Active Authorisation Effluent into Land to Limited Land TAPU Water Discharge s15(1)(b) Holmes Issued - RMA Human Contaminant RD Consultants CRC063498.1 Discharge to Road, TAI EC265662 CO6C/30375 Inactive Authorisation Effluent into Land to Limited Land TAPU Water s14(2) Take, Rhodes Issued - RMA Water Take CRC146755 Use, Dam, or Road, TAI Rosemary Ford EC164437 CRC146755 Active Authorisation Take/Use Groundwater Divert Water TAPU s14(2) Take, Rhodes Issued - RMA Irrigation Take CRC146755 Use, Dam, or Road, TAI Rosemary Ford EC164437 CRC146755 Active Authorisation Area Groundwater Divert Water TAPU Table 5. Consented Activities
The nearest proposed discharge is located >100m away from the LAS. The cumulative effects of this discharge should be less than minor when compared to the terminated and existing resource consents in the area due to the reduction in nitrate and coliform levels through percolation, adequate setback distances and the discharge through a system with better attenuation.
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3. DESIGN FLOWS CALCULATION
The discharge field calculations including the DIR for the chosen category soils for the proposed site are as follows:
DLR/DIR from Table 5.2 NZS1547
Design Loading Rate 24 mm/day
Required area for LAS: Area 17x5m m2 Table 6. Discharge field calculation
3.1 EXISTING WASTEWATER MANAGEMENT SYSTEM
Figure 7. Oasis S2000
• 1,750l primary chamber • Zabel a100 filter on outlet of primary chamber • 2 stage aeration chamber • Settlement chamber • Pump out chamber with high water alarm • High level alarm • The tank includes a minimum 24-hour retention period. • BOD5: Suspended Solids <20mg/L • Total Nitrogen <25 mg/L
It is the installer/contractor’s responsibility to ensure the existing pump and float switch design is suitable for the EcoTrench manifold design as detailed in the drawings and is fit for purpose.
The installer/contractor shall be responsible to ensure that all work carried out and any design completed by himself/herself is safe, suitable for the purpose intended and in accordance with the relevant codes and local territorial authorities’ requirements. Acceptance of the completed works shall in no way relieve the Hydraulic Contractor from such responsibility.
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High level and/or pump failure alarms shall be located in an externally visible position from the road/dwelling. Details of the installer and servicing agent shall be located on the alarm panel.
It is the installer/contractor’s responsibility to ensure the provided wastewater treatment system(s), pump(s), rising main(s) and sequencing valves are suitable for the land application system design as detailed in the drawings and fit for purpose.
3.2 DISCHARGE FIELD DETAILS - ECOTRENCH
Please refer to the Appendix for details of the EcoTrench and cross section.
The EcoTrench is designed to hydraulically load the soil efficiently till it’s capacity has been reached. After this point the gravel bed stores peak effluent volumes; discharging to ground over time (this is the same principal that has been used in commercial stormwater systems such as buried arches or geogrid storage chambers).
Once the storage capacity of the gravel and topsoil have been exceeded; under drainage divers excess treated waste water back into the treatment system or into a separate chamber to be pumped out once full.
Secondary treated effluent is managed and processed through several processes:
• Effluent is discharged in an oxygen rich environment over mulch resulting in efficient filtration, degradation
and stabilisation of remaining effluent organics (TSS, BOD 5) by the humus ecology. • Partially filtered effluent enters the 2A sand column to further attenuate pathogens. • A small volume of effluent enters dripperlines (split at the distribution manifold) to ensure consistent and reliable vegetation growth. • Landscaping enhances evapotranspiration and reduces the load to ground. • Excess volume is stored within the base gravel as a buffer. • The Advanced Secondary/highly treated effluent soaks into ground at the base of the EcoTrench. • Under-drainage prevents risk of surface ponding should the hydraulic capacity of the soakage bed base be exceeded. • Due to the sloped surface of the EcoTrench, minimal stormwater should discharge through the EcoTrech. Resulting in a predominately wastewater to be discharged into the ground below the gravel base.
3.3 ECOTRENCH DESIGN CRITERIA
For secondary effluent the recommended design parameters of the EcoTrench sand filter:
• Max hydraulic loading rate 1 200L/ m 2. 2 • Max organic loading rate for secondary effluent of 0.04 kg BOD 5/ m .
The hydraulic loading rate to a recirculating sand filter can be higher than for an intermittent single pass sand filter because the quality of the effluent is of a higher standard. The quality of the evenly loaded secondary treatment plant effluent applied to the sand column is expected to be better than 20/30 (BOD 5/TSS).
The actual hydraulic (and organic) loading rates to the sand column:
• Max hydraulic loading rate 135 – 147 L/m 2.day • Max organic loading rate < 0.003 kg/m 2.day • Maximum hydraulic loading rate 22 L/m 2.day
1 Auckland Regional Council Technical Publication No. 58 (TP 58) On-site Wastewater Systems: Design and Management Manual. Water Res 1996;30(11):2785–97A. W (Sandy) Ormiston, Robyn E Floyd.
170606 SC01 DESIGN REPORT HEATON RD ECOTRENCH ISSUE 1 28 MAY 2018 MKJ 16
• Estimated dripper-line loading rate <3 L/m 2.day • Estimated storage capacity within base gravel 4,845L
Figure 8. Typical EcoTrench installation (without a plastic arch) provided by EcoEng Limited
• An as-built plan shall be prepared for future maintenance and servicing and shall be provided to the Engineer. No exceptions. • Dripperlines shall be Metzerplas or Netafim Bioline pressure compensating dripperlines, No alternatives; 16mm self-compensating drip irrigation pipes with emitters of 1.6 to 2.0L/hr (at 600mm centres) and the individual lines are spaced at 525mm centres . • The LAS shall be appropriately signed and suitably landscaped/fenced to prevent access. No tractors or vehicles shall enter the LASE as this will inevitably cause damage. Livestock shall not graze within the LASE. • The LAS shall only be planted with approved plantings. Refer to planting guide. • The manifold design shall enable the drippers and PVC distribution line to be individually turned off and purged. Install ball valves in toby boxes as shown on the drawings to facilitate purging of each line. • The land application area shall comply with the required 10m separation distance from any drains or waterways, 6m from any building, 50m from any bore/well and 2m (dripperlines) and 5m(trenches) from any boundary and any other requirement not detailed here as detailed in AS/NZS1547:2012 Table R1 and other documents such as ARC TP58:2004 Table 5.2. • Where overland flow or ponding has occurred in the past or could occur in the future (including ponding caused by the LAS and landscaping); surface water cut-off and or under drainage shall be installed around the LAS to divert water away, preventing erosion of, and protecting the LAS. This is additional scope that shall be design and build by the Contractor and included in the asbuilt documentation. • The installer/contractor shall confirm these requirements on site and shall be liable for any failures due to improper installation and or location in the LASE. • The information detailed in this design report and on drawings does not intend to provide all details of common practise methodology and by no means shall be interpreted in any way so as to not comply with the relevant codes, standards and territorial authority requirements.
3.4 ITEMS TO AVOID IN WASTEWATER SYSTEM
• Sanitary towels, nappies, baby wipes • Coffee grounds • Antibiotics or pharmacy drugs • Dyes • Fatty or oil substances, e.g. food scraps • Fibres, cloths • Cigarette stubs • Acids
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• Bleach • Pesticides, herbicides • Solvents • Oil, lubes, thinners, spirits, paints • Dressings, paper towels plasters
3.5 PATHOGEN ATTENUATION
The attenuation of pathogens is based on Liping Pang (ESR Christchurch). Microbial removal rates in subsurface media estimated from published studies of field experiments and large intact soil cores 2. See Figure 9. Minimum setback distance Liping Pang (ESR Christchurch) below for details.
Figure 9. Minimum setback distance Liping Pang (ESR Christchurch)
Pathogen reduction through secondary treatment
Variable Description Value Reference Treatment Unit ST Seccondary Treatment 2 OSET NTP Trial 2008/9 Backfill Hf Backfill thickness 0.6 2 A Sand ƛf Backfill removal rate 6 EPA932-F-067 Sept 1999. Note 3. Soil Hs Soil thickness 0.1 ƛs Soil removal rate 2.4 Crites et al
Vadose Hv Depth of unsaturated soil to GW 2 ƛv Vadose removal rate 3 EPA932-F-067 Sept 1999. Note 4.
Aquifer Ha Aquifer thickness 0 ƛa Aquifer removal rate 0 n log reduction 11.844 6 log reduction = 1,000,000 times Input FC Concentration Cfu/100ml 1.00E+07 smaller FC count Output FC Concentration Cfu/100ml 0.00
Table 7. Pathogen attenuation
As can be seen in the above Table 7, the output Faecal Coliform concentration should be reduced from approximately 1,000,000,000(primary)/ 10,000,000(secondary) Cfu/100ml 3 to less than 1 Cfu/100ml at 2mBGL. These calculations only consider 2m of unsaturated soil, in reality this should only occur in periods of the highest ground water levels. During lower ground water level periods, the effective attenuation should provide even lower FC concentrations due to increased unsaturated soil depths.
Therefore, there is a less than minor risk locating the LAS 10m horizontally from the stream (2m vertically below the field).
2 J.of Environmental Quality. Vol 38. July-Aug 2009. pp 1531-1559. OSET NPT Trial results , Crites and Tchobanoglous and Table 10, Liping Pang (ESR CHCH) report 3 Rose JB, Dickson LJ, Farrah SR, Carnahan RP. Removal of pathogenic and indicator microorganisms by full-scale water reclamation facility. Water Res 1996;30(11):2785–97
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The measured ground water quality concentrations are likely to represent groundwater quality of the shallow aquifers and not the water quality of the perched water table. As the discharge is occurring over an aquifer, any confining layer will act as a form of protection for the aquifers where drinking water is sourced and therefore not affect the water quality of deeper groundwater. Therefore the realistic groundwater where drinking water abstraction occurs is detailed in Table 4. Ground water quality.
3.6 NITROGEN ATTENUATION
The attenuation of nitrogen has been approximated from the results in the On-site Effluent Treatment National Testing Programme (OSET NTP) and Small and decentralized wastewater management systems, Crites and Tchobanoglous 1998.
Table 8 below calculates the nitrogen discharge throughout the year assuming a year round P.E. of 3 occupants; rather than the 2.5-2.7p.e/household average dwelling occupancy according to Statistic NZ. The average raw influent quality into each system has been measured to be between 85-83 mg/L TN 4.
Nitrate Nitrogen through secondary treatment Variable Description Value Reference P.E. Population Equivalent 3 Table J1 NZS1547:2012 Report-2006-OSETTrial1-2005- Raw TN g/p.e. day Grams of TN per p.e. per day 15 2006pdf.pdf Chapter 1 Wastewater volume p.e. per Figure 4 of the design report TP58:2004 Volume L/p.e. day 200 day NZS1547:2012 Total vol/day in L Vol x number p.e. 600 Table J1 NZS1547:2012, TP58 3rd Ed. Avg wastewater TN Raw TN emmision/p.e. g/day 15 g/day concentration per p.e./day No days/yr 365 Average recorded TN in OSET NTP Trial 3, Treated Effluent TN mg/L Output effluent TN quality 15 2007/2008 Approximate reduction at Report-2006-OSETTrial1-2005- Reduction at treatment 60% treatment 2006pdf.pdf Chapter 1 Approximate reduction in Treatment in sand bed. Crites et al 1998, Reduction in land application 55% sand bed Table 11-13, p743. Note 1. Approximate reduction at Treatment in sand bed. Crites et al 1998, Reduction in vadose zone 5% LAS Table 11-13, p743. Note 1. Total kg/yr released 2.8 kg/year Total kg/yr/Ha released 0.6 kg/year/Ha
Table 8. Nitrogen discharge
The expected nitrogen due to percolation at the point of the discharge into ground water should be <3kg/year per dwelling. These values are considered to be very conservative. The discharge is considered less than minor when rated relative to other rural sources, and particularly agriculture. The additional nitrogen reductions will occur via the vegetated land application system as nitrogen is likely to be assimilated by overlying plants and microbial activity.
The Ministry of Health has set a Maximum Acceptable Value (MAV) of 11.3mg/L for drinking water. Given the proposed discharge volume and the expected level of treatment from the system; the nitrate nitrogen concentrations should not significantly increase and exceed the MAV.
Figure 10 details that this site is located in a low risk area.
4 UN Department of Technical Cooperation for Development (1985) and Average recorded TN in OSET Trial 4 (2008/2009)
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Figure 10. Site is located within a low risk area
3.7 RISK ASSESSMENT
The summary of assessment for identified pathogen and nitrate risks is as follows:
Risk Consequence Risk Likelihood
Weight Descriptor Weight Descriptor 0.5 Minor 1 Rare 1 Important 2 Unlikely 1.5 Serious 3 Possible 4 Major 4 Likely 5 Catastrophic 5 Almost Certain Table 9. Risk consequence and likelihood The consequence is multiplied with the likelihood to produce a risk rating:
Almost 2.5 5 7.5 20 25 Certain Moderate High High Extreme Extreme 2 4 6 16 20 Likely Moderate Moderate High Very High Extreme 1.5 3 4.5 12 15 Possible Low Moderate High Very High Very High 1 2 3 8 10 Unlikely
Likelihood Likelihood Low Moderate Moderate High Very High 0.5 1 1.5 4 5 Rare Low Low Low Moderate High Minor Important Serious Major Catastrophic Consequence Table 10. Risk rating
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Risk evaluation and further steps:
Act now. Do something about the risk immediately. These risks require urgent Extreme attention. Director's sign off is essential. Very High These risks urgently require the highest available management decision.
High Management instructions regarding the risks should be followed. This level of risk is still considered unacceptable in circumstances. Line management Moderate attention required. Low Okay for now. Client is expected to review regularly and reduce risk where possible.
Table 11. Risk evaluation
The risk assessment has been based on the LASE 1 location for access, construction, buried services, pathogen and nitrate attenuation, erosion risk and ease of maintenance.
• The risk rating of the EcoTrench located in LASE 1 is expected to have a LOW risk. • The risk rating of the EcoTrench located in LASE 2 (due to erodibility and unstable ground) is expected to have a MODERATE risk.
Therefore, LASE 1 is the ideal location for effluent discharge on this site.
3.8 CULTURAL IMPACT
The discharge was covered by the Taumutu and Rapaki Wairewa Rūnanga.The ECAN GIS mapping shows this site is not in a silent file area. This report does not consider and or assess the impact to the site and application caused by any silent file intersection(s). It is the Client’s responsibility to ensure that any and all requirements arising from the cultural impact of this activity are taken care of. Any excavation discovering an archaeological site will cease so as to not damage the Ngāi Tahu heritage. The site is not within a statutory acknowledgement area and will not discharge to surface or ground waters directly. Based on this, a formal consultation with the Iwi was not arranged.
3.9 CONSIDERATION OF ALTERNATIVES
At the time of writing, there were no public networks available for the discharge. The site and soils assessment highlighted areas where setback distances were required as detailed in the LASE. Trenches, dripper line systems, peat beds, recirculating sand filters and mounded alternatives were considered along with requirements based on the GWL. From this information; the optimum system is detailed in this report.
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4. RESULTS SUMMARY
The following sections outline the LWRP criteria.
4.1 LWRP RULE 5.8 CRITERIA
The discharge of wastewater from a new or upgraded on-site domestic wastewater treatment system onto or into land in circumstances where a contaminant may enter water is a permitted activity, provided the following conditions are met:
Condition LWRP Rule 5.8 Criteria New/Modified or Upgraded Domestic Complies 1 The discharge volume does not exceed 2 m 3 per day and; ✓✓✓ 2 The discharge is onto or into a site that is equal to or greater than 4 hectares in area; and ✓✓✓ The discharge is not located within an area where residential density exceeds 1.5 dwellings a ✓✓✓ per hectare and the total population is greater than 1000 persons; and 3 The discharge is not onto or into land: a Where there is an available sewerage network; ✓✓✓ b That is contaminated or potentially contaminated; ✓✓✓ c That is listed as an archaeological site; ✓✓✓ d In circumstances where the discharge would enter any surface water body; ✓✓✓ e Within 20 m of any surface water body or the Coastal Marine Area; XXX f Within 50 m of a bore used for water abstraction; ✓✓✓ g Within a group or community drinking water protection area as set out in Schedule 1. ✓✓✓ Where there is, at any time, less than 1 m of vertical separation between the discharge h ✓✓✓ point and groundwater; The treatment and disposal system is designed and installed in accordance with Sections 5 4 and 6 of New Zealand Standard AS/NZS 1547:2012 – On-site domestic wastewater ✓✓✓ management; The treatment and disposal system is operated and maintained in accordance with the system’s design specification for maintenance or, if there is no design specification for 5 ✓✓✓ maintenance, Section 6.3 of New Zealand Standard AS/NZS 1547:2012 – On-site domestic wastewater management. 6 The discharge does not result in wastewater being visible on the ground surface; ✓✓✓ 7 The discharge does not contain any hazardous substance. ✓✓✓ Table 12. LWRP criteria
5. FURTHER DISCUSSION & MOVING FORWARD
Please come back to the author below at TMCO for clarification and moving forward.
MARC JENSEN Senior Hydraulic Engineer, BEngTech (Mech), NatDip (Mech), Dip (Mech)
P. (03) 348 6066 | C. 027 302 8659 | F. (03) 348 6065 | E. [email protected] | www.tmco.co.nz
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6. APPENDIX
6.1 LOADING CERTIFICATE
The following sections are in accordance with AS/NZS1547:2012, Section 7.4.2.
Criteria Details System capacity Maximum daily wastewater load, combined black and greywater: 2,000 L/day . Refer Table 1 3 day peak treatment capacity of treatment unit: 2,000L/day Emergency storage capacity of treatment unit: 2,540L Dwelling fixtures, Standard water reduction fixtures such as a dual flush toilet . Refer Table 1. Site details . fittings and appliances. Variable flow and The dwelling at this stage should be permanently occupied; should seasonal loadings occur the loading. system has some inbuilt resilience. If the system is over loaded for a long duration, the LAS and OWMS could fail to provide treatment. Description of OWMS discharging to EcoTrench LAS. Refer Table 1. Site details and Section 3.1 . treatment plant. Description of LAS EcoTrench with arch and cut -off/surface drains where required. Design Criteria, LAS Max loading of 24 mm/day. Refer Table 1. Site details . GW -5.3 mBGL . Location of OWMS, Location of the OWMS and LAS to be confirmed. Reserve area as detailed in LASE, refer Figure LAS, and reserve 1. The Client shall be fully responsible for any issues or health problems arising directly or area indirectly from the system and or activities on site. Consequences of Over loading may have an impact on the OWMS performance; it may give rise to odours. over loading Medium-sized but long term overloading would result in the system having less buffer capacity and be less able to absorb the surges that happen throughout the day. Extreme overloading will restrict or cut off the oxygen supply to the bed resulting in the bed turning anaerobic. Odour results and the biofilm will become les permeable – effluent will be unable to exit into the bed. Consequences of Under loading could prevent the bacteria from effectively treating the next surge . Long under loading inactive durations could result in the bacteria dying off completely.
Consequences of O&M by a competent servicing person is strongly recommended for the on -going required lack of operation performance of this OWMS. Failure to provide this O&M could ultimately result in failure of and maintenance the LAS and consequential costs to the owner. (O&M) Table 13. LWRP criteria
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6.2 LAND CARE RESEARCH SOIL REPORT
Figure 11. Landcare Research soils report
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6.3 LAS DRAWINGS
Refer to the attached wastewater drawings (overleaf).
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Heaton Drive - Septic System 1-83 Heaton Drive, Tai Tapu HYDRAULIC SERVICES
RESOURCE CONSENT DATE: 24/05/2018
DRAWING INDEX H0.0 Cover Page H0.1 EcoTrench Detail
JOB # 170606-SC01 Pumped treated wastewater from treatment plant. Refer to Construction Hold Points: Scope of Works the design report for details. There are some critical construction points that must be The Contractor shall confirm with the following points: supervised by the designer or experienced installer for Ball valves labelled Under-drain connecting to first-time-installers of the EcoTrench. The hold points are: 1. Type and brand of treatment plant unit matches the V4 V3 for system tuning storage or pump chamber. design report. 1. EcoTrench base has been excavated, prior to 20-12 1000 gravel back fill, the Contractor shall confirm the base 2. Final location of the treatment plant, EcoTrench and is level. stormwater diversion. Driveway 8 dripper laterals at 2. Prior to covering the under-drain the Contractor shall 3. Extent of fencing and or demarcation required to comply 525mm spacing confirm 75mm clearance from the soil base is with the design report and Local TA requirements. provided beneath the under-drain. 4. Planting and landscaping requirements to ensure 3. Prior to back filling the EcoTrench slope, the evapotranspiration and not damage the EcoTrench. Contractor shall confirm the quality of topsoil fill 40mm (distributed pipes) drilled (conforms to silty or sandy loam texture). 5. Check location of existing underground and overhead PVC. Details to be provided by services (cables, pipes, overhead wires). TM Consultants Limited. 100Ø @ 1:60 min to pump chamber of treatment plan 4. During sand fill the Contractor shall confirm the sand grade (2A sand) and PE lining installation against 6. Provide a site-specific safety plan. Erect safety fencing retaining wall/earth bank is suitable without any holes and signage for site work. or damage. 7. Check all consent (Resource Consent and Building 5. The Contractor shall confirm the the installed Consent) requirements and conditions. Orion shall maintain complete unrestricted distribution pipe is level, the specified drilled hole access to their easement no portion of the Driplines diameter and spacing as per the design report. 8. Notify ECan 2 days before commencement of Ecotrench shall enter the power easement construction. 6. At commissioning the Contractor shall confirm the plumbing layout and valve setting provides the 9. Book Building Inspector inspections as required. estimated discharge volumes and squirt height (1-1.5m). 10. The site is to be cleared and prepared.
7. Ensure appropriate intercepting field drains are 11. It is the installers responsibility to assess groundwater correctly installed and discharge into the stormwater depth at time of installation and make appropriate 25mm labelled Allow to batter slope to system without requiring a resource consent. provision for inground tanks and pump chamber suit driveway proximity manual flush valves V2 V1 installation including anti-floatation rings etc. 8. The following construction photos are to be provided to the designer: 12. Decommission, as appropriate, any existing wastewater system. · Installed underdrain. 800mm · Puncturing of geofabric prior to covering with 13. Check all drains (for inflow/infiltration) to the treatment min top-soils. plant and repair or replace as required. · Lining of the retaining wall earth bund with 250micron PE sheet or equivalent. 14. Supply and install OWMS as specified. · Drilled PVC pipe with squirt height test. Completed installation. · 15. Commission completed OWMS.
16. Remove excess soils off site and reinstate ground back to original condition. Disclaimer: 17. Erect signage for the EcoTrench. · This drawing shall be read in conjunction with all other design documentation, not necessarily only the 18. Provide completion documents. Aerated Septic Tank design report (for instance fencing, signage, landscaping, separation distances and loading requirements are not provided on this drawing). · The contractor shall comply with all local TA Stormwater and surface water requirements and the design report. (Refer to section 1 of the design report for the full disclaimer). diversion:
No stormwater is to be discharged into or on to the irrigation field area. EcoTrench Pipework Schematic Completion documentation: Scale: NTS Commissioning report, Operator Manual, Servicing Manual, Copy of servicing contract (if required), Loading certificate, Installation producer statement (PS3) with as-built plans and photos, Certificate of Code Compliance.
40mm PVC pipe drilled with 3.5mm holes at UV resistant 500-600mm 16mm pressure compensating drip irrigation 1,000mm crs. Two holes at 1 and 2 length are to be wide Promax Fluming, plastic pipe with 1.6-2L/hr emitters at 600mm crs. 3 3 A 24/05/18 For Resource Consent drilled at base of pipe. See report for details arch, Reln arch or FarmBoss installed as per the pipework schematic. cut in half. Suitably fixed to Issue Date Description prevent wind up-lift.
Heavy duty 100-200mm large stones Driveway 800 (250micron) polyethylene sheet 6 covering underdrain 1
100mm layer of bark chip or mulch 150
1000mm min HYDRAULIC SERVICES 600mm 2A sand Approved topsoil with less than 20% 525 clay. Silty or sandy loam texture. 300 Job Title
50mm peagravel (no fines) Cut off Heaton Drive - Septic 150mm layer of 20-40mm aggregate drain Interceptor drain may be required. System 450 min Washed 12-20mm gravel/tailings no 650 4350 fines. Bidm A19 and 100mm 1-83 Heaton Drive Existing ground - vegetation perforated Novaflow or drilled PVC Tai Tapu removed and surface tilled connecting into stormwater system. 75mm min Drawing Name 5000 200 EcoTrench Detail Heavy duty Base shall be perfectly level in all Punctured Bidum A19 Slotted (or drilled 2x10mm holes @ 250mm (250micron) directions geofabric on a 500mm grid spacing, 4 and 8 O'clock) 80-100mm PVC Engineered by : Marc Jensen polyethylene sheet with a sharp spike under-drain laid level in trench and 1:60 to Drawn by : Royce Herrera emergency storage or pump chamber Drawing Scale As Shown @ A2
THIS DRAWING IS COPYRIGHT © 2018
17m Long EcoTrench Land Application System Cross CONTRACTOR MUST VERIFY ALL DIMENSIONS ON SITE Section Sheet No: Job No: Issue: Scale: 1:25 H0.1 170606-SC01 A