26 GLENAVY TAWAI ROAD, GLENAVY, WAIMATE DISTRICT.
SECTION 89 TN OF GLENAVY
WASTEWATER DESIGN REPORT
ISSUE 1: October 15 SUBMITTED BY MARC JENSEN
EXECUTIVE SUMMARY
TM Consultants Limited was commissioned by Cunningham Plumbing Ltd to produce a wastewater design report for 26 Glenavy Tawai Road, Glenavy, Waimate District. Cunningham Plumbing Ltd completed site and soils assessments in June 2015 to determine the suitability of a wastewater system to adequately treat and dispose onto land and the expected waste flow from this property.
This application is to apply for resource consent to install a suitable wastewater treatment system replacing the existing system that will be/has been decommissioned for the office at 26 Glenavy Tawai Road, Glenavy, Waimate District.
DWELLING DETAILS: 26 Glenavy Tawai Road, Glenavy, Waimate District. PROPERTY AREA: 0.3225 Ha LEGAL DESCRIPTION: Section 89 TN OF Glenavy MAP REFERENCE: Longitude: 171.099514 / Latitude: -44.915242 DISTRICT COUNCIL: Waimate REGIONAL COUNCIL: Canterbury TYPE OF DWELLING(S): 5 Room Office and Workshop BUILDING CONSENT NUMBER: Unknown SLOPE: Flat – Determined By Site Assessment, Google Earth WATER SUPPLY: Council Supply SOIL CATEGORY: Sandy Loams (Cat 2) USAGE PROFILE: Intermittent NUMBER OF PEOPLE: 20 WASTEWATER LOADS L/person/day: 50 WASTEWATER LOADS: 1,000 L/Day TYPE OF SEPTIC TANK: Hynds Aerated Lifestyle Advanced TYPE OF DISCHARGE FIELD: Trench APPLICATION RATE mm/day: 50 REQUIRED AREA m 2: 20 Table 1. Site details
GW flow
Figure 1. Site map
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COVER SHEET FOR WASTEWATER APPLICATIONS
PLANNING ASSESSMENT
Natural Resources Regional Plan
Rule WQL9 Discharge of contaminants into land from an on-site wastewater system
Condition Does your activity Explanation where relevant comply with this condition?
All systems
1. The discharge shall be only wastewater. Y N
2. The maximum volume of the discharge from a system shall not exceed two cubic Y N metres per day.
3. There shall be no discharge of wastewater to surface water or into groundwater. Y N
4. The discharge shall not result in wastewater flowing, seeping, or ponding on the surface Y N of the ground.
5. There is no sewerage pipeline network available to collect the discharge. A Y N connection shall be made to a sewerage pipeline network within six months of a network becoming available. For the purpose of this condition, “available” means: (a) a sewerage pipeline network system passes within 30 metres of the property boundary; and (b) the property from which the wastewater is generated is less than four hectares in area; and (c) the distance to the network from the building in which the wastewater is generated is less than 60 metres; and (d) the network operator will accept the discharge. Existing systems
6. When there is an increase in the volume of the discharge, or any modification to Y N N/A the system, as a result of: (a) an alteration of a building that requires authorisation under the Building Act 2004; or (b) the connection to the system of a new or replacement building, or relocated building; or (c) any alteration to the existing system, excluding routine maintenance of the system; the discharge shall comply with Conditions 1 to 5 and 8 to 20 inclusive of this rule. 7. Where the discharge occurs in a Community Drinking Water Supply Protection Zone for Y N N/A a well listed in Schedule WQL2, or within the Christchurch Groundwater Protection Zone 1, or Zones 1A, 1B, 1C, or 1D, or Zone 2 the discharge shall comply with Conditions 1 to 5 and 8 to 19 inclusive of this rule by 1 November 2015.
Does your activity New systems comply with this Explanation where relevant condition?
8. The discharge shall not occur:
(a) within 20 metres of a river, lake, artificial watercourse, or the Coastal Y N marine area; or (b) at an elevation higher than 1000 metres above sea level; or Y N
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(c) on land with a slope greater than 20 degrees; or Y N
(d) on land: (i) that is likely to be flooded from a river or lake in an event with an Annual Exceedance Probability of two percent (1 in 50 year event) Y N or more; or (ii) where water is known to pond for at least two hours in a rainfall Y N event, on average, at least once in every five years; or (e) within 20 metres of a wetland boundary. Y N
9. The discharge shall not occur where the land is located over:
(a) an unconfined or semi-confined aquifer, where the highest groundwater Y N N/A -2 mBGL level, which can reasonably be expected at the point of discharge based upon relevant and available groundwater data is: (i) less than two metres from the ground surface; and (ii) less than six metres from the ground surface unless the land application consists of a drip irrigation system as described in Condition 12(b); or (b) the Coastal Confined Gravel Aquifer System, and there is: Y N N/A -2 mBGL (iii) less than two metres of undisturbed material between the point of discharge and the Aquifer 1; or (iv) less than two metres of unsaturated sediment above any water table overlying Aquifer 1. 10. Separation distances shall be maintained:
(a) between a well and a discharge system that occurs outside of a Y N N/A Community Drinking Water Supply Protection Zone, as specified in Part A of Schedule WQL6; and (b) between discharge systems, as specified in Part B of Schedule WQL6 Y N N/A unless the land application system consists of a drip irrigation system as described in Condition 12(b), and the site in addition to all adjacent properties are either on a reticulated water supply or are one hectare or more in size. 11. The minimum separation distance between the land application system and a property boundary shall be:
(a) 20 metres to the nearest down gradient boundary in the direction of Y N N/A groundwater flow at the site and five metres to any other property boundary; or (b) two metres to any property boundary if the land application system Y N N/A consists of a drip irrigation system as described in Condition 12(b) and the discharge is into soil. 12. The land application system shall consist of either:
(a) a treatment trench, bed or mound: Y N N/A (v) with media of at least 600 millimetres thick; and, (vi) of which the media shall be of a grade that fits within the 2A envelope on the diagram in Schedule WQL8; and (vii) to which the discharge is pumped, or is dosed in fixed quantities, so that the effluent is applied to the treatment trench, bed or mounds evenly at a rate of not more than 50 millimetres per day; or (b) a pressure compensating drip irrigation system through which the Y N N/A discharge is applied evenly, and at a rate which shall not exceed the value in Table 4.2A4 in the Australian/New Zealand Standard 1547:2000 On-site domestic wastewater management for the soil type at the site. 13. Where the land application system consists of a treatment trench, bed or mound, as Y N N/A Section 2.2 specified in Condition 12(a), there shall be sufficient additional land available on the property to allow a replacement land application system to be installed.
14. The wastewater shall pass through a proprietary effluent filter before discharge to the Y N land application system.
15. A copy of the design plan of the treatment and land application system shall be Y N submitted to Environment Canterbury at least twenty working days prior to the
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installation of the system.
16. When the construction of the treatment and land application system is Y N completed: (a) the work shall be certified by a suitably qualified and competent person as having been carried out in accordance with the design plan; and (b) a copy of the certificate shall be forwarded to Environment Canterbury within twenty working days following completion of the work. 17. The treatment and land application system shall be operated and maintained in Y N accordance with the system's design specification for maintenance.
18. The primary treatment tank or chamber shall: Y N (c) have an access point or points for inspecting and maintaining the effluent filter, monitoring the accumulation of sludge and desludging the tank or chamber. The access point or points shall be accessible for these purposes at all times; and (d) be inspected at least once every three years and the depth of accumulated sludge in the primary treatment tank or chamber measured; and (e) be desludged when the accumulated scum and sludge occupy more than two thirds of the volume of the tank or chamber. 19. The following information shall be recorded, and a copy of these records made Y N N/A available to Environment Canterbury upon request: (f) maintenance of the treatment and land application system, including inspection, desludging or remedial work; and (g) date works are undertaken and the name of the company and person undertaking the work. 20. The discharge shall not occur within a Community Drinking Water Supply Protection Y N Zone for a well listed in Schedule WQL2.
Please note that the activity may be covered by other rules in this plan (e.g. Rules WQL 10- to 14). Please ensure your activity is assessed under the correct rule.
Proposed Land and Water Regional Plan (Decisions version)
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
Condition Does your activity Explanation where relevant comply with this condition?
1. The discharge volume does not exceed 2 m 3 per day; and Y N
2. The discharge is onto or into a site that is equal to or greater than 4 hectares in area; and Y N
2a. The discharge is not located within an area where residential density exceeds 1.5 dwellings Y N 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; 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 Y N body; or (e) within 20 m of any surface water body or the Coastal Marine Area; or Y N
(f) within 50 m of a bore used for water abstraction; or Y N
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(g) within a Group or Community Drinking-water supply Protection Zone area Y N as set out in Schedule 1; or (h) where there is, at any time, less than 1 m of vertical separation between Y N the discharge point and groundwater; and 5. The treatment and disposal system is designed and installed in accordance with Sections 5 Y N 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
Proposed Variation 1 to the Proposed 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
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
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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 NATURAL RESOURCES REGIONAL PLAN – CHAPTER 4 – WATER QUALITY Chapter 4 Issue WQL1 – Surface Water quality Y N N/A Objective WQL1 – (Water quality outcomes for rivers and lakes) – Manage water quality in rivers and lakes so that it meets the outcomes in Tables WQL5 and 6 Policy WQL1 (Point source discharges that may enter surface water) – ensure good practice measures to minimise contaminant, that water quality meets standards. Policy WQL3 (Prevent the discharge of certain contaminants to surface water) Policy WQL4 (Minor point source discharge to surface water) Chapter 4 Issue WQL2 – Groundwater quality and contaminants in land Y N N/A Objective WQL2.1 - Water quality outcomes for groundwater
Objective WQL2.2 - Contaminated land Policy WQL7 (Point source discharges onto land which affect soil or groundwater quality) Policy WQL8 (Minor point source discharges onto or into land uses that may affect groundwater quality) Policy WQL9 (Prevent the entry of hazardous contaminants to groundwater) Policy WQL11 (Avoid contamination of groundwater via bores / excavation) Chapter 4 Issue WQL3 - Community drinking water sources Y N N/A Objective WQL3 (Water quality of community drinking water sources)
Policy WQL13 (Avoid contamination of community drinking water sources) Chapter 4 Issue WQL3 - Christchurch groundwater Y N N/A Objective WQL4 (The quality of Christchurch groundwater)
WQL14 (Effects of activities in the Chch Groundwater Protection Zone 1) WQL15 (Effects of activities in Zone 1A (Urban)) WQL16 (Effects of activities in Zone 1B (Mineral Extraction)) WQL17 (Effects of activities in Zone 1C (Christchurch International Airport)) WQL18 (Effects of activities in Christchurch Groundwater Protection Zone 1D WQL19 (Effects of activities in Zone 2)
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WQL19 (Effects of activities in Zone 3) PROPOSED LAND AND WATER REGIONAL PLAN (DECISIONS) Objectives Y N N/A Objective 3.1 (recognise and enable Ngāi Tahu culture, traditions, customary uses and relationships with land and water) 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) Objective 3.24 (Activities operate at good environmental practice or 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 aquifers does not decline) 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) 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;
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(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.
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
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Maps) OTHER PLANS Y N N/A Policy of Regional Plan
Policy of Regional Plan
PART 2 MATTERS
Please provide an assessment of the proposed activity against Part 2 of the RMA by indicating whether the proposed activity is consistent with the purpose of the RMA (Section 5), and indicate which Matters of National Importance and Other Matters are relevant, and whether the activity is consistent with these and Section 8, which deals with the Treaty of Waitangi.
Section 5: Purpose
The purpose of the Resource Management Act is to promote the sustainable management of natural and physical resources (section 5 – view here ).
Do you consider your proposed activity meets the purpose of the RMA? Yes No
Section 6: Matters of National Importance (view here )
Does your proposed activity take into account the Matters of National Importance? Yes No
Section 7: Other Matters (view here )
Does your proposed activity take into account Other Matters? Yes No
Section 8 Treaty of Waitangi (view here )
Does your proposed activity take account of the principles of the Treaty of Waitangi? Yes No
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 (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.
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CONTENTS
CONTENTS ...... 10 1. INTRODUCTION ...... 11
2. BUILDING AND SITE INFORMATION ...... 12 2.1 SITE PLAN ...... 12 2.2 SITE DETAILS ...... 12 2.3 SOILS ASSESSMENT ...... 13 2.4 GROUND WATER ASSESSMENT ...... 14 2.5 GROUND WATER QUALITY ...... 14 2.6 CONSENTED ACTIVITIES ...... 15 2.7 FLOOD HAZARD ASSESSMENT ...... 17 3. DESIGN FLOWS CALCULATION ...... 18 3.1 PROPOSED WASTEWATER MANAGEMENT SYSTEM ...... 18 3.2 DISCHARGE FIELD DETAILS ...... 19 3.3 DISCHARGE FIELD DETAILS CONTINUED ...... 20 3.4 PATHOGEN ATTENUATION ...... 21 3.5 NITROGEN ATTENUATION ...... 22 3.6 CULTURAL IMPACT ...... 23 4. FURTHER DISCUSSION & MOVING FORWARD ...... 24 5. APPENDIX ...... 24 5.1 LOADING CERTIFICATE ...... 24 5.2 LAND CARE RESEARCH SOIL REPORT ...... 25
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1. INTRODUCTION
TM Consultants Limited was commissioned by Cunningham Plumbing Ltd to produce a wastewater design report for the office extension at 26 Glenavy Tawai Road, Glenavy, Waimate 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 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 plan and site and soils assessments provided by Cunningham Plumbing Ltd. 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.
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2. BUILDING AND SITE INFORMATION
2.1 SITE PLAN
N
3m Boundary Separation
LASE Office Location
Hynds Lifestyle Advanced Septic Tank
Figure 2. Proposed site with land application system envelope
2.2 SITE DETAILS
The following section details the site conditions and soil type.
Figure 3. Soils tests location
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Figure 4. Test bore and soils profile
• The site receives relatively uninterrupted sunlight due to the lack of large trees and shading. • Ground water was not encountered in the test hole. • The site has reserve area to allow for potential additions to the irrigation if any of the areas are unacceptable in the long-term acceptance.
Figure 5. Landcare Research soils summary
2.3 SOILS ASSESSMENT
The following section details the soil conditions as shown in Table 2.
SOILS TEST DETAIL BORE LOCATION: In discharge envelope. BORE TYPE: Excavated. Top soil: Topsoil Thickness of layer: 300 mm Subsoil 1: Stony Sandy Loam Thickness of layer: 700 mm
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BORE DEPTH: 1.0m+ CATEGORY (Table E1, 1547) Sandy Loams (Cat 2) Table 2. Soils test
2.4 GROUND WATER ASSESSMENT
The following section details the ground water conditions.
Well Number Distance from LAS Depth Readings Highest Water Reading Start Readings End Readings
J41/0158 840m S 5.5 1 -0.61 10/03/1954 10/03/1954 J41/0182 370m N 0.0 13 -1.05 6/27/1985 6/27/1986 J41/0016 380m N 3.1 2 -1.30 2/23/1996 5/13/1996 J41/0157 190m NE 0.0 1 -2.00 9/14/1978 9/14/1978 J41/0013 560m SE 6.0 2 -2.70 2/27/1996 5/10/1996 J41/0031 400m W 0.0 8 -3.01 4/10/2001 1/15/2004 J41/0020 50m N 7.1 1 -3.50 2/23/1996 2/23/1996 J41/0018 330m SE 7.9 101 -3.61 2/23/1996 10/02/2015 J41/0032 130m S 0.0 1 -4.00 2/27/1996 2/27/1996 J41/0069 430m E 9.4 110 -5.10 9/14/1950 4/12/1955 J41/0019 150m SW 9.8 1 -5.80 2/23/1996 2/23/1996 Table 3. Well Assessment
Table 3 details that the closest well (J41/0020) has a recent well reading of -3.5mBGL, and the average groundwater readings across all of the wells are -2.97mBGL, with the highest reading in the past year being -3mBGL+. As there are no other nearby mounded systems and wells with deeper water readings occur between the site and J41/0182, the minimum GWL is approximately -2 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 an unnamed stream 350m SE.
2.5 GROUND WATER QUALITY
The following section details the ground water quality within 1,000m.
Highest Well Distance from Highest FC Depth Readings Nitrate Date Number LAS Reading Reading J41/0018 330m SE 7.9 88.0 120 cfu/100ml 7.7 mg/L 1996 -2015 J41/0019 150m SW 9.8 2.0 30 cfu/100ml 1.9 mg/L 1996 J41/0020 50m N 7.1 2.0 430 cfu /100ml 2.2 mg/L 1996 J41/0034 180m S N/A 2.0 4 cfu/100ml 1.3 mg/L 1996 Table 4. Ground water quality
Please refer to section 3 for the pathogen and nitrate attenuation calculations.
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2.6 CONSENTED ACTIVITIES
The following section details the consented activities within 1,000m of the property.
Activity Record Consent No Consent Status Permit Type Location Holder Name Type Terminated - Glenavy Tawai Road, CRC000334 Water Permit ALLOCATION QTY Mr B A & Mrs K J Joyce Replaced WAIMATE Terminated - IRRIGATED AREA Glenavy Tawai Road, CRC000334 Water Permit Mr B A & Mrs K J Joyce Replaced PARAMS WAIMATE Terminated - Glenavy Tawai Road, CRC000334.1 Water Permit SWAP DETAILS Waitaki North Limited Replaced WAIMATE Terminated - Glenavy Tawai Road, CRC000334.1 Water Permit ALLOCATION QTY Waitaki North Limited Replaced WAIMATE Terminated - IRRIGATED AREA Glenavy Tawai Road, CRC000334.1 Water Permit Waitaki North Limited Replaced PARAMS WAIMATE Terminated - Land Use New Zealand Dairy CRC012316 STRUCTURE Te Maiharoa Road, GLENAVY Expired Consent Research Institute Terminated - Discharge 4962 Waimate Highway, CRC050843 HUMAN EFFLUENT Mr & Mrs C J & S G Paul Replaced Permit GLENAVY Terminated - Discharge 4962 Waimate Highway, Mr K A & Mrs A A CRC050843.1 HUMAN EFFLUENT Replaced Permit GLENAVY Kruger Discharge 4962 Waimate Highway, Mr K G Chamberlain & CRC050843.2 Issued - Active HUMAN EFFLUENT Permit GLENAVY Miss P C Dench Terminated - Discharge Mr & Mrs G A & S J CRC050927 HUMAN EFFLUENT State Highway 1, GLENAVY Replaced Permit Bignell Terminated - Discharge Mr & Mrs G A & S J CRC050927.1 HUMAN EFFLUENT State Highway 1, GLENAVY Replaced Permit Bignell Discharge Riverside Village Body CRC050927.2 Issued - Active HUMAN EFFLUENT State Highway 1, GLENAVY Permit Corporate 361694 Application Certificate of Mr & Mrs G A & S J CRC060873 RESIDENTIAL State Highway 1, GLENAVY Declined Compliance Bignell Application Certificate of Mr & Mrs G A & S J CRC060873 RESIDENTIAL State Highway 1, GLENAVY Declined Compliance Bignell Permitted Application Mr & Mrs E J & P M CRC061756 Activity HUMAN EFFLUENT 8 McLean Street, GLENAVY Declined Latimer. Confirmatn Discharge Mr & Mrs E J & P M CRC062241 Issued - Active HUMAN EFFLUENT 8 McLean Street, GLENAVY Permit Latimer. Application Certificate of Mr & Mrs G A & S J CRC062687 RESIDENTIAL State Highway 1, GLENAVY Declined Compliance Bignell Application Certificate of Mr & Mrs G A & S J CRC062687 RESIDENTIAL State Highway 1, GLENAVY Declined Compliance Bignell Terminated - Discharge Mr & Mrs G A & S J CRC063348 RESIDENTIAL State Highway 1, GLENAVY Replaced Permit Bignell Terminated - Discharge Mr & Mrs G A & S J CRC063348 RESIDENTIAL State Highway 1, GLENAVY Replaced Permit Bignell Discharge Riverside Village Body CRC063348.1 Issued - Active RESIDENTIAL State Highway 1, GLENAVY Permit Corporate 361694 Discharge Riverside Village Body CRC063348.1 Issued - Active RESIDENTIAL State Highway 1, GLENAVY Permit Corporate 361694 Terminated - Discharge CRC064220 HUMAN EFFLUENT Redcliff Road, GLENAVY Gary Peter Stocker Replaced Permit Mr D D & Mrs V J Terminated - Discharge CRC064220.1 HUMAN EFFLUENT Redcliff Road, GLENAVY Chalmers & H C Replaced Permit Trustees 2007 Limited Discharge CRC064220.2 Issued - Active HUMAN EFFLUENT Redcliff Road, GLENAVY Murphy Farms Limited Permit Permitted Application Mr M G & Mrs K Y CRC070559 Activity HUMAN EFFLUENT 1 Ruane Street, GLENAVY Declined MacPherson Confirmatn Terminated - Discharge Mr M G & Mrs K Y CRC071053 HUMAN EFFLUENT 1 Ruane Street, GLENAVY Replaced Permit MacPherson
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Terminated - Discharge White Street & Innes Street, CRC071240 HUMAN EFFLUENT Ashbury Vets Limited Replaced Permit GLENAVY Terminated - Discharge White Street & Innes Street, CRC071240.1 HUMAN EFFLUENT Lorraine Mary Green Replaced Permit GLENAVY Discharge Redcliff Road and State Veterinary Centre CRC072769 Issued - Active HUMAN EFFLUENT Permit Highway One, GLENAVY Limited Terminated - Discharge Glenavy Developments CRC073302 HUMAN EFFLUENT 6 Stocker Lane, GLENAVY Replaced Permit Limited Discharge Glenavy Developments CRC082156 Issued - Active RESIDENTIAL State Highway 1, GLENAVY Permit Limited Discharge Glenavy Developments CRC082156 Issued - Active RESIDENTIAL State Highway 1, GLENAVY Permit Limited Terminated - Discharge CRC083758 HUMAN EFFLUENT Redcliff Road, GLENAVY Ronald Colin Harris Replaced Permit Discharge Mr R T & Mrs E M CRC083758.1 Issued - Active HUMAN EFFLUENT Redcliff Road, GLENAVY Permit Murphy WORKS FOR Application Land Use Morven Glenavy Road, CRC092990 MAINT/PROTECTIO Murphy Farms Limited Returned Consent GLENAVY N Application Land Use Morven Glenavy Road, CRC092990 STRUCTURE Murphy Farms Limited Returned Consent GLENAVY WORKS FOR Application Land Use Morven Glenavy Road, CRC093014 MAINT/PROTECTIO Murphy Farms Limited Returned Consent GLENAVY N Application Land Use Morven Glenavy Road, CRC093014 STRUCTURE Murphy Farms Limited Returned Consent GLENAVY WORKS FOR Land Use Morven Glenavy Road, CRC093776 Issued - Active MAINT/PROTECTIO Murphy Farms Limited Consent GLENAVY N Land Use WORKS TO DIVERT Morven Glenavy Road, CRC093776 Issued - Active Murphy Farms Limited Consent WATER GLENAVY Terminated - Morven Glenavy Road, CRC093788 Water Permit SWAP DETAILS Murphy Farms Limited Expired GLENAVY Terminated - Morven Glenavy Road, CRC093788 Water Permit ALLOCATION QTY Murphy Farms Limited Expired GLENAVY Terminated - IRRIGATED AREA Morven Glenavy Road, CRC093788 Water Permit Murphy Farms Limited Expired PARAMS GLENAVY Permitted CRC100786 Issued - Active Activity HUMAN EFFLUENT 10 McLean Street, GLENAVY Helen Lois Pluck Confirmatn Terminated - Discharge Mr J G & Mrs A J CRC110238 HUMAN EFFLUENT 6 Parker Street, GLENAVY Surrendered Permit Prescott Discharge Mr A M & Mrs A CRC141736 Issued - Active HUMAN EFFLUENT 17 Cherry Avenue, Glenavy Permit McAuley Discharge CRC143674 Issued - Active HUMAN EFFLUENT 6 Pyke Street, Glenavy Mr M W & Mrs M Giles Permit Discharge White Street & Innes Street, CRC145572 Issued - Active HUMAN EFFLUENT Vanessa May Hawkins Permit GLENAVY Glenavy Tawai Road, CRC145704 Issued - Active Water Permit SWAP DETAILS Mr B A & Mrs K J Joyce WAIMATE Glenavy Tawai Road, CRC145704 Issued - Active Water Permit ALLOCATION QTY Mr B A & Mrs K J Joyce WAIMATE IRRIGATED AREA Glenavy Tawai Road, CRC145704 Issued - Active Water Permit Mr B A & Mrs K J Joyce PARAMS WAIMATE Land Use New Zealand Transport CRC150683 Issued - Active STRUCTURE Waitaki River, GLENAVY Consent Agency.... Land Use New Zealand Transport CRC150683 Issued - Active STRUCTURE Waitaki River, GLENAVY Consent Agency.... Discharge CRC151461 Issued - Active HUMAN EFFLUENT 1 Ruane Street, GLENAVY Mr B A & Mrs K J Joyce Permit Discharge South Canterbury Road CRC161661 Issued - Active HUMAN EFFLUENT 6 Stocker Lane, GLENAVY Permit & Sewage Limited Discharge Morven Glenavy & CRC897382 Issued - Active WATER - PURE Ross Rd, GLENAVY Permit Ikawai Irrigation
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Company Limited Terminated - Land Use Waimate District CRC970951 BORE GALLERY State Highway 1, GLENAVY Expired Consent Council Terminated - Land Use Waimate District CRC970951 BORE GALLERY State Highway 1, GLENAVY Expired Consent Council Terminated - Discharge WASTE TO Glenavy Landfill, Te Maiharoa Waimate District CRC972269 Replaced Permit LANDFILL Road, GLENAVY Council Discharge Glenavy Landfill, Te Maiharoa Waimate District CRC972269.1 Issued - Active LEACHATE Permit Road, GLENAVY Council Application Discharge Mr D D & Mrs V J CRC990251 WATER - PURE Andrews Road, GLENAVY Returned Permit Chalmers Terminated - IRRIGATED AREA Electricity Corporation WTK690871 Water Permit , GLENAVY Replaced PARAMS of New Zealand Limited Terminated - Electricity Corporation WTK690871 Water Permit WELL DETAILS , GLENAVY Replaced of New Zealand Limited Terminated - Meridian Energy WTK690871.1 Water Permit WELL DETAILS , GLENAVY Surrendered Limited, Christchurch Terminated - IRRIGATED AREA Meridian Energy WTK690871.1 Water Permit , GLENAVY Surrendered PARAMS Limited, Christchurch Terminated - Discharge Electricity Corporation WTK690872 HUMAN EFFLUENT , GLENAVY Replaced Permit of New Zealand Limited Terminated - Discharge Meridian Energy WTK690872.1 HUMAN EFFLUENT , GLENAVY Surrendered Permit Limited, Christchurch Terminated - WTK860641A Water Permit ALLOCATION QTY Prohibition Road, OMARAMA Fulton Hogan Limited.... Surrendered Terminated - IRRIGATED AREA WTK860641A Water Permit Prohibition Road, OMARAMA Fulton Hogan Limited.... Surrendered PARAMS Terminated - Discharge CONTAMINATED WTK860641B Prohibition Road, OMARAMA Fulton Hogan Limited.... Surrendered Permit WATER Terminated - IRRIGATED AREA WTK863801 Water Permit Glenavy, GLENAVY B I Marshall Expired PARAMS Terminated - WTK863801 Water Permit WELL DETAILS Glenavy, GLENAVY B I Marshall Expired Terminated - Discharge North Eyre Road, WEST Mr & Mrs T M & S M CRC063509 HUMAN EFFLUENT Surrendered Permit EYRETON Twiddle Terminated - Discharge 1344 Poyntz Road, CRC071763 HUMAN EFFLUENT M H D & L J B Patton Surrendered Permit HORREVILLE Terminated - IRRIGATED AREA 1245 Poyntzs Road, E C Briden & Sons CRC991288 Water Permit Surrendered PARAMS RANGIORA Limited Terminated - 1245 Poyntzs Road, E C Briden & Sons CRC991288 Water Permit WELL DETAILS Surrendered RANGIORA Limited Table 5. Consented Activities
The nearest proposed discharge is located >50m 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.
2.7 FLOOD HAZARD ASSESSMENT
It is unknown if a flood hazard assessment has been completed for this site.
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3. DESIGN FLOWS CALCULATION
The discharge field calculations including the DIR for the chosen category soils above for the proposed site are as follows:
DLR/DIR from Table 5.2 NZS1547
Design Loading Rate 50 mm/day
Required area for LAS: Area 20 m2 Table 6. Discharge field calculation
3.1 PROPOSED WASTEWATER MANAGEMENT SYSTEM
Figure 6. Hynds Lifestyle Advanced
The wastewater treatment system consists of the following:
• 4,500l primary chamber • Zabel a1800 filter on outlet of primary chamber • 2 stage aeration chamber • Settlement chamber • Pump out chamber with high water alarm • 1050mm chamber access • High level alarm • The tank includes a minimum 24-hour retention period. • BOD5 : Suspended Solids < 20 : 20 mg/L • Ammonia < 5 mg/L • 99% faecal coliform removal • Total Nitrogen < 25 mg/L (Lifestyle ‘Advanced’)
It is the installer/contractor’s responsibility to ensure the provided pump is suitable for the manifold design as detailed in the drawings.
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3.2 DISCHARGE FIELD DETAILS
The discharge field cross section is shown in Figure 7 below:
Figure 7. Discharge field cross section
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3.3 DISCHARGE FIELD DETAILS CONTINUED
• The trench system shall not be installed unless free draining soils have been found and tested to achieve adequate and consistent drainage. • If free draining soils have not been reached before the base of the 2A sand; 600x2,000mm shafts at 3,000mm crs in the shall be excavated down until free draining soils are found. • Once free draining soils have been found, the shaft can be filled with river run media with a layer of pea gravel at the intersection of the 2A sand. • The land application irrigation field will be buried with a minimum of 100mm of soil above each line, and an as-built plan shall be prepared for future maintenance and servicing. • The effluent lines are at 600mm centres along the width of the trench with staggered Ø3.5mm holes spaced at 600mm crs. • Holes in the effluent lines shall be covered by a cap to prevent soil intrusion and allow free draining. • A single capped Ø3.5mm hole shall be top mounted at the end of each effluent line to facilitate venting. • The LAS shall not be installed in areas of greater than 20° slopes. • The LAS shall be appropriately signed and landscaped to prevent easy access; if this is not possible with plantings the area shall be fenced accordingly. • The LAS shall only be planted with approved plantings. Refer to Hynds requirements. • Risers at the end of each dripper line shall be installed for purging and servicing. • The land application area shall comply with the required 20m separation distance from any drains or waterways, 50m from any bore/well and as detailed in AS/NZS1547:2012 Table R1. • The LAS shall not be installed closer than 3m from any boundary. • 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. • 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 above drawing 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.
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3.4 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 1. See Figure 8. Minimum setback distance Liping Pang (ESR Christchurch) below for details.
Figure 8. 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 No backfill ƛf Backfill removal rate 0 Soil Hs Soil thickness 0 ƛs Soil removal rate 0.0
Vadose Hv Depth of unsaturated soil to GW 1 ƛv Vadose removal rate 3.7 Table 10 Aquifer Ha Aquifer thickness 0 ƛa Aquifer removal rate 0 n log reduction 5.7 6 log reduction = 1,000,000 times Input FC Concentration Cfu/100ml 1.00E+07 smaller FC count Output FC Concentration Cfu/100ml 19.95
Table 7. Pathogen attenuation
As can be seen in the above Table 7, the output Faecal Coliform concentration should be reduced from approximately 10,000,000 Cfu/100ml 2 to less than 20 Cfu/100ml at 1mBGL with full treatment after a further 500mmBGL. These calculations only consider 1m 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.
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.
1 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 2 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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3.5 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 3.
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 Volume L/p.e. day 200 NZS1547:2012 day Total vol/day in L Vol x number p.e. 600 Table J1 NZS1547:2012 Avg wastewater TN Average recorded TN in OSET Trial 4 Raw TN Concentration gm/m3 83 concentration per m3 (2008/2009) No days/yr 365 Hynds output effluent TN ave TN 14.3 mg/L. OSET Trial 4 Treated Effluent TN mg/L 14.3 quality (2008/2009) Hynds . Approximate reduction at Report-2006-OSETTrial1-2005- Reduction at treatment 50% treatment 2006pdf.pdf Chapter 1 Approximate reduction at Reduction in land application 30% Conservative estimate LAS Total kg/yr released 2.2 kg/year
Table 8. Nitrogen discharge
The expected nitrogen due to percolation at the point of the discharge into ground water should be <10kg/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
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.
3 UN Department of Technical Cooperation for Development (1985) and Average recorded TN in OSET Trial 4 (2008/2009)
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3.6 CULTURAL IMPACT
The discharge was covered by the Te Rūnanga o Waihao Rūnanga. The ECAN GIS mapping shows this site is in a silent file area. The client has/intends to liaise with a Ngāi Tahu representative. This report does not consider and or assess the impact to the site and application caused by the silent file intersection. 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.
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. FURTHER DISCUSSION & MOVING FORWARD
Please come back to the author below at TMCO for clarification and moving forward.
MARC JENSEN Mechanical and 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
5. APPENDIX
5.1 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: 1,000 L/day . Refer Table 1 3 day peak treatment capacity of treatment unit: 2,000L/day Emergency storage capacity of treatment unit: 1,820L Dwelling fixtures, Standard fixtures such as a dual flush toilet . Refer Table 1. Site details fittings and appliances. Variable flow and The dw elling at this stage should be intermittent ly occupied; should seasonal loadings occur loading. the 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 Aerated OWMS discharging to Trench LAS. Refer Table 1. Site details and Section 3.1 . treatment plant. Description of LAS Trench with cut -off/surface drains where required. Design Criteria, LAS Max loading of 50 mm/day. Refer Table 1. Site details . GW -2 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. If LAS is located less than 50m away from any bore; the Client shall be aware that cross area contamination could occur. The Client shall be fully responsible for any issues or health problems arising directly or 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 9. LWRP criteria
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5.2 LAND CARE RESEARCH SOIL REPORT
Figure 9. Landcare Research soils report
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