SOIL INVESTIGATION AND EFFLUENT DISPOSAL

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1 Job Ref EFF 12 August 2008 REPORT FOR SOIL INVESTIGATION AND EFFLUENT DISPOSAL AT OBI OBI HALL, KENILWORTH MAPLETON ROAD, OBI OBI CLIENT: CLIENT ADDRESS: Kidman Creek Plumbing Obi Obi Hall BLACKALL RANGE CONSULTING ENGINEER Campbell J Foster MIEAust, RPEQ 7228 National Provider Number 1479

2 TABLE OF CONTENTS 1.0 INTRODUCTION 2.0 SITE DESCRIPTION 3.0 SOIL EVALUATION PROCEDURE 4.0 SOIL EVALUATION FINDINGS 4.1 Soil Profile and Ground Conditions 4.2 Indicative Soil Permeability 4.3 Ground water 5.0 WASTE WATER DISPOSAL 5.1 Effluent Quantity 5.2 Effluent Disposal Design 5.3 Evapo-transpiration Beds 5.4 Installation of Septic Tank and Evapo-transpiration Beds 5.5 Viral Die-Off Calculation and Recommendations 5.6 Setback Requirements 5.7 Discussion 6.0 RECOMMENDATIONS 7.0 MAINTENANCE NOTES 7.1 General 7.2 Items to Avoid for Better Treatment Plant Operation 7.3 Cleaning Products and Cleaning Hints APPENDICIES Appendix A - Bore Logs Appendix B - Standard Water Reduction Fixtures Checklist Appendix C - Land Disposal Area Sizing Calculations Appendix D - Viral Die-off Calculation DRAWING - 1-8/14/2008

3 1. Introduction As requested by Kidman Creek Plumbing a site and soil evaluation was carried out adjacent the Obi Obi Hall, Kenilworth Mapleton Road, Obi Obi, July The purpose of the site and soil evaluation was to determine the soil profile and soil indicative permeability (effluent infiltration rate) at a suitable location on the allotment. The proposed effluent disposal system will serve both the Obi Obi Hall and the Obi Obi Rural Fire Brigade that intend setting a shed to the rear of the allotment. 2. Site Description The allotment is Ha in area and located on the southern side of Kenilworth Mapleton Road. The allotment is relatively flat in the vicinity of the Hall and to the rear of the allotment. The north western corner of the allotment slopes towards Kenilworth Mapleton Road with an approximate slope of 1 in 15 to 20. The effluent disposal area will be located towards the north western side of the Obi Obi Hall, as indicated on the drawings. The current land use in the vicinity of the proposed effluent disposal area is predominantly pasture grass with one or two scattered mature trees. There were no water bores or dams identified on the allotment or adjacent allotments within a 50 metre radius. 3. Soil Investigation Procedure The soil evaluation and interpretation of site conditions were carried out in general accordance with the following Australian Standards: AS1726 Geotechnical Site Investigations AS1547 On-Site Domestic Waste Water Management The On-site Sewerage Code July 2002, Department of Natural Resources and Mines The site evaluation was carried out by Blackall Range Consulting Engineer. The investigation comprised the following stages: a) Site investigation in accordance with AS Geotechnical Site Investigations. Drilling of 2 boreholes using a hand auger, or truck mounted mechanical auger to a depth not less than 600mm below effluent disposal depth (borehole locations are shown on the Site Plan in Appendix A). Soil classification by qualified and experienced geotechnical engineer. Sampling of representative soils throughout the depth of the borehole Site description, including but not limited to vegetation cover, subsurface water table, general topography of site and proximity to existing dwellings. b) Contour survey of proposed allotment as provided on the Site Plan. 4. Soil Evaluation Findings 4.1 Soil Profile and Ground Conditions Two Boreholes were completed in the vicinity of the proposed effluent disposal area using a 90mm diameter hand operated auger, BH1 and BH2, as indicated in Appendix A and shown on the Site Plan, Figure 1. The soil profile encountered in both boreholes was generally similar and comprised dark brown, silty/loamy to a brown, silty loam with some clay at depth, moist (saturated), low plasticity, weak to mod structure (loam). Soil samples throughout the depth of each borehole where visually and texturally classified based on these findings the soil would be classified as Category 4/5, moderate structure, in accordance with Table 4.2A1, AS /14/2008

4 4.2 Indicative Permeability A constant head test was undertaken at BH1 in accordance with Appendix 4.1F, AS The indicative permeability (Ksat) for BH1 was calculated at 0.66 m/d, which confirms the soil as Category 3/4. A conservative rate for Ksat of 0.5 m/d (as indicated in Table 4.2A.1 of AS ) and design load rate (DLR) of 10mm/day is to be adopted to counter any variability within the soil profile across the proposed effluent disposal area. 4.3 Groundwater No ground water was encountered in either bore hole. 5. Waste Water Disposal 5.1 Effluent Quantity A daily effluent flow rate of 525 litres per day has been adopted for the existing Obi Obi Hall and proposed Fire Brigade Building. The daily effluent flow rate has been calculated based on the following: Obi Obi Hall - 50 persons per 20 Litres/person/day (averaged over month) Fire Brigade Building - 12 persons twice per 10 Litres/person/day (averaged over month) Water Supply Tank Water Reduction Fixtures Standard Typical Wastewater Flow 50 L/person/day (Appendix 4.2D of AS 1547) The effluent disposal area has been calculated on a peak flow rate of 525 Litres/day. The above wastewater flow rate is based on the use of standard water reduction fixtures: dual flush toilet(s), aerators on taps, basins and sinks, water saving shower nozzles and front loading washing machine. A Checklist is provided in Appendix B, which should be completed and forwarded to the Local Government Authority with certification of the wastewater treatment plant documentation. 5.2 Effluent Disposal Design The anticipated quality of waste water (influent) prior to treatment and the effluent standard to be provided following treatment (primary quality effluent) is outlined in Table 1. Table 1. Wastewater Standards Primary Effluent Effluent Parameter Expected Influent Quality (mg/litre) Expected Effluent Quality (mg/litre) BOD ± /-60 Suspended Solids 300 ± /-60 Thermotolerant Org. (Org./100ml) Evapo-transpiration Beds In consideration of the site permeability rate and the adequate soil cover, it appears effluent produced at this site could be disposed of via absorption beds or evapo-transpiration beds. The design of the beds for the proposed allotment is calculated in accordance with AS/NZS as shown in Table 2. Table 2. Evapo-transpiration Beds Daily Flow (litres/day) 525 Soil Category 3/4 DLR (mm/day) 10 Base Area Reqd.(m 2 ) 68 Bed Width (m) 1.5 min Depth of Beds (m) 0.45 min Bed Length Required (m) 2No.x18m Land Disposal Area Sizing Calculation provided in Appendix C - 3-8/14/2008

5 5.4 Installation of Septic Tank and Evapo-transpiration Beds The proposed absorption or evapo-transpiration beds have been designed in accordance with AS/NZS and the Onsite Sewerage Code Installation should be carried out incorporating the following: Beds to be located wherever possible in an unobstructed and shaded area. Beds to be located in an area not subject to any vehicle traffic. Beds to be located where at least 1.35m of soil cover to bedrock is available. Provision for a replacement disposal field is to be set aside. This replacement field is to satisfy all set back requirements and be of similar size to the proposed disposal field. Beds located on slopes greater than 15% shall be terraced.\ A distribution box is to be provided and should be designed to divide the effluent flow equally between the pipelines and to allow the flow of effluent to any pipeline to be shut off without interrupting the flow to other lines. Surface water should be drained away from the Beds using earth bunds of subsurface drains. The area immediately down slope of the Beds should be grassed or landscaped with appropriate shrubs or plants. 5.5 Setback Requirements The septic tank and absorption/evapo-transpiration beds should be setback a distance measured horizontally from the following: 4m from any property boundary, path or walkway on the down slope side 2m from any property boundary, path or walkway on the up slope side 50m from the bank of a permanent watercourse, intermittent watercourse or dam 50m from a bore or well used for domestic water supply. 6m from a swimming pool 4m up slope or 2m down slope from a building 1.0 m between adjoining irrigation fields. 5.6 Discussion 6 Conclusion The proposed absorption/evapo-transpiration beds have adequate setback from all boundaries, as indicated in Drawings. The allotment is large enough in size (0.344 ha) and is set in a rural area that may warrant a primary effluent disposal waste water treatment system. The intermittent use of the system also favors a septic tank and ETA beds. We recommend that on-site disposal be via septic tank producing primary quality effluent and two (2) 18m long by 1.5m wide absorption or evapo-transpiration beds, having a total disposal area of 54 m 2, as shown on the Drawings. Adequate area on the allotment exists for duplication or extension of the Absorption/ETA Beds. With respect to the above information effluent disposal for the proposed residential dwelling at Obi Obi Hall appears adequate. Considering the soil profile, permeability rates, distance to a pond located centrally within the allotment, and providing all other setback requirements are met the likely hood of re-emergence of the effluent and pollution occurring downstream of the site would seem unlikely /14/2008

6 7 Maintenance Notes 7.1 General The treatment plant is to be maintained in accordance with the manufacturer s specification. Some component of the plant may require replacement or re-establishment within the service lifetime of the plant, such as, but not limited to: Mechanical and electrical equipment Some pipe work, fittings and valves filters Irrigation areas The septic tank and absorption/evapo-transpiration beds proposed for the above allotment has been designed for a maximum flow of 525 L/day of domestic waste water flow. The domestic waste water is a combination of black and grey water. To achieve the above maximum waste water flow the residence is to have standard water reduction fixtures installed throughout the house and verified by the Local Government Authority. Care and maintenance instructions should be followed in accordance with manufacturer s instructions. If care and maintenance of the system is not followed carefully or abnormal loadings are imposed then the treatment system may cease to be a viable on-site effluent disposal system. If this occurs then the system may need to be modified to better suit the actual loadings and house holders commitment to site maintenance. 7.2 Items to Avoid for Better Treatment Plant Operation Disposal of the following items into the sewerage system will compromise or seriously impair the operation of the treatment plant: Disposal of newspapers, sanitary napkins, rubber products, nappy liners, cotton buds etc. Use of an in-sink garbage disposal units are not recommended as they can add additional loading to the treatment plant equivalent to 2 additional persons. Use of strong caustic soda, acids, alkalis or chemical detergents can damage the system and cause dad odour Use of disinfectants or other bactericides can kill the bacteria activity within the treatment plant Placement of grease/fats/cooking oil or food scraps down the kitchen sink can put extra load on the treatment system. Grease/fats/cooking oil and food scraps should be removed from plates/pots prior to washing. Disposal of excess grease/fats/cooking oil down the sink can cause excess accumulation of fat in the treatment plant and also cause clogging of pipe work. 7.3 Cleaning Products and Cleaning Hints Toilets: Cleaning the Bath: Bleach: Wash Frequency: Avoid: Pine-O-Clean or Toilet Duck must be used in very limited quantities. Ajax or similar products may be used if the plug of the bath is in and the bulk of the Ajax is wiped away. Spray and Wipe can also be used for this purpose. Should not be used in the system. Ideally 1 to 2 loads of washing over a period of several days. This reduces the hydraulic load on the treatment plant. Using showers, washing machines, etc. at the same time or in close succession should be avoided, to again reduce the hydraulic load on the treatment plant. Most dishwashing detergents are alkaline and should be used in moderation. When shopping for various cleaners, detergents, toilet paper etc., check the labels to determine their suitability in relation to treatment plant operations, based on the above provided information. Failure to comply with these recommendations can result in problems with the treatment system. Many products labeled Safe for Septic should not adversely affect the treatment system /14/2008

7 LIST OF APPENDICIES APPENDIX A BORE LOGS CLIENT Kidman Creek Plumbing SITE LOCATION Obi Obi Hall BOREHOLE 1 BOREHOLE 2 Depth below ground level (mm) Soil Group Symbol Soil Description Depth below ground level (mm) 0 0 SC Dark brown silty, clay, low to mod. plasticity, moist, with some organic material SC Brown, Silt/loam with trace of Clay, low plasticity, moist, weak to mod. Structure SC 800 Brown, Silt/loamy with some Clay, low plasticity, moist, weak to mod. Structure SC Hole Terminated Soil Group Symbol SC SC SC SC Soil Description Dark brown silty, clay, low to mod. plasticity, moist, with some organic material. Brown, Silt/loam with trace of Clay, low plasticity, moist, weak to mod. Structure. Brown, Silt/loamy with some Clay, low plasticity, moist, weak to mod. Structure. Hole Terminated - 6-8/14/2008

8 APPENDIX B STANDARD WATER REDUCTION FIXTURES CHECKLIST This effluent disposal system has been designed for households with Standard water reduction fixtures in accordance with AS/NZS , Appendix 4.2D. To verify completion of the wastewater treatment plant and effluent disposal system installation such that a final inspection certificate can be issues the plumber must complete the standard water reduction fixtures checklist provided below. The completed checklist is to be returned to Blackall Range Consulting Engineer either prior to or at the time of the final inspection. Duel Flush 11/5.5 litres water closet Model/Type:. No. of Units:. Places Installed: (Tick Box) Main Wash Room Bathroom Ensuite Other Aerator Faucets (Taps) Model/Type:. No. of Units:. Places Installed: (Tick Box) Laundry Kitchen Bathroom Ensuite Bar Other Shower Flow Restrictors Model/Type:. No. of Units:. Places Installed: (Tick Box) Bathroom Ensuite Other Water Conserving Washing Machine Model/Type:. No. of Units:. Places Installed: (Tick Box) Laundry Other VERIFICATION OF INSTALLATION OF DEVICES: Plumbers Name: Signature: Date: - 7-8/14/2008

9 APPENDIX C LAND DISPOSAL AREA SIZING CALCULATION - 8-8/14/2008

10 APPENDIX D VIRAL DIE-OFF CALCULATION - 9-8/14/2008

11 DRAWINGS /14/2008

FORM B: ONSITE DISCHARGE OF TREATED EFFLUENT

APPLICATION FOR RESOURCE CONSENT FORM B: ONSITE DISCHARGE OF TREATED EFFLUENT NOTES Resource use activities must meet all the conditions of any relevant Permitted Activity Rules in the Waikato Regional