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15461 Septic Tank | Sewage Treatment | Septic Tank
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This Joint Australian/New Zealand Standard was prepared by Joint Technical Committee WS/13 On-site Domestic Wastewater Management. It was approved on behalf of the Council of Standards Australia on 13 February 1998 and on behalf of the Council of Standards New Zealand on 9 January 1998. It was published on 5 April 1998. ________________ The following interests are represented on the committee responsible for this draft Australian/ New Zealand Standard: Association of Certification Bodies (Australia) Australian Society of Soil Science Inc. Australian Water and Wastewater Association Bureau of Steel Manufacturers of Australia Composites Institute of Australia Inc. Department of Health New South Wales Department of Health Tasmania Department of Human Services Victoria Department of Natural Resources Queensland Environment Protection Authority of Victoria Environment Management Industry Association of Australia Health Department of Western Australia Institution of Engineers Australia Master Plumbers Australia National Precast Concrete Association of Australia Plastics and Chemical Industries Association Incorporated Public Works Department New South Wales Queensland Confederation of Industry Queensland Department of Housing Local Government and Planning South Australian Health Commission Victorian Precast Septic Tank Manufacturers Association Inc. Association of Rotational Moulders (Australasia) Composite Association of New Zealand Institute of New Zealand Plumbing and Drainage Inspectors Institution of Professional Engineers New Zealand Local Government New Zealand Ministry of Health New Zealand New Zealand Institute of Environmental Health Incorporated New Zealand Manufacturers Federation New Zealand Society of Master Plumbers & Gasfitters New Zealand Water and Wastes Association The University of Auckland Department of Civil and Resource Engineering ________________
Review of Standards. To keep abreast of progress in industry, Joint Australian/New Zealand Standards are subject to periodic review and are kept up to date by the issue of amendments or new editions as necessary. It is important therefore that Standards users ensure that they are in possession of the latest edition, and any amendments thereto. Full details of all Joint Standards and related publications will be found in the Standards Australia and Standards New Zealand Catalogue of Publications; this information is supplemented by the magazines 'The Australian Standard' and 'Standards New Zealand', which subscribing members receive, and which give details of new publications, new editions and amendments, and of withdrawn Standards. Suggestions for improvements to Joint Standards, addressed to the head office of either Standards Australia or Standards New Zealand, are welcomed. Notification of any inaccuracy or ambiguity found in a Joint Australian/New Zealand Standard should be made without delay in order that the matter may be investigated and appropriate action taken. ________________ This Standard was issued in draft form for comment as DR 96033.
Originated in Australia as AS A178-1968. Final Australian edition AS 1546-1990. Originated in New Zealand in part as NZCP 44:1961. Final New Zealand edition NZS 4610:1982. AS 1546-1990 and NZS 4610:1982 jointly revised, amalgamated and redesignated AS/NZS 1546.1:1998.
PUBLISHED JOINTLY BY: STANDARDS AUSTRALIA 1 The Crescent, Homebush NSW 2140 Australia STANDARDS NEW ZEALAND 155 The Terrace, Wellington 6001 New Zealand
ISBN 0 7337 1882 5
This Standard is one of a series being prepared by the Joint Standards Australia/Standards New Zealand Committee WS/13 on On-site Domestic Wastewater Management. It will supersede AS 1546-1990, Small septic tanks, and NZS 4610:1982 (in part), Household septic tank systems. Other Standards covering aerated wastewater treatment systems and waterless composting toilets are in the course of preparation. There is a twofold objective in this Standard. The first is to provide a set of performance statements which define the requirements of a septic tank and which provide a base against which any septic tank, conventional or innovative may be assessed. The second is to provide manufacturers of conventional septic tanks and associated fittings systems made of various materials with basic manufacturing and test specifications. These will enable certification bodies to check that a product conforms to the Standard. The illustrations used in this Standard are diagrammatic only and are chosen to illustrate principles of design or operation. The terms normative and informative have been used in this Standard to define the application of the appendix to which they apply. A normative appendix is an integral part of a Standard, whereas an informative appendix is only for information and guidance. Clauses prefixed by C and printed in italic type are comments, explanations, summaries of technical background, recommended practice or suggest approaches which satisfy the intent of the Standard. Corresponding mandatory clauses are not always present.
Copyright STANDARDS AUSTRALIA/STANDARDS NEW ZEALAND
Page Preface ........................................................................................................................................... 2 Referenced documents .............................................................................................................................. 7 SECTION 1 GENERAL 1.1 Objective............................................................................................................................. 6 1.2 Scope .................................................................................................................................. 6 1.3 Application ......................................................................................................................... 6 1.4 Legislation .......................................................................................................................... 7 1.5 Referenced documents ........................................................................................................ 7 1.6 Definitions ........................................................................................................................ 7
PERFORMANCE 2 PERFORMANCE REQUIREMENTS AND PERFORMANCE CRITERIA 2.1 Scope ................................................................................................................................ 10 2.2 Function and context of use ............................................................................................. 10 2.3 Performance requirements ............................................................................................... 10 2.4 Performance criteria ........................................................................................................ 11
MEANS OF COMPLIANCE 3 GENERAL REQUIREMENTS OF CONVENTIONAL SEPTIC TANKS 3.1 Scope ................................................................................................................................ 16 3.2 Septic tank capacities ........................................................................................................ 16 3.3 Materials durability........................................................................................................... 16 3.4 Design .............................................................................................................................. 16 3.5 Inlet fittings and outlet fittings .......................................................................................... 16 3.6 Position of inlet and outlet fittings in tank......................................................................... 18 3.7 Gas baffles ........................................................................................................................ 18 3.8 Partitions .......................................................................................................................... 18 3.9 Vents ................................................................................................................................ 19 3.10 Access openings and covers............................................................................................... 19 3.11 Extensions ........................................................................................................................ 19 3.12 Marking............................................................................................................................ 19 3.13 Installation........................................................................................................................ 19 MARKING OF SEPTIC TANKS 4.1 Scope ................................................................................................................................ 24 4.2 General ............................................................................................................................ 24 4.3 Requirements .................................................................................................................... 24 TESTING REQUIREMENTS OF SEPTIC TANKS 5.1 Scope ................................................................................................................................ 25 5.2 Type testing ...................................................................................................................... 25 5.3 Routine quality testing ...................................................................................................... 25 5.4 Quality certification .......................................................................................................... 25
Page PRECAST CONCRETE STEEL REINFORCED SEPTIC TANKS AND PRECAST CONCRETE STEEL FIBRE REINFORCED SEPTIC TANKS 6.1 Scope ................................................................................................................................ 26 6.2 Materials........................................................................................................................... 26 6.3 Concrete............................................................................................................................ 26 6.4 Testing.............................................................................................................................. 27 6.5 Manufacture...................................................................................................................... 27 6.6 Thickness of tank components........................................................................................... 29 6.7 Reinforcement................................................................................................................... 30 6.8 Provision of fittings, partitions and their assembly ............................................................ 31 CAST-IN-SITU CONCRETE SEPTIC TANKS 7.1 Scope ............................................................................................................................... 32 7.2 Performance...................................................................................................................... 32 7.3 Materials........................................................................................................................... 32 7.4 Design .............................................................................................................................. 32 7.5 Marking............................................................................................................................ 32 REINFORCED CEMENT MORTAR SEPTIC TANKS 8.1 Scope and general ............................................................................................................. 33 8.2 Performance...................................................................................................................... 33 8.3 Manufacture...................................................................................................................... 33 GLASS FIBRE-REINFORCED PLASTIC SEPTIC TANKS 9.1 Scope ................................................................................................................................ 34 9.2 Performance requirements................................................................................................. 34 9.3 Design .............................................................................................................................. 34 9.4 Manufacture...................................................................................................................... 35 9.5 Testing.............................................................................................................................. 38 PLASTIC (POLYOLEFIN) SEPTIC TANKS 10.1 Scope ............................................................................................................................... 40 10.2 Performance requirements................................................................................................. 40 10.3 Design .............................................................................................................................. 40 10.4 Manufacture...................................................................................................................... 41 10.5 Testing.............................................................................................................................. 42
APPENDICES A B C D E F G H I J K Referenced documents ................................................................................................................. 44 Septic tank capacities................................................................................................................... 47 Test of the manufacturers instructions for the installation of fittings in a sound and watertight manner ................................................................................ 48 Determination of the resistance of a partition to a hydrostatic head (pumpout test)....................... 49 Determination of watertightness................................................................................................... 50 Determination of resistance to lateral load - hydraulic test method ............................................... 53 Determination of resistance to lateral load - point load test method .............................................. 55 Determination of resistance to top loading .................................................................................. 58 Installation of septic tanks............................................................................................................ 61 Determination of the hardness of glass fibre-reinforced plastic composites................................... 63 Determination of the impact resistance of moulded polyolefin septic tanks................................... 64
Page TABLES 6.1 6.2 6.3 6.4 6.5 B1 Concrete characteristics ............................................................................................................... 27 Methods for manufacture ............................................................................................................. 28 Minimum concrete thickness ....................................................................................................... 29 Minimum concrete cover ............................................................................................................. 30 Minimum quantity of steel reinforcement measured as cross-sectional area.................................. 31 Conventional septic tank capacities in litres ................................................................................. 47
FIGURES 3.1 3.2 3.3 3.4 3.5 E1 H1 Typical arrangement of a septic tank............................................................................................ 20 Typical UPVC fittings ................................................................................................................. 21 Typical alternative arrangement for precast concrete tanks with a U-section scum baffle (outlet only).................................................................................. 21 Typical installation arrangement of inlet and outlet fittings.......................................................... 22 Typical gas baffle designs ............................................................................................................ 23 Watertightness test arrangement for horizontal and vertical tank ................................................. 52 Typical load testing set-up ........................................................................................................... 60
STANDARDS AUSTRALIA/STANDARDS NEW ZEALAND Australian/New Zealand Standard On-site domestic wastewater treatment units Part 1: Septic tanks
1.1 Objective The objective of this Standard is to identify performance requirements and performance criteria for septic tanks, to specify technical means of compliance and to provide test specifications that will enable septic tanks to be manufactured to comply with the performance requirements and criteria. C1.1 Performance requirements and criteria for septic tanks are found in Section 2. Sections 3 onwards cover means of compliance and testing for materials currently used to manufacture septic tanks. 1.2 Scope This Standard covers the manufacture of conventional septic tanks and their associated fittings for the treatment of domestic wastewater only. This range of tanks typically is designed to cater for: All-waste (Blackwater + Greywater) Blackwater only Greywater (with or without kitchen waste included) only and as Holding tanks (collection wells). Septic tanks covered by this Standard are suitable for a flow of domestic wastewater of up to 14,000 litres per week. C1.2 This flow limit represents an average daily flow of 2000 litres, being from up to 10 persons in a single residence, or an institutional or commercial facility which may have a varying 7 day or 5 day operation averaged out over a full week. 1.3 Application This Standard is intended for use by consultants, designers, manufacturers, certifying bodies, installers and regulators. 1.3.1 General This Standard covers only the purpose and requirements of septic tanks and associated fittings. It does not cover the drainage systems leading to the tank, (refer to AS/NZS 3500.2), nor the effluent disposal systems associated with septic tanks, (refer to AS/NZS 1547, (in course of preparation).) 1.3.2 Conventional designs and materials Traditionally certain materials, designs and techniques have been used and have become established. The materials and associated designs shown in Sections 6 to 10 of this Standard have been proven through use and are presented as examples of solutions that are a means of compliance with the provisions of this Standard.
1.3.3 Non-standard materials, installations or designs This Standard does not preclude the manufacture of septic tanks from any material, or in any unusual design, or installation in any non-standard fashion, provided that the completed product and its installation meets the performance requirements and performance criteria given in Section 2 of this Standard. C1.3.3 It may be necessary to obtain and supply evidence of third party certification or opinion from people or organisations recognised as having the authority to do so before a regulatory authority will accept a new material or design. 1.3.4 Operation and maintenance Septic tank systems need maintenance and regular desludging. Operation and maintenance requirements are covered in AS/NZS 1547 (in course of preparation). 1.4 Legislation
1.4.1 This Standard shall be read in conjunction with the by-laws and regulations of the regulatory authorities in Australia, and of the New Zealand Building Code in New Zealand. 1.4.2 Australia The collection and treatment of domestic wastewater is the responsibility of the regulatory authority. 1.4.3 New Zealand Septic tank systems and associated land application areas come within the description of a building in Section 3 of the Building Act 1991. The performance requirements of systems that store and treat liquid waste are given in New Zealand Building Code contained in the First Schedule of the Building Regulations 1992. Septic tanks constructed to this Standard meet the requirements of the New Zealand Building Code in respect of: Clause B1 Clause B2 Clause G14 Structure Durability Industrial Liquid Waste
Through the Resource Management Act, Regional Councils will have established a regional plan which will control the nature of effluent released to the environment. Territorial authorities will either give consent to install a system or will advise if a special resource consent is required. 1.5 Referenced documents A listing of referenced documents is to be found in Appendix A.
1.6 Definitions For the purpose of this Standard, the definitions below apply: ACCESS OPENING means an opening in the top surface of the tank fitted with a cover which is removable to allow access for desludging and for visual inspection of the interior of the tank and contents. Access openings are not intended to allow people to enter a tank. ANCHORAGE means a device/technique for holding the tank in the ground against hydrostatic uplift pressures. BLACKWATER means wastes discharged from the human body either direct to a vault toilet or through a water closet (flush toilet) and/or urinal.
CAPACITY means the volume of the tank below the invert of the outlet. COLLECTION WELL (see HOLDING TANK) CURE means the chemical reaction resulting in the final product. It may be effected at ambient temperature or at an elevated temperature. DAILY FLOW means the daily flow to the septic tank. DESLUDGING means removal of the accumulated sludge and scum from a septic tank. EFFLUENT means the liquid discharged from a wastewater treatment process. EXTENSION means a structure used to bring the access or inspection cover to ground level. FOUL WATER (see WASTEWATER) GAS BAFFLE means a device, usually a simple deflecting plate, installed internally on the outlet of a septic tank, or the outlet of a second chamber, to prevent gas borne solids passing from the tank into the effluent land application system. GEL-COAT means, for glass fibremanufacture, the thin layer of unreinforced resin on the surface of a laminate. The gel-coat covers the fibre of the reinforcement, protects the bond between resin and reinforcement, and provides special surface properties. It may be pigmented. GREYWATER means the domestic wastes from baths, showers, basins, laundries and kitchens specifically excluding water closet and urinal wastes. Greywater does not normally contain human wastes unless laundry tubs, or basins are used to rinse soiled clothing or baby's napkins. HOLDING TANK means a tank used for holding domestic wastewater prior to pumping out (sometimes called COLLECTION WELL). HYDROSTATIC FLANGE means a horizontal projection on the wall of the septic tank designed to prevent the tank being forced out of the ground by hydrostatic pressure in areas having a high water table. Sometimes called an anchor collar, or ground retention lip. INLET FITTING means a device that allows a connection to be made between the drainage system carrying the wastewater and the septic tank. INSPECTION OPENING means opening in the top surface of the tank which allows for inspection of the inlet or outlet fitting.
INVERT means the lowest point of the internal surface of a pipe. LAMINATE means, for glass fibremanufacture, the set layer or layers of reinforcement impregnated with polyester or other resin forming a thick structural membrane. The laminate does not include the gel-coat. LAND APPLICATION means the application of effluent to areas of land for further treatment. LATERAL LOAD means the load applied sideways onto a buried tank due to the combined effects of soil, water and traffic. LAYING-UP means, for glass fibre manufacture, a process of applying or producing laminates in position on a mould prior to cure.
OUTLET FITTING means a device that allows a connection to be made between the outlet of the tank and the drainage system that conducts the effluent away for further treatment. PARTITION means an internal wall which may or may not permit the passage of liquid and solid waste between compartments within the septic tank. PERFORMANCE REQUIREMENTS means the functions that a system has to perform in order to operate as defined PERFORMANCE CRITERIA means the qualitative or quantitative description of the performance requirements. PRETREATMENT SYSTEM means a system in which wastewater is partially treated before discharge into the septic tank. REGULATORY AUTHORITY means the authority which is empowered by statute to be responsible for managing/controlling domestic on-site wastewater. SCUM means the floating mass of wastewater solids buoyed up by entrained gas, grease or other substances which form an accumulating layer on the liquid surface inside the septic tank. SEPTIC TANK means a single or multiple chambered tank through which wastewater is allowed to flow slowly to permit suspended matter to settle and be retained, so that organic matter contained therein can be decomposed (digested), by anaerobic bacterial action in the liquid. The term covers tanks used to treat wastewater, greywater and blackwater. SERVICEABLE LIFE means the period of time in which with only normal and routine maintenance, the septic tank and associated fittings perform satisfactorily without failure. SEWAGE means any wastewater, including all faecal matter, urine, household and commercial wastewater that contains human waste. SLUDGE means the semi-liquid solids settled from wastewater in septic tanks. SOLIDS means material in the solid state. VENT means a device, usually a pipe, which allows odours to be removed from the tank. WASTEWATER means the spent or used water of domestic or commercial origin which contains dissolved and suspended matter. (NOTE: Wastewater is defined as FOUL WATER in the New Zealand Building Code.)
2.1 Scope This section of the Standard specifies the performance requirements and performance criteria for septic tanks and associated fittings. 2.2 Function and context of use
2.2.1 Function The function of a septic tank is to provide a relatively still zone of adequate size for the treatment of all domestic wastewater at all flow rates from a household, or institutional or commercial facility. Scum, and solids capable of settling, are separated from the wastewater flow. The solids are retained, digested and consolidated between maintenance operations. The tank design allows for the liquid above the settled solids (sludge) and below the scum layer to be either discharged to a land application system or to be removed for disposal in some other manner, and for essential regular desludging to be carried out so that the volume for storage and treatment of wastewater is maintained. 2.2.2 Context of use
2.2.2.1 Septic tanks are either installed in the ground or freestanding in the open air. In these situations, they are exposed to the effects of the weather, internal loads/pressures, external loads/pressures, and any ground movement. In addition corrosion of the tank material is possible internally from the wastewater, and externally from the surrounding environment. 2.2.2.2 When installed in the ground, the top surface of the tank is either placed at or just above the ground surface; (so that inspection and access covers are readily accessed and ingress of surface water is prevented), or the tank is installed deeper. When the tank is installed deeper, provision is made for a watertight vertical extension to be installed above the access and inspection openings to hold the access and inspection covers at or just above finished ground level. 2.3 Performance requirements
2.3.1 General The tank and associated fittings and extensions shall be constructed of durable materials. The tank shall be watertight, be capable of withstanding loads imposed on its roof and walls, and shall be constructed and installed so that flotation will not occur in areas of high water-table level or when the tank is emptied. 2.3.2 Septic tanks Septic tanks shall be constructed:
With capacity for the settlement of solids from the design wastewater flow; To allow for scum and sludge retention between desludging operations; To allow entry of waste with the minimum of disturbance to surface layers under normal operating conditions; To prevent the direct flow of wastewater between inlet and outlet; To avoid the likelihood of blockage;
So that the entire structure of the tank and its associated inspection and access covers and/or extensions, is integrally sound and penetration by roots; entry of ground water; or entry of insects is avoided; To avoid contamination of soils, groundwater and waterways; From materials which are resistant or impervious both to the waste contained in the tank and to groundwaters for the serviceable life of the tank; To avoid the likelihood of foul air and gases creating an odour nuisance and entering buildings; With access for removal of tank contents; To reduce the likelihood of unauthorised access by people; To remain integral for their serviceable life;
(m) To prevent the likelihood of damage from superimposed loads or normal ground movement; (n) (o) To be able to resist hydrostatic uplift pressures; To be able to perform adequately with only normal maintenance over their serviceable life.
2.3.3 Serviceable Life The serviceable life of a septic tank and associated fittings shall be a minimum of 15 years provided the tank is used and installed in accordance with the manufacturers recommendations as defined in this Standard. C2.3.3 The New Zealand Building Code requires a durability of 15 years for tank envelopes, non-hidden fittings, and other tanks elements having moderate ease of access but which are difficult to replace. 2.4 Performance criteria Alternative designs or developments must meet the performance requirements of Section 2.3 and the associated performance criteria in this section. 2.4.1 Capacities Recommended minimum capacities for conventional wastewater treatment units are given in Appendix B. 2.4.1.1 All-waste tanks The capacity of all-waste tanks shall be calculated to provide for at least 24 hours retention for the daily flow of waste from the premises plus an allowance of 80 litres/person/year of capacity for scum and sludge accumulation. It shall be assumed that the tank will be desludged at regular intervals of 3 - 5 years. C2.4.1.1 The allowance for scum and sludge accumulation in the conventional all-waste tank does not allow for extra solids from garbage grinders. The disposal of garbage grinder solids into conventional all-waste tanks is not recommended, see AS/NZS 1547 (in course of preparation). 2.4.1.2 Greywater tanks The capacity of greywater tanks shall be calculated to provide at least 32 hours combined retention and hydraulic buffering for daily greywater flows, with up to 40 litres/person/year of capacity allowed for scum and sludge accumulation. It is assumed that the tank will require pumpout/desludging at intervals of not greater than 5 years.
C2.4.1.2 The allowance for scum and sludge accumulation in the conventional greywater tank does not allow for extra solids from garbage grinders. The disposal of garbage grinder solids into conventional greywater tanks is not recommended, see AS/NZS 1547 (in course of preparation). 2.4.1.3 Blackwater tanks The capacity of blackwater tanks shall be calculated to provide for at least 24 hours retention for daily water-closet flows, with 50 litres/person/year of capacity allowed for scum and sludge accumulation over a 3 - 5 year period when the tank will require pumpout/desludging . 2.4.1.4 Design capacity The wastewater treatment unit shall be designed to cater for the number of people for which the dwelling is designed. 2.4.2 Flow path The flow path of wastewater, measured from the inlet to the outlet, shall be a minimum length of 1200 mm. 2.4.3 Inlet fittings and outlet fittings Inlet and outlet fittings shall have a cross-sectional area sufficiently large to allow the passage of solids of a size expected in the system. 2.4.4 Joints The joints between a fitting and the wall of a septic tank and between tank components eg. wall and lid, shall have a durable seal, be watertight, and have sufficient integral strength and/or flexibility to maintain a sound structure. The verification test for joints around fittings is given in Appendix C. 2.4.5 Partitions When a septic tank is divided into chambers: (a) The partition(s) shall be structurally sound and fixed without diminishing the integrity of the tank;
(b) The tank shall be able to be pumped out without the partition collapsing, or permanently deforming. A verification test is given in Appendix D. 2.4.6 Access openings and covers Access openings are not intended to allow people to enter the tank. Where it is envisaged that a person must be able to enter the tank, e.g. for the purposes of repairs and maintenance, the access opening size shall comply with the appropriate regulations. (a)
Access openings shall be located to allow access for desludging of the chamber(s); Access openings shall be of sufficient size to allow the desludging mechanism to reach all parts of the chamber(s); Access openings shall either be at or above ground level, or be able to be extended to the finished ground level if installed underground; Access openings and covers shall provide an effective, durable and watertight seal. They shall be able to be resealed each time the cover is removed; Access covers shall be durable and able to withstand superimposed loads; Access covers shall be secure and shall be designed to prevent removal by children.
2.4.7 Inspection openings and covers (a) Inspection openings shall be located to give access to the inlet and outlet fittings; (b) (c) Inspection openings shall have a cross-sectional area of not less than 7,500 mm2; Inspection openings shall either be at or above ground level, or be able to be extended to the finished ground level if installed underground; Inspection openings and covers shall provide an effective, durable and watertight seal. They shall be able to be resealed each time the cover is removed; Inspection covers shall be durable, and able to withstand superimposed loads; Inspection covers shall be able to be easily removed and replaced.
2.4.8 Extensions (a) Extensions to access and inspection openings shall be fitted so that a watertight seal is achieved; C2.4.8 Requirements for covers to extensions are given in Clauses 2.4.6 and 2.4.7. (b) Extensions shall be fitted into tank openings so that the extension and the joint are able to withstand external loads and pressures.
2.4.9 Watertightness (a) When assembled ready for use the septic tank, fittings and covers shall be watertight; (b) Test for leakage When tested in accordance with Appendix E: (i) Concrete septic tanks shall not show a leakage rate greater than 4 drops/min from any single point of leakage; Plastic or fibreglass tanks shall show no leakage or damp patches. Integrity
(ii) 2.4.10
2.4.10.1 The integrity of the tank shall be such that no crack shall develop a width greater than 0.1 mm (approximately) during any stage of production. Further widening or lengthening of any crack shall not occur during subsequent handling, installation, or use.
C2.4.10.1 It is known from experience that cracks of less than 0.1 mm will self-seal with time due to solids build-up from the inside of the tank. See Clause 2.4.9. 2.4.10.2 Fibre reinforced concrete tanks For tanks made of concrete reinforced with fibres, the verification test for integrity is ASTM C 1018. C2.4.10.1 Further details of the test and criteria for integrity are given in Clause 6.3.3.
Loads on tanks
2.4.11.1 General Tanks shall be designed and constructed to resist loads incurred during transport and installation. If buried in the ground, tanks shall resist lateral and top loads, uplift loads from groundwater, and where applicable superimposed loads from vehicular traffic. Freestanding tanks shall resist snow loads and shall be anchored against ground movement or seismic loads if such requirement is applicable. 2.4.11.2 Integrity during handling or installation There shall be no structural failure when the tank is lifted, or is moved during installation. Any cracking shall be limited to that defined in Clauses 2.4.9 and 2.4.10. Verification test: A tank shall be selected that matches the manufacturers nominated delivery age. The tank shall be lifted using the manufacturers nominated lifting method and shall show no structural failure or substanial visible cracking (see above) after being so lifted for 5 minutes. 2.4.11.3 Hydrostatic uplift An installed septic tank shall not move when subjected to uplift forces generated by surrounding ground water. 2.4.11.4 Lateral loads Septic tanks shall be designed so that there shall be no structural failure or undue distortion due to external hydrostatic ground water and soil loading of 6.6 kPa/m depth. Account shall be taken of any loads imposed on the tank structure as a result of the technique used to anchor the tank in the ground. Verification test methods are given in Appendix F and in Appendix G. Either test may be used. 2.4.11.5 Top Loads Septic tanks shall be designed to withstand a top load of 5kN. The verification test is Appendix H. In addition, there shall be: (i) (ii) no cracking in excess of that permitted by Clauses 2.4.9 and 2.4.10, no other failure.
SECTIONS 3 TO 10 OF THIS STANDARD PROVIDE GENERAL REQUIREMENTS AND ALTERNATIVE MEANS OF COMPLIANCE WITH THE PERFORMANCE REQUIREMENTS OF SECTION 2
Sections 3 to 10 cover the manufacture of conventional septic tanks in various materials. Sections 3, 4, and 5 cover general requirements common to all tanks. Sections 6 to 10 cover material-specific manufacture of tanks, and are intended to be used for third party audit/certification purposes.
NOTE: These means of compliance sections are only a way of achieving the objectives of the Standard. Non-standard materials, installations and designs shall meet the performance requirements and performance critieria of Section 2.
GENERAL REQUIREMENTS OF CONVENTIONAL SEPTIC TANKS
3.1 Scope This section of the Standard specifies general requirements of conventional septic tanks, fittings, access/inspection provisions, partitions and extensions that will be a means of compliance to the performance requirements of Section 2 of this Standard. It contains some performance requirements which allow for new materials, forms of construction etc. 3.2 Septic tank capacities This standard does not specify minimum capacities for septic tanks. Recommended minimum capacities for conventional systems are given in an informative appendix, Appendix B. 3.3 Materials durability All materials used to manufacture septic tanks and their fittings shall have a serviceable life of at least 15 years. C3.3 The ultimate durability of some materials is unknown. Accelerated test results are difficult to relate to actual in-service conditions. The use of new materials or formulations is usually justified on the basis of long term testing, experience, and assessment against existing similar materials. This type of evidence for durability should be available to and retained by the manufacturer. 3.4 Design The completed design shall meet the performance requirements of Section 2. 3.4.1 Tank Figure 3.1 shows two typical arrangements of the parts of a septic tank. 3.4.2 Tank chambers The tanks may be of single or multi-chamber configuration. C3.4.2 For twin chamber septic tanks, the ratio of the volume of upstream chamber to the downstream chamber is recommended to be 2:1. 3.4.3 Handling and transport Septic tanks shall be able to be handled, transported and installed in accordance with the manufacturers instructions without damage occuring. See Clause 2.4.11.2. 3.4.4 Anchorage In situations when flotation due to hydrostatic uplift from a high water-table is possible, the septic tank shall be provided with a means of being anchored. This may be by use of extensions attached to the tank or by other proven means of holding the tank down, details of which shall be provided by the tank manufacturer with the installation instructions. 3.4.5 Vehicular loads Tanks that will be subjected to top loading from vehicular traffic (e.g. tanks installed underground) shall be designed to carry the expected loads. The tank lid shall be subject to engineering design and a certificate verifying the load-carrying capacity shall be provided with the tank lid. 3.5 Inlet fittings and outlet fittings
3.5.1 Performance Performance requirements covering inlet and outlet fittings are given in Section 2.
3.5.2 Design The designs requirements of the inlet and outlet fittings are: (a) (b) (c) To reduce short-circuiting of liquid between inlet and oulet; To allow clearance of any internal blockage; To ensure that solids that form the scum layer do not flow through the outlet.
3.5.2.1 Configuration Two types of fittings are shown in Figures 3.2, and 3.3. These are based on: (a) (b) A fitting formed using a T shaped pipe junction, (Figure 3.2) and A manufactured baffle that is sealed on to the tank wall (Figure 3.3).
3.5.2.2 Size Typical minimum dimensions for fittings are shown in Figures 3.2 and 3.3. 3.5.2.2.1 Internal dimensions (a) The inlet and outlet fittings of conventional septic tanks shall be capable of passing a 90 mm diameter sphere. C3.5.2.2.1(a) The inlet pipe nominal size is, typically, 100 mm diameter. Pipe sizes smaller than 100 mm may be used but only if there is a pretreatment system that changes the nature or size of the solids. The outlet pipe nominal size is also, typically, 100 mm diameter. (b) Any reduction in size of the outlet pipe shall be achieved in the pipework external to the tank. C3.5.2.2.1(b) Reduction of this size is possible and could be achieved by improving the quality of the outgoing effluent e.g. by use of filters. 3.5.2.2.2 External dimensions For effective performance several minimum dimensions are identified: (a) The inlet and outlet fittings shall extend to not less than 170 mm above the invert of the outlet (the tank liquid level). See Clause 3.6.2.2. C3.5.2.2.2(a) This is to prevent scum spilling into the inlet or outlet. (b) i) The fittings shall extend downwards to be not less than 75 mm below the expected depth of scum after 3 years use. ii) The outlet fitting shall extend downwards for a suffient depth to minimize the flow of any grease, fat or scum through the outlet pipe. C3.5.2.2.2(b) The conventional length of fitting is a depth of 205 mm below the invert of the inlet, and 330 mm below the invert of the outlet.
Position of inlet and outlet fittings in tank
3.6.1 Inlet pipe The position of the inlet fitting inlet pipe below the tank rim or tank top shall be governed by the depth of cover that is intended to be used when installing the tank. This depth of cover is specified in AS/NZS 3500.2.2, and takes into account the location of the pipe in terms of vehicular traffic above it. C3.6.1 For installation in areas not subject to vehicular traffic AS/NZS 3500.2.2 currently requires a 300 mm depth of cover for pipes (not made of iron) measured from the finished surface to the top of the pipe socket. This depth may only be reduced by the use of concrete, brick or paving in conjunction with 50 mm of overlay according to AS/NZS 3500.2.2. 3.6.2 Inlet and outlet fittings
3.6.2.1 Inlet and outlet fittings shall be installed so that: (a) (b) There is a fall between the invert of the inlet and the invert of the outlet of not less than 50 mm; The top of the fitting (or baffle) is not less than 50 mm below the tank rim or roof, whichever is the lower.
These requirements are shown in Figure 3.4. 3.6.2.2 The requirements of Clauses 3.5.2.2.2(a) and 3.6.2.1 lead, as minimum dimension, to the invert of the inlet being not less than 170 mm and the invert of the outlet being not less than 220 mm below the underside of the lid, roof or tank rim of the septic tank (whichever is the lowest point), at a point directly above the intlet or outlet. 3.7 Gas baffles A gas baffle is a device designed to prevent the carry-over of gas-borne solids through the outlet. Its use is recommended. Typical designs are shown in Figure 3.5. 3.8 Partitions
C3.8 Partitions are optional. They have the potential to improve the quality of effluent by preventing carryover of solids by providing control of short-circuiting of the flow of waste. Partitions allow the tank to be divided to provide a desired chamber size ratio and they assist with hydaulic buffering. Partitions may be manufactured separately, or be integral with the tank, and so may improve long-term structural and hydraulic integrity.
When installed: (a) (b) A partition is normally positioned at 900 to the liquid flow; The partition shall have a means of allowing fluid to transfer across it which reduces/prevents the transfer of any solid matter. See Figure 3.1; C3.8(b) Any opening in the partition for this purpose has traditionally been a rectangular area of 15000 m2 located at half the operating depth.. However, the alternate H shaped pipe system operates with a pipe diameter of 100 mm and an area of 7,850 mm2.
The partition shall be able to withstand pump-out. See Clause 2.4.5(b) and Appendix D; C3.8(c) Over time loosely fitting partitions will become 'sealed' into position. During pump-out/desludging this 'seal' may hold or may break releasing fluid into the chamber being pumped out and thus relieving the hydrostatic head against the partition. However, this effect cannot be assumed to take place in all cases, and partitions must be able to show that they can withstand any effects from the pump-out operation as specified in Clause 2.4.5.
3.9 Vents Venting of septic tank systems shall be in accordance with AS/NZS 3500.2. 3.10 Access openings and covers
3.10.1 Access openings are typically 500 mm x 450 mm rectangular or 500 mm diameter circular, located over the tank partition. C3.10.1 The size and siting of one or more access openings are governed by the size of the desludging equipment and the need to be able to desludge all chambers in a tank. 3.10.2 Access covers shall be designed to prevent removal by children. 3.10.3 A corrosion-resistant means of lifting the covers shall be provided. 3.11 Extensions
C3.11 The burial of septic tanks so that the access and inspection covers become situated below ground level is forbidden by some Regulatory Authorities. Other Authorities allow burial but usually with the expectation that this would be 300 - 500 mm below ground level at the most and that extensions are used to bring the access and inspection covers up to ground level. In the latter case, the extensions are typically short and in one piece. The following requirements apply to these types of extension. 3.11.1 Performance Performance requirements of extensions are given in Section 2. 3.11.2 Installation (a) Extensions shall be fitted and made watertight against ingress of water in accordance with instructions provided by the manufacturer; (b)
The installed extensions shall withstand any normally expected loads and pressures. In meeting these requirements, the manufacturer shall base the choice of materials, the design and the installation instructions for extensions, on a certificated report from a structural engineer.
3.12 Marking Tanks and components of tanks separately manufactured shall be marked as described in Section 4. 3.13 Installation Recommendations for installation are given in Appendix I.
TYPICAL ARRANGEMENTS OF A SEPTIC TANK (Diagrammatic only)
NOTE All dimensions are minimum and in millimetres
FIGURE 3.2 TYPICAL UPVC FITTINGS (Diagrammatic only)
NOTE: All dimensions are minimum and in millimetres FIGURE 3.3 TYPICAL ALTERNATIVE ARRANGEMENT FOR PRECAST CONCRETE TANKS WITH A U-SECTION SCUM BAFFLE (OUTLET ONLY) (Diagrammatic only)
FIGURE 3.4 TYPICAL INSTALLATION ARRANGEMENT OF INLET AND OUTLET FITTINGS (Diagrammatic only)
TYPICAL GAS BAFFLE DESIGNS (Diagrammatic only)
MARKING OF SEPTIC TANKS
4.1 Scope This section of the Standard defines the minimum marking requirements for septic tanks. 4.2 General Marking is necessary to provide a traceable route to the manufacturer and to the date of manufacture. Marking is often a prerequisite for quality assessment. 4.3 Requirements
4.3.1 Minimum information Tank marking shall include, as a minimum, the following information: (a) (b) (c) (d) (e) (f) The manufacturers name or trademark; The date of manufacture; The capacity in litres; Identification of the inlet to the tank; Top load limitations; Weight of tank.
Information required by (a) (c) and (e) shall be the on the top external face of the tank adjacent to the inlet fitting. Other information shall be marked either on the top external face, or on the tank itself adjacent to the inlet fitting. 4.3.2 Other components Any other component of the tank that may be separately manufactured and subsequently assembled with the tank e.g. a lid, access cover or partitions shall be marked with the date of manufacture. 4.3.3 Permanence and visibility All marking shall be permanent, legible, and clearly visible when the tank is installed. C4.3.3 This might be achieved through the use of stencilling, or embossing by incorporation in the resin or moulding.
TESTING REQUIREMENTS OF SEPTIC TANKS
5.1 Scope Two forms of tests are identified in this Standard, type tests and routine manufacturing process quality control tests. 5.2 Type testing
5.2.1 Section 2.4 specifies a series of type tests which all septic tanks shall be capable of passing. The tests and the relevant Clauses and Appendices are set out below: (a) Test for the installation of fittings in a sound and watertight manner. See Clause 2.4.4 Appendix C; Pump-out tests for tanks with partitions. See Clause 2.4.5(b) Appendix D; Method of testing the watertightness of tanks. See Clause 2.4.9 and Appendix E; Integrity test for fibre reinforced concrete tanks when fibre load is less than 75 kg/m3. See Clause 2.4.10.2 and 6.3.3; Resistance to handling and installation loads. See Clause 2.4.11.2; Resistance to lateral loads. See Clause 2.4.11.4 and Appendix F and G: either test may be used; Resistance to a top load. See Clause 2.4.11.5 and Appendix H.
In addition fibre-reinforced tanks shall meet the integrity test specified for concrete fibre-reinforced tanks. See Clause 2.4.10.2. Type testing shall be carried out on initial production or whenever a change is made that may affect the performance of the finished tank. C5.2.1 Typically this would be when there is a totally new design, a change of component design, a change of materials, techniques of production, etc. 5.2.2 Systems developed to meet the Section 2 requirements for the watertightness of covers and the proper installation of extensions may require further (specially developed) type testing. 5.3 Routine quality testing Routine quality control testing shall be carried out to ensure that a consistent quality of product is maintained. These tests are identified in the relevant material-based sections of this Standard. C5.3 Type tests in this standard may also be suitable for use as routine quality control tests. 5.4 Quality certification If it is intended to seek certification against this Standard the testing regime (i.e. type of test, number of samples, and frequency of testing) for both type testing and routine quality control testing shall be established in consultation with the quality audit organisation or certification body involved.
PRECAST CONCRETE STEEL REINFORCED SEPTIC TANKS AND PRECAST CONCRETE STEEL FIBRE REINFORCED SEPTIC TANKS
6.1 Scope This section sets out the requirements for conventional septic tanks made from concrete reinforced with steel or steel fibre. 6.1.1 General Performance requirements and performance criteria are given in Section 2 of this Standard. Section 3 gives further information about septic tank fittings and accessories. 6.2 Materials
6.2.1 Cement Cement for use in concrete septic tanks shall comply with AS 3972 or NZS 3122. 6.2.2 Aggregate Aggregate for use in concrete shall comply with AS 2758.1 or NZS 3121. The maximum aggregate size shall be chosen that will permit flow of the concrete into thin wall sections and around close-spaced reinforcement. 6.2.3 Admixtures Admixtures shall conform to AS 1478 or NZS 3113. Calcium chloride shall not be used. 6.2.4 Steel reinforcement
6.2.4.1 Steel bars, fabric and wire Steel bars, fabric and wire shall be as specified in AS 1302, AS 1304 and AS 1303, or NZS 3402, NZS 3422 and NZS 3421 respectively. 6.2.4.2 Steel fibre Steel fibre shall have a minimum tensile strength of 600 MPa. 6.3 Concrete
6.3.1 General Concrete, (including steel fibre reinforced concrete), shall be of adequate strength to allow stripping from the mould, handling, transporting to site and placing in position without incurring cracking which would impair the effectiveness of the unit. 6.3.2 Specification The characteristics of the concrete used in the manufacture of precast septic tanks shall be as given in Table 6.1. 6.3.3 Fibre reinforced concrete When tested according to ASTM C 1018 the fibre reinforced concrete shall achieve a minimum flexural (first crack) strength of 5.5 MPa at 28 days, and either: (i) (ii) A minimum mean toughness index I5 value of 4.75, or A minimum mean toughness index I30 value of 20.0 and an I30 - I10 value of 12.0 minimum.
TABLE 6.1 CONCRETE CHARACTERISTICS Steel reinforcement Compressive strength minimum At 28 d MPa Cylindrical or rectangular Cylindrical Fibre
Prior to delivery MPa 25
Bars, fabric or wire
Most appropriate compressive strength specification in New Zealand is 35 MPa.
6.4 Testing (See Section 5: Testing requirements of septic tanks) 6.4.1 Type testing
6.4.1.1 Steel fibre concrete (a) Steel fibre reinforced concrete with a steel fibre content of less than 75 kg/m3 shall be type tested to achieve the requirements of Clause 6.3.3. (b) If the steel fibre specification changes in a mix that contains less than 75 kg/m3 of steel fibre, or the steel content is changed to be less than 75 kg/m3, then the product shall be retested as required by Clause 6.3.3.
6.4.1.2 Completed Tank Type testing of completed septic tanks shall be carried out as required by Section 2 of this Standard. All septic tanks shall be capable of complying with these type tests. 6.4.2 Routine quality control testing Manufacturers shall establish tests on tank materials and finished tanks and a frequency of testing that will demonstrate that a consistent quality of product is being produced. For tanks made in accordance with the requirements of this Section of the Standard the routine quality control tests shall, as a minimum, be to determine the compressive strength of the concrete, and the watertightness test. 6.4.2.1 Compressive strength When tested in accordance with AS 1012.9 or NZS 3112 Part 2, the 28 day compressive strength of each test specimen shall be not less than that given in Table 6.1. Test specimens shall be either made and cured (see AS 1012.8); or secured from hardened concrete (see AS 1012.14). 6.4.2.2 Watertightness Watertightness testing shall be undertaken in accordance with the procedures in Appendix E. 6.5 Manufacture The manufacturing process shall be carried out in a controlled manner to produce a consistent product checked by a quality assurance process.
6.5.1 Methods Methods currently used for the manufacture of components for precast, steel or steel fibre reinforced concrete septic tanks are given in Table 6.2. The technique of manufacture shall comply with AS 3600 or NZS 3109. TABLE 6.2 METHODS FOR MANUFACTURE
Type of septic tank Wall(s) Cylindrical with vertical axis Centrifugally cast or cast and vibrated Base
Component Lid Cast and vibrated separately, in one or two sections, for later connection to each other and the wall with a watertight joint End Not applicable
Cast and vibrated separately for later structural connection to the wall with a watertight joint or cast integrally with the wall and vibrated Not applicable
Cylindrical with horizontal axis
Centrifugally cast or cast and vibrated
Cast and vibrated separately for later structural connection to the wall with a watertight joint Not applicable
Cast integrally and vibrated
As for cylindrical with vertical axis
6.5.1.1 Cylindrical walls The walls of circular precast concrete tanks shall be reinforced with hard drawn steel bars, fabric or wire, or steel fibres that comply with Clause 6.7. The reinforcing shall be formed into a cage consisting of a reinforcement fabric, or a circumferential helix held in shape with longitudinal wires. 6.5.1.2 Tank ends Ends of tanks (lids and bases) may be cast integrally with the walls or cast separately. If cast separately the tank end shall be securely jointed, keyed or mortared to the walls of the tank to provide a watertight unit.
6.5.1.3 Steel fibre reinforced tanks 6.5.1.3.1 Mixing of steel fibre The concrete shall be batched and mixed according to the fibre suppliers recommendations and directions which will lead to a uniform distribution of the fibre throughout the mix. C6.5.1.3.1 The appearance of fibre balls in the mix is evidence of segregation or poor mixing. 6.5.1.3.2 Concrete finish Any fibres which are left protruding from the concrete surface after casting shall be removed flush with the tank wall.
6.5.1.3.3 Fibre content If the tank section thicknesses are greater than the minimum values shown in table 6.3, then the fibre content may be reduced in proportion to the increase in section thickness provided the original steel fibre reinforced concrete mix complied with Clause 6.4. 6.6 Thickness of tank components The wall thickness of tank components shall be sufficient to produce a tank of adequate strength to resist damage during handling, transporting, installation, and during service. A critical consideration is that there shall be a minimum cover of concrete over the reinforcement to assist in corrosion protection of the steel. See Clause 6.7. The minimum concrete thickness of components of precast concrete septic tanks shall be as given in Table 6.3. TABLE 6.3 MINIMUM CONCRETE THICKNESS Minimum concrete thickness Type of septic tank Steel reinforcement Wall(s) Centrifugally cast Cylindrical with vertical axis Bars, fabric and wire Helical cage+ Fibre Cylindrical with horizontal axis Bars, fabric and wire Helical cage+ Fibre Rectangular Bars, fabric and wire Cast and vibrated mm 50 55 30 50 55 30 NA 60 55 40 60 55 40 75 65 65 40 or 65* NA NA NA 75 mm 65 65 65 NA NA 65 65 mm NA NA NA 65 NA 40 or 65* NA Base Lid End
The lower value applies when cast integrally with the wall(s), and the higher value, when cast and vibrated separately to be keyed, at the time of its manufacture, to the wall with a watertight joint. + Helical cage refers to a circumferential cage made from hard drawn steel wire. NA Not applicable
6.7.1 Cover The minimum distance between the face of steel reinforcement and the nearest concrete surface of a precast septic tank shall be as given in Table 6.4. TABLE 6.4 MINIMUM CONCRETE COVER Minimum cover Type of septic tank Steel bars, fabric and wire Wall(s) Centrifugally cast mm Cylindrical Rectangular 15 Not applicable Cast and vibrated mm 20 20 Steel fibre
Base, lid or end mm 20 20
6.7.2 Corrosion protection When manufacturing septic tanks using cast and vibrated methods, the ends of every non-corrosionresistant reinforcement support (bar chairs or similar devices) shall be covered/coated with a corrosionresistant material. 6.7.3 Quantity of reinforcement
6.7.3.1 Steel reinforcement The quantity and placement of steel reinforcement in the shape of bars, fabric and wire shall comply with AS 3600 or NZS 3109 but in no case be less than given in Table 6.5. 6.7.3.2 Steel fibre Sufficient steel fibre shall be incorporated so that either: (a) (b) The steel fibre content shall be a minimum of 75 kg/m3 of concrete, or The final mix meets the requirements of Clause 6.4;
C6.7.3.2 The amount/quantity of reinforcement incorporated into the tank structure is designed to limit the formation of any cracks to a width of approximately 0.1 mm maximum. It is known from experience that cracks up to this size will self-seal with time.
TABLE 6.5 MINIMUM QUANTITY OF STEEL REINFORCEMENT measured as cross-sectional area in mm2/m* Type of septic tank
Cylindrical, Internal diameter < 1800 mm# Wall Base, Top and end slabs mm2/m 126
Rectangular Walls and Base mm2/m 188 Lid
mm2/m Fabric Wire (a) helical (b) longitudinal * 126
mm2/m 188
The values given are for NOMINAL mesh wire sizes and are subject to tolerances specified by the appropriate Standard. Cylindrical tanks with internal diameter > 1800 mm to be as specified by a structural engineer. Lapping of reinforcement
6.7.4.1 Tank ends If the tank end is cast integrally with the walls the longitudinal reinforcement shall be bent 900 and placed radially into the base or end slab to provide a minimum lap of 150 mm with the base reinforcement. 6.7.4.2 Fabric All fabric lap splices shall be achieved by an overlap of not less than two crosswires. 6.8 Provision of fittings, partitions and their assembly
6.8.1 Inlet and outlet fittings (a) Inlet and outlet fittings may be installed either by the manufacturer prior to delivery of the septic tank or by the licensed plumber/drainlayer at the time of installation of the septic tank.
When inlet and outlet fittings, access and inspection covers, partition, anchorage device, and any necessary fasteners are provided separate to the tank for installation on-site then detailed installation instructions shall be provided by the manufacturer with each tank at the time of despatch.
6.8.2 Partitions The permanent fixing of a partition into the septic tank shall be in accordance with the manufacturers instructions and may be carried out on-site at the time of installation of the tank.
CAST-IN-SITU CONCRETE SEPTIC TANKS
7.1 Scope This section of the Standard covers the basic requirements of septic tanks made on site (cast-in-situ). 7.2 Performance The performance requirements of Section 2 of this Standard apply. 7.3 Materials
7.3.1 General The materials used in the construction of concrete cast-in-situ septic tanks shall comply with AS 3600 or NZS 3109. Ready-mixed concrete shall comply with AS 1379 or NZS 3104. 7.3.2 Cast-in-situ concrete tanks shall be structurally sound, internally smooth, and watertight.
7.3.3 Walls and floors shall be rendered using a 1:3 cement:sand mortar to a minimum thickness of 12 mm. 7.4 7.4.1 Design Thickness, reinforcement and strength of concrete
7.4.1.1 Floor and walls The thickness of concrete floors and walls in a rectangular cast-in-situ concrete septic tank shall be: (a) (b) Not less than 150 mm of unreinforced concrete having minimum strength of 25 MPa. Not less than 100 mm of reinforced concrete having a minimum strength of 25 MPa and using reinforcement as specified by Table 6.5.
7.4.1.2 Roof The roof of a cast-in-situ concrete septic tank shall be a slab of reinforced concrete, and shall be designed to comply with the requirements of Section 6. 7.4.1.3 Cover to reinforcement The cover to the reinforcement in a cast-in-situ concrete septic tank for roof slabs, floors, walls, and covers to access and inspection openings, shall be not less than 40 mm. 7.5 Marking
Cast-in-situ septic tanks shall be marked as required by Section 4.
REINFORCED CEMENT MORTAR SEPTIC TANKS
C8.1.2 Tolerances in construction must be closely controlled. The manufacture and application of mortar is a skilled operation and it is important that high standards of construction are maintained. It is for these reasons that NZS 3106 requires that construction is only carried out by those able to demonstrate the necessary skills, usually in a factory environment. 8.1 Scope and general
8.1.1 Scope This section of the Standard is for a reinforced composite system that allows for the development of high stresses in the composite and less cover over the reinforcement. 8.1.2 General (a) Cement mortar elements of tanks shall be constructed by specialist firms able to demonstrate satisfactory experience; (b) 8.2 Continuous supervision shall be provided as specified in NZS 3106. Performance The performance requirements of Section 2 of this Standard apply.
8.3 Manufacture For guidance with design, selection of materials, mortar application and thickness, and testing refer to NZS 3106. C8 Tanks of reinforced cement mortar have been in service in New Zealand for many years. Typically they are reinforced with layers of very small diameter reinforcing separated by separately applied layers of high strength mortar. Their construction is covered in NZS 3106.
GLASS FIBRE-REINFORCED PLASTIC SEPTIC TANKS
9.1 Scope This section of the Standard covers the construction of septic tanks using glass fibre-reinforced resin. The use of other fibres or other resins is not excluded provided that the provisions of this section of the Standard are met. 9.2 Performance requirements
9.2.1 General Performance requirements and performance criteria are given in Section 2 of this Standard. Section 3 gives further information about septic tank fittings and accessories. 9.2.2 Performance aspects of the Section 2 requirements that have a greater relevance to glass fibrereinforced plastic materials are: (a) The resistance of the septic tank, lid, access opening cover, and the inspection opening cover to ultraviolet light degradation; The design and construction of the tank, lid and access cover to resist installation and inservice loads; The provision of the septic tank with a means of anchorage (antifloatation measure) to prevent the tank from moving from its installed position.
9.2.3 Other requirements (a) The surfaces of a septic tank, lid, access opening cover and other components shall be smooth and impervious to liquids; (b) All fasteners shall be of durable material, resistant to the corrosive environment, and if inaccessible shall be effective for the serviceable life of the septic tank. See Clause 9.4.1.4. Design
9.3.1 General The design of a glass fibre-reinforced plastic septic tank shall be such as to prevent deformation and flexing and to take account of: (a) (b)
Internal and external pressures; Mass of tank and contents; Localized loads acting at the supports, lugs and other attachments; Normal loads applied during transport and installation; Material fatigue; Soil conditions and expected loading.
9.3.2 Design basis The design of glass fibre-reinforced plastic tanks shall be based on the following: (a) (b) Tank seams and openings shall be designed in accordance with either BS 4994, or PS 15:69; Tops of tanks and access covers shall be designed in accordance with Clause 9.2.2(b).
9.3.3 Anchorage All glass fibre-reinforced plastic septic tanks shall be provided with a means of anchorage. C9.3.3 Two typical examples are given below: (a) Hydrostatic flange An L-shaped section constructed not less than 65 mm wide and not less than 4 mm thick which is bonded to the outside circumference of the tank. The flange may be continuous around the circumference or may be in at least two sections each of not less than 600 mm long and bonded to opposite sides of the tank. For a vertical cylindrical tank the flange is bonded not more than 300 mm from the base, and for a horizontal cylindrical tank the flange is situated along the line of the greatest horizontal perimeter. (Hydrostatic flanges are usually bonded to the tanks under controlled conditions near the site of installation.) (b) Loops to be affixed at the time of installation. Each side of the tank is held into the ground by a piece of pipe, typically 100 mm PVC sewer grade pipe, attached to the tank by two durable plastic ropes. These ropes are anchored in the rim of the tank and have a loop in the other end at excavation ground level. Both pipes have a length of not less than the diameter of the tank and each is passed through two loops. Backfilling then covers the pipes. 9.4 Manufacture
9.4.1 Materials The materials used in the manufacture and construction of septic tanks shall comply with the following: 9.4.1.1 Resin The resin shall be polyester resin or equivalent resin that:
Has a minimum heat distortion temperature of 65oC when tested in accordance with ISO 75-3 and is capable of being used in the manufacture of a laminate that complies with Clause 9.4.2; Will cure at ambient or higher temperature with the addition of a catalyst and, if necessary, promoters or accelerators used in accordance with the manufacturers or suppliers recommendations, and; Contains: (i) (ii) (iii) Not less than 50% w/w of non-volatile materials; No pigment or fillers; and Not more than 2% w/w of thixotropic agents.
9.4.1.2 Reinforcement (a) Glass-fibre The reinforcing material shall be a suitable grade of glass fibre having a glass finish compatible with the resin used and complying with BS 3396 Part 3, BS 3496, BS 3691, or BS 3749, as appropriate. (b) Other reinforcement The use of non-glass reinforcement is possible provided the finished product meets the test requirements of Clause 9.5, (excluding Clause 9.5.6.).
9.4.1.3 Gelcoats (a) Polyester A polyester gelcoat shall be a suitable chemical resistant resin with a minimum heat distortion temperature of 65oC when tested in accordance with ISO 75-3. Polyester gelcoats shall comply with the following requirements, as appropriate: (i) Internal gelcoat: Internal gelcoats shall cure with the addition of a catalyst and if necessary, promoters or accelerators used in accordance with the manufacturers or suppliers recommendations. The gelcoat shall be free of any pigment or filler. Thixotropic agents of up to 3% w/w are permitted. The gelcoat shall be a minimum of 0.4 mm thick. (ii) External gelcoat: External gelcoats shall cure with the addition of a catalyst and, if necessary, promoters or accelerators used in accordance with the manufacturers or suppliers recommendations. The gelcoat for the tank and cover may contain up to 10% w/w pigment paste. The cured gelcoat shall be free from cracks, pinholes and surface defects and shall not be less than 0.4 mm thick. (b) Other gelcoats Other materials used as gelcoats shall meet the test requirements of Clause 9.5. These gelcoats shall be prepared and applied in accordance with the manufacturers or suppliers instructions.
9.4.1.4 Fasteners All fasteners shall be of durable material, resistant to the corrosive environment, and be either: (a) (b) (c) Stainless steel, grade 316 (see AS 1449 or NZS/BS 1449); or Copper alloy, grade 443 (see AS 2738.2 or NZS/BS 1400); or a suitable equivalent.
9.4.2.1 General The manufacturing process shall be carried out in a controlled manner to produce a consistent product checked by a quality assurance process. The method for the manufacture of components for glass fibre-reinforced plastic septic tanks shall be by: (a) (b) The even application of resin and glass to the mould; Rolling the lay-up to achieve: (i) (ii) (iii) Complete wetting of the fibres; Removal of air bubbles from the surface; Reduction of air bubbles to diameters not greater than 1.5 mm and to less than 10 per 625 mm2; and
Rounding of all internal corners with a radius of not less than 6 mm;
The mass of glass rovings shall be determined continuously as the material is applied. 9.4.2.2 Laminate and thickness The composition and thickness of the laminate shall be as follows: (a) Tank The laminate shall contain not less than 30% glass strands. No fillers or pigments shall be included in the laminate; The thickness of the laminate shall be not less than 4 mm. The thickness shall be increased to be not less than 6 mm for a distance of not less than 40 mm from all edges of openings and the edges of upstands for access and inspection covers. Changes in thickness shall be by smooth transitions. The external surface of the tanks shall be coated with either a clear layer of catalysed resin or an external gelcoat as defined in Clause 9.4.1.3, Section (b), of not less than 0.4 mm thick. (b) Access opening cover and top of vertical tanks Access, inspection covers and tops of tanks shall contain not less than 30% chopped glass strands. The thickness of the laminate shall be not less than 4 mm. This shall be increased to 6 mm within 40 mm of any edge. 9.4.2.3 Surface finish The internal and external surface of the septic tank shall be smooth, unbroken and impervious. 9.4.2.4 Inlet and outlet holes The inlet and outlet holes shall be cut or formed in the tank wall prior to the septic tank leaving the manufacturers premises.
Provision of fitting, partitions and their assembly
9.4.3.1 Inlet and outlet fittings (a) Inlet and outlet fittings may either be installed by the manufacturer prior to delivery of the septic tank, or be installed by the licensed plumber/drainlayer at the time of installation of the septic tank. (b) When inlet and outlet fittings, access and inspection covers, partition, anchorage device, and any necessary fasteners are provided separate to the tank for installation on-site detailed installation instructions shall be provided by the manufacturer with each tank at the time of despatch.
9.4.3.2 Partitions The permanent fixing of a partition into the septic tank shall be in accordance with the manufacturers instructions and may be carried out on-site at the time of installation of the tank. 9.5 Testing Refer Section 5: Testing requirements of septic tanks. 9.5.1 Type testing
9.5.1.1 Completed tanks Type testing of completed septic tanks shall be carried out as required by Section 2 of this Standard against relevant appendices, (listed in Section 5, Clause 5.2.1). All septic tanks shall be capable of complying with these type tests. 9.5.1.2 In addition the following type testing shall be carried out when changes to design, raw materials or manufacturing process are made. 9.5.1.2.1 Test specimens All test specimens shall be prepared in accordance with ISO 1268. 9.5.1.2.2 Flexural strength and modulus of elasticity When tested in accordance with ISO 178, the flexural strength and modulus of elasticity of each test specimen shall be not less than 110 MPa and 4830 MPa, respectively. 9.5.1.2.3 Impact resistance When tested in accordance with ISO 179-2, the test specimen shall have no surface cracks visible to normal or corrected normal vision. 9.5.1.2.4 Hardness When tested in accordance with Appendix J, the Barcol hardness number of each test specimen and any part of each test septic tank shall be not less than 35.
9.5.1.2.5 Water absorption When tested in accordance with ISO 62, the amount of water absorption of each test specimen shall be not greater than 0.75%. 9.5.1.2.6 Glass fibre content When tested in accordance with ISO 1172, the glass content of each test specimen shall be not less than 30% w/w. 9.5.1.2.7 Tensile strength When tested in accordance with ISO R527, the tensile strength shall not be less than 63 MPA. 9.5.1.2.8 Tensile Elongation When tested in accordance with ISO R527, the tensile elongation shall not be less than 1.5% minimum.
9.5.1.2.9 UV light degradation Testing of glass fibre-reinforced plastics for the resistance to U.V. light degradation is usually the responsibility of the resin/gel-coat manufacturer prior to recommending products and mixes as suitable for outdoor exposure. See Clause 3.3. 9.5.2 Routine quality control testing
9.5.2.1 General Manufacturers shall establish tests on tank materials and/or finished tanks, and a frequency of testing that will demonstrate that a consistent quality of product is being produced. 9.5.2.2 Test Specimen Quality control testing shall be carried out on specimens prepared according to ISO 1268. 9.5.2.3 Tests It is recommended that the following tests are considered for quality assurance of manufacture: Laminate thickness measurement Thickness of gelcoat at time of application Hardness Reinforcing fibre content 9.5.2.4 Frequency (a) The frequency of testing will be governed by the needs of any internal quality assurance programme, or external quality assessment programme. 9.5.2.5 Pass/Fail The test results should meet the criteria set for the tests in this section of the Standard. 9.5.2.6 Test records The report shall include the following information for each test specimen: (a) (b) (c)
Identification of persons/organisation carrying out test; Identification of the sample tested; Date of test; The test results; Reference to the test method.
Test records shall be kept as required by the quality assurance programme. (A minimum of ten years is recommended.)
PLASTIC (POLYOLEFIN) SEPTIC TANKS
10.1 Scope This section of the Standard covers the construction of septic tanks using polyolefin thermoplastics. C10.1 The two most commonly used polyolefins are polyethylene which is usually rotationally moulded, or polypropylene which is usually injection moulded. 10.2 Performance requirements
10.2.1 General Performance requirements and performance criteria are given in Section 2 of this Standard. Section 3 gives further information about septic tank fittings and accessories. 10.2.2 are: (a) Aspects of the Section 2 requirements that have a greater relevance to polyefin plastic materials
The resistance of the septic tank, lid, access opening cover and the inspection opening cover to ultraviolet light degradation; The design and construction of the tank, lid and access cover to resist installation and inservice loads; The provision of the septic tank with a means of anchorage (antifloatation measures) to prevent the tank from moving from its installed position. Other requirements
10.2.3 (a)
The surfaces of a septic tank, lid, access opening cover and other components shall be smooth and impervious to liquids; Fasteners used in plastic septic tanks shall be manufactured from materials which are durable and resistant to the corrosive environment and if inaccessible shall be effective for the serviceable life of the tank. See Clause 10.4.1.2. Design
10.3.1 General The design of a plastic (polyolefin) tank shall be such as to prevent deformation and flexing and to take into account:
Internal and external pressures; Mass of tank contents; Localized loads acting at the supports, lugs and other attachments; Normal loads applied during transport and installation; Material fatigue; Soil conditions and expected loadings.
10.3.2 Thickness The thickness of the tank walls, base, access opening covers and lids shall be not less than 6 mm. Polyolefin materials that allow a thinner component to be made shall meet the performance requirements and tests of this Standard. 10.3.3 Anchorage All plastic (polyolefin) septic tanks shall be provided with a means of anchorage. C10.3.3 Typical examples are: (a) Hydrostatic flange An integrally moulded flange of similar size to the anchor collar in 10.3.3 (b). Anchor collar to be affixed at the time of installation: An L-shaped anchor collar section constructed not less than 65 mm wide and not less than 6 mm thick to be fixed to the outside circumference of the tank with durable material protected from the corrosive environment. The collar may be continuous around the circumference or may be in at least two sections each not less than 600 mm long and fixed to opposite sides of the tank. For a vertical cylindrical tank the flange is fixed not more than 300 mm from the base, and for a horizontal cylindrical tank the flange is situated along the line of the great horizontal perimeter. (c) Loops to be affixed at the time of installation Each side of the tank is held into the ground by a piece of pipe, typically 100 mm PVC sewer grade pipe, attached to the tank by two durable plastic ropes. These ropes are anchored in the rim of the tank and have a loop in the other end at excavation ground level. Both pipes have a length of not less than the diameter of the tank and each is passed through two loops. Backfilling then covers the pipes. Manufacture Materials
10.4.1.1 Polymer The polymer utilised by the manufacturer shall be suitable so that the finished product meets the performance requirements as set out in this Standard. 10.4.1.2 Fasteners All fasteners shall be of durable material, resistant to the corrosive environment, and be either:
Stainless steel, grade 316 (see AS 1449 or NZS/BS 1449); or Copper alloy, grade 443 (see AS 2738.2 or NZS/BS 1400); or a suitable equivalent Manufacturing process
10.4.2.1 General The manufacturing process shall be carried out in a controlled manner to produce a consistent product checked by a quality assurance process.
10.4.2.2 Joints The lid and the access opening cover shall be bedded on a bead of flexible mastic sealant in accordance with the manufacturers instructions and then secured in a position with fasteners to provide a permanent water-tight seal. 10.4.2.3 Fasteners Fasteners shall be provided where required in the tank design to ensure joint seals are secure. 10.4.2.4 Provision of fittings and their assembly 10.4.2.5 Inlet and outlet fittings (a) Inlet and outlet fittings may either be installed by the manufacturer prior to delivery of the septic tank, or be installed by the licensed plumber /drainlayer at the time of installation of the septic tank. (b) When inlet and outlet fittings, access and inspection covers, partition, anchorage device, and any necessary fasteners are provided separate to the tank for installation on-site detailed installation instructions shall be provided by the manufacturer with each tank at the time of despatch.
10.4.2.6 Partitions The permanent fixing of a partition into the septic tank shall be in accordance with the manufacturers instructions and may be carried out on-site at the time of installation of the tank. 10.5 Testing Refer Section 5: Testing requirements of septic tanks. 10.5.1 Type testing Type testing of completed septic tanks shall be carried out as required by Section 2 of this Standard against relevant appendices, (listed in Section 5, Clause 5.2.1). All septic tanks shall be capable of complying with these type tests. 10.5.2 Routine quality control testing
10.5.2.1 General Manufacturers shall establish tests on tank materials and/or finished tanks, and a frequency of testing that will demonstrate that a consistent quality of product is being produced. The testing of the properties of the polyolefin tank material during/after manufacture is essentially an internal quality function because the nature and thickness of materials used will vary from one manufacturer to another. 10.5.2.2 Test specimen (a) The test specimen shall reflect the manufacturing process;
The test specimen shall reflect a typical cross section of the septic tank; The specimen shall be manufactured at the same time as the septic tank; The specimen may be cut from a vertical section of the tank wall using a low speed cutting tool to prevent heat damage or other damage to the specimen; The dimensions of the test specimen shall be appropriate for the required tests.
10.5.2.3 Tests Manufacturers shall set up tests to determine flexural modulus, and to determine resistance to impact, as a minimum.
C10.5.2.3 A modified ASTM impact test that has been found to be satisfactory with polyolefin samples taken from, or made to represent, a septic tank wall is to be found in Appendix K. 10.5.2.4 Frequency (a) The frequency of testing will be governed by the needs of any internal quality assurance programme, or external quality assessment programme; 10.5.2.5 Pass/fail The test results should meet the criteria set for the tests in this section of the Standard. 10.5.2.6 Test records The report shall include the following information for each test specimen: (a) (b) (c) (d) (e) Identification of persons/organisation carrying out test; Identification of the sample tested; Date of test; The test results; Reference to the test method.
APPENDIX A REFERENCED DOCUMENTS (Normative) STANDARDS AUSTRALIA AS 1012 AS 1012.8 NEW ZEALAND Methods of testing concrete Part 8: Method for making and curing concrete compression, indirect tensile and flexure test specimens, in the laboratory or in the field Part 9: Method for the determination of the compressive strength of concrete specimens Part 14: Method for securing and testing cores from hardened concrete for compressive strength NZS 3112:1986 NZS 3112:Part 2 AS 1302 NZS 3402:1989 AS 1303 NZS 3421:1975 Methods of test for concrete Tests relating to the determination of strength of concrete Steel reinforcing bars for concrete Steel bars for the reinforcement of concrete Steel reinforcing wire for concrete Specification for hard drawn mild steel wire for concrete reinforcement Welded wire reinforcing fabric for concrete Specification for welded fabric of drawn steel wire for concrete reinforcement The specification and manufacture of concrete Specification for concrete production - High grade and special grade Wrought alloy steels - Stainless and heat-resisting steel plate, sheet and strip Steel plate,sheet and strip. Part 2: Specification for stainless and/heat resisting steel plate, sheet and strip Chemical admixtures for concrete Specification for chemical admixtures for concrete Small septic tanks Specification for household septic tank systems Precast reinforced concrete box culverts Small culverts (not exceeding 1200 mm width and 900 mm depth). Copper and copper alloys designations Part 2: Wrought products Compositions and
AS 1012.9 AS 1012.14
AS 1304 NZS 3422:1975
AS 1379 NZS 3104:1991
AS 1449 NZS/BS 1449 NZS/BS 1449.2:1983
NZS 3113:1979 AS 1546 NZS 4610:1982 AS 1597 AS 1597.1
AS 2738 AS 2738.2
Specification for copper alloy ingots and copper alloy and high conductivity copper castings Aggregates and rock for engineering purposes Part 1: Concrete aggregates Specification for water and aggregate for concrete Concrete structures Specification for concrete construction Portland and blended cements Specification for Portland and blended cements (General and special purpose) Code of practice for concrete structures for the storage of liquids
AS 2758 AS 2758.1 NZS 3121:1986 AS 3600 NZS 3109:1987 AS 3972 NZS 3122:1995
JOINT AUSTRALIA/NEW ZEALAND AS/NZS 1547 On-site domestic preparation) wastewater management (in
AS/NZS 3500.2 AS/NZS 3500.2.2 AMERICAN ASTM C 1018:1994
Sanitary plumbing and drainage Part 2.2 Acceptable solutions
Test method for flexural toughness and first-crack strength of fiber-reinforced concrete (using beam with third-point loading) Test methods for impact resistance of flat, rigid plastic specimens by means of a tup (falling weight) Custom contact-moulded reinforced-polyester chemical resistant process equipment (U.S. Department of Commerce)
ASTM D 3029:1990
PS 15:69
BRITISH BS 3396:1987
Woven glass fibre fabrics for plastics reinforcement Specification for E glass fibre chopped strand mat for reinforcement of polyester and other liquid laminating systems Specification for E glass fibre rovings for reinforcement of polyester and epoxy resin systems Specification for E glass fibre woven roving fabrics for the reinforcement of polyester and epoxy resin systems Specification for design and construction of vessels and tanks in reinforced plastics
BS 3496:1989
BS 3691:1990
INTERNATIONAL (ISO) ISO 62: 1980 ISO 75-3: 1974 Plastics - Determination of water absorption Plastics - Determination of temperature of deflection under load. Part 3 High strength thermosetting laminates and longfibre- reinforced plastics Plastics - Determination of flexural properties Plastics - Determination of Charpy impact strength. Plastics - Determination of tensile properties Part 1: General principles Part 2: Test conditions for moulding and extrusion plastics Textile-glass-reinforced plastics - Prepregs, moulding compounds and laminates - Determination of the textile glass and mineral-filler content - Calcination methods Plastics - Preparation of glass fibre reinforced, resin bonded, low-pressure laminated plates or panels for test purposes
ISO 178:1993 ISO 179:1993 ISO 527:1993
NOTE: AS/NZS denotes a jointly developed and published Australian/ New Zealand Standard. NZS/AS or NZS/BS denotes an Australian or British Standard approved and adopted for use in New Zealand without technical change. NEW ZEALAND LEGISLATION Building Act 1991 Building Regulations 1992 Resource Management Act 1991 New Zealand Building Code 1991
APPENDIX B SEPTIC TANK CAPACITIES (Informative) B1 Scope This appendix gives recommended minimum capacities for conventional septic tanks. B2 Application and context of use
B2.1 Application The capacities are sufficient for normal domestic premises that are not fitted with water-conserving devices or a garbage grinder. (Refer also Clause 2.4.1.) B2.2 Context of use Septic tanks of these capacities are already in use in parts of Australia and New Zealand but have not been adopted as minimum sizes throughout. They are presented as a guide for authorities and manufacturers to work towards. The capacities have been calculated using relevant flow data and other considerations in AS/NZS 1547 (in course of preparation). CB2.2 AS/NZS 1547 (in course of preparation) should be consulted for the derivation of tank sizes for the nonstandard situations not covered in Table B1. B3 Conventional septic tanks The minimum capacity of conventional septic tanks for treatment of domestic wastewater flow is recommended to be as shown in Table B1: TABLE B1 CONVENTIONAL SEPTIC TANK CAPACITIES (LITRES) Type of wastewater 1 to 5 L All-waste Greywater only Blackwater only
Persons 6 to 10 L 4500 2700 2500 1 to 3 L 3000 1800 1500
Bedrooms 4 to 6 L 4500 2700 2500
3000 1800 1500
APPENDIX C TEST OF THE MANUFACTURERS INSTRUCTIONS FOR THE INSTALLATION OF FITTINGS IN A SOUND AND WATERTIGHT MANNER (Normative) C1 Scope This Appendix sets out a method for the type testing of the manufacturers instructions for the installation of fittings in a sound and watertight manner, whether the fittings are installed in the factory or on site. C2 Principle The fittings in a tank are subjected to a low hydrostatic pressure from inside the tank. (It is assumed that a fitting installation that is watertight in this situation will also be watertight in respect of water ingress to the tank through the fittings.) C3 (a) (b) (c) (d) Testing A tank is set up for the watertightness test as required by Appendix E, Clause E4.1; Fittings are installed in accordance with the manufacturers instructions; Openings in the fittings are sealed to allow water to build up behind the fitting during the test; The tank shall be filled with water to the rim.
C4 Pass/Fail There shall be no leakage of water through the join of the fitting and tank, or through any joins in the fittings themselves. C5 Test records The report shall include the following information for each test specimen: (a) (b) (c) (d) (e)
Identification of person/organisation carrying out test; Identification of the fitting systems(s) tested; Date of test; The results of the test; Reference to this test method, i.e. AS/NZS 1546, Appendix C.
Test records shall be kept as required by the quality assurance programme. CC5 A minimum of 10 years is recommended.
APPENDIX D DETERMINATION OF THE RESISTANCE OF A PARTITION TO A HYDROSTATIC HEAD (PUMPOUT TEST) (Normative) D1 Scope This Appendix sets out a method for type testing the resistance of a tank partition to the effects of pumping out fluid from one side of the partition. D2 Principle With the removal of fluid from one side of a partitioned tank during pump-out, the partition may be subjected to a hydrostatic pressure head. This test reproduces those conditions and then checks for any signs of weakness or failure of the partition. D3 Testing This test may be carried out in conjunction with the watertightness test, see Appendix E. (a) (b) A tank is set up for the watertightness test as required by Appendix E, Clause E4.1 (a) to (c); The tank is either filled with water as required by Appendix E, Clause E4.1(d), or to the top of the partition or to the level of any hole through it; Water is pumped out from one side of the partition. If the partition is situated so that there is a greater quantity/head of water on one side as compared to the other then the water shall be pumped out from the side that has the least quantity/head; Observe the reaction of the partition to the effects of the pumpout process, and if necessary over a period of at least 5 minutes.
D4 Pass/Fail The tank shall be able to be pumped out without the partition collapsing or permanently deforming. D5 Test records The report shall include the following information for each test specimen: (a) (b) (c)
Identification of person/organisation carrying out test; Identification of the tank tested; Date of test; The results of the test; Reference to this test method, i.e. AS/NZS 1546, Appendix D.
Test records shall be kept as required by the quality assurance programme CD5 A minimum of 10 years is recommended.
APPENDIX E DETERMINATION OF WATERTIGHTNESS (Normative)
E1 Scope This Appendix sets out a method of testing of the watertightness of septic tanks. The test is used as a type test and as a quality control test when required E2 Principle The tank is subjected to a hydrostatic pressure head and is then examined for signs of water leakage. E3 Apparatus At least three bearing blocks are required: 500 mm (minimum) length x 100 mm wide x 100 mm deep; E4 Testing
E4.1 Procedure The procedure shall be as follows: (a) Tanks that can be stood in position without the need of support shall be placed on the bearer blocks, (see Figure E1(a)); Tanks that need support in order to remain in position e.g. horizontal cylinders shall be placed on timber bearers and held in place with chocks, (see Figure E1(b)). Horizontal cylindrical tanks shall be supported sufficiently so as to counter any bending and induced tension; Tanks shall be levelled on the supports; The tank shall be filled with water to a depth of 900 mm or to the invert of the outlet pipe, whichever is the greater depth; Allow to stand for a minimum of 4 hours; Top up with water and start test observations; Observe for any leakage and count the drops per minute from any single point. CE4.1(g) Damp patches in concrete tanks are not considered leakage.
E4.2 (i) (ii)
Test criteria Concrete septic tanks shall not show a leakage rate greater than 4 drops/min; Glass fibre-reinforced or plastic tanks shall have no leakage, and no damp patches;
E4.3 Frequency The frequency of testing will be governed by the needs of any internal quality assurance programme, or external quality assessment programme. CE4.3 When used as a quality control test it is recommended that at least one septic tank per week be tested. This should be representative of the capacity and design of tank made in that week. When a number of different capacity or design tanks are made in a manufacturing period then each capacity or design should be tested on a rotation basis of a minimum rate of one per week.
E5 Pass/fail Should the leakage rate be exceeded or there is visible cracking, the septic tank shall be rejected. E6 Repair Isolated minor leakages in concrete tanks may be repaired so as to effectively and permanently seal the leak. After repair, the tank must be retested. E7 Test records The report shall include the following information for each test specimen: (a) (b) (c) (d) (e) Identification of person/organisation carrying out test; Identification of the tank tested; Date of test; The leakage rate, in drops per minute; Reference to this test method, i.e. AS/NZS 1546, Appendix E.
Test records shall be kept as required by the quality assurance programme. CE7 A minimum of ten years is recommended.
Dimensions in millimetres FIGURE E1 WATERTIGHTNESS TEST ARRANGEMENT FOR HORIZONTAL AND VERTICAL TANK (Diagrammatic only)
APPENDIX F DETERMINATION OF RESISTANCE TO LATERAL LOAD - HYDRAULIC TEST METHOD (Normative) F1 Scope This appendix sets out a method for testing the resistance of a septic tank to an applied lateral load. An alternative test (based on point load testing) is given in Appendix G. F2 Principle The lateral (side loading) forces on a septic tank due to soil in a fully or partially saturated state, together with any accidental (incidental) additional loading due to the presence of earth moving equipment adjacent to the tank wall may be represented by a circumferential load applied to the wall of the septic tank. These forces equate approximately to the forces applied to an empty tank held submerged in water. The test method requires that compression forces due to any anchorage technique normally used with the septic tank are simulated during the test. F3 Apparatus This test is carried out using: (a) A container large enough to allow the test tank to fit within and for the tank to be submerged in water; Weights or hydraulic ram assembly used to reproduce any compression induced in a tank by the mechanism of anchorage, if any; The test tank complete with lid. Procedure The container base shall be levelled; CF4(a) This may be achieved on a sand bed of sufficient area. The top and bottom surfaces of the sand bed should be level and the sand should be not less than 100 mm deep. (b) The empty test tank shall be installed and restrained as necessary in the container. If it is necessary to reproduce anchorage compression, weights shall be placed on the upper rim of the tank cylinder; The holding down of the tank shall be such as to not provide any lateral stability to the tank in excess of that of that provided by the lid, when installed. (c) The outer container shall be filled with water up to the outlet level of the test tank. The water temperature shall not exceed 230C.
(c) F4 (a)
F5 Assessment Inspection shall show that there have been no leaks and that the integrity of the tank has not suffered permanent damage. See Clause 2.4.10. F6 Frequency The testing shall be carried out as per the requirement of any internal quality assurance programme or external quality assessment programme.
F7 Retesting Should a tank fail the lateral load test a further two tanks shall be selected from the same batch as the tank that failed. These tanks shall be tested as above. If the two additional tanks meet the load requirements the batch shall be deemed to meet the test requirements. If one of the additional tanks fails the batch shall be rejected or every tank subjected to the lateral load test. CF7 Should a prototype tank fail, a new design and testing programme will be required. F8 Test records The report shall include the following information for each test specimen: (a) (b) (c) (d) (e) Identification of person/organisation carrying out test; Identification of the tank tested; Date of test; The presence and size of any cracking, and any other defects noted; Reference to this test method, i.e. AS/NZS 1546, Appendix F.
Test records shall be kept as required by the quality assurance programme. CF8 A minimum of ten years is recommended.
APPENDIX G DETERMINATION OF RESISTANCE TO LATERAL LOAD - POINT LOAD TEST METHOD (Normative) G1 Scope This appendix sets out two methods for testing the resistance of a septic tank to an applied lateral point load. An alternative test is given in Appendix F. G2 Principle The lateral (side loading) forces on a septic tank due to soil in a fully or partially saturated state, together with any accidental (incidental) additional loading due to the presence of earth moving equipment adjacent to the tank wall may be represented by a point load applied to the wall of the septic tank. The lateral load is applied to the tank by the application of thrust on the side wall of the tank through a bearing block using a controlled and measured force. Different loads are applied depending on whether the septic tank is tested empty or full of water. The test method requires that compression forces due to any anchorage technique normally used with the septic tank are present during the test. G3 Apparatus This test is carried out by using: (a) (b) (c) (d) (e) A bearing block 250 x 250 x 100 mm shaped to match the external shape of the tank to be tested; A rubber pad, 13 mm thick to fit the bearing block, of Shore durometer hardness 45-55; A hydraulic ram to which the bearing block is fixed; A pressure gauge from which the pressure recorded can be used to calculate the total force applied; A frame to hold the hydraulic ram, gauge and pad assembly at the required position depending on the geometry of the tank; CG3(e) Such a frame is described in AS 1597.1 (Appendix B, figure B1). This frame is also used for the top load test described in Appendix H of this Standard. (f) Circumferential or line support shall be provided; (i)
Circumferential support. Circular/curved septic tanks shall be supported by a length not greater than one quarter of the external perimeter centrally located opposite the applied lateral point load. The support shall be provided for the full height of vertical tanks or full length of horizontal tanks. For non-circular tanks the support shall be provided to the side opposite the applied lateral load. Line support shall be provided for the full height of vertical tanks or full length of horizontal tanks directly opposite the applied lateral point load.
A sand bed positioned beneath the test frame of sufficient area to accommodate the test tank. The top and bottom surfaces of the sand bed shall be level and the sand shall be not less than 100 mm deep; CG3(g) This sand bed is also used for the top load test described in Appendix H of this Standard.
Weights or hydraulic ram assembly used to reproduce any compression induced in a tank by the mechanism of anchorage, if any; Crack measuring gauge; Test tank complete with lid. Procedure
(i) (j) G4
G4.1 Testing of tank filled with water Tanks may be tested in a vertical or horizontal position. (a) Assemble test tank on the bed of sand beneath the test frame complete with circumferential or line support and, if needed, anchorage compression; Apply a lateral point load one third of tank height from the base, or at the spring line for horizontal circular tanks; Apply a lateral point load of (i) (ii) d) 25 kN if circumferential support is provided, or 12.5 kN if line support is provided;
The load shall be increased uniformly so that the specified value is reached in 5 minutes. The load shall be applied via the bearing block and rubber pad.
G4.2 Testing of empty septic tank Testing shall be as described in Clause G4.1 with load applied to be 17 kN if circumferential support is provided or 8.5 kN if line support is provided. G5 Assessment If cracks occur they shall be checked by means of the test crack measuring gauge. The load shall than be released and the surface again examined to check whether all test cracks have closed. The tank shall be free of fractures and cracks wider than 0.15 mm and residual cracks wider than 0.1 mm (approximately) and from other defects arising from faulty materials or faulty methods of manufacture. The dimensions of the test cracks shall be determined in accordance with AS 1597 Part 1, Section 3 Clause 3.2.1.
G6 Frequency The testing shall be carried out as per the requirement of any internal quality assurance programme or external quality assessment programme. G7 Retesting Should a tank fail the load tests a further two tanks shall be selected from the same batch as the tank that failed. These tanks shall be tested as above. If the two additional tanks meet the load requirements the batch shall be deemed to meet the test requirements. If one of the additional tanks fails the batch shall be rejected or every tank subjected to the lateral load test. CG7 Should a prototype tank fail the load tests, a new design and retesting will be required.
G8 Test records The report shall include the following information for each test specimen: (a) (b) (c) (d) (e) Identification of person/organisation carrying out test; Identification of the tank tested; Date of test; The presence and size of any cracking, and any other defects noted; Reference to this test method, i.e. AS/NZS 1546, Appendix G.
Test records shall be kept as required by the quality assurance programme. CG8 A minimum of ten years is recommended.
APPENDIX H DETERMINATION OF RESISTANCE TO TOP LOADING (Normative) H1 Scope This appendix sets out a method for testing the resistance of a septic tank to an applied top load. H2 Principle A vertical downward top load is applied to the tank lid and access opening cover. The test method is based on that given in AS 1597.1, Section 3, and allows for both proof and ultimate load testing. H3 Apparatus (a) A frame and winch assembly that straddles a sand bed, (see Figure H1), being an adaption of the test rig in AS 1597.1; (b) (c) (d) (e) H4 A bearing block - 250 x 250 x 100 mm; A rubber pad, 13 mm thick to fit bearing block, of Shore durometer hardness 45-55; A proof test load of 5 kN (approx. 510kg); Crack measuring gauges. Procedure
H4.1 General Three vertical tanks or three horizontal tanks complete with lids and access opening covers, shall be tested in accordance with AS 1597.1, Load test requirements, with a proof load of not less than 5 kN as shown in Figure H1. H4.2 Load application The load shall be increased uniformly so that the specified value is reached in 5 minutes. The load shall be applied via the bearing block and rubber pad. H5 Assessment If cracks occur they shall be checked by means of the test crack measuring gauge. The load shall than be released and the surface again examined to check whether all test cracks have closed. The tank, lid and access opening cover shall be free of fractures and cracks wider than 0.15 mm and residual cracks wider than 0.1 mm (approximately) and from other defects arising from faulty materials or faulty methods of manufacture.
The dimensions of the test cracks shall be determined in accordance with AS 1597 Part 1, Section 3 Clause 3.2.1. H6 Frequency The testing shall be carried out as per the requirement of any internal quality assurance programme or external quality assessment programme. H7 Retesting Should a tank fail the load tests a further two tanks shall be selected from the same batch as the tank that failed. These tanks shall be tested as above. If the two additional tanks meet the load requirements the batch shall be deemed to meet the test requirements. If one of the additional tanks fails the batch shall be rejected or every tank subjected to the top load test.
CH7 Should a prototype tank fail the load tests, a new design and retesting will be required. H8 Test records The report shall include the following information for each test specimen: (a) (b) (c) (d) (e) Identification of person/organisation carrying out test; Identification of the tank tested; Date of test; The presence and size of any cracking, and any other defects noted; Reference to this test method, i.e. AS/NZS 1546, Appendix H.
Test records shall be kept as required by the quality assurance programme. CH8 A minimum of ten years is recommended.
Typical vertical septic tank with lid and access opening cover in place
Typical horizontal septic tank with access opening cover in place FIGURE H1 TYPICAL LOAD TESTING SET-UP (Diagrammatic only)
APPENDIX I INSTALLATION OF SEPTIC TANKS (Informative) I1 Scope This section gives guidance for the on-site installation of septic tanks. I1.1 Siting of tanks
Australia The siting of tanks is subject to regulatory authority approval and may require the submission of a certified engineering design to allow construction close to buildings and in trafficable areas. New Zealand The siting of tanks may be subject to regulatory authority approval and may require the submission of a certified engineering design to allow construction close to buildings and in trafficable areas. General In general, tanks should be installed clear of any buildings so as not to affect any structural elements of buildings. CI1.1 As a guide tanks should be installed sufficiently clear of buildings to provide an angle of repose of at least 45o between the bottom of the footing and the base of the tank. NOTE: The possible escape of highly explosive gases from septic tanks must receive consideration in the installation design. I1.2 Soil Tanks should be installed in stable soil conditions. Where there is doubt the installer should give full details and specifications on how it is intended to provide a sound foundation for the tank. I1.3 Surface Water Surface waters should be diverted from the tank installation. Special measures need to be taken in case of a high ground water table or flood prone areas. I1.4 Location on Site The location of septic tanks on sites is subject to approval by the regulatory authority. In any case, there shall be compliance with building clearances and block/section boundaries as provided for in by-laws and Regulations. I1.5 Drainage The drainage system shall comply with AS/NZS 3500.2 or the NZ Building Code. All drainage levels should be considered to ensure appropriate gradients leading into the tank and to allow gravity discharge of effluent to the top of the disposal area, (where appropriate). I1.6 Desludging The tank(s) should be sited with due consideration for future de-sludging operations and the siting of the effluent treatment system. Where access for desludging by vehicle is not available the application for approval of the installation must state the manner in which it is intended to desludge the tank at the necessary intervals without creating a health nuisance.
I2.1 General Manufacturers should ensure that installation instructions are supplied that are relevant to the material from which the tank is constructed. I2.2 Councils It is recommended that regulatory authorities require that installation instructions are provided with the building permit/consent application. I2.3 Manufacturer For each installation the manufacturer should supply written instructions which are specific to their product and the materials used. The instructions should allow installation in a safe and workmanlike manner. The instructions should cover, but be not necessarily restricted to, the following information: (a) Special provisions concerning excavation relevant to the tank type or special provisions if the installation is freestanding; The preparation of the bottom of the excavation; The method of safe handling and lifting; Special instructions where the installation could be subject to ground water or floatation; Fitting of any components inlets, outlets, partitions, square junctions and gas baffles; Backfilling - recommendation of choice of material and the method of backfilling to be adopted; Need to fill tank with water during backfilling operations; Methods of sealing and re-sealing tank lids and access/inspection covers/openings and associated extensions; Commissioning instructions.
I2.4 Repairs Any repairs should be done so that the tank meets the requirements of this Standard.
APPENDIX J DETERMINATION OF THE HARDNESS OF GLASS FIBRE-REINFORCED PLASTIC COMPOSITES (Normative) J1 Scope This Appendix sets out a method for determining the hardness of reinforced plastic laminates for septic tanks. J2 Principle The Barcol hardness test gives a measure of the degree of cure of the glass fibre-reinforced composite. J3 Apparatus A Barcol Impressor Model GYZJ-934-1*, or equivalent. J4 Test specimens The hardness test may be carried out directly on the tank or on test specimens prepared in accordance with ISO 1268. The test specimens shall have been manufactured for not less than 48 hours, be substantially flat, have a smooth surface and be at least 2.5 mm thick. J5 Procedure The Barcol Impressor shall be applied to the surface and pressed firmly, and the dial gauge reading simultaneously noted. Not less than 20 readings shall be taken on the laminate of each tank or specimen in random fashion over the surface being tested. The top three and bottom three readings shall discarded and the remaining 14 shall be averaged. J6 Frequency The testing shall be carried out as per the requirement of any internal quality assurance programme or external quality assessment programme. J7 Test records The report shall include the following information for each test specimen: (a) (b) (c) (d)
Identification of person/organisation carrying out test; Identification of the tank tested; Date of test; The average Barcol hardness number; References to this test method, i.e. AS/NZS 1546, Appendix J.
Test records shall be kept as required by the quality assurance programme. CJ7 A minimum of ten years is recommended.
* Made by the Barber Colman Co., Rockford, Illinois, U.S.A.
APPENDIX K DETERMINATION OF THE IMPACT RESISTANCE OF MOULDED POLYOLEFIN SEPTIC TANKS (Informative) K1 Scope This Appendix sets out a method of determining the impact resistance of polyolefin septic tanks. It applies to tanks made in any manner using thermoplastic polyolefin resins The test is essentially an internal quality control test that will ensure that a constant moulding is being made. Results are dependent on the thickness of the material being tested. K2 Principle Method F of ASTM D 3029: 1990 allows the mean energy to cause specimen failure to be calculated after a dart-shaped weight is allowed to fall vertically on to the test specimen. K3 Apparatus The following apparatus is required. It should, unless otherwise detailed, conform with Method F of ASTM D3029:1990. It is comprised essentially of: (a) A supporting frame mounted on a rigid base fitted with levelling screws, and capable of allowing a steel dart to fall freely and centrally from a height of 100 mm; A clamping frame to carry the test panel, mounted on the base of the supporting frame in such a position that the steel dart will fall centrally into the clamping frame. The test panel support clamping plate has a hole of 20 mm diameter placed centrally beneath the dart; A steel dart of configuration of Figure 3B of ASTM D 3029 and manufactured as per Standard; A steel dart support capable of supporting a 13.5 kg weight, complete with release mechanism; Weights, cylindrical, which will fit onto the shaft of the steel dart.
K4 Procedure (a) The test specimens shall be cut from a test panel prepared in accordance with Clause 10.4.1; (b) (c) (d)
The test specimen shall be clean; Visually examine the surface of the test specimen using the x 10 eyepiece for any sign of cracks; The test specimen shall be fitted and secured into a clamping frame; The steel dart is allowed to drop onto the test specimen from a height of 100 mm. The dart shall be loaded with weights to that amount which is expected to cause half the specimens to fail; Failure is defined as the presence of a crack or split created by the impact of the falling steel dart, that can be seen under normal laboratory lighting conditions.
K5 Frequency The testing shall be carried out as per the requirement of any internal quality assurance programme or external quality assessment programme.
K6 Test records The report shall include the following information for each test specimen: (a) (b) (c) (d) Identification of person/organisation carrying out test; Method of preparation of test specimens and as necessary the identification of any tank tested; Weights required to cause failure; Types of failure eg crack or cracks on one surface only, cracks that penetrate the thickness, brittle shatter, ductile failure, other observed deformation; Date of test; References to this test method, i.e. AS/NZS 1546, Appendix K.
Test records shall be kept as required by the quality assurance programme. CK6 A minimum of ten years is recommended.
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