NCC 2019 Volume Three
Tas Section H On-site waste water systems

Tas Section H On-site waste water systems

Tas Part H1 On-site waste water management systems

Tas Introduction to this Part

This Part sets out the requirements for the design, construction, installation, replacement repair, alteration and maintenance of any part of an on-site wastewater management system.

Explanatory information:

Explanatory information:

Objective

Tas HO1

The Objective of this Part is to—

  1. safeguard people from illness, injury or loss (including loss of amenity) due to the failure of an on-site wastewater management system installation; and
  2. ensure that an on-site wastewater management system installation (including an installation provided for use by people with a disability) is suitable; and
  3. conserve water and energy; and
  4. safeguard the environment; and
  5. safeguard public and private infrastructure; and
  6. ensure that an on-site wastewater management system installation is designed and is capable of being maintained so that throughout its serviceable life it will continue to satisfy Objectives (a) to (e).

Functional statements

Tas HF1.1

On-site wastewater management systems must collect, contain, treat and assimilate and process domestic-wastewater, human excreta, or both so that public health and environmental standards required by the authority having jurisdiction are achieved.

Performance Requirements

Tas HP1.1 Health, environment and amenity

(1)

An on-site wastewater management system must ensure the following:

(a)

Risks associated with the discharge of treated wastewater to the environment are minimised.

(b)

Risks associated with the discharge of the end product of a composting toilet to the environment are minimised.

(c)

Surface and ground water are not polluted.

(d)

Soil productivity is maintained or enhanced.

Tas HP1.2 Infrastructure

(1)

Wastewater must be transferred to an on-site wastewater management system in a way that avoids the following:

(b)

Entry of foul air and gases into buildings.

(2)

Wastewater must be transferred to an on-site wastewater management system in a way that ensures the following:

(a)

Safe and hygienic transferal of waste.

(b)

Safe access for maintenance.

Tas HP1.3 On-site waste water management

(1)

An on-site wastewater management system must avoid the following:

(a)

Contamination of drinking water, soils, ground water and waterways.

(c)

Foul air and gases accumulating within or entering buildings.

(d)

Unauthorised access by people.

(e)

Entry of stormwater to the system.

(2)

An on-site wastewater management system must ensure the following:

(a)

Cleaning, maintenance, measurement and performance sampling can be conducted as appropriate.

(b)

The manufacturer, model, serial number and designed capacity is easily identifiable after installation.

(c)

Materials which are resistance to the water and waste that will be disposed.

(d)

Appropriate treatment and storage capacity for the volume of waste and frequency of disposal.

(e)

Appropriate size, strength and rigidity for the nature, flow rates, volume of wastes and/or waste products which must be processed.

(f)

Vehicle access for the collection of waste water.

(g)

The installation throughout its serviceable life will continue to satisfy the requirements of items Tas HP1.3(2)(a) to Tas HP1.3(2)(f).

Tas HP1.4 Land application systems

(1)

An on-site wastewater management system and associated land application system must avoid the following:

(a)

Damage from root penetration, superimposed loads or ground movement.

(b)

Entry of water, foul air or gases from the system into buildings.

(c)

Entry of stormwater to the system.

(d)

Blockage and unintended or uncontrolled discharge.

(2)

An on-site wastewater management system, and any associated land application system must provide the following:

(a)

Protection against internal contamination.

(b)

Access for maintenance and cleaning.

(c)

Ventilation to avoid foul air and gases accumulation in the system.

(3)

A facility must continue to satisfy the requirement of items Tas HP1.4(1) – Tas HP1.4(2).

Verification Methods

There are no Verification Methods in this Part.

Deemed-to-Satisfy Provisions

Tas H1.1 Application

(1)

Performance RequirementsTas HP1.1 to Tas HP1.4 are satisfied by complying with Tas H1.2.

Tas H1.2 General requirements

(1)

The manufacture of septic tanks and their associated fittings for the treatment of domestic wastewater up to 14,000 litres per week must be in accordance with AS/NZS 1546.1.

(2)

Waterless composting toilets must meet the requirements of AS/NZS 1546.2.

(3)

The design, means of compliance and specification for testing of aerated wastewater treatment systems and associated fitting must be in accordance with AS/NZS 1546.3.

(4)

The design and installation of sanitary plumbing and drainage systems must be in accordance with AS/NZS 3500.2 and the requirements of this Part.

(5)

The design and sustainable management of domestic land application systems must be in accordance with AS/NZS 1547.

(6)

An on-site wastewater management system must be designed and constructed in accordance with a Certificate of Accreditation issued under Tas I102.

(7)

The installation of an on-site wastewater management system must comply with the additional installation requirements set out in Tas H101.

Tas Part H101 On-site wastewater management systems - additional requirements

Tas H101.1 Scope

This Part is an addition to Tas Part H1 and sets out the requirements for the connection of water flushed sanitary fixtures and sanitary appliances to an on-site wastewater management system other than a sewerage system. It also sets out the installation requirements for on-site wastewater management systems.

Tas H101.2 Installation requirements

(1)

Installation must be in accordance with Tas Figure H102.2 and in accordance with Parts C1 and C2 for pipework and venting arrangements.

(2)

An overflow relief gully must be installed and positioned so as to provide protection against surcharge of waste into a building.

(3)

An alternative to the ground vent may be used by extending a vent to terminate as an upstream vent, with the vent connection between the last sanitary fixture or sanitary appliance and the on-site wastewater management system.

(4)

Inspection openings must be located at the inlet to an on-site wastewater management system treatment unit and the point of connection to the land application system and must terminate as close as practicable to the underside of an approved inspection opening cover installed at the finished surface level.

(5)

Access openings for desludging or maintenance of on-site wastewater management system treatment units must terminate at or above finished surface level.

Tas Figure H101.2 Alternative venting arrangements
v3_Tas_Fig_H1012_2019.svg

Tas Part H102 On-site Domestic Wastewater Treatment Units — greywater treatment systems.

Tas H102.1 Application

This Part sets out the requirements for how greywater is managed for domestic premises in Tasmania. It also sets out classification levels and methods of disposal for each of the three options.

Tas H102.2 Installation requirements

(1)

A greywater re-use system may be achieved through any one of the following options:

(a)

Treatments systems.

(b)

Diversion.

(c)

Manual Bucketing (exempt from Tas H102.2).

Note 1:

Note 1:

Options (a) and (b) must be designed by a suitably qualified designer in accordance with the Tasmania Occupational Licensing Act.

Explanatory information:

Explanatory information:

The type of option selected will depend on what the water is to be used for and how much land is available.

(2)

Option (a), treatment systems, must be designed, installed and maintained in accordance with AS/NZS 1546.4, the system must be accredited in Tasmania and maintained in accordance with the schedule of maintenance determined under the Tasmanian Building Act provisions.

(3)

Option (b), Diversion systems, must be designed, installed and maintained in accordance with AS/NZS 3500.2, the Tasmanian Consumer Building and Occupational Services — Guide to Domestic Greywater Re-use and the schedule of maintenance (as applicable) and as determined under the Tasmanian Building Act provisions and Tas A5.3(1)(c).

(4)

Option (c) there are no installation requirements.

Tas Part H2 On-site liquid trade waste systems

Tas Introduction

This Part sets out the requirements for the design, construction, installation, replacement, repair, alteration and maintenance of any part of a system of a property used for the on-site treatment, conveyance and/or disposal of liquid trade waste.

Performance Requirements

Tas HP2.1 Health, environment and amenity

(1)

An on-site liquid trade waste system must ensure the following:

(a)

Risks associated with the discharge of treated liquid trade waste to the environment are minimised.

(b)

Surface and ground water are not polluted.

(c)

Soil productivity is maintained or enhanced.

Tas HP2.2 Transferal

(1)

Liquid trade waste must be conveyed within the disposal system and treatment devices in a way that avoids the following:

(b)

Entry of foul air and gases into buildings.

(2)

Liquid trade waste must be conveyed within the disposal system and treatment devices a way that ensures the following:

(a)

Safe and hygienic transferal.

(b)

Safe access, as appropriate, for clearing blockages.

Tas HP2.3 Design, construction and installation

(1)

A trade waste treatment device must:

(a)

Have appropriate treatment and storage capacity for the volume of waste and frequency of disposal.

(b)

Be of the appropriate size, strength and rigidity for the nature, flowrates, volume of wastes, by-products and residues which must be processed.

(c)

Have vehicle access, for collection.

(d)

Be of an appropriate structural strength for where pedestrian or vehicular traffic is likely.

(e)

Be constructed of materials which are resistant to water and the expected waste that will be disposed.

(2)

A trade waste treatment device must avoid the likelihood of the following:

(a)

Contamination of drinking water, soils, ground water and waterways.

(b)

Foul air and gases accumulating within or entering buildings.

(d)

Unauthorised access by people.

(e)

Entry of stormwater to the sewerage system.

Application 1:

Application 1:

Tas HP2.3(2)(e) does not apply in cases where a contaminated stormwater discharge of limited volume is accepted by the Network Utility Operator as a trade waste.

(3)

A trade waste treatment device must be designed, constructed and installed to allow the following:

(a)

Cleaning, maintenance, measurement and performance sampling provisions to the requirements of the Authority having Jurisdiction.

(b)

Identification of the manufacturer, model, serial number and capacity after installation.

(4)

A trade waste treatment device must continue to satisfy the requirements of items Tas HP2.3(1) – Tas HP2.3(3) throughout its expected lifetime.

(5)

be a trade waste treatment device approved by the receiving Network Utility Operator or for on-site disposal the Authority having jurisdiction.

Verification Methods

There are no Verification Methods in this Part.

Deemed-to-Satisfy Provisions

Tas H2.1 Application

(1)

Performance RequirementsTas HP2.1 to Tas HP2.3 are satisfied by complying with Tas H2.2.

Tas H2.2 General requirements

(1)

Where pre-treatment facilities are required, they must comply with the requirements of the authority having jurisdiction, including receiving Network Utility Operator (where relevant) and those responsible for occupational health and safety, dangerous goods management and environmental protection.

(2)

Where the written agreement of the authority having jurisdiction and the receiving Network Utility Operator is required, the liquid trade waste systems and pre-treatment facilities are to comply with the requirement of the authority having jurisdiction and the receiving Network Utility Operator.

(3)

Where pre-treatment facilities are not required by the Network Utility Operator or the permit authority, Tas HP2.2 or Tas HP2.3 must comply with AS/NZS 3500.2 and Tas Part H201 and Tas Part H202 as appropriate.

(4)

If a Network Utility Operator accepts the discharge of a liquid trade waste to their sewerage system after pre-treatment—

(a)

the pre-treatment equipment or system is deemed to satisfy the Performance Requirements of Tas HP2.1 – Tas HP2.3, if the equipment or system is capable of discharging liquid trade waste at a quality set under a Consent to Discharge issued for that equipment or system by the Network Utility Operator; and

(b)

that part of the installation used to convey the liquid trade waste after treatment must comply with AS/NZS 3500.2, Tas H201, Tas H202, and the Network Utility Operator's Guidelines, insofar as the provisions relate to the system.

(5)

The use of a product or system must comply with the details described in Tas H201 and Tas H202 insofar as they relate to the product or system installed in systems not connected to the Network Utility Operator's infrastructure.

(6)

The use of a product or system must comply with the details described in Tas H201, Tas H202 and the Network Utility Operator's Guidelines, insofar as they relate to the product or system installed in systems connected to the Network Utility Operator's infrastructure.

Explanatory information: Cross-volume considerations

Explanatory information: Cross-volume considerations

Part B1 of NCC Volume One sets out requirements relevant to the excavation of pipework adjacent to a building and footings for the purpose of installing liquid trade waste systems in Class 2 to 9 buildings

Tas Part H201 Roofing of liquid trade waste generation areas

Tas H201.1 Scope

(1)

This Part is an addition to Tas Part H2 and sets out the requirements for the roofing of liquid trade waste generation areas to prevent entry of stormwater to an approved disposal system other than a sewerage system.

(2)

Roofing requirements for systems connected to the Network Utility Operator's sewerage system must as a minimum comply with Tas Figure H201.2.

Tas H201.2 Installation requirements

(1)

When a liquid trade waste generating process does not fully occur within a building, suitable roofing must be installed to prevent the entry of stormwater to the disposal system. For a structure where one or more sides are open to the weather, at least 10 degrees from the vertical overhang of the roofing must be provided.

(2)

To ensure that surface water cannot flow onto the liquid trade waste generating process area a bund or other feature (speed hump) at least 150 mm high around the area must be installed. On the upper side of the area, stormwater drains alone are not adequate as stormwater flows will often bridge over the grate and enter the process area. The overall surface water flow across the site is to be considered and the height of the bund or other feature must be increased where the calculated stormwater flow will enter the process area.

(3)

This design is likely to allow wind driven rainwater to enter under the roof in extreme storm conditions. The roof must overhang by an amount not less than that shown in Tas Figure H201.2.

Tas Figure H201.2 Roofing of liquid trade waste generation areas
v3_Tas_Fig_H2012_2014.svg

Tas Part H202 Liquid trade waste products

Tas H202.1 Scope

This Part is an addition to Tas Part H2 and depicts low risk trade waste products and installations connected to an approved disposal system other than a sewerage system.

Tas H202.2 Application

(1)

This Part applies to trade waste installations not connected to a Network Utility Operator's system.

(2)

Trade waste products or installations depicted in Tas Section H are considered low risk and may be used if they are installed in accordance with the details shown therein and the following.

(3)

Low risk liquid trade wastes can be described as those water-borne discharges — other than sewage —that are classified by the permit authority as presenting a low risk to cause harm to the environment and on-site wastewater management systems. These discharges must be trapped and partially treated before being permitted to enter the on-site wastewater management system.

Explanatory information:

Explanatory information:

Examples of low risk liquid trade wastes are discharges from—

  1. food preparation in take-away shops, restaurants, hotels, motels and the like;
  2. laboratories in education institutions such as schools and universities; or
  3. service stations, vehicle detailing and washing.

It is the role of the permit authority to determine whether the trade waste discharge is high risk or low risk when installed in areas outside the jurisdiction of the Network Utility Operator.

Tas H202.3 General installation requirements

(1)

Location

Low-risk trade waste appliances must be located as close as practicable to the fixtures and floor waste gullies served whether installed internally or externally and may be above or below ground. Portable appliances may only be installed above ground.

(2)

Covers

Trade waste appliances must be fitted with covers which can withstand vehicular or pedestrian traffic or other loads likely to be imposed on them and be easily removable by one person.

(3)

Materials

Trade waste appliances must be constructed of materials suitable for the nature of the liquid wastes likely to be discharged through the appliance.

(4)

Ventilation

Where airtight covers are fitted, trade waste appliances must be vented with either a DN 50 or DN 80 vent (refer to relevant figure). Outlet ventilation is to be provided by either a—

(a)

DN 100 riser from a disconnector gully outside a building (refer clause 4.6.2 AS/NZS 3500.2); or

(b)

DN 50 vent from a disconnector gully at the outlet of a non-portable appliance inside a building (refer clause 4.6.5 AS/NZS 3500.2); or

(c)

DN 50 vent from a DN 80 trap riser at the outlet of a portable appliance, inside a building (refer clause 4.6.5 AS/NZS 3500.2).

Trade waste appliance vents and outlet vents may be combined inside a building (refer clause 6.8.3 AS/NZS 3500.2).

(5)

Connections

Unless otherwise permitted by the permit authority, the plumbing and drainage installation upstream of a low-risk trade waste appliance must comply with AS/NZS 3500.2 and be compatible to the nature of the waste.

A trap must be fitted to the outlet pipe of every appliance and sized as follows—

(a)

DN 50 minimum for a portable appliance with hydraulic loading up to 5 fixture units.

(b)

DN 80 minimum for a portable appliance with hydraulic loading greater than 5 fixture units

(c)

DN 100 minimum for all other appliances.

Tas H202.4 Installation diagrams and notes

The low risk trade waste products and installations depicted below may be used if they are installed in accordance with the diagrams and notes shown.

Tas Figure H202.4a Typical silt pit
v3_Tas_Fig_H2024a_2015.svg

Notes:

  1. The silt pit is to be connected as specified by the designer and authorised by the Permit Authority.
  2. The bucket is to be constructed of mild steel plate, a minimum of 3 mm thick with 4 rows of 10 mm diameter holes at 25 mm centres. The bucket must be hot dip galvanised after fabrication.
  3. Sizes shown are minimum permissible dimensions.
  4. All dimensions shown are in millimetres.
Tas Figure H202.4b Typical silt trap
v3_Tas_Fig_H2024b_2015.svg

Notes:

  1. The silt trap is to be connected as specified by the designer and authorised by the Permit Authority.
  2. The bucket is to be constructed of mild steel plate, a minimum of 3 mm thick with 5 rows of 10 mm diameter holes at 25 mm centres. The bucket must be hot dip galvanised after fabrication.
  3. Sizes shown are minimum permissible dimensions.
  4. All dimensions shown are in millimetres.
Tas Figure H202.4c Typical straining pit
v3_Tas_Fig_H2024c_2015.svg

Notes:

  1. The straining pit is to be connected as specified by the designer and authorised by the Permit Authority.
  2. The basket is to be constructed of mild steel wire —a minimum of 2.5 mm in diameter —woven to give 7 mm aperture widths on a 32 x 32 x 3 mm angle iron frame with mitred corners. The top is to be welded from angle iron frame. The basket is to be hot dip galvanised after manufacture. Alternatively the basket may be constructed from mild steel plate a minimum of 3 mm thick with 6 mm diameter holes at 12 mm centres over the entire area of the basket. The basket is to be hot dip galvanised after manufacture.
  3. All dimensions are in millimetres.
Tas Figure H202.4d Typical straining trap
v3_Tas_Fig_H2024d_2015.svg

Notes:

  1. The straining trap is to be connected as specified by the designer and authorised by the Permit Authority.
  2. The basket is to be constructed of mild steel wire — a minimum of 2.5 mm in diameter — woven to give 7 mm aperture widths on a 32 x 32 x 3 mm angle iron frame with mitred corners. The top is to be welded from angle iron frame.
  3. The basket is to be hot dip galvanised after manufacture. Alternatively the basket may be constructed from mild steel plate, a minimum of 3 mm thick with 6 mm diameter holes at 12 mm centres over the entire area of the basket. The basket is to be hot dip galvanised after manufacture.
  4. Straining traps to be used in installations connected to the Network Utility Operator's sewerage system must comply with the requirements of the Network Utility Operator's Guidelines for pre-treatment device requirements.
  5. All dimensions are in millimetres.
Tas Figure H202.4e Typical grease interceptor appliance (for above or below ground installation)
v3_Tas_Fig_H2024e_2015.svg

Notes:

  1. The capacity of the grease interceptor appliance below the outlet is to be as specified in the design and authorised by the Permit Authority. The capacity of the interceptor shown is 1080 L.
  2. Where not specified, the capacity below the outlet is to be equivalent to the maximum hourly discharge provided that the minimum capacity below the outlet is at least 250 L.
  3. As the contents of the unit may become slightly acidic, it is recommended that the internal concrete surfaces below outlet level be provided with an acidic resistant lining.
  4. If installed above ground the grease interceptor appliance may be constructed using other authorised materials provided adequate structural support for the grease interceptor appliance is provided.
  5. The grease interceptor appliance is to be located in a position so as to provide ready access for maintenance and inspection purposes.
  6. Where a grease interceptor appliance is to be installed outside a building, consideration should be given to fitting airtight covers, venting the chamber and providing a screwed cap and DN 50 vent to the disconnector gully.
  7. All dimensions are in millimetres.
Tas Figure H202.4f Typical portable grease interceptor appliance (for above ground installation)
v3_Tas_Fig_H2024f_2015.svg

Notes:

  1. The capacity of the grease interceptor appliance below the outlet is to be as specified in the design and authorised by the Permit Authority. The capacity of the interceptor shown is 162 L.
  2. Where not specified, the capacity below the outlet is to be equivalent to the maximum hourly discharge provided that the minimum capacity below the outlet is at least 100 L.
  3. The interceptor and baffle is to be constructed of 6 mm unplasticised polyvinyl chloride (PVC-U); galvanised sheet steel with a minimum width of 0.79 mm; sheet copper or 316 grade stainless steel with a minimum width of 0.63 mm, all welded construction, or other authorised material.
  4. Airtight cover(s) (using lever clips) to be provided to the grease interceptor appliance and the vent is to be extended to open air in accordance with clause 6.8.3 of AS/NZS 3500.2.
  5. The grease interceptor appliance is to be located in a position so as to provide ready access for maintenance and inspection purposes.
  6. If the grease interceptor appliance is to be installed externally it is to be protected from direct sunlight.
  7. All dimensions are in millimetres.
Tas Figure H202.4g Venting of grease trap chambers
v3_Tas_Fig_H2024g_2015.svg
Tas Figure H202.4h Alternative (mechanical) venting of grease trap chambers
v3_Tas_Fig_H2024h_2015.svg
Tas Figure H202.4i Grease trap installation within multi-storey building
v3_Tas_Fig_H2024i_2015.svg
Tas Figure H202.4j Typical oil and petrol interceptor
v3_Tas_Fig_H2024j_2015.svg

Notes:

  1. The capacity of the interceptor appliance below the outlet is to be as specified in the design and authorised by the Permit Authority. The capacity of the interceptor shown is 1140 L.
  2. Where not specified the capacity below the outlet is to be at least 1140 L.
  3. Airtight covers are required and are to be of a suitable size and be readily removable by one person. A 600 mm x 600 mm or 600 mm diameter cover is required over the inlet and outlet of the pit.
  4. Where subject to traffic loadings, suitable covers capable of withstanding such loads are to be provided.
  5. The vent is to be extended to the open air in accordance with clause 6.8.3 of AS/NZS 3500.2.
  6. The DN 100 cast iron pipe outlet fitting is to be manufactured in one piece.
  7. PVC-U shall not be used for the construction, connecting or venting of this unit.
  8. This interceptor may accumulate quantities of explosive and/or flammable materials and therefore care is to be exercised in the maintenance and general use of the interceptor.
  9. The interceptor is to be located in a position so as to provide ready access for maintenance and inspection purposes.
  10. Oil and petrol interceptors and/or treatment devices connected to the Network Utility Operator's sewerage system must comply with the requirements of the Network Utility Operator's Guidelines for pre-treatment device requirements.
  11. All dimensions are in millimetres.
Tas Figure H202.4k Typical acid neutralising tank
v3_Tas_Fig_H2024k_2015.svg

Notes:

  1. The capacity of the tank below the invert level of the outlet pipe is to be as specified by the designer and authorised by the Permit Authority. The capacity of the tank shown above is the minimum requirement of 27 L between the marble chip level and the outlet level.
  2. The tank and fixed baffles are to be constructed of unplasticised polyvinyl chloride (PVC-U) sheet with a minimum width of 6 mm; acid resistant stainless steel all welded construction with a minimum width of 0.63 mm; or other authorised acid and alkali resistant material and construction methods.
  3. The diameter of the outlet pipe is to be at least one size larger than the inlet pipe (i.e. DN 65 inlet – DN 80 outlet). Where the diameter of the inlet pipe is DN 100, the diameter of the outlet may be DN 100.
  4. The three baffles are to be equally spaced through the tank length.
  5. The 32 x 32 x 25 mm deep PVC-U test block bracket is to be fitted as close as practicable to the outlet.
  6. The 150 x 25 x 25 mm cement mortar test block is to be supplied and fitted to the satisfaction of the Permit Authority.
  7. The size of the marble chips are to be within the range of 40 mm to 60 mm.
  8. The tank is to be located in a position so as to provide ready access for the fitting of the cement mortar test block, obtaining samples from the sampling valve, replacement of the marble chips and for ongoing maintenance purposes.
  9. Where the unit is to be located below ground level—
    1. The unit is to be surrounded with thick concrete walls and base with a minimum of 100 mm.
    2. The DN 25 sampling valve is to be omitted.
    3. The outlet level is to be no greater than 600 mm below surface level.
    4. The outlet pipe diameter is to be at least DN 100.
    5. The outlet is to be connected to a disconnector gully fitted with a loose fitting grate or screwed cap.
  10. All dimensions are in millimetres.
Tas Figure H202.4l Typical mixing tank
v3_Tas_Fig_H2024l_2015.svg

Notes:

  1. The capacity of the tank below the invert level of the outlet pipe is to be as specified by the designer and authorised by the Permit Authority. The capacity of the tank shown above is the minimum requirement of 100 L.
  2. The tank and baffles are to be constructed of 6 mm min. unplasticised polyvinyl chloride (PVC-U) sheet; 0.63 mm min. acid resistant stainless steel all welded construction; or other authorised acid and alkali resistant material and construction methods.
  3. The diameter of the outlet pipe is to be at least one size larger than the inlet pipe (i.e. DN 65 inlet – DN 80 outlet). Where the diameter of the inlet pipe is DN 100, the diameter of the outlet may be DN 100.
  4. The three baffles are to be equally spaced through the tank length.
  5. The 32 x 32 x 25 mm deep PVC-U test block bracket is to be fitted as close as practicable to the outlet.
  6. The 150 x 25 x 25 mm cement mortar test block is to be supplied and fitted by the water authority's authorised officer.
  7. Consideration should be given to the provision of adequate structural support for the tank.
  8. The tank is to be located in a position so as to provide ready access for the fitting of the cement mortar test block, obtaining samples from the sampling valve, replacement of the marble chips and for ongoing maintenance purposes.
  9. Where the unit is to located below ground level—
    1. The unit is to be surrounded with concrete walls and base, at least 100 mm thick.
    2. The DN 25 sampling valve is to be omitted.
    3. The outlet level is to be no greater than 600 mm below surface level.
    4. The outlet pipe diameter is to be not less than DN 100.
    5. The outlet is to be connected to a disconnector gully fitted with a loose-fitting grate or screwed cap.
  10. All dimensions are in millimetres.
Tas Figure H202.4m Typical settling tank
v3_Tas_Fig_H2024m_2015.svg

Notes:

  1. The capacity of the tank below the invert level of the outlet pipe is to be as specified by the designer and authorised by the Permit Authority. The capacity of the tank shown above is the minimum requirement of 72 L.
  2. The tank and baffles are to be constructed of unplasticised polyvinyl chloride (PVC-U) sheet a minimum of 6 mm thick; galvanised steel sheet a minimum of 0.79 mm thick; a minimum width of 0.63 mm or 316 grade stainless steel all welded construction; or other authorised acid and alkali resistant material and construction methods.
  3. The diameter of the outlet pipe is to be at least one size larger than the inlet pipe (i.e. DN 65 inlet – DN 80 outlet). Where the diameter of the inlet pipe is DN 100, the diameter of the outlet may be DN 100.
  4. The tank is to be located in a position so as to provide ready access for obtaining samples from the sampling valve and for ongoing maintenance purposes.
  5. Where the unit is to located below ground level:
    1. The unit is to be surrounded with 100 mm min. thick concrete walls and base.
    2. The DN 25 sampling valve is to be omitted.
    3. The outlet level is to be no greater than 600 mm below surface level.
    4. The outlet pipe diameter is to be not less than DN 100.
    5. The outlet is to be connected to a disconnector gully fitted with a loose-fitting grate or screwed cap.
  6. All dimensions are in millimetres.