Click here for instructions on How to Print a Web Page

Drainage and Sewer

Materials

  • Materials and products used in sanitary plumbing and drainage systems must be as approved sample and in accordance with Clause 2.3 of AS 3500.2.


Below Ground Clearance



Below Ground Backfill and Cover


Bedding Materials


  • Filling materials used for bedding of drains must be one of the following:
  • Crushed rock, gravel screenings or similar recycled materials of nominal size of 7–10 mm
  • Cement mortar containing 1 part of Portland cement to 4 parts of sand by volume, thoroughly mixed with clean water to a workable consistency.
  • Free-running sand capable of passing through a 2 mm mesh sieve containing no clay, organic or any other deleterious materials.


  • Sanitary drainage must be:
  • Surrounded with not less than 75 mm of compacted sand or
  • Fine-grained soil, with no hard-edged object coming in contact with or resting against any pipe or fitting.
  • Installed with underground pipe warning tape installed 150 mm above all underground pipes for the full length of the pipe.

Backfill


  • Backfill must be free from builder’s waste, bricks, concrete pieces, rocks or hard matter larger than 25 mm and have no soil lumps larger than 75 mm.




Cover 


  • Drains must be installed with a minimum depth of cover, measured from the top of the pipe socket or inspection opening to the finished surface level, as specified in Table 3.7.2 of AS 3500.2 outlined below.

Casting into Concrete


Plastic pipe in accordance with Clause 5.3.4 of AS2032 which is completely concrete encased must be fully wrapped prior to encasement with a compressible material with a nominal thickness of 6mm.



Above Ground Clearances


Separation from above-ground electrical conduit, wire, cable, gas or water pipes in accordance with Clause 3.6.2 of AS 3500.2 must be at least 100mm.



Brackets and Supports 


Brackets, clips and hangers must be installed at the spacings as specified in horizontal pipe support spacing and vertical pipe support spacing.



Insulation 


Insulation for above-ground sanitary plumbing pipework within residential buildings and hotels must be provided.

Protection of Drains


Drains are to be protected to stop construction waste entering and blocking waste pipes.

Step up to Floor Wastes


  • Sanitary drainage system floor waste as per AS3500.2 Clause 6.5.2.1 must be provided with step ups as per the below detail.

Access for Maintenance 


Air admittance valves (AAVs), pressure attenuators, inspection openings must be accessible as required by AS3500.2 Clause(s) 6.9.3, 6.10.3.



Inspection Openings (Sewer Drainage)


Except where inspection chambers are provided, inspection openings for maintenance purposes in accordance with Clause 4.7.1 AS3500.2 must be provided:

  • Outside of buildings, not further than 2.5m along each branch drain connecting one or more water closets or slop hoppers
  • At intervals of not more than 30m with a minimum of one inspection opening on each main drain
  • At the connection to the network utility operator’s sewer if not provided by the network utility operator
  • On the downstream end of the drain where any drain passes under a building except where waste fixtures only are concerned
  • Where any new section of drain is connected to an existing drain
  • Immediately at or upstream of the upper bend of a jump-up.



Location of testing and inspection openings (general pipework) 


All common discharge pipes and stacks in accordance with Clause 10.5.2 AS3500.2 must be provided with openings for inspection and testing in the following locations:

  • In any common discharge pipe where necessary for inspection and testing.
  • At the base of every stack.
  • At any level of a stack where necessary for inspection and testing.
  • At intervals not greater than 30m in every common discharge pipe.
  • At every junction fitting that connects a common discharge pipe to a stack, or in the upstream section of the common discharge pipe.




Testing 


  • Sanitary plumbing and sanitary drainage installations must be tested:
  • Prior to the placement of the trench fill (backfill).
  • By hydrostatic, air pressure or vacuum testing to demonstrate that they are watertight in accordance with Clause 15 of AS 3500.2 or as per specification.
  • CCTV acceptance inspection of sanitary drains must be conducted in accordance with the requirements of AS 2032 Appendix E or as per specification.
Share by: