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Stormwater Pipework

Materials 


Materials and products used in stormwater systems must be as per approved sample.



Below Ground Clearances


Separation between any underground stormwater drain and other services must be in accordance with Clause 6.2.6 of AS 3500.3 (outlined in 'Below Ground Separation Distances').




Below Ground Backfill and Cover 


Bedding Materials 


  • Embedment material must comply with the relevant standards outlined below.
  • AS/NZS 2041.1 and AS/NZS 2041.2 for corrugated metal pipes
  • AS/NZS 2032 for PVC pipes
  • AS/NZS 2033 for polyethylene pipes
  • AS/NZS 2566.2 for flexible pipes and fittings
  • AS/NZS 3725 for FRC and reinforced concrete pipes.



Trench Fill and Backfill 


  • Trench fill in accordance with Clause 6.2.10 of AS 3500.3 must either:
  • be material excavated from the trench or imported, provided the material placed within 300mm of the top of pipes is free from builders’ waste, bricks, pieces of concrete, rocks or similar material that would be retained on a 75 mm sieve or
  • be embedment material.
  • Trench fill must be placed in loose layers not more than 200mm thick and compacted to not less than 90% or 95% under pavements of the standard maximum dry density.

Cover


  • Cover must be not less than that given in Table 6.2.5 of AS 3500.3 outlined below:
  • Underground plastic pipes in accordance with Figure 5.1 of AS2032 is to have a minimum of 100mm cover with the required depth of bedding, foundation material.

Casting into Concrete 


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



Brackets and Supports


Brackets, clips and hangers must be installed at the spacings specified in chapter 'Horizontal Pipe Support Spacing' and chapter 'Vertical Pipe Support Spacing'.



Above Ground Clearances 


Separation between any above-ground stormwater drain and other services must be in accordance with chapter Above Ground Separation Distances.



Protection and Pits and Drains


Drains and pits must be protected from physical damage and construction waste entering the system.



Box Gutters


Refer this link to access Metal Roofing section of the handbook. 



Stormwater Pits


Stormwater pits must be installed on a stable, well-compacted foundation to avoid future settlement (subsidence).



Siphonic Roof Drainage


  • Siphonic roof drainage systems inclusive of design, pipes and fittings, bracketing, roof outlets and installation should be:
  • Designed by a qualified engineer
  • Installed by a siphonic specialist contractor
  • Siphonic rainwater outlets must:
  • Be made of robust materials, suitable for the installed location
  • Incorporate leaf guards to restrict the entry of debris into the system without restricting the flow.


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Subsoil Drainage 


  • Subsoil drainage pipe must be slotted UPVC or perforated, ribbed HDPE to AS2439.1
  • Subsoil drains as required by AS3500.3 clause 6.4.1 must be laid:
  • With clean-out points for pipes.
  • With a 50mm minimum pipe underlay of filter material in the trench to take out any irregularities in the trench bed and provide a drainage path underneath subsoil drain.
  • With an appropriate filter material aggregate (13mm max).
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