Part 5 – Wastewater Drainage

5.9    Pipeline Construction

The construction of the pipelines shall be carried out in accordance with good engineering practice. 

Note:  The MPDC Infrastructure Code of Practice provides a useful guide.

5.9.1    Requirements for Building near to or over Drainage Pipelines.

• No structural loads are to be placed on public drainage pipelines.
  • The first row of piles must be at least 1 m clear of the outside of the pipe and down to a depth of at least 1 m below the invert of the pipe.
  • Subsequent rows of piles must be constructed to a depth of at least 1 m below the 45 degree influence line form the pipe invert.
  • All structural loads on piles shall be absorbed outside the 45 degree envelope and below the pipe invert level of the first row of pipes.
• No pile ramming is permitted within 5 m from the sewer centre line, or within the 45 degree envelope (piles within 5 m must be drilled).
• The building or other work must be designed and constructed so that the sewer and trench line is not adversely affected by any future excavation necessary for maintenance of the sewer.
• The structure must allow for settlement of the sewer trench line and backfill.
• Drawings of the proposed works must accurately identify the location of the drainage pipeline affected and the distances with cross section details for all structures, footings or piles within the 45 degree line.
• Buildings are not permitted to be located over connections to pipes or manholes.
• Pipes to be built over shall be jetted and CCTV’d before and after construction work.