Drainage below ground

5.3.3Preliminary work

Drainage systems shall be checked on site to ensure that the design can be achieved.

Check that the following are as specified in the design:

  • invert levels and locations of existing sewers
  • ground floor levels of homes
  • external finished levels.

Percolation tests should be verified where treated effluent disposal is through field drains. The length of any field drains specified in the design should be accommodated within the site boundaries.