Technical Booklet C Site Preparation and Resistance to Contaminants and Moisture·Page 20·4.3
Existing subsoil drains passing under buildings
If an active subsoil drain route would pass under the building, it must be relaid with sealed joints and access points, rerouted around the building, or redirected to another outfall.
4.3 If the route of an existing active subsoil drain would pass under the building it should be –
(a) relaid in pipes with sealed joints and have access points before and after it passes under the building;
(b) rerouted around the building; or
(c) redirected to another outfall.
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