This document is the Pipe Under Structure Detail. Pipe detention and membrane liner details explained with descriptions and notes provided.

There are 7 special provisions for pipe detention below structure. ASTM D2321 specifications for installation and the site engineer determine where the pipe is to be laid in proximity to buildings/structures, a pre-construction meeting is required. The site engineer inspection and post inspection ensures that ASTM D2321 is enforced. Precaution is required to mitigate all construction loading and loading must be evaluated.

4 backfill figures show the correct and incorrect backfill and perimeter requirements. A diagram of the installed pipe under structure included.

The general notes for membrane liners, follow ASTM D2321 specifications. The contracture must ensure that no damage occurs to the installed liner system during construction and backfill.

Membrane liner notes state that thickness be at least 30 mil. The liner system shall be installed per manufacturer’s recommendations. The scope of the liner system includes nonwoven membrane protection layers, installation of membrane, welding of seams and boots or special fittings at pipe penetration.

Additional requirements for contractors include preparation of sidewall and bottom of excavation, provide anchor trenches, stone foundation spread on nonwoven protective layer and rolling of foundation stone allowable to a maximum drum weight of 5000 lbs.