Standard Laying Conditions

ANSI/AWWA C150/A21.50
ANSI/AWWA C151/A21.51

Flat-bottom trench.1 Loose backfill. (Not recommended for 14" and larger pipe.)


Flat-bottom trench.1 Backfill lightly consolidated to centerline of pipe.


Pipe bedded in 4” minimum loose soil.2 Backfill lightly consolidated to top of pipe.


Pipe bedded in sand, gravel or crushed stone to depth of 1/8 pipe diameter, 4” minimum. Backfill compacted to top of pipe. (Approximately 80% Standard Proctor, AASHTO T-99.)

1.) “Flat-bottom” is defined as undisturbed earth.
2) “Loose soil” or “select material” is defined as native soil excavated from the trench, free of rocks, foreign material and frozen earth.
3.) Granular materials are defined per the AASHTO Soil Classification System (ASTM D3282) or the Unified Soil Classification System (ASTM D2487), with the exception that gravel bedding/backfill adjacent to the pipe is limited to 2" maximum particle size per ANSI/AWWA C600.