This document is the Grease Interceptor Installation Guide. Backfill materials & envelope construction and trench construction discussed.

The recommendations detail how to correctly install Grease Interceptors. Installation with proper backfill materials, compaction levels, and placement procedures are essential to achieve long term system performance. These recommendations assume the drainage designer used design criteria available from ASTM D2321 and ADS.

Structural backfill material must be a Class I material. Native soil meeting class II, III, or I VA are NOT acceptable initial backfill materials. However, they may be used as final backfill once the initial backfill is placed and compacted. In regions where Class I backfill material may not be readily obtainable, flowable fill may be a suitable alternative. Where flowable fill is used, precaution must be taken to prevent flotation during installation. A table with the values for backfill material and compaction requirements shown.

For trench construction, trench or ditch should be just wide enough to place and compact backfill around the entire Grease Interceptor. More instruction is offered with supporting charts, figure and soft foundation/rock or unyielding material diagrams.

Backfill envelope construction lists steps when placing unit and initial backfill. A diagram is provided. Inlet/outlet connections include installation tips and 2 diagrams. The backfill around the unit and final cover and riser extensions include installation tips and diagrams.