top of page

Fiberglass Tank Backfill Guidelines

For the most part underground fiberglass tank manufacturers have similar backfill requirements. The standard backfill is pea gravel or crushed rock. If using pea gravel it must be 3/4 minus. Three quarter minus is round, washed, free flowing rock 1/8”-3/4” in diameter. No more than 5% may pass through a #8 sieve. If you decide to go with crushed rock the installation guidelines is going to require 1/8” - 1/2” diameter.

Sometimes the construction zone has ideal native soil, and in efforts of saving money the contractor may elect to use it. The contractor would send in a sieve analysis to the manufacturer to get a alternate materials approval. You can acces the PDF download version of our backfill guidelines in our library.

bottom of page