The use of proper backfill is critical to long term underground storage tank performance. Only approved backfill is allowed when installing fiberglass storage tanks and the backfill must meet ASTM C-33 Fine Aggregate requirements for deleterious substances and soundness. To verify that your backfill material meets our specifications, use the Approved Backfill Calculator. Material like limestone, sandstone, crushed concrete, seashells or shale should not be used as backfill, because it may break down over time.
To begin: Select the backfill material you wish to verify. Then enter the required data from your provider’s sieve analysis and if your material meets our specification, you will receive a confirmation email from our Tank Technical Support department.