Utility Vault Installation Guide - Shaw Precast Solutions

4. Specifications for BackfillingStructural Backfill used in the Utility Vault sides shall be of crushed and screened gravel or rock havingthe following Gradation Requirements when following ASTM C117 and C136 test methods:Sieve Size_mPer cent Passing112 000 10040 000 60 - 855 000 25 - 50315 5 - 1580 2 - 7Backfill against the structure shall be completed in layers no greater in depth than 300 mm and compactedto 95 % Standard Proctor. The backfill envelope around the structure should extend a minimum of 600mm around the Utility Vault’s perimeter. This operation is continued until the fill zone is at an elevation equalto the concrete deck of the Utility Vault.UTILITY VAULTINSTALLATION8U T I L I T Y V A U L T I N S T A L L A T I O N G U I D E