11 02/18 trench in one-foot lifts and compact as above. For trenches excavated in roads, streets, or located under structures, place backfill in 6- inch layers to the top of the trench and compact each layer to at least 95 percent maximum density (ASTM D1557, Method D). START-UP PROCEDURE: Start-up procedure shall conform to generally accepted practices and be done in a workman-like manner. Improper start-up of high temperature lines may damage the piping system and attached equipment. MANUFACTURERS WRITTEN CERTIFICATION: After testing and prior to start-up of the system, the manufacturer must certify in writing that the system was installed per the manufacturer’s installation instructions.