The specifications for Backfill Materials are as follows: a. 3/8" CRUSHED LIMESTONE This material shall consist of crushed, washed limestone (Modified Grade 5). All crushed limestone furnished under this specification shall meet the minimum requirements of San Antonio Water System Standard Specifications for Construction, Item No. 804, Excavation, Trenching and Backfill. b. 1-1/2" WASHED GRAVEL This material shall consist of rounded river rock. All Washed Gravel mixture furnished under this specification shall meet the minimum requirements of City of San Antonio Standard Specifications for Construction, Item 410, “Gravel Subgrade Filler,” June 2008 or latest version. Note: Rounded river rock meeting the gradation requirements provided in Item 410 – Subgrade Filler of the City of San Antonio Standard Specifications for Construction is required. Rounded rock is specified over crushed stone because SAWS prefers rock without jagged edges as bedding material for our pipe. c. WASHED SILICA SAND The material shall consist of washed silica sand, which is one of the raw materials used in the SAWS concrete mix. Silica sand consists of tiny granules of quartz, but also consists of other fine particles of rock and mineral. Washed Silica Sand shall be an evenly graded material having not less than 95 percent passing the No. 4 sieve and not more than 3 percent passing the No. 200 sieve. Additionally, all Washed Silica Sand material furnished under this specification shall meet the minimum requirements of City of San Antonio Standard Specifications for Construction, Item 300, “Concrete,” June 2008 or latest version.
