1. 1-1/2" x 3/4" filter gravel in 4000# sacks without pallets 2. 3/4" x 3/8" filter gravel in 4000# sacks without pallets 3. 3/8" x 3/16" filter gravel in 4000# sacks without pallets PHYSICAL CHARACTERISTICS OF GRAVEL All filter gravel shall be composed of quartz, flint granite, quartzite, or other siliceous or igneous material. Filter gravel shall be visually free of shale, mica, silt, clay, dirt and organic impurities. The saturated surface-dry specific gravity of the filter gravel shall not be less than 2.50 and not more than 1% by weight and shall have a specific gravity of 2.25 or less. Individual pieces of gravel shall be reasonably smooth and well rounded, with a thickness not less than one-third the length or onehalf the breadth. N
