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• <br />3.12 Investigations for borrow within the reservoir area <br />included IO test pits and bo~eholes by U.S. Bureau of Reclamation <br />(BuRec) in 1976, and 50 test pits and 3 seismic traverses by SWEC <br />in 1985. The reservoir borrow areas under consideration <br />generally include the alluvial and colluvial deposits. on .the <br />right side of the reservoir below high water level, designated <br />Borrow Aria 1; and the Savery and Little Sandstone Creek valley <br />bottoms, designated Borrow Area 2 (appendix A). Borrow Area 2 <br />was located east of Savery Creek for borrow estimating purposes, <br />but could be expanded westward with the stream channel realigned <br />to increase borrow quantities, if needed. <br />3.13 An estimated 6,000,000 cubic yards of material are <br />available from Borrow Area 1 for the central impervious core and <br />the pervious outer shells. An estimated 1,200,000 cubic yards of <br />materials are available from Borrow Area 2 for the upstream free- <br />drainage zone fill and professing for drain material and concrete <br />aggregate. <br />3.14 Hard and durable riprap greater than 1 foot in diameter is <br />not available on-site. The most probable sources of riprap are <br />found in the Pot Hook area of Colorado,. approximately 7 miles <br />east-southeast of the town of Savery, Wyoming. <br />3.15 Foundation treatment for Sandstone Dam would consist of <br />excavation of unsuitable soil and rock, sloping back steep rock <br />slopes, grouting and drainage. Dense, pervious sand and gravel <br />was found in the valley bottom and directly above bedrock on the <br />left abutment. This material would be left in place in the <br />valley bottom and under the downstream slope of the left <br />abutment. All other soil overburden would be excavated to rock. <br />A core trench would be excavated through the alluvium left in <br />place and ripped about 10 feet into rock. No blasting is <br />contemplated in the trench. <br />3-6 <br />