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hour storm events to assure the 1990 impoundment configuration met the <br />performance standards. The design evaluation indicated that the spillway <br />configurations present (circa -1990) were inadequate for a permanent <br />impoundment. Consequently, SCC proposed to implement a remedial action <br />plan to satisfy the permanent impoundment requirements (see Appendix 7 -6g, <br />page 7 -6g -18 and Exhibit 7 -18, Proposed Permanent Impoundment Pecoco). The <br />remedial action plan covered the following four items: <br />1) Replace the existing 24 -inch corrugated metal pipe (CMP) with a <br />proposed 24 -inch CMP with an anti -seep collar to the line and grade <br />as shown on Exhibit 7 -18. <br />2) Replace existing v- shaped emergency spillway with proposed <br />trapezoidal channel as depicted on Exhibit 7 -18. <br />3) Raise the embankment to the line and grade as shown on Exhibit 7 -18. <br />4)' Install a fence to maintain safe access to the impoundment area. <br />In their Technical Revision 37 (TR -37) adequacy review comments dated July <br />11, 2005, CDMG requested that SCC submit documentation that demonstrates <br />the remedial action items proposed on page 7 -6g -18 were implemented. <br />I <br />As -Built Configuration <br />SCC completed a survey in August and October 2005 to document the existing <br />impoundment configuration. A drawing developed to document the 2005 survey <br />information is presented as Exhibit 7 -18A, PECOCO Impoundment As- Built. <br />The 2005 survey shows that PECOCO covers approximately 2.6 acres. The <br />permanent pool, at an elevation of 6,775.5 feet, is approximately 2.0 acres <br />in size and has a storage capacity of 19.6 acre -feet (ac -ft). The <br />permanent pool elevation is maintained by spoil spring seepage, which <br />averages about 40 gallons per minute (see Annual Hydrology Reports for flow <br />records for site SSSPG5). <br />The survey indicates a top of embankment elevation of 6,780.0 ft. The top <br />width is approximately 15 feet with minimum upstream and downstream slopes <br />of 4.5H:1V and 3H:1V, respectively. The embankment elevation of 6.780.0 ft <br />is similar to the elevation shown on Exhibit 7 -18. <br />TR -37 2 Revised 10/05 <br />