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11 <br />C <br />• 60 -mil HDPE secondary geomembrane <br />• Geosynthetic clay liner ((jCL,) <br />• Prepared subgrade <br />'WMU F -North was constructed in 1999 and is an approximately 1.3 -acre triangular- <br />shaped impoundment located just north of the South Branch of the SOttth Fork of <br />Littlelohns Creek. WMU F -West was constructed in 2003 and is an approximately 0.97 - <br />acre rectangular -shaped impoundment located directly west of WMU FU -03. Details on <br />the capacity of the impoundments and other associated design criteria, including average <br />leachate generation at the site, are listed in Table 1. <br />TABLE 1 — CLASS 11 IMPOUNDMENT DE7"AI1,S <br />Crest Area (sf) 59,242 42,183 <br />Base Area (sf) 44,550 27,153 <br />Crest Elevation (ft msl) 39.0 35.0 <br />Kase Elevation (ft msl) 27.0- 29.0 19.0-20.5 <br />Ballast on Base I -ft thick soil No ballast <br />Average Depth (ft) 10 15.25 <br />Average Precipitation (in) 13.76 13.76 <br />Estimated Pan Evaporation (in) 78.43 78.43 <br />Total Pond Volume (gal) 3,930,344 4,059,359 <br />2 -ft Freeboard Volume (gal) 785,400 617,795 <br />Net Pond Capacity (gal) 3,144,944 3,441,564 <br />- Storage Required for Precipitation (gal) <br />508,156 <br />361,831 <br />--> Approx Equivalent Pond Depth (ft) <br />1.15 <br />1.15 <br />+Capacity Available from Evaporation `s (gal) <br />2,537,263 <br />1,694,964 <br />—> Approx Equivalent Pond Depth (ft) <br />6.54 <br />6.54 <br />-Average Annual Leachate Generated' (gal) <br />612,322 <br />612,322 <br />Approx Equivalent Pond Depth (ft) <br />1.58 <br />2.36 <br />Average Available Capacity6 (gal) <br />4,561,729 <br />4,162,375 <br />APPROXIMATE TOTAL AVAILABLE CAPACITY = 8,724,100 <br />Nates: I. Precipitation obtained from Western Regional Climate Center for Stockton WSO for period from 1948 to <br />2013 (see Attachment A). <br />2. Evaporation data from Forward 3 I (BAS. GLA. 2007). <br />3. Precipitation storage calculated using crest area of pond. <br />4. Evaporation capacity available calculated using average of crest and base area. <br />5. Based on Forward leachate records from 1991 to 2012. Leachate assumed to be divided equally between <br />ponds. See Attachment A for leachate data. Equivalent pond depth calculated by dividing average leachate <br />volume by average pond area. <br />6. Available capacity calculated by subtracting precipitation and leachate storage and adding evaporation <br />storage to net pond capacity. <br />