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Applegate <br />Group, Inc. <br />Water Resource Advisors for the West <br />May 20, 2015 <br />Ms. Ioana Comanichiu <br />Division of Water Resources <br />1313 Sherman Street, Suite 818 <br />Denver, Colorado 80203 <br />RE: Request for 90 -Day Test Approval of the SerFer Pit Liner <br />Mine ID No. M-2008-006 <br />Dear Ms. Comaniciu: <br />The 90 -day period for the liner leak test on the SerFer Pit has completed. During the initial 66 <br />days of the test the reservoir had standing water in the bottom. On April 14, 2014 at your request <br />the standing water was pumped out of the reservoir. The contractor scarified and recompacted <br />the reservoir bottom and the reservoir bottom remained dry with the exception of precipitation <br />for the remainder of the leak test period. Due to heavy rainfall and scheduling for the final survey <br />the testing period was 91 rather than the required 90 days. Calculations were adjusted <br />accordingly. <br />Procedure <br />A rain gage is located on-site and data collection was performed weekly and specifically after all <br />precipitation events. Precipitation data was also gathered at nearby weather stations. As <br />mentioned above, water was pumped out of the reservoir on April 14, 2014. The total volume <br />pumped was 2.66 acre-feet. No other water entered or left the pit or repaired areas during the 91 - <br />day test except through precipitation and evaporation. A copy of the rain gage data is included as <br />an attachment to this letter. <br />Because there were two distinct periods of testing, calculations were performed in two parts: day <br />1 through day 66 with standing water on the bottom of the reservoir, and days 67 through 91 <br />with little to no standing water. A water balance equation was applied to the data to determine <br />the amount of water that seeped into the test area during the two phases of the testing period. <br />Evaporation was considered in these calculations since standing water was present. The seepage <br />calculation has been compared with the allowable seepage calculation derived from the equation <br />provided by the State. <br />Weather data was collected from two nearby weather stations, one located in southwest Windsor <br />and one in Highpointe Estates. The Southwest Windsor weather station is located at Lat: N <br />7405 W. Highway 50, Suite 123 1490 W. 121" Avenue, Suite 100 118 W. 6`1' Street, Suite 100 <br />Salida, CO 81201 Denver, CO 80234 Glenwood Springs, CO 81601 <br />303-452-6611 <br />www.applegategroup.com <br />