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DEERE & AUL'T <br />May 23, 2006 <br />Mr. Dave Nettles, P.E. <br />State Engineer's Office <br />810 9th Street, Suite 200 <br />Greeley, Colorado 80631 <br />Re: Brannan Pit No.29; South Cell 30 Day Interim Leak Test Results, <br />United Water and Sanitation District; D&A Job No. CG0178.002.00 <br />Dear Mr. Nettles: <br />This letter provides a summary of the liner system leak test currently ongoing at the Brannan Pit <br />No. 29 South Cell. The 90-day leak test is progressing in conformance with the State of Colorado's <br />August 1999 State Engineer Guidelines for Lining Criteria for Gravel Pits. The test period began <br />on April 10, 2006. The leak test is progressing as outlined in the work plan submitted by Deere and <br />Ault Consultant's Inc. (D&A) on February 13, 2006. <br />ALLOWABLE LEAKAGE RATES <br />State guidelines describe allowable leakage rates as a function of liner wall area and the area of the <br />reservoir floor encompassed by the liner. The allowable leakage rate calculated for the Brannan Pit <br />site south cell equates to 80,496 gallons per day (gpd) or approximately 56 gallons per minute <br />(gpm). The leakage defined by the performance standard is three times the design standard for a <br />total of 241,488 gpd (-168 gpm). <br />LEAK TEST PROCEDURE <br />Pump discharges from the south cell are measured using a meter on the pump discharge line. The <br />pump operates as needed to maintain a minimal level of pooled water, which is controlled by an <br />automatic switch attached to a floatation device. <br />Precipitation inflows have been estimated by measuring a rain gauge daily, measuring snowfall <br />depth (if appropriate), and observing values recorded at a nearby weather station. A daily log of <br />discharged water and precipitation has been maintained. Daily values will be totaled from the test <br />duration and compared with the allowable values per State guidelines. <br />600 S. Airport Road, Building A, Suite 205 <br />Longmont, CO 80503 <br />Phone: 303-651-1468 Fax: 303-651-1469