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Mr. David LaGrone <br /> Mr. Tim Carey <br /> June 29, 2005 <br /> Page 2 <br /> • Two 6" pumps have been placed at the north end of the east pond and are used to pump <br /> surface water into the"U-shaped pond; <br /> • An overflow culvert has been placed at the southeast end of the "L"-shaped pond so that <br /> excess surface water can flow south into the dry slough. From the dry slough, the surface <br /> water flows into an overflow culvert and into the Cache La Poudre River. <br /> • Groundwater seepage from the "L"-shaped pond into the mitigation area occurs when the <br /> "U-shaped pond is at a normally full level of surface water. <br /> Weld County will pump surface water from the east pond into the"L"-shaped pond during mining <br /> activities and in non-mining times when drought conditions or xeric conditions occur to keep <br /> surface water levels at a normal elevation. The mitigation area is being intensely monitored for this <br /> end. Keeping the surface water levels normal in the "L"-shaped pond encourages groundwater to <br /> seep north and east into the mitigation area. As described in the 2002 Annual Monitoring Report, <br /> natural conditions (which occur at natural surface water levels in the "U-shaped pond) support a <br /> diverse and viable wetland. Weld County intends to maintain the overflow hydrology system and <br /> surface water pumping system as part of the mining operation. Post-mining conditions within the <br /> Geisert Pit Mining Area will support exceeding to near normal surface water hydrology to the <br /> mitigation area as natural fluctuations of the groundwater and surface water stratum will not be <br /> tempered with pumping but will be a direct result of the flows of the Cache La Poudre River. <br /> If you have any questions or need additional information please feel free to contact me at 970-356- <br /> 4000, ext. 3750. <br /> Sincerely, <br /> Frank B. Hempen, Jr., P.E. <br /> Director of Public Works/County Engineer <br /> PC: Jeff Jerome, Operations Division Manager <br /> Darcy Tiglas <br /> Greg Nelson,Mining Supervisor <br /> Geisert Gravel Pit file <br /> M TRANK\2005\Geisan Pit hydrology letter to David LaGrone.doc <br />