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i` <br />ALBERT FREI & SONS <br />February 23, 2010 <br />RE,C;:IVF <br />FEB r 4 Z010 <br />omwon o+ ,--ec; OUW, <br />Wing and 80* <br />Mr. David Bird <br />Division of Reclamation, Mining & Safety <br />1313 Sherman St., Suite 215 <br />Denver, Co 80203 <br />Dear Mr. Bird; <br />RE: Technical Revision <br />Stagecoach Pit <br />Permit #M-1983-067 <br />P.O. BOX 700 <br />HENDERSON, CO 80640 <br />(303) 289-1837 <br />(303) 289-2865 FAX <br />ne¢y <br /> <br />This Technical Revision addresses how Albert Frei and Sons, Inc., will correct the <br />impacts the Stagecoach Pit slurry wall is having on the ground water levels east of the mine. It <br />addresses the single corrective action noted in your Inspection Report dated May 27, 2009. In <br />this condition, the Division required us to file a Technical Revision to address the noted <br />highwater in the Zigan Lake and elevated ground water levels noted in the monitoring wells <br />along the east side of the slurry wall. In addition it addresses the concerns Mr. Ebert raised in his <br />pit inspection dated 2/26/2009 regarding the topsoil pile located in the mining area. <br />In July 2009 the Zigan Lake Homeowner's Association (HOA) and Albert Frei and Sons, <br />Inc. reached an agreement to temporarily install a pump in their lake to regulate the water level. <br />Their records showed the lake was as much as 6 feet higher then historic levels. Pumping began <br />in August and the lake level was lowered to normal levels. It has remained at this lower level <br />since September. The regulation of the lake level lowered the ground water level to the west <br />showing that there is a direct correlation between the lakes elevation and the level of the water <br />behind the slurry wall. Once this was established we have devised a plan to permanently fix the <br />problem by regulating the lake's level. <br />Attached are plans for installing a permanent drain structure between the Zigon Lake and <br />the South Platte River that will allow the HOA to control the lakes elevations. Deere & Ault. <br />Consultants, Inc. was retained to design the permanent fix based on the data collected since <br />August. This involves installing a lake level control structure, an eighteen inch pipe to carry the <br />overflow from the lake to the river crossing the south end of the mine and a ground water <br />recharge pond. The intake structure will be placed in the lake area so no pumping will be needed