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2273 River Road, P.O. Box 3609 21830 Hwy. 550 South, P.O. Box 1909 1300 County Road 44ZN, P.O, Box 928 <br />• - Cnand Junction, CO 81502 Montrose, CO 81402 Norwood, CO 81423 <br />(970) 243-4900 (970) 249-1815 (970) 327-4586 <br />FAX: (970) 243-5945 FAX: (970) 240-8497 Fell(: (970) 327-4113 <br />July 9, 2002 <br />[3~d~/~Q3 Received <br />Mr. Steve Shuey 4~a~, ~~~ ~ 9 2002 "~ <br />Environmental Protection Specialist ~ ~~` ~~ <br />Colorado Division of Minerals and Geolo / ;~qP Grand Junction Fieid Office <br />$y /G ~ ~~~visio~ of Minerals & Geology <br />Grand Junction Field Office Qr~o~ ~ !~l <br />101 South Third Street, Room 301 pn„ <br />Grand Junction, CO 81501 / ~ioo4o0~ -"! <br />Dear Steve, j ~-©~./ cPO~Oar <br />In response to your Second Ade ac eview (July 5, 2002) of UyiYed Companies' <br />proposed Technical Revision No. for the Preston Pit Extensio (M-1980-022)(/ <br />submitted on May 31,2002, please accept and evaluate the following additional <br />information. <br />I believe that Technical Revision 1 was actually submitted for this permit and approved <br />by the Mined Land Reclamation Board on March 24, 1983. Technical Revision 1 <br />changed the shape but not the area of the peninsula. I regret any confusion that this <br />mistake has or will create. <br />This proposal should be referred to as Technical Revision 2. <br />ADEQUACY ISSUES <br />3. Please specify what the total depth of Till is above and below the water line. <br />I used the Mesa County map of the site and the Typical Slope Section that was <br />transposed from the original Reclamation Plan Map for this site to estimate the backfill <br />thickness. The Mesa County map shows 14 feet of elevation difference typically <br />between the lake surface and the level land surface in the area where backfill <br />placement is proposed. <br />I used the Typical Slope Section to predict the lake's water depth. The elevation at the <br />bottom of the lake is shown as 4526 feet. The water line is shown as 4535 feet. (This is <br />reasonably close to the water line shown on the Mesa County topographical map, 4534 <br />feet.) <br />A reasonable prediction of average thickness, at the existing shore location, would be <br />to combine the fill thickness predictions for the proposed backfill zone or 14 feet <br />(above the waterline) plus 9 feet (below the waterline) for a total of 23 feet. <br />1 <br />