2012-01-24_PERMIT FILE - M2011054 (4)

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MN Paul Banks and Associates, LLC January 20, 2012 Dear Travis: ILO L' DivIsiun of :v famaUUn, Mining & SF-ifety Travis Marshall Division of Reclamation, Mining and Safety Grand Junction Field Office 101 South 3rd — Suite 301 Grand Junction, CO 81501 - rm 720 Kipling Street — Suite117 Lakewood, Colorado 80215 (303) 274 -4277 (303) 274 -8329 Fax www.paulbanksandassociates.com ReceivED JAN 2012 arm) C :i i f EU) 111.11 DIVISOCN RIGINAATVON WINO a wee Subject: Response to Adequacy Review for Debeque Sand and Gravel Resource, Permit No. M- 2011 -054. Oldcastle Southwest Group, Inc. On behalf of the applicant we are submitting a response to your adequacy review letter dated January 11, 2012. Our responses are given below in the order presented by Division (with the Divisions' comments in italics for reference): 1. In accordance with Rule 6.4.7 (2)(b), the Division requests that the applicant identify and characterize the aquifer to be mined in or through. The Division also requests that the applicant define or predict the cone of depression expected for any areas to be dewatered. The cone of depression and assessment of other effects should define, at a minimum, the horizontal and vertical extent of expected impacts. If during the assessment, the applicant determines that a drawdown effect will occur offsite that may impact a current groundwater user, the applicant should explain any mitigation measures to be implemented and trigger points that would cause mitigation measures to be put into effect. The Applicant will also need to establish a baseline for the current groundwater levels through at least 5 quarters of groundwater level measurement. Attached to this letter is a report on the impacts of dewatering at the Debeque Sand and Gravel Resource property. The report was prepared in 2008 for the previous DRMS permit application on this property. The report characterizes the aquifer and predicts the cone of depression resulting from the dewatering. The report predicts that there will be some off site drawdown of ground water levels but that the wells will still be able to pump at pre- mining rates. It should be noted that the computer model used very conservative assumptions and that the location of wells in the area is from the State Engineer's Office database and is not reliable for identifying accurate location of wells. Also, the model assumed no recharge to the aquifer, which is a very conservative assumption. A monitoring and mitigation plan is also attached to this letter.