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<br />November 16, 2010 <br />Mr. Jared Ebert <br />Environmental Protection Specialist <br />Division of Reclamation, Mining and Safety <br />1300 Sherman Street, Suite 200 <br />Denver, CO 80203 <br />Re: <br />jtl/? ar GX aJC'c?- ,'9 <br />4V <br />Permit No. M-2000-082 - East 8th Street Operation <br />Technical Revision (TR91); Response to Adequacy Review #1 <br />Dear Mr. Ebert: <br />In response to the Division's November 5, 2010 adequacy review regarding Aggregate <br />Industries' (Al) technical revision request of October 27, 2010 (TRO 1): <br />Phase 2 Monitoring: <br />Aggregate Industries commits to installing two additional groundwater elevation <br />monitoring wells in accordance with the Division's direction. One well will be <br />positioned between the Phase III mining area and the northern Duggan well and the other <br />well will be positioned between the Phase III mining area and the southern Duggan well. <br />The approximate proposed locations are identified as MW-3 and MW-4 on the enclosed <br />drawing. Al proposes to install these additional monitoring wells a minimum of twelve <br />(12) months prior to commencement of dewatering activity in the Phase III mining area, <br />with the wells to be monitored on a monthly basis from the time of installation until <br />reclamation is complete and the Division releases the financial warranty bond. Results of <br />the monthly measurements will be submitted with the annual reclamation report to the <br />Division. <br />The design for the proposed wells will be consistent with the design and installation of <br />the existing Phase 1 wells at the site. A bore hole at each location will be advanced <br />through the sand and gravel sediments (alluvium) to an approximate depth of 50 feet. <br />Cuttings from bore holes will be geologically logged, with drive samples typically <br />collected every five feet. A two-inch diameter, PVC casing will be constructed in each <br />bore hole, with the majority of the casing being slotted. The slotted portion of the well <br />will be surrounded by natural sand and gravel and/or a silica sand filter pack. The wells <br />will then be backfilled to just below the ground surface with bentonite chips to provide a <br />seal against surface water. Each well will be completed with an above ground locking <br />Aggregate Industries <br />West Central Region, Inc. <br />1707 Cole Blvd., Suite 100 <br />Golden, CO 80401 <br />Fr AGGREGATE <br />INDUSTRIES <br />A-__ <br />Connie N. Davis, Land Advisor <br />P. O. Box 337231, Greeley, CO 80633 <br />Phone: (970) 396-5252 <br />Telephone: 303-985-1070 An Equal Opportunity Employer