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iii iiiiiiiuiiu iii 999 ~~ Banks and Gesso, LLC ~~ • 720 Kipling St.,Suite117 Lakewood, Colorado 80215 (303) 274-4277 Fax (303) 274-8329 www. banksandgesso. com January 15, 2002 Tom Schreiner Colorado Division of Minerals and Geology 1313 Sherman Street, Room 215 Denver, CO 80203 fia~1 -- Dear Mr chreiner, RECEIVED JAN 16 2002 Division of Minerals and Geology On behalf of Loveland Ready Mix Concrete, Inc., we have reviewed the January 8, 2002 letter from the Division of Minerals and Geology, regarding proposed Technical Revision 1 to the Green/Croissant Sand and Gravel Mine 112 Permit (M-2001-022). This letter responds to the Division's comments in that letter, with our intent being the resolution of all DMG concerns prior to the date noted for approval, January 18"'. Your letter provided comment under three numerical headings, which this letter will respond to in kind Groundwater Monitoring Program 1.) Loveland Ready Mix Concrete, Inc installed three monitoring wells in October 2001. As proposed, these wells have been constructed in a manner that takes advantage of the entire potentiometric surface of the underlying bedrock. As of January 15, 2002, four months of water level data have been collected for each of the three monitoring wells (see enclosed spreadsheets). These four months of baseline information provide representative measurements for one quarter, as requested by the DMG. It is also very likely that four quarters of data will, as recommended, be available and submitted to the DMG prior to exposure of groundwater at the Green/Croissant property. 2.) Because of studies previously conducted in this area, as well as the nature of the proposed groundwater monitoring and mitigation program, we do not believe that it will be necessary to install a fourth monitoring well at the Green/Croissant site. Attached Figures 1 through 4 (pages from Geohydrology of the Shallow Aquifers in the Fort Collins -Loveland Area, Colorado, S.G. Robson, L.R. Arnold, and J.S. Henry; USGS Atlas HA-7466) show the direction and indicate a probable gradient for groundwater in the immediate vicinity of the site. You may orient the site on these pages by finding common elements on the Banks and Gesso, LLC site location map, including: the Hillsboro Ditch and Big Thompson (unlabeled on USGS) River, and the small reservoir along the Hillsboro Ditch located near the southwest corner of the Green/Croissant Property. The enclosed figures suggest that the water table, bedrock surface and direction of groundwater flow all contour toward the northeast corner of the subject property, with an average saturated thickness of approximately 20 feet. Given this study and other well data for the area, the aquifer characteristics for the Green/Croissant Property are relatively well-established, and provide an adequate framework for making hydrological inferences.