2008-11-03_REVISION - M1999098 - Laserfiche WebLink

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EXHIBIT G-4 GROUNDWATER MONITORING AND MITIGATION PLAN PURPOSE This Groundwater Monitoring and Mitigation Plan presents the methods for monitoring of groundwater during mining and reclamation, and for mitigating groundwater impacts due to mining. This Plan is prepared for incorporation into the Colorado Division of Reclamation, Mining and Safety amended permit (DRMS Permit No. M-1999-098) for the Aggregate Industries' Riverview Resource operation. Aggregate Industries-WCR, Inc. has an existing gravel pit well permit (Well Permit No. 62555-F) for this facility and operates under Aggregate Industries South Platte Combined Replacement Plan, which covers depletions caused by gravel mining operations at multiple mine sites operated by Aggregate Industries, including the Riverview Resource site (aka W. W. Farm Pit). The gravel pit will permit and temporary substitute water supply plan will be amended with the State Engineer's Office as necessary to address any additional depletions resulting from operations as they occur within the amendment areas. GROUND WATER MONITORING Monitoring Well Installation In December, 2001, thirteen monitoring wells (MW-1 through MW-13) were installed at the Riverview Resource site and a monthly water level monitoring program began. Thirteen (13) months of data were collected from these wells prior to commencement of de-watering of the existing, permitted site in January, 2003. Measurements of these wells has continued on a monthly basis throughout operations on the existing permitted site and data collected is submitted annually to the DRMS together with the annual fee and report for M-1999-098. In January of 2008, seven (7) additional monitoring wells, MW-14 through MW-20, were installed and incorporated into the monthly monitoring program. Monitoring wells will continue to be monitored on a monthly basis until reclamation is complete and the DR-MS releases the financial warranty bond, or portions thereof for which certain well monitoring data is no longer deemed necessary by DR-MS. All monitoring wells were installed outside the limits of mining so that groundwater could be monitored during and after mining. Locations of the wells are shown on Exhibit C Pre-Mining and Mining Plan Maps. The objectives of the well installation and monitoring program are to monitor groundwater conditions and provide a basis for assessing the impacts of mining on surrounding groundwater. Through the well monitoring program, pre-mining groundwater elevations, flow patterns across and near the property, and seasonal fluctuations have been, and will continue to be, documented. Aggregate Industries-WCR, Inc. - Riverview Resource - 1 - February 11, 2008 Groundwater Monitoring and Mitigation Plan River Resource Amendment to Permit M1999098 112C Page G8 of G37