2005-10-24_REVISION - M2000016 (2)

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Provide a water tank and deliver water as necessary to meet documented historic well production or need; Other means acceptable to both the well owner and Lafarge. Long-Term: - Cleaning a well to improve efficiency. - Providing an altemative source of water or purchasing additional water to support historic well use in terms of water quantity and quality. If needed, water quality parameters will be checked in affected wells to ensure altemative sources support the historic use. - Modifying a well to operate under lower groundwater conditions. This could include deepening existing wells or lowering the pumps. Al] work would be done at Lafarge's expense with the exception of replacing equipment that was non- functional prior to mining. - If existing wells cannot be retrofitted or repaired: replacing the impacted well with a new well. - Providing flood imgation to address concerns over impacts to sub-irrigated lands adjacent to the site. • If a groundwater mitigation action is required, Lafazge will notify the Weld County Engineer and the DMG of the condition, action taken, and result. TREES AND WETLANDS Two yeazs prior to mining, Lafarge will hire a qualifed expert to inventory the off-site vegetation. Lafarge will attempt to obtain access ageements from adjacent landowners to install shallow wells in the cottonwood galleries and identified wetlands. Impacts to trees will be mitigated through monitoring and if necessary, managed recharge of the alluvial aquifer or watering of the trees. The frequency of monitoring will be as described above. If the water level data indicates that the water table beneath the trees declines by more than one foot of the pre- mine water levels during the growing season, or the trees show signs of stress, Lafarge will commence mitigation measures within 10 days of the determination of impacts. Lafarge will hire a qualified expert to perform regular inspections of offsite vegetation. The inspection frequency will be twice per year, once in the spring and once in the summer. The mitigation measures would be by one of two methods: 1) Watering of the wetlands or trees using dewatering water, or 2) Managed recharge of the alluvial aquifers. The managed recharge would be accomplished using basins positioned between the mine cells and the wetlands or trees. The basins would be filled with dewatering water. The basins would extend along the perimeter of the mine cell between the cell and the trees. The basins would be excavated to the top of the gravel (about 5-8 feet) with side slopes of 2:1 (horizontal:vertical). The bottom width would be about 4-8 feet. Lafarge West, Inc. Aiverbend - S - October 2005 Groundwater Monitoring and Mitigation Plan H:\4137_012_02\Groundwater\Riverbend GW Mon & Mitigation Plan 8-2605.doc