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Windsor East Mine, Exhibit G – Water Information September 2022 <br /> Page 10 | 11 <br />2.2.3 Domestic and Irrigation Water Wells <br />No active water wells (water-supply wells) were present within 600 ft of the lease area. <br />2.2.4 Dewatering Discharge <br />Based on data collected from monitoring wells on the adjacent Parsons Mine property, the depth to groundwater <br />fluctuates by two feet depending on the season but averages about 7 feet below ground surface. Due to the <br />absence of large quantities of potential pollutants on site (no on-site processing or concrete or asphalt <br />production), the mining and reclamation operations are not likely to affect groundwater quality on or off the site. <br />Martin Marietta’s Parsons facility complies with applicable requirements in the site CDPS General Permit <br />COG501594 for Discharges Associated with Sand and Gravel Mining and Processing. CDPHE WQCD considers <br />stormwater runoff combined with mine dewatering water to be process water. Currently permitted discharges at <br />the Martin Marietta Windsor East Site and Parsons Pit are permitted as process water discharges. As such, <br />process water discharges are subject to the process water provisions in the general permit. Martin Marietta plans <br />to obtain a City of Windsor Grading, Erosion and Sediment Control Plan (GESCP) Permit and comply with <br />applicable requirements as stated in the City of Windsor’s Municipal Code/Ordinance Chapter 13, Article, <br />Stormwater Quality. <br />2.3 MITIGATION <br />The available monitoring well data will be used to identify changes in alluvial groundwater flow associated with <br />mining and reclamation activities. Baseline data collected from the monitoring program will provide a range of <br />relative water levels associated with pre-mining groundwater conditions. These data will be utilized to evaluate the <br />nature and extent of the change to the prevailing hydrologic balance and if necessary, provide for the <br />development of corrective actions. Well owners in the section below refer specifically to owners of wells from <br />which extracted water is put to beneficial use, such as water wells, irrigation wells, etc. Owners of monitoring <br />wells are not considered well owners in this context, since a change in water levels for these wells does not <br />represent material damage. <br />In the event of a well owner complaint within 600 feet of the Affected Area, Martin Marietta will review the <br />available monitoring information and submit a report to the DRMS within 30 days. The report will include <br />discussions with any well owner who has contacted Martin Marietta regarding a concern and a review of baseline <br />data from the well and vicinity to evaluate whether changes may be due to seasonal variations, climate, mining or <br />other factors. The report will identify the extent of potential or actual impacts associated with the changes. <br />If the extent of groundwater changes due to mining or reclamation activities is determined to be a significant <br />contributing factor that has or may create adverse impacts, the mining-associated impacts will be addressed to <br />the satisfaction of the DRMS. If the DRMS determines that the impact on a well for which temporary mitigation <br />has been initiated is not a result of Martin Marietta’s activities or is not solely a result of Martin Marietta’s activities, <br />Martin Marietta will reduce or cease mitigation accordingly. <br />If a well goes dry, Martin Marietta will implement mitigation measures within 7 days. Mitigation measures would <br />include providing a temporary alternative water supply that meets the documented historic well production, or <br />need until further investigation can be conducted to determine if the well condition is due to the mining operation. <br />Martin Marietta will begin to implement one or more mitigation measures if mining or reclamation activity is <br />determined to be a significant contributing factor to groundwater changes requiring mitigation. <br />Temporary mitigation measures may include, but are not limited to: <br /> Compensation for well owners to use their existing treated water system to replace the well production <br />loss; <br /> Provision of a water tank and delivery water as necessary to meet documented historic well production or <br />need; <br /> Other means acceptable to both the well owner and Martin Marietta.