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Mr. Larry Oehler <br />TETRA TECH RMC Adequacy Response M-2004-044 <br />November 22, 2004 <br />Page 17 of 20 <br />understanding from the Ditch Companies. We will forward to.the Division upon <br />receipt. <br />3. Aggregate Industries must ag-ee to mitigate any negative impacts to the water <br />supply of neighbors within 600 feet of a,,(/ected land caused by the mining <br />operation <br />Owners of wells within 600 feet of extraction cells will be contacted and asked to <br />sign a 600-Foot Well Spacing Statement. If the owners indicate that the wells are <br />in use, Aggregate Industries will attempt to measure well depth, pumping rate, <br />pumping water level, and non-pumping water level prior to mining. Additionally, <br />if requested by the well owner, Aggregate Industries will attempt to measure <br />water levels in these wells quarterly prior to mining. <br />To establish a baseline, Aggregate has installed monitoring wells at the mining <br />site and will measure water levels monthly prior to beginning of mining, and <br />quarterly thereafter. Monitoring data will be used to identify potential changes in <br />alluvial groundwater flow or elevation associated with mining and reclamation <br />activities. Baseline data collected from the monitoring program will provide a <br />range of relative water levels associated with pre-mining groundwater conditions. <br />Experience at other sand and gravel mine sites in similaz geologic settings has <br />found that groundwater levels tend to fluctuate between two to four feet each <br />yeaz, being highest in the summer and lowest in the winter and early spring. <br />If, during mining, the relative seasonal groundwater elevation at any of the <br />domestic wells or monitoring wells differs from the baseline conditions by <br />more than two feet, and the condition was not observed during baseline <br />monitoring, or if Aggregate Industries receives a complaint from any well <br />owner within 600 feet from the site boundazy, then Aggregate Industries will <br />evaluate the eauseand-take aetion within 30 daysattd the DMGwiHire <br />notified. <br />ARer the DMG has been notified, Aggregate Industries will review the <br />available data and information and submit a report to the DMG within 30 <br />days. The evaluation will include discussions with any well owner who has <br />contacted Aggregate Industries regarding a concern and review of baseline <br />data from the well and vicinity to evaluate whether changes maybe due to <br />seasonal variations, climate, mining, or other factors. The report will identify <br />the extent of potential or actual impacts associated with the changes. If the <br />extent of groundwater changes due to mining or reclamation activities is <br />determined to be a significant contributing factor that has or may create <br />adverse impacts, the mining associated impacts will be addressed to the <br />satisfaction of the DMG. <br />H:U919 019_01\MLRB\DMC Response\1 st Adequacy Response to DMG I 1-5-04.doc <br />