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MEMO <br /> <br />TO: <br /> Steve Rohlf <br />COMPANY: <br /> City of Elk River <br />FROM: <br /> Matthew Ledvina, P.E. <br />DATE: <br /> August 10, 2004 <br />RE: <br /> J&B Mining - Groundwater Monitoring Plan, Storm Water Pollution Prevention Plan and <br /> Environmental Spill Plan Review <br />NOTES/COMMENTS: <br /> <br />As requested, I have reviewed the above referenced documents for the J&B Mining Gravel Mine. <br />The following comments are provided in support of Conditional. Use Permit (CUP) development for <br />the Site. <br /> <br />Groundwater Monitorin.q Plan Groundwater elevations were measured in June and July 2004. The <br />relatively large size (40+ acres) of the area to be mined warrants a more detailed assessment of the <br />near surface deposits and determination of the groundwater flow direction. Hydrogeologic cross- <br />sections should be developed to propose a conceptual groundwater flow model and the definition of <br />groundwater flow pathways. The consistency of the groundwater level data should be assessed. <br />The groundwater flow interpretation for the site should be assessed in relation to the regional <br />hydrogeology. <br /> <br />In the conclusion section of the Plan, it is stated: "The groundwater elevation data from MW-l, MW-2, <br />MW-3 and the wells on the adjacent Schmidt Gravel property are similar. The Groundwater <br />Monitoring Plan for the Schmidt Gravel Property identifies a southeast groundwater flow while the <br />J&B Mining Plan identifies an east-northeast groundwater flow. These interpretations are somewhat <br />in conflict and the conclusions should represent joint analysis of all groundwater level data for the two <br />sites. <br /> <br />The groundwater elevations reported for the monitoring wells are roughly 943 to 945 feet. The <br />elevation of the drainage ditch bottom is 940 (or lower) near the east property line. This implies that <br />the ditch is likely a local groundwater discharge point and groundwater flow at the site may not be in <br />a uniform direction. The relationship between surface water ditch and groundwater at the site must <br /> <br /> · O O <br /> MINNEAPOLIS HOUSTON DENVER <br /> 1000 lEtS Center Suite 200 Tower One, Suite .580 <br /> <br /> 80 South Eighth Street 520 Post Oak Boulevard 151.5 Arapahoe Street <br />Minneapolis, MN .5.5402 Houston, TX 77027 Denver, CC) 80202 <br /> 612.347.6789 832.203.1492 720.9,56..5300 <br /> <br /> O O <br /> PROVIDENCE ANCHORAGE <br /> Suite 2020 Key Bank Plaza, Suite <br /> 301 <br />One Financial Plaza 601 W. Fifth Avenue <br />Providence, RI 02903 Anchorage, AK 99501 <br />401.278.4300 907.777.5300 <br /> <br /> <br />