5.3. PCSR 08-24-2004 - Laserfiche WebLink

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NATURAL RESOURCE GROUP, INC. MEMO TO: Steve Rohlf COMPANY: City of Elk River FROM: Matthew Ledvina, P.E. DATE: August 10, 2004 RE: J&B Mining — Groundwater Monitoring Plan, Storm Water Pollution Prevention Plan and Environmental Spill Plan Review NOTES/COMMENTS: As requested, I have reviewed the above referenced documents for the J&B Mining Gravel Mine. The following comments are provided in support of Conditional Use Permit (CUP) development for the Site. Groundwater Monitoring Plan Groundwater elevations were measured in June and July 2004. The relatively large size (40+ acres) of the area to be mined warrants a more detailed assessment of the near surface deposits and determination of the groundwater flow direction. Hydrogeologic cross- sections should be developed to propose a conceptual groundwater flow model and the definition of groundwater flow pathways. The consistency of the groundwater level data should be assessed. The groundwater flow interpretation for the site should be assessed in relation to the regional hydrogeology. In the conclusion section of the Plan, it is stated: "The groundwater elevation data from MW-1, MW-2, MW-3 and the wells on the adjacent Schmidt Gravel property are similar. The Groundwater Monitoring Plan for the Schmidt Gravel Property identifies a southeast groundwater flow while the J&B Mining Plan identifies an east-northeast groundwater flow. These interpretations are somewhat in conflict and the conclusions should represent joint analysis of all groundwater level data for the two sites. The groundwater elevations reported for the monitoring wells are roughly 943 to 945 feet. The elevation of the drainage ditch bottom is 940 (or lower) near the east property line. This implies that the ditch is likely a local groundwater discharge point and groundwater flow at the site may not be in a uniform direction. The relationship between surface water ditch and groundwater at the site must • 0 0 0 0 MINNEAPOLIS HOUSTON DENVER PROVIDENCE ANCHORAGE 1000 IQS Center Suite 200 Tower One,Suite 580 Suite 2020 Key Bank Plaza,Suite 301 80 South Eighth Street 520 Post Oak Boulevard 1515 Arapahoe Street One Financial Plaza 601 W.Fifth Avenue Minneapolis,MN 55402 Houston,TX 77027 Denver,CO 80202 Providence, RI 02903 Anchorage,AK 99501 612.347.6789 832.203.1492 720.956.5300 401.278.4300 907.777.5300