5.1 PCSR 03-28-1995 - Laserfiche WebLink

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03/22/95 14:32 $612 559 2202 BA LIESCH 002/003 • LIENCH B.A,LIESCH ASSOCIATES, INC, 13400 15TH AVE.N. MINNEAPOLIS, MN 55441 612/559-1423 FAX:612/559-2202 MEMORANDUM TO: Mr. Steve RohIf - City of Elk River FROM: Mark Olson and John Lichter DATE: March 15, 1995 RE: Northern Con-Agg., Inc. Gravel Mining Plan At your request we have completed a review of the Northern Con-Agg application entitled "Conditional Use Permit Update for Mining and Processing at the Existing Northern Con-Agg., Inc. Elk River Gravel Mine." The application was well organized and generally addressed the potential environmental concerns identified by the Elk River Sand and Gravel Mining District EIS. The following few comments regarding the proposed water level and quality monitoring • are offered for your consideration and use in completing the conditional use permit process. Pages 11 and 12 of the application indicate that gravel mining is targeted for a base elevation of 955 which is approximately 10 feet above the water table. However, dependant on market demand and the quality of the material available, it is stated that mining may extend to a lower elevation which is below the water table. If mining is to extend below the water table, two water quality monitoring events for volatile organic compounds (VOCs) are proposed. The sampling events are to occur before excavation below the water table begins, and again during mining activities. It is assumed that the proposed monitoring is to be protective of the increased potential for impacts to come in contact with the exposed water table from mining equipment. It is not stated where the water samples will be collected. Based on the potential source of impacts, which are principally the fluids associated with mining machinery, it may appear prudent to add Diesel Range Organics (DRO) and Gasoline Range Organics (GRO)to the parameter list. In addition, the sampling locations should include the two shallow on-site wells (Northern Con-Agg Wells #1 and #2), and the nearby Nemeth residential well. For clarification, it is noted that Northern Con-Agg Well#1 is the 4-inch scale house well designated as well "E" in the EIS (see Table 3.3-2 and Figure 3.3-1 in the EIS); and Well #2 is the 16-inch wash water well designated in the EIS as well "F". The Nemeth residential well is located due south of Northern Con-Agg Well 4'2 (well "F"). With regard to sampling frequency, it may be desirable to identify that a sampling event occur • at the cessation of mining activities for the year. This latter sampling event could be in addition to, or in place of, the second sampling event proposed in the document. If a spill should occur, it is stated that floating booms be used to collect the product spilled product. Sampling during mining activities may best take place in the event of such a release.