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need to indicate the linear footage of slurry wall to be constructed and <br />provide a time schedule for when various portions of the slurry wall will <br />be completed. <br />Response: The Division is referred to the response to Item #13 above and to <br />Attachments #5, 6, and 7 regarding slurry wall construction. <br />29. Comment: The applicant has referenced probable impacts to ground water relating <br />to mine dewatering and final reclamation activities via the January 28, <br />1997 RMC letter to Scott Gudahl. These probable impacts are based on <br />RMC's experience with other pits sealed with either liners or slurry <br />walls. In order to accwately evaluate the impacts to surface and/or <br />ground water at the Lyons Pit-Rockin' WP site and surrounding azea, <br />the Division requests that the applicant provide a detailed hydrogeologic <br />evaluation of the expected impacts to surface and/or groundwater <br />during both mining and during final reclamation. This evaluation should <br />include the depth and lateral extent of the cone(s) of depression <br />expected during the various phases of the mine plan when dewatering is <br />employed. The evaluation should also include an inventory of all wells <br />(regazdless of use) that occw within the cone(s) of depression and an <br />assessment of the impact expected to each particular well. The well <br />inventory should include the following information for each well: owners <br />name and address, location, use(s), depth, screened interval, yield, and <br />construction details. The applicant will also need to provide a revised <br />map showing the location of each of these wells. The hydrogeologic <br />evaluation should also define the vertical and lateral extent of impacts to <br />ground water for all lined water featwes All wells that occw within the <br />upgradient and/or downgradient zone of influence should be inventoried <br />and assessed as discussed above These wells should also be located on a <br />revised map (The operator may also delineate on a revised map the <br />location of all wells on or within 600 feet of the distwbed land that aze <br />not expected to be affected by dewatering or slurry wall construction). <br />Response: The Division is referred to Attachment #8, "An Analysis of Possible <br />Groundwater and Surface Water Impacts Resulting from the Lyons- <br />Roclcin' WP Gravel Pit," prepared by Bishop Brogden Associates, Inc. <br />DMG Adequacy Review Response Page 12 <br />