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Applicant's Response to Second Adequacy Letter <br />Grand River Park Project, DRMS File M-2006-046 <br />January 2, 2007 <br />Page 19 <br />excavation and de-watering activities. If a slurry wall will not be installed, <br />the Division requests that the applicant provide a comprehensive "Water <br />Management Plan" and schematic which describes how pit inflows and pit <br />outlaws from de-watering operations will be managed during each phase <br />of the operations, i.e.: Phases 1a, 1b, 2, 3a, & 3b. The Water <br />Management Plan must include a schematic diagram for each phase of <br />operation showing how water inflows and outflows will be managed and <br />routed so as to minimize impacts to water dependent sources. <br />A slurry wall will not be installed at the site, as this feature would not be <br />economical to install or to maintain in the intended post-mining use, nor would it <br />resolve groundwater issues without generating potentially problematic conditions <br />itself. <br />Please see the attached reports and plans by Martin & Wood Water Consultants <br />and R. Mike McDermid, P.E., for additional response to this question. <br />g. The application references two (2) irrigation ditches that cross through the <br />proposed permit boundary. Please provide a discussion of the physical <br />condition of the portions of the Rising Sun Ditch and Last Chance Ditch <br />that pass through the proposed permit area and the potential for them to <br />be adversely affected by pit dewatering operations. For example, are the <br />ditches lined or unlined? What type of leakage rates do they exhibit? <br />What times of year are they typically in use? Do either of the ditches have <br />a direct hydrologic connection with the shallow groundwater surface in the <br />area? What is the potential for an adverse impact to either ditch due to <br />de-watering? Please respond. <br />The physical condition of the Rising Sun Ditch and the Last Chance Ditch is, in <br />both cases, typical of smaller irrigation projects. The attached adequacy <br />response letter from Martin & Wood Water Consultants discusses, in detail, the <br />physical condition of the ditches and considerations that minimize risks to water <br />rights. Furthermore, in response to Comment 21 e, above, the applicant provides <br />a detailed discussion of the potential for adverse effects to irrigation ditches that <br />cross through the subject property. <br />The applicant notes that excavation is setback at least 25 feet from the ditch, with <br />only vehicular access (along existing driveway alignments) actually encroaching <br />on the ditch corridors. Mining operations are not anticipated to physically alter <br />the condition of the ditches and will not undermine the stability of the ditch <br />channels; the attached stability report by Lyman Henn, Inc., finds that mining <br />slopes will be safe for an adjacent ditch if excavation activities adhere to specific <br />engineering criteria, including mining to a 2:1 slope from a 25-foot no-mining <br />setback. <br />