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To: Mr. Peter Hars <br /> Date: Fcbruaiti 21,2022 <br /> Pa<ue 19 <br /> CDWR Comment 3 <br /> The Applicant has conducted a baseline groundwater assessment to determine support <br /> geotechnical analyses, wetland mitigation decisions, and to assess potential impacts <br /> associated with the proposed sand and gravel mine. As part of the baseline groundwater <br /> assessment the applicant has constructed four monitoring wells. <br /> CDWR Response 3 <br /> Point of clarification,LRM installed 10 monitoring wells as shown in Figure 4 of the Dunn <br /> Pit Groundwater Baseline Report and well construction permits are included in Appendix <br /> A of the application. <br /> DUNN PIT (PERMIT NO. M-2021-059), ADEQUACY REVIEW OF <br /> APPLICATION WITH FOCUS ON INLET PROTECTION DESIGN <br /> AND HEC-RAS 2D MODEL — MEMO FROM ROB ZUBER, DRMS <br /> TO PETER HAYS, DRMS <br /> Comment 1 <br /> Please explain why the 9,000 cfs event is used for determining maximum velocities for weir <br /> designs. Were flows and velocities for larger storms not considered? In particular, the <br /> 100 year storm is listed as 20,309 cfs. <br /> Response 1 <br /> The DRMS Permit Application Appendix B2—Inlet Protection calculation documentation <br /> incorrectly states in the data and assumptions that the 100-year flood flow is 20,309 cfs <br /> (this is from other regulatory requirements). The table located in the revised inlet <br /> protection calculations correctly states that 9,000 cfs is associated with an —102.8-year <br /> recurrence interval. Return interval calculations for this analysis were derived from <br /> historical records obtained from gauging station "BIGLOVCO" located approximately 10 <br /> miles WNW (upstream) of the proposed Dunn Pit. Attachment 14 presents the revision to <br /> this calculation set(Appendix B2). <br /> Comment 2 <br /> Please provide design drawings for the pit inlet weirs, or reference other reports <br /> associated with this submittal that contain the drawings. <br /> 20220209_1045_DRMS_Adequacy_ReviewResponse_MASTE <br /> R.docx TELEST© <br />