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Mineral Joe Mine — Drainage Design Plan 31 <br />5. PEAK FLOW MODEL RESULTS <br />Peak flow rates were calculated for five design storms, including the 10-year 24-hour storm, 25-year 24- <br />hour storm, 50-year 24-hour storm, and 100-year 24-hour storm. As discussed previously, the design <br />criteria for stormwater conveyance structures at the Mineral Joe Mine is the ability to pass the 100-year 24- <br />hour storm. The design criteria for retention structures is the ability to retain the 10-year 24-hour storm and <br />to pass the 100-year 24-hour storm. The flow rates and channel depths associated with these storm events <br />were determined using the WinTR-55 model and the results are described below. <br />5.1 Peak Flow Rates <br />The UDS conveys the highest flows at the site. Peak flow through the UDS ranges from 20.15 cfs for the <br />10-year 24-hour storm to 62.40 cfs for the 100-year 24-hour storm (Table 17). Most of the runoff to the <br />UDS is provided by Sub-Basin N-A, with additional contributions to peak runoff derived from Sub-basins <br />N-B and N-C and the small triangular parcel in the adjacent eastern sub-basin (Table 17). <br />60- <br />so <br />40 <br />LL <br />30- <br />20 <br />101 <br />----------- ----------------------- ----------- ----------- ---------- <br />----------------------------------- ----------- ----------- ---------- <br />----------- ----------------------- ---------------------------------- <br />................................ ........... ........... .......... <br />---------------------------------------------------------------------- <br />--------°- 4 ----------- #---°°----i--------- -. ----------- ---------- <br />----------- ----------- ----------- ----------- ----------- ----------- <br />LVOMM e(cfs) <br />100_yr. LVAVM {cfs) <br />----------- ----------- ---------- <br />----------- ----------- ----------- ----------- ----------- ----------- <br />........... L ........... L ........................ ........................ <br />---------- ------------ ----------------------- ------------ I ------------ I- <br />- --------- ------------ I ----------- ----------- ----------- ----------- <br />TIM E(W) <br />Figure 16. Hydrograph for the Upper Diversion Structure <br />4148B.131029 Whetstone Associates 6 <br />