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JD -7 Mine — Drainage Design Plan 43
<br />4.6 Model Implementation of Stormwater Routing
<br />Due to the size and relative complexity of the JD -7 site, stormwater runoff in the current condition was
<br />modeled in four model runs covering different areas of the site (Table 19) for the current condition. Non -
<br />contact stormwater runoff from the crest of the escarpment to the valley floor reports to six outlets shown
<br />in Figure 21.
<br />The model implementation of stormwater routing for the four model runs is shown schematically in Figure
<br />22 through Figure 25. The sub - basins included in each WinTR -55 or HydroCAD model are also
<br />summarized in Table 20.
<br />Model run JD7_OPWDC_l l.hcp simulates the six sub - basins contributing runoff to the Open Pit Waste
<br />Rock Diversion (Figure 22). Model run JD7_PDEC_06.w55 simulates nine sub - basins contributing runoff
<br />from the escarpment to the valley floor and to the Pit Diversion East (PDE) (Figure 23).
<br />Model run JD7_CV 123 02.w55 evaluates runoff in the mine area north of the open pit and south of access
<br />road EEIT As shown schematically in Figure 25, stormwater is routed to one of three existing culverts
<br />(CV I, CV2, and CV3).
<br />Model run JD7_MYAC_05.hcp evaluates runoff in the mine yard area and underground- waste -rock pile
<br />area, north of the open pit and south of the access road prior to the improvements to Catchment OO1B -A
<br />North and 00113-A South. Stormwater runoff in the mine yard area is controlled by diversion ditches and
<br />catchment ponds which permanently or temporarily detain stormwater, by pond evaporation, by infiltration
<br />in the mine yard area, and by pumping and water treatment. These aspects of hydrologic routing were
<br />implemented using the HydroCAD® software. However, the HydroCAD model may overestimate
<br />downstream runoff from the mine yard area because pumping from the stormwater catchments into the
<br />water treatment system was not simulated. Instead, the model assumes that all stormwater reporting to the
<br />catchments is either retained or allowed to overflow into the receiving channels. Pumping to the water
<br />treatment ponds is a form of upstream storage that was conservatively not included in the runoff modeling.
<br />Model run JD7_MYAC_05.hcp evaluates runoff in the mine yard area and underground - waste -rock pile
<br />area after the improvements to Catchment 001B -A North and 001B -A South are completed (Plate 4).
<br />Table 19. List of Runoff Model Runs - Current Condition
<br />Model File Name/Description Sub - basins Reaches Storage Structures Outlets
<br />JD7_OPWDC_I l.hcp N -D, N -E, N- PitDivW, NE_Ch2,
<br />Non - contact water to OP waste rock diversion, F, D -1, D -8, NE_ChI, WR Divl, None VF1_Out
<br />current condition D -9 WR Div2
<br />N -A, N -B, N-
<br />VF2_Out,
<br />JD7_PDEC_06.w55 C N -G N -H, VF3_Out,
<br />Non - contact water to valley floor & pit N I N -J, N -K, PitDivE, D15-Ch None VF4 —Out,
<br />diversion east, current condition D -15 VF5_Out,
<br />PDE Out
<br />JD7_CV123_02.w55 D -2 D -3 D -4 None None CV 1, CV2,
<br />North portion of site to culverts CV3
<br />4149A.140207 Whetstone Associates •
<br />UGWRP -CDN,
<br />00 1 B-A-North, 001B-
<br />JD7_MYAC_05.hcp
<br />D -5, D -6, D -7,
<br />UGWRP -CDS,
<br />A- South, Yard Area, D7 Ch2
<br />Mine Yard Area
<br />D -16, D -17
<br />D6Ch, D7Chl,
<br />—
<br />UGWRP -NFA
<br />D7Ch2
<br />TD7_ MYAC_05.hcpJD7_MYAC_10_expN.hcp
<br />D -5, D -61 D -7,
<br />UGWRP -CDN,
<br />UGWRP -CDS,
<br />OO1B -A -North, 001B-
<br />A- South, Yard, D7_Ch2
<br />Mine Yard Area w/ Improvements
<br />D -16, D -17
<br />D6Ch, D7Ch1 & 2
<br />UGWRP -NFA
<br />4149A.140207 Whetstone Associates •
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