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JD -7 Mine - Drainage Design Plan 38 <br />to retain storm water from the 10 -year 24 -hour storm event and slow its velocity such that any suspended <br />sediment is deposited and contained onsite. <br />Drainage ditches have been constructed to collect and route water from the perimeter of the underground - <br />waste -rock pile to the south catchment (Catchment 001B -A South) and north catchment (Catchment 00113- <br />A North). Stormwater that collects in Catchment 00113-A North is pumped to Settling Pond #1 with a <br />sump pump on an automatic float switch. Stormwater in Catchment 00113-A South is pumped to Settling <br />Pond #3 using a manually activated pump. The settling ponds are operated in accordance with the <br />Discharge Permit for the site. <br />Table 15. Existing Stormwater Retention Ponds <br />Current Current <br />Facility Name Size Size Routed To <br />(ft) (acres) <br />Stormwater Catchment OO1B -A South 1,000 0.023 Pumped to Settling Pond #1, on <br />float switch <br />Stormwater Catchment 001B -A North 1,040 0.024 Pumped to Settling Pond #3, <br />manual <br />Table 16. Stage- Storage Data for Existing Stormwater Retention Ponds 001B -A South and <br />001 B -A North <br />Catchment 001B -A North <br />Catchment 001B -A South <br />Elevation <br />Depth <br />Surface Area <br />Elevation <br />Depth <br />Surface Area <br />ft <br />ft <br />(ft) <br />ft <br />ft <br />5742.0 <br />3.0 <br />275.00 <br />5736.5 <br />3.5 <br />103.1 <br />5742.5 <br />2.5 <br />371.25 <br />5737.0 <br />3.0 <br />175.0 <br />5743.0 <br />2.0 <br />480.00 <br />5737.5 <br />2.5 <br />265.6 <br />5743.5 <br />1.5 <br />601.25 <br />5738.0 <br />2.0 <br />375.0 <br />5744.0 <br />1.0 <br />735.00 <br />5738.5 <br />1.5 <br />503.1 <br />5744.5 <br />0.5 <br />881.25 <br />5739.0 <br />1.0 <br />650.0 <br />5745.0 <br />0.0 <br />1,040.00 <br />5739.5 <br />0.5 <br />815.6 <br />5739.75 <br />0.25 <br />905.5 <br />5740.0 <br />0.0 <br />1,000.0 <br />4149A.140207 Whetstone Associates <br />