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Control Runoff from Disturbed Areas. Storm runoff collected by the storm sewer in the <br />• plant area and runoff from the fill azea will be discharged to Arroyo "F" Sediment and Detention <br />Pond (see Figure 3). Runoff will be temporarily stored to facilitate sedimentation of particulate <br />matter before being released Arroyo "E." The Pond will provide sufficient storage for the entire <br />25-yeaz 24-hour flood event, plus sediment loads. Stored runoff will be tested for pH, total <br />suspended solids (TSS), oil and grease, chemical oxygen demand (COD), and, potentially, <br />blasting residuals (such as nitrates) and reported quarterly. <br />Calculations to size the Arroyo "F" Sediment and Detention Pond are provided in Part D <br />of the Calculation Appendix and include anazea-capacity chart for the proposed pond. <br />Manage Process Water Without Surface Water Discharge. Although process water <br />management is not part of the 112 Application, process water discharges were considered when <br />developing the surface water management plan. Anticipated dischazge rates were used to <br />approximate the area required for an evaporative pond located north west of the plant azea. <br />Possible locations for the evaporative pond were determined to have no effect on the surface <br />water management plan or the leach field for wastewater dischazges (see below). <br />Manage Domestic Wastewater. Domestic wastewater managment is not part of the 112 <br />Application, but wastewater discharges were considered when developing the surface water <br />management plan. Anticipated discharge rates were used to calculate the area required for a <br />septic system leach field located north west of the plant azea. Possible locations for the leach <br />field were determined to have no effect on the surface water management plan or the evaporative <br />• pond for process water dischazge (see above}. <br />Mining Activities <br />Mining activities include the initial box-cut, temporary stockpiles, blasting, removal of <br />resource material, backfill and reclamation of the land surface. Management of surface runoff <br />from these activities will include detention, sediment ponds and diversion ditches with the <br />following goals and objectives: <br />^ Control storm water within active mining azea. <br />^ Control storm water discharges from active mining area. <br />Control Storm Water Within Active Mining Area. During the initial box-cut operation, <br />there will be limited space available to stockpile materials within the mining area. Therefore, <br />temporary stockpiles will be placed near the northeast side of panel 1 for a period likely less than <br />1-year. Storm runoff from these temporary piles will be trapped by earth or hay bale dikes <br />constructed along the down slope perimeter of the stockpiles. Sediment in the runoff will be <br />deposited by gravity in ponding that occurs adjacent to the dikes and/or filtered by the hay bales <br />before dischazging to Diversion Ditch #1 and Arroyo "E." <br />After the initial box cut expands to the full panel size, management of surface runoff and <br />. sediment will adjust to the larger azea. Storm water generated in the pit (and including tributary <br />5 WMP BC June 28 2002.doc, 06/28/02 <br />