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Only limited areas outside the undisturbed Southern Pit area remain. Mining during 2016 will excavate <br /> the remaining sections of paying gravels outside the Southern Pit area. All remaining mining will take <br /> place south of Access#4,which was the historic sluice route. Initial tailings and overburden from mining <br /> the South Pit will be utilized to backfill and contour some remaining areas that require fill north of <br /> Access#3. Once those areas are filled all material handling will occur only in and around the South Pit. <br /> Previously a series of ditches and ponds were planned to be used to control run off in this area. Instead <br /> the first cut will be utilized as the impoundment for all surface run off within the South Pit area. <br /> Progression of the cuts within the South Pit will backfill the previous cuts while still utilizing the active <br /> as the impoundment. Initially a diversion, as shown on enclosed map, will divert all site water within <br /> the planned affected area to Cut A of the South Pit. As the cuts are filled the diversion will be moved <br /> uphill to maintain an appropriate flow path for storm water. <br /> The ditch will be oversized and dug with an excavator. Ditch dimensions will at a minimum be 3 deep <br /> and 6 feet wide. The ditch will have a minimum fall of 2%. The resulting channel capacity for this <br /> minimum designed ditch would be a-100 cfs at a depth of 1.3 feet. This leaves 1.7 feet of freeboard for <br /> additional safety. Run-on water will be diverted around the area by the existing Columbia Ditch, which <br /> was designed to convey 60 cubic feet per second and is not actively used over this section. <br /> A minimum of 6 feet of freeboard within the current phase Cut A was observed on our site visit in April <br /> 2016. This was prior to any pumping and during spring runoff conditions. Total surface of Cut A is—5 <br /> acres. This results in a pond capacity of 30 acre feet. 100-year 24-hour event for the areas is 3.0". If <br /> 100% of the water within the South Pit area(35.4 acres) reports to this pound the volume would be 8.9 <br /> acre feet. After this type of event there would still be 21.1 acre feet of available storage or 2.9 feet of <br /> freeboard. During operation the cut will be pumped leaving 20-60 feet of available freeboard during <br /> operation. <br /> The South Pit will be mined in 3-5 acre blocks. 2H:1V side slopes will be developed by benching to get <br /> to the bedrock. These sequential cuts are labeled on the South Pit Mine Phasing Plan Map. South Pit Cut <br /> A has already been dug. Its topsoil has been used to develop the berm shown on the enclosed map. This <br />