2013-09-16_REVISION - M1983028 - Laserfiche WebLink

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Exhibit Page 17 so that the County has responsibility for the work of reducing the highwall. The area east of the plant and stockpile area will be in reclamation: at final grade, with soil placed and in process of vegetation, up to 300 feet in width. Once operations move to the west of the McClellan property, the working face will be up to 500 feet long, and mining will move west and downhill a block at a time (most blocks are approximately 500 feet square). Highwalls will drop in height steadily until daylighting near the south (downhill) edge of the property, with a shallow swale and short berm. The highwalls on the permit/property boundary will continue to be reduced not more than 150 feet behind the working face, and the working face will generally be cut at a 2:1 slope to facilitate reclamation, so that no more than 200 feet of vertical highwall will be open at any time. Once mining is done in that western portion of the permit area, the space around the original Wallace Pit area (on the 78 -acre Stone property) will be mined in a similar manner. At this time, the pre -2013 disturbed area of 3.76 acres will be fully mined and reclaimed. Affected lands include roads, stockpile areas, berms, areas to be /being backfilled, and areas in buffer zones where sand and gravel are not actually mined. The actual area required for all mining /processing operations at any one time is between 5.75 and 8.26, averaging 7 acres. Other lands not appropriate for reclamation release; including the old 110 permit workings, areas in grass but not able to be released, water controls, temporary roads and stockpiles, and equipment storage; will average 7 acres. Mining area size assumes that all areas will be mined. However, in practice some areas may not be mined, due to excessive overburden, poor quality of material, or terrain. Permanent roads will be either retained or replaced on the floor of the pit as mining progresses, 200 to 300 feet at a time (at the same time soil is placed on land to either side of the road). Permanent roads will be built or rebuilt to County specifications. STOCKPILE CONSTRUCTION: SOIL: As much as possible, soil will be immediately spread on areas being reclaimed. In some cases, temporary stockpiles may be necessary. Stockpiles will either be berms (generally 10 -20 feet wide and 5 -10 feet high) used for storm water control, or in large stockpiles of varying sizes, to be determined. The berms and stockpiles will have a maximum slope of 1:1, and will be prepared (including stabilization against erosion), seeded, mulched (if needed) and fertillized (if needed) as they are completed. As stripping will generally be done in late summer or early fall, immediately prior to mining, seeding would usually be done in the fall, as recommended by NRCS. "EXCESS ": Overburden and fines from screening will also be backfilled immediately in reclamation areas, unless it is absolutely needed to stockpile in the same manner as soil. Fines will be able to be treated and used as subsoil and backfill, for reclamation. No toxic or acidic overburden or fines are anticipated. RAW AND PROCESSED MATERIALS: Stockpiles of raw and processed materials will be located in the mining and work areas, in such ways as to provide wind screens for plants and other stockpiles (for air emissions control and visibility reduction). Stockpiles will normally not be wetted or vegetated. Since there may be some fines from crushing and screening not sold, and sediment removed from storm water controls, these may be stockpiled similarly before backfill use. Various plants for processing and use of mined materials may be located in the mining and work areas, with necessary protection and controls. Because soil /overburden /waste fines stockpiles will be used only when it is not feasible to immediately backfill and replace topsoil in areas which have been mined, specific topsoil and overburden stockpiles, sizes, and locations are not shown in this plan, but will be shown on annual report maps. The exception is the existing stockpiles in the 110 permit area. SURFACE WATER MANAGEMENT: