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Rensian d I -Page 5 0(30 mining progresses across [he permit area. The pumps will discharge the groundwater into a settlement pond that will be located near the northwest comer of the site. Once the groundwater enters the settlement pond, it will percolate and recharge back into the water table or discharge to the Canning Factory Ditch located on [he north side of G Road. (4) Mining for sand and gravel will lag slightly behind the overburden highwall. The height of the sand and gavel highwall will be approximately 400-ft long and 12-ft tall. As the sand and gravel material is removed, it will be conveyed or trucked out of the pit for further processing. If the sand and gravel highwall is located within 100-ft of the north, south or west Permit boundary areas, all mining below the water table shall occur at a 3:1 max slope to minimize the potential of a landslide large enough to damage offsite structures. (5) Once the area has been mined for the sand and gravel, overburden material removed in front of the active sand and gravel highwall azea (and imported inert fill material) will be placed. The backfilling operations will lag behind the active sand and gravel highwall area . The backfill will be placed such that adequa[e compaction of the fill material can take place. The may be accomplished by backfilling the area in lifts, or by placing the fill on a gradual slope such that equipment have safe access to place and compact the fill material. Backfill materials will not be placed underwater. (6) Site reclamation m accordance with the reclamation plan section. (b) Earthmoving initial earthmoving on the project site will be performed to ensure all drainage will be contained within the project site. This will require a surface drainage Swale to be installed along the southern edge of the project site to contain surface flows within the project area. The drainage Swale will slope towards a new retention pond, which will be excavated near the west properv line. Another drainage Swale will be cut along the north and northwestern portion of the project site to collect runoff from within [he project site and divert it to the new retention pond. The new retention pond, located along the west property line, will be sized to reta'm the I DD-year storm event, as specified in the May 1996 edition of [he Stormwater Management Manual jot the City ojGrand Junction and ~Nesa County. The pond will have a storage volume of approximately 104,000 cubic feet, and will be approximately 600 ft Fong by 50 ft wide, and 6 ft deep. The project wit I also require the construe[ion of a settlement pond near the northwest comer of the site. The settlement pond wit{ be a maximum of one acre in size, with 3H:1 V side slopes. The overburden removed from [he pond area will be stockpiled around the pond perimeter. Earthmoving for the sand and gavel mining operations will consist of excavating the overburden soils, mining the sand and gravel, and backfilling the excavated areas using overburden soil and imported si[e materials. The typical sequence of operations is discussed in pan (a) above. (e) All water diversion and impoundment's The project site is currently hydraulically isolated from upgradient and adjacent property surface Flows. An irrigation ditch located on the adjacent property to the east collects upgadient runoff and divers it to the south. An existing catch basin located at the southeast comer of 23 Road and G Road collects stormwater runoff from the south half of G Road. Once the Flows enter the catch basin, it is routed through a culvert pipe under G Road and dump into the Canning Facton~ Ditch located along the north side of G Road.