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• • Revision#I-PageSo(30 <br />mining progresses across the permit azea. The pumps will discharge the groundwater into a <br />settlement pond that will be located near the northwest corner of the site. Once the <br />grotmdwater enters the settlement pond, it will percolate and recharge back into the water <br />table or discharge to the Canning Factory Ditch located on the north side of G Road. <br />(4) Mining for sand and gravel will lag slightly behind the overburden highwall. The height of <br />the sand and gravel highwall will be approximately 400-ft long and 12-ft tall. As the sand and <br />gravel material is removed, it will be conveyed or trucked out of the pit for further processing. <br />(5) Once the area has been mined for the sand and gravel, overburden material removed in front <br />of the active sand and gravel highwall area (and imported inert fill material) will be placed. <br />The backfilling operations will lag behind the active sand and gavel highwall area . The <br />backfill will be placed such that adequate compaction of the fill material can take place. The <br />may be accomplished by backfilling the area in lifts, or by placing the fill on a gradual slope <br />such that equipment have safe access to place and compact the fill material. Backfill <br />materials will not be placed underwater. <br />(6) Site reclamation in accordance with the reclamation plan section. <br />(6J Earthmoving <br />Initial earthmoving on the project site will be performed to ensure all drainage will be contained <br />within the project site. This will require a surface drainage Swale to be installed along the <br />soutfietn edge of the project site to contain surface flows within the project area. The drainage <br />Swale will slope towards a new retention pond, which will be excavated near the west property <br />line. Another drainage Swale will be cut along the north and northwestern portion of the project <br />site to collect runoff Rom within the project site and divert it to the new retention pond. <br />The new retention pond, located along the west property line, will be sized to retain the 100-year <br />storm event, as specified in the May 1996 edition of the Stormworer Management Manual jot the <br />City ojCrand Junction and Mesa County. The pond will have a storage volume of approximately <br />109,000 cubic feet, and will be approximately 600 R long by 50 ft wide, and 6 ft deep. <br />The project will also require the constmction of a settlement pond near the northwest comer of the <br />site. The settlement pond will be a maximum of one acre in size, with 3H:1 V side slopes. The <br />overburden removed from the pond area will be stockpiled around the pond perimeter. <br />Earthmoving for the sand and gravel mining operations will consist of excavating the overburden <br />soils, mining the sand and gravel, and backfilling the excavated areas using overburden soil and <br />imported site materials. The typical sequence of operations is discussed in part (a) above. <br />(c) A!! water diversion and impoundment's <br />The project site is currently hydraulically isolated Rom upgradient and adjacent property surface <br />Flows. An irrigation ditch located on the adjacent property to the east collects upgradient mnoff <br />and diverts it to the south. An existing catch basin located at the southeast comer of 23 Road and <br />G Road collects stormwater mnoff from the south half of G Road. Once the Flows enter the catch <br />basin, it is routed through a culvert pipe under G Road and dump into the Canning Factory Ditch <br />located along the north side of G Road. <br />During the mining and reclamation process, all precipitation within the project site will be <br />collected and remain on the project site. A drainage Swale will be installed along the north, west <br />and south property lines, which will collect and divert surface flows into a new retention pond <br />