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E%HIBIT "G" WATER IHFORY4ATIOH The opeartion of the gravel pit is not expected to directly affect surface or ground water systems. The site is proposed to be surface mined for the extraction of soil and gravel. The mining area boundary is south of the hilltops, therefore only south flawing runoff is impacted by the development. Runoff to the north is not disturbed and will continue to follow historic routes and flowrates. The excavation will not be visible from the north. The site does not have any surface water or ground water present due to the low water table at the mining site. The area is in a desert setting and not prone to flooding from adjoining properties. Any precipitation percolates faster than run off. Drainage on much of the sloped southern part of the permit area is toward the west. Runoff from the mining area is currently retained by a pond constructed near the southwest property corner with an estimated storage capacity of 75,000 cubic feet. A small earth dam approximately 6 feet high and 120 feet long blocks flow through an existing natural runoff channel and creates the pond. The pond will remain through out mining and after reclamation. Proposed mining activities will create additional storage capacity ~ through excavation of material which will leave voids for storage of runoff. All disturbed areas will drain into the property and~wiTl not produce offsite runoff. The existing retention pond is within the mining area and, if mined, could only produce additional storage for retention. Under the requirements of other regulatory agencies, the site must be revegetated as a reclamation condition. This reclamation will consist of reseeding the disturbed areas with native grasses and shrubs which will reduce runoff volumes and aid in erosion protection of the surface. Attached are calculations (Page G-2) for runoff volumes produced by the -~~ mining area under developed conditions prior to reclamation and revegetation (worst case). From a drainage standpoint, no adverse impact is created by the proposed gravel pit. Historic and developed runoff from the mining area is shown to be retained, thereby having no effect on offsite properties. Mining activities during development of the pit can only increase the amount of available retention storage, given an excavation and grading scheme as proposed. Reclamation revegetation, required for the pit, will aid in the reduction in surface erosion once established.