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QX 99-2 INITIAL STUDY Project Description The project is a quarry excavation to remove 2.5 million tons of aggregate in two phases over twelve years. Excavated material will be extracted using a back-hoe type loader and transported along private roads by haul trucks to an existing aggregate processing plant across the Mokelumne river and about one-half mile west. The trucks will cross the river on an existing private bridge currently used for the adjacent quarry excavation to the south. Reclamation of the site will occur simultaneously with excavation. Topsoil and overburden will be removed from about five acres and set aside. The excavation will then progress in approximately five-acre increments. The topsoil and overburden removed from the subsequent five acres will be placed on the preceding five acres until the site is mined. The original stockpiled material will then be placed on the remaining five acres. General Considerations: The site of the proposed quarry excavation is adjacent to the Mokelumne River, a County park, and a currently operating quarry excavation. It is about two miles downstream from a fish hatchery, and less than half a mile from the town of Clements. An Environmental Impact Report (ER-90-8) was prepared for the adjacent excavation, 2.4 million tons of material over approximately 10 years, and some of the information from that EIR may be used as baseline information for this project. However, the location of this proposed quarry presents several issues not addressed in ER 90-8. This Initial Study was prepared without the benefit of responses from responsible and interested agencies and parties and is based upon experience with similar quarry excavation projects and analysis already completed. It will be amended, where appropriate, when referral responses are received. Environmental Impacts: la County Flood Control expressed concerns with the project. A portion of the project is located in both the 100 hundred and 500 hundred year flood zone. Though no structures are planned on the site, a flood event would cause the entire project site, as well as the adjacent quarry site to the south, to be inundated with floodwater. 1 bcd The removal of 2.5 million tons of material will result in alteration of runoff and drainage patterns at the site, may result in the reduction of surface water quality, and result in sedimentation to the Mokelumne River. If floodwater from a 100 hundred year event or unusually heavy precipitation were to occur, floodwater entering the site would result in erosion of the site and its banks and sedimentation to the river, causing degradation of water quality and potential alterations to downstream river flows. Any floodwater trapped on the site, according to the applicant, would be pumped into the river. This may also add