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Soil &Groundwater Excavation Work Plan Advanced Environmental Concepts, Inc. 3.0 SITE CHARACTERISTICS The following sections summarize the project site features and conditions along with regional and local geological and hydrological characteristics. w 3.1 Site Description The subject property consists primarily of fallow ground primarily used for seasonal cover crops. A farm compound is located in the central area of the property p p p rty and includes a residence, storage barn (former almond huller), and a quonset but used to store and distribute lubricating oils,solvents, and paints. +r 3.2 Regional Geology v San Joaquin County is part of four separate physiographic regions in California. The majority of the county is located within the lower San Joaquin Valley,which extends from north to south through the eastern portion of the county. Most of the remainder of the county, in the western area, is located in the Sacramento-San Joaquin Delta. Foothills of the Sierra Nevada occupy the easternmost edge, and portions of the Coastal Ranges occupythe southwestern portion. Landforms of the lower San Joaquin Valley include flood plains, alluvial fans, fan terraces, basins, dunes, and low and high terraces. �., Surface topography is generally flat, although relief in some areas ranges from undulating to hilly due to dissection and erosion. Nearly level flood plains are located along the Stanislaus, Calaveras, San Joaquin, and Mokelumne Rivers. All of these flood plains were subject to regular flooding prior to development of levees and reservoirs. Natural drainage ways in San Joaquin County generally flow from east to west;the San Joaquin River,largest in the county,flows from south to north. Flood plains are also located along Hospital, Lonetree, and Corral Hollow Creeks. Flood waters in these areas dissipate on leveled alluvial plains before reaching the San Joaquin River. The Stanislaus and Mokelumne Rivers deposit alluvial material originating the Sierra Nevada Mountains, forming extensive alluvial fans and fan terraces. Wind-deposited sand dunes were once common along the Stanislaus River. Many of these dune areas have been artificially leveled and reclaimed for agricultural use. Many low and high terraces along the eastern edge of the San Joaquin Valley have developed complex surface drainage patterns and microrelief. One of these drainage patterns occurs as a meandering or disarranged pattern of intermittent channels which double back on each other. In some areas,short segments terminate at small closed basins that commonly fill with water during the winter ,r and spring. These features are identified as vernal pools and provide habitat for sensitive ecosystems. 3.3 Local Geology and Hydrology The property is located on gently sloping southwest grade with an average elevation of 50-feet above mean sea level. Surface sediments consist of unconsolidated,poorly bedded clays and silts with minor +� sand components. The majority of groundwater pumped from the area occurs within unconsolidated continental deposits. Regional groundwater flow direction (gradient) beneath the site area is generally toward the north and west. Depth to first unconfined groundwater is estimated to range between 2 and 14 feet below grade level (BGL) beneath the site. Irrigation and domestic water is obtained from `r approximately 60 feet BGL. The local gradient beneath the subject property is estimated to be toward the north and east. 4 Project: AEC 97V-1805 6 .ENVIRONMENTAL CONCEPTS WITH DESIGN IN MINI). 4400 ASHE ROAD,0206 BAKERSFIELD.CA 93313 8051831-1646 . FAX 8051831-1771