WORK PLANS - Laserfiche WebLink

Home Browse Search

v Site Assessment Work Plan Advanced Environmental Concepts, Inc. 3.0 SITE CHARACTERISTICS 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 4 easternmost edge, and portions of the Coastal Ranges occupy the 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 and spring. These features are identified as vernal pools and provide habitat for sensitive ecosystems. 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, The local gradient beneath the subject property is estimated to be toward the north. 4.0 WORK PLAN Advanced Environmental Concepts, Inc. proposes to advance a total of six soil borings, three around each former UST emplacement, to establish the potential presence and define the horizontal and vertical extent of hydrocarbon migration in the vicinity of the former UST's. Any boring in which both petroleum hydrocarbons and groundwater are encountered will be completed as groundwater monitoring wells. 4 4.1 Boring Locations and Depths AEC plans to advance six borings (B-1 through B-6) at the approximate locations plotted on Figure 2. One boring identified as B-1 will be drilled through the estimated center of Project: AEC 96C-1707 3 I.+ • ENVIRONMENTAL CONCEPTS WITH DESIGN IN MIND 4400 ASHE ROAD.#206 BAKERSFIELD.CA 93313 8051831-1646 FAX 8051831-1771