ARCHIVED REPORTS_CONCEPTUAL SITE MODEL

Home Browse Search

1 1. Introduction ' 1.1 Introduction On behalf of Chevron Environmental Management Company (Chevron), Blasland, Bouck & Lee, Inc. (BBL) has prepared this Conceptual Site Model (CSM) for Chevron Bulk Fuel Terminal 1001621 (site) located at 22888 Kasson Road in Banta, California. This CSM has been prepared in response to the San Joaquin County Environmental Health Department (SJC-EHD) letter dated August 12, 2004 (Appendix A). A copy of the California Regional Water Quality Control Board, Central Valley Region (CRWQCB-CVR) — Cleanup and Abatement Order(CAO)No. R5-2002-0718, dated August 15, 2002, and the CRWQCB-CVR—Monitoring and Sampling Program (MRP)No. R5-2002-0806, dated March 26, 2002, are also included in Appendix A. 1.2 Site Description and Features The site is located approximately five miles east of Tracy, in the agricultural community of Banta, California (Figure 1). The active fuel terminal has been in operation since 1966 and consists of nine-above ground fuel storage tanks (AST),tank-truck loading racks (TTLR), above- and below-ground piping, and an office building. An unmanned cardlock fueling facility known as the Banta Cardlock Fueling Network (CFN), located at Kasson Road and Interstate 5 (1-5) immediately southeast of the site (illustrated on Figure 2), is operated by Woolsey Oil Company and is not connected to the Chevron Bulk Fuel Terminal 1001621 (SECOR, 2003a). The tank farm area, which includes nine ASTs, is enclosed by a 3-foot high secondary containment berm. A portion of this berm forms a spill containment area, which is located in the northern portion of the terminal. ' Fuel lines from the fuel storage tanks run above ground within the secondary containment area as well as below ground within the TTLR (Figure 2). Retention ponds located on the north side of the terminal are used to store storm water as needed (SECOR, 2003a). 1.2.1 Geology tThe site is located in the Central Valley, which is a structural depression (approximately 400 miles long and 20 to 70 miles wide) extending from near Redding in the north to the Tehachapi Mountains in the south. Water- producing deposits in the valley consist primarily of unconsolidated continental deposits (alluvium) of Pliocene age that extend to depths of up to 3,500 feet below grade (USGS, 1998a). Stratigraphy is relatively consistent across the site. The local geology consists of recent unconsolidated alluvial and fluvial deposits to the total depths explored of approximately 65 feet below ground surface (bgs). These sediments are a mixture of gravels, sands, silts and clays; however, are principally mixtures of sandy-silts and silty-clays. Specifically, lean clay extends from the ground surface down to approximately 10 feet bgs, which is underlain by silty sand to poorly graded sand to a depth of approximately 30 feet bgs. Generalized geological cross sections are included as Figures 3 and 4. • BLASLAND,BOUCK&LEE, INC. 3124106 engineers,scientists,economists 1-1 J:\D0006\44634_00161022_Conceptual Site Model.doc