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Site Investigation Report for the '
<br /> Former UST Locations at Stockton AASF
<br /> California Army National Guard ,
<br /> 1.0 SITE DESCRIPTION
<br /> 1.1 Site Location ,
<br /> The AASF is located in one of four CA ARNG divisional areas in the vicinity of 2000 Stimson Road, '
<br /> Stockton, Califomia.The divisional areas comprise the AASF,the Combined Support Maintenance
<br /> Shop (CSMS),the Field Maintenance Shop(FMS), and the Armory.Figure 1-1 shows the general
<br /> layout of the areas and site features. ,
<br /> 1.2 Installation Description and History
<br /> 1.2.1 The Stockton AASF, CSMS,FMS, and Armory are State-owned facilities operated by the ,
<br /> CA ARNG.The post consists of administrative offices; facility engineering; classrooms; training
<br /> facilities; security facilities;maintenance facilities; a gas station(previous); and several equipment,
<br /> vehicle, aircraft,and material storage locations/structures. '
<br /> 1.2.2 The AASF comprises a maintenance building(hangar),work bays and shop, supply areas, a
<br /> latrine, and offices; a wash rack; various storage sheds; concrete pads and ramps; and a refueling area ,
<br /> containing dispensers with three former 5,000-gallon USTs and two former 20,000-gallon USTs.
<br /> 1.2.3 Two former 20,000-gallon steel tanks were located at the AASF fueling area.The 20,000- '
<br /> gallon tanks were placed within a cement-lined constructed pit.The tanks had approximately half of
<br /> their surface area extending above the ground surface.For the purposes of this report,these two
<br /> 20,000-gallon tanks will be referred to as USTs. The single-walled USTs were removed in the mid- '
<br /> 1990s; the USTs historically contained jet propulsion(JP)-4/8 fuels (Lance, 2007).The two former
<br /> 20,000-gallon USTs were replaced with one 20,000-gallon aboveground storage tank(AST)located
<br /> immediately south of the two former USTs(the new AST contains JP-8 fuel).This AST is connected '
<br /> to the fuel island approximately 50 feet northwest of the AST.The fuel island location is also the
<br /> location of an existing 15,000-gallon UST containing JP-8 (Figure 1-2).
<br /> 1.2.4 Northwest/west and adjacent to the former two 20,000-gallon USTs are the three former USTs r
<br /> (5,000 gallons each)that were constructed of steel and installed in the early 1950s.The former USTs
<br /> were removed by Wallace-Kuhl in 1990.The former USTs were placed beneath the ground surface ,
<br /> and rested on a 6-inch-thick concrete slab. The slab remains in place and is estimated to exist at a
<br /> depth of 11 feet below ground surface(bgs). The fuel dispensers were moved from the northern side
<br /> of the UST location to the east side, approximately 30 feet away from the former UST area, during
<br /> the expansion project completed in 1974. Aviation gasoline was stored in the former USTs until '
<br /> 1962,at which time the USTs were then filled with JP-4,until 1989 (Versar, Inc., 2004).
<br /> 1.2.5 In April 2002, a release of approximately 5 gallons of fuel occurred adjacent to and south of '
<br /> both of the former 5,000-gallon and 20,000-gallon UST locations.The spill impacted approximately
<br /> 20 square feet of soil. The spill was reported and excavated immediately after the occurrence. On
<br /> 31 January 1990, an Unauthorized Release Form(No. 90-U1 l)was completed and submitted to the ,
<br /> San Joaquin County Public Health Services, Environmental Health Department(PHS-EHD)
<br /> (Versar, Inc., 2004).
<br /> K:\Wprocess\00251\CA ARNG\Stockton AASF SI\FINAL\SI Rpt.doc 2 lune 2008 ,
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