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<br />The AST system currently includes one 20,000-gallon diesel tank and one 10,000-gallon <br />gasoline [aril: within a bermed area. A leaking 10,000-gallon diesel tank was removed from <br />the berried area in March 1996. The AST-system berm consists of a 3-foot high concrete <br />wall surrounding the tanks and ahigh-density polyethylene (HOPE) membrane underlying <br />the tanks. Located approximately 20 feet to the south of the bemted area is an AST <br />dispenser island. A buried gasoline line and an aboveground diesel line run from the <br />location of the ASTs to the dispenser island. <br />1.0 FIELD ACT/VITIES <br />On Iviay 8, 1996, prior to conducting intrusive field activities, Geo-Recovery Systems, Inc. <br />(Geo-Recovery) was contracted to locate buried utilities in the vicinity of the AST system. <br />With the aid of a schematic drawing provided by SWPC illustrating the approximate <br />location of buried utilities, Geo-Recovery employed geophysical techniques to identify and <br />mark the location of utility corridors. The locations of buried utilities in the vicinity of the <br />AST system are shown on the attached Figtue 2. Also shown on the Figure 2 is the location <br />of an abandoned north-south trending surface-water drainage ditch, located to the east of the <br />AST system. This ditch was described by S WPC personnel as a "V"-shaped, concrete-lined <br />swcture extending 2 to 3 feet below ground surface. The surface-drainage ditch has been <br />abandoned and filled with soil to a level flush with the surrounding concrete slab-covered <br />ground surface. <br />Areas of pooled free diesel product were observed within bcm\cd area of the AST system. <br />The pooled product was initially observed beneath the HOPE mcmbrmtc. During sample <br />hole installation, several incisions were made in the membrane, allowing the free product to <br />pool above the membrane. Oil staining was observed on concrete surfaces in the vicinity of <br />the AST system. This staining was observed on: 1) the inside lower portion of the AST <br />berm walls; 2) the outside lower portion of the south and cast berm walls; 3) the ground <br />surface of an adjacent bermed area to the west, 4) the immediate area of the frlel dispensers; <br />and, 5) at the joints of the concrete surface to the south and east of the AST system. The <br />area of observed oil staining is shown on the attached Figure 2. <br />Also on May 8, sample holes SH-1 and SH-2 were advanced within the bermed area of the <br />AST system to collect soil and groundwater samples. On May 9, seven boreholes were <br />advanced in the vicinity of the AST system. Six of the boreholes were converted into <br />temporary groundwater monitoring wells. The locations of the AST investigation sample <br />holes, boreholes, and monitoring wells aze shown on the attached Figure 2. <br />ERh1-ROCr:Y h10UNrAIN, MC. <br />P:\100015 WPC1961019ViEPORT.DOC Printed on Rr:cyeled Paper <br />2 <br />