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1.0 INTRODUCTION This work plan specifies the work steps proposed to further investigate the extent of impacted soil and groundwater beneath the site. 1.1 Site Description The subject site is located at 1040 Moffat Boulevard in the city of Ripon and county of San Joaquin, California (Figure 1). The site is an operating cement mixing plant, situated east of Jack Tone Road between Moffat Boulevard and State Highway 99. One, 4,000-gallon diesel underground storage tank (UST) was previously removed from the northwest part of the site and one, 500-gallon gasoline UST was a"andon ped on the northwest side of the plant building (f=igure 2). 1.2 Previous Work On April 14, 1995, SEMCO removed one, 4,000-gallon, steel, diesel UST from the north side of the site. The PHS/EHD inspector noted "obvious signs of contamination and odor". Two soil samples (TK-N and TK-S) were collected from beneath the ends of the UST, at a depth of 12 feet below ground surface (bgs). The soil sample collected from beneath the north end of the UST (TK-N) contained 4,100 milligrams per kilogram (mg/kg) of Total Petroleum Hydrocarbons (TPH)- as-diesel and low concentrations of ethylbenzene (0.41 mg/kg) and xylenes (1.3 mg/kg). Benzene, toluene, TPH-as-kerosene and TPH-as-motor oil were not detected in this soil sample. The soil sample collected from beneath the south end of the UST contained only 4.2 mg/kg of TPH-as-diesel. Benzene, toluene, ethylbenzene, xylenes (BTEX), TPH-as-kerosene, and TPH- as-motor oil were not detected in this soil sample. In June 1996, under contract to Rajappan & Meyers, Inc., Michael Brandman Associates completed an Initial Site Assessment (ISA) for the Route 99/Jack Tone Road Interchange Reconstruction Project. The ISA concluded that the site required a Preliminary Site Investigation (PSI) to evaluate potential soil contamination in the vicinity of the interchange. Subsequently, Rajappan & Meyers, Inc. contracted with URS Greiner, Inc. to complete the PSI. During the week of May 9, 1997, URS Greiner, Inc. completed the PSI. The scope of the PSI included the drilling of 4 soil borings on the Nelson Ready-Mix site. Soil and groundwater-grab samples were collected for analysis from each of the 4 on-site soil borings. Soil and groundwater- grab samples collected from soil boring (SBA), drilled on the west side of the former UST 4