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C'EARWATER <br /> G R O iJ P, I N C. <br /> 1 . <br /> 1.0INTRODU ION <br /> �- This report presents the results third quarter 1995 groundwater monitoring <br /> performed by Clearwater Group, Inc. (Clearwater) on October 18, 1995 at 1210 Vera i <br /> Avenue in Ripon, California (Figure 1). The tasks performed during this phase of <br /> work included groundwater gauging, well purging, and groundwater sample <br /> collection. In addition, the top of casing on ead i well was re-surveyed at the request <br /> of the San Joaquin County Public Health Sery ces, Environmental Health Division <br /> (PHS/EHD). <br /> 2.0 BACKGROUND <br /> The project site is located on the southerly outskirts of Ripon in an agricultural and ; <br /> residential area. The Stanislaus River meanders in a southwesterly ,direction <br /> approximately 2,000 feet south of the site (Figure 1). Municipal water treatment <br /> ponds are located approximately 1,000 feet south. and east of the site. <br /> 1 Two 10,000 gallon underground storage tanks (UST's) were removed from the <br /> subject location on May 23; 1990. The site currently has at least one above ground <br /> fuel tank. The site layout, including former UST locations, is presented in Figure 2. <br /> A review of available tank removal documents indicated that the tanks were used <br /> to store regular gasoline and diesel fuel. Soil samples collected from beneath the <br /> UST's during removal did not contain total Fetroleum hydrocarbons as gasoline <br /> (TPHg), kerosene, or motor oil, benzene, toluene, ethylbenzene, and total xylenes <br /> (BTEX) or tetra-ethyl lead above respective method detection limits. One sample <br /> contained total petroleum hydrocarbons as diesel (TPHd) at a concentration of 9,800 ' <br /> parts per million (ppm). <br /> Three 2-inch-diameter monitoring wells were stalled by Clearwater on February <br /> 23, 1995. No petroleum hydrocarbons were detected in soil samples collected during. <br /> soil borehole drilling, however, all three.groundwater samples collected from the <br /> monitoring wells on February 28, 1995 contained TPHd in concentrations up to 330 <br /> parts per billion_ (ppb): <br /> ` D-104 3Q95 Q 1 November 28,1995 <br />