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Former Discovery Chevrolet . <br /> March 22, 1995 <br /> Quarterly monitoring and sampling of the monitoring wells begin in March 1995. <br /> Historically, depth to groundwater has fluctuated between 9.86 and 11.53 feet bgs. <br /> Groundwater appears to flow toward the north-northwest at a gradient of approximately <br /> 0.003. Floating product has not been observed in the monitoring wells. TPHg, BTEX, or <br /> Oil and Grease have not been detected in well MW-3. TPHg concentrations in wells MW-1 <br /> and MW-2 have ranged from 60 to 17,000 ppb, and benzene concentrations have ranged <br /> from 10 to 3,100 ppb. Historical quarterly groundwater monitoring and chemical analytical <br /> data are summarized in Table 1. <br /> PRESENT QUARTER FIELD ACTIVITIES <br /> Quarterly monitoring and sampling of the groundwater monitoring wells for the first quarter <br /> 1996 was performed by G-R on February 20, 1996. Field monitoring and chemical <br /> analytical data from the current quarter are summarized in Table 1. The G-R groundwater <br /> sampling procedures are summarized in Appendix A. Copies of the G-R field data sheets <br /> are presented in Appendix B. Copies of the laboratory analytical report and completed <br /> chain-of-custody form are presented in Appendix C. <br /> Groundwater Monitoring and Gradient Evaluation <br /> "r= Depth-to-water (DTW) measurements were obtained by G-R from groundwater monitoring <br /> wells MW-1 through MW-3 prior to well purging and sample collection.. Static groundwater <br /> levels were measured from the north edge of the top of each well casing and recorded to the <br /> nearest ±0.01 foot. Groundwater was measured between 9.25 and 10.18 feet bgs. These <br /> water-level data were used to construct a Potentiometric Map (Figure 3). Based on these <br /> data, the shallow groundwater beneath the subject site appears to flow toward the northwest <br /> at a gradient of approximately 0.02. Each well was inspected for the presence of floating <br /> product. Floating product or a product sheen was not observed in any of the groundwater <br /> monitoring wells this quarter. <br /> Laboratory Analytical Data <br /> The groundwater samples were collected in sample containers supplied by the laboratory. <br /> The samples from well MW-1 through MW-3 were analyzed for TPHg by Environmental <br /> Protection Agency (EPA) Method 5030/GC-FID, and for benzene, toluene, ethylbenzene, <br /> and total xylenes (BTEX) by. EPA Method 8020. The sample from well MW-3 was also <br /> analyzed for TPHd by EPA Method 50301GC-FID, and chlorinated hydrocarbons (Cl-HCs) <br /> by EPA Method 8010. The samples were analyzed by American Environmental Network <br /> (ELAP #f1172) located in Pleasant Hill, California. <br /> TPHg and benzene were detected in the groundwater samples from wells MW-1 (3,300 and <br /> 880 ppb, respectively) and MW-2 (8,600 and 800 ppm, respectively). TPHg, BTEX, and <br /> 8146.03.1 3 <br />