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• Work PIan For A Limited Subsurface Investigation - Chevron Service Station 99-1848 <br /> June 26, 1997 <br /> elevation of approximately 27 feet above mean sea level (MSL) Locations of pertinent <br /> site features are shown on Figure 2, <br /> PREVIOUS ENVIRONMENTAL WORK <br /> According to the data provided by Chevron, three gasoline USTs and one waste-oil UST <br /> were removed and the gasoline USTs were replaced as shown on Figure 2 Three <br /> groundwater monitoring wells(C-1 through C-3)were installed by GeoStrategies Inc (GSI) <br /> in July 1991 Data pertaining to the UST removal or groundwater monitoring well <br /> installation were not available for inclusion in this work plan <br /> Quarterly Monitoring <br /> Groundwater monitoring wells C-1 through C-3 have been monitored and sampled since <br /> July 1991 by Blaine Tech Services, Inc Samples are currently analyzed for Total <br /> Petroleum Hydrocarbons as gasoline (TPHg), for benzene, toluene, ethylbenzene, total <br /> xylenes (BTEX), and for Methyl-tert-butyl-ether (MTBE) First quarter 1997 groundwater <br /> samples collected from C-1 through G-3 did not contain detectable concentrations of TPHg <br /> or BTEX compounds Groundwater samples from wells C-1 and C-3 did not contain <br /> concentrations of MTBE However, the groundwater sample from well C-2 contained <br /> concentrations of MTBE at 1,100 parts per billion or ppb <br /> HYDROGEOLOGIC CONDITIONS <br /> Historical monitoring data indicate depth to groundwater has fluctuated from approximately <br /> 12 to 20 feet below ground surface (bgs) During the first quarter 1997 monitoring, <br /> groundwater was measured at 12 29 to 13 37 feet bgs. Historically, groundwater flow has <br /> been toward the northeast at approximate gradients of 0.002 to 0 008 ft/ft <br /> SCOPE OF WORK <br /> To further delineate dissolved hydrocarbons (including MTBE) in groundwater in the <br /> vicinity of the site, GR proposes to advance exploratory soil borings Grab groundwater <br /> samples will be collected from each of the borings GR's Field Methods and Procedures <br /> are included in Appendix A <br /> To implement the proposed scope of work, GR proposes the following four tasks <br /> 639201-2 2 <br />