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WORK PLAN FOR ADDITIONAL SITE INVESTIGATION Irerracon <br /> Vacant Property Tracy, California <br /> April 16, 2021 Terracon Project No. NA197074B <br /> estimated to remain in the subsurface soil. The excavated area near the pipeline release is still <br /> visible at the site. <br /> In May 2004 Kleinfelder performed a limited soil and groundwater assessment in the vicinity of the <br /> ruptured former Chevron pipeline. According to Kleinfelder's October 25, 2005 Work Plan/Scope <br /> of Work: <br /> `A total of twenty-nine (29) push probes were advanced during the field activities. <br /> A total of twenty-two 4-point composite soil samples, 26 discrete soil samples and <br /> 4 groundwater samples were submitted for chemical analyses for purgeable and <br /> extractable petroleum hydrocarbons and benzene, toluene, ethylbenzene, and <br /> xylenes BTEX) compounds. Twenty-five (25) shallow probes were advanced to <br /> total depths ranging from approximately 8 to 24 feet below ground surface (bgs). <br /> Four deeper groundwater push probes were advanced to total depths ranging from <br /> 44 to 58 feet bgs. Groundwater was noted approximately 43 feet bgs in these four <br /> deeper borings. <br /> A summary of Kleinfelder's findings are summarized as follows: <br /> 1) Twelve discrete soil samples were collected and analyzed from perimeter <br /> pushprobe borings at depths ranging from 5 to 43 feet bgs. Based on this data, it <br /> is Kleinfelder's opinion that petroleum impacted soil has not migrated laterally a <br /> significant distance beyond the footprint area. Please note this finding does not <br /> include potential soil vapor migration of volatile compounds, since soil vapor <br /> sampling was not conducted as part of this assessment. <br /> 2) A total of four grab groundwater samples were collected, one in the footprint <br /> area and three from perimeter locations. Relatively low concentrations of <br /> petroleum constituents were detected in two of the four groundwater samples <br /> collected. The levels detected at the depths (first encountered groundwater) and <br /> locations in groundwater at the site were below state and federal Maximum <br /> Contaminant Levels (MCLs) for drinking water. The extent and distribution of <br /> hydrocarbons in groundwater is unknown at this time. Based on the relatively low <br /> levels detected, and since applicable petroleum constituents are below drinking <br /> water standards (MCLs), Kleinfelder at this time does not recommend clean-up or <br /> additional groundwater monitoring activities related to petroleum constituents <br /> detected in groundwater, <br /> 3) Kleinfelder anticipates that approximately 47,000 cubic yards of soil was <br /> impacted by petroleum constituents. Please note, onsite stockpiles of petroleum <br /> impacted soil from Chevron's clean-up activities are not included in this estimate. <br /> Kleinfelder anticipates remedial excavation depths will range from 5 to 13 feet bgs. <br /> Responsive■ Resourceful ■ Reliable 2 <br />