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As directed by Mr. Bill Snavely PHS-EHD, analysis for the soil samples from
<br />below Tank 1 were to be analyzed as if the tank last contained leaded gas. These
<br />analyses were for Total Petroleum Hydrocarbons as Gasoline (TPH-G), Benzene,
<br />Toluene, Ethyl Benzene and Xylene (BTEX), Total Lead (Pb), and Ethylene dibromide
<br />(EDB). The soil samples from below Tank 2 were to be analyzed as if the tank last
<br />contained waste oil. The sample analyses for Tank 2 were Total Petroleum
<br />Hydrocarbons as Gasoline (TPH-G), Total Petroleum Hydrocarbons as Diesel (TPH-D),
<br />Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX), Chlorinated Hydrocarbons (CL
<br />HC), Metals (Cadmium, Chromium, Lead, Nickel and Zinc), and Polychlorinated
<br />Biphenyls (PCB's). The samples were analyzed on a 24 hour turnaround basis due to
<br />the urgency of the Eleventh Street project.
<br />Excavation of Petroleum Impacted Soil
<br />During the tank removal process there was petroleum hydrocarbon stained
<br />soil contained within the sidewalls of both tank excavations. After consulting with
<br />Mr. Bill Snavely of PHS-EHD, this stained soil was removed until there was no visible
<br />sign of the contamination remaining on the sidewalls of the excavation. The total
<br />depth of the excavation was approximately 12.5 feet which extended approximately 1
<br />foot below the level of groundwater. The volume of the soil removed from both
<br />excavations was approximately 125 cubic yards. As identified in the tank closure
<br />application submitted to PHS-EHD all soil removed from the excavations (property
<br />under the jurisdiction of the City of Tracy) was relocated to the Tracy Airport, Land
<br />Treatment Facility (LTF). The LTF documents provided to Wright by The City of Tracy
<br />and conversations with City Staff indicated that non-hazardous soils could be treated
<br />at the LTF site.
<br />Backfill of Excavation
<br />On October 27, 1993 the excavation was backfilled with clean, 3/4" crushed rock
<br />in 12" lifts to within three feet of the existing grade. A Geotextile fabric was then
<br />placed over this permeable backfill and the the excavation was then brought to grade
<br />with 3/4" class two base rock. After the excavation was brought to sub-sidewalk
<br />grade, two heavy duty, sealed monitoring well boxes were placed above the center
<br />line of each former tank location in order to prevent damage to the new sidewalk
<br />during any subsequent site investigation work. Load tickets for the backfill material
<br />and the Backfill Excavation Certificate is enclosed in Appendix E.
<br />Discussion
<br />Laboratory analysis of the sample taken below Tank 1 detected TPH-G at 590
<br />parts per million (ppm), Toluene at 0.87 ppm, Ethyl Benzene at 2.2 ppm, and Xylene at
<br />3.7 ppm in soil. The soil sample taken from the spoils stockpile associated with Tank
<br />1, was reported to contain 190 ppm of an unknown hydrocarbon. Ethyl Benzene at
<br />0.34 ppm, and Xylene at 0.90 ppm.
<br />Laboratory analysis of the sample take from below Tank 2, detected 28,000 ppm
<br />of an unknown hydrocarbon by method 8015m for TPH-G, Toluene at 4.1 ppm, Ethyl
<br />Benzene at 32.0 ppm, and Xylene at 9.4 ppm in the soil. Motor Oil was reported at 7,200
<br />ppm by method 8015m, for TPH-D, Toluene at 4.1 ppm, Ethyl Benzene at 32.0 ppm, and
<br />Xylene at 9.4 ppm in the soil below Tank 2. Tetrachloroethylene (PCE) was detected at
<br />1.0 ppm in the soil below Tank 2, however, PCE was not detected in the sample from
<br />the spoils stockpile for Tank 2. There were no detectable concentrations of PCB's in
<br />the either of samples associated with Tank 2.
<br />A sample from the spoils stockpile from Tank 2 detected concentrations of
<br />Motor Oil reported at 2,000 ppm by method 8015m for TPH-D, Toluene at 1.0 ppm, Ethyl
<br />Benzene at 2.3 ppm, and Xylene at 9.3 ppm; an unknown hydrocarbon was detected at
<br />500 ppm by 8015m for TPH-G.
<br />Detectable concentrations of Cadmium, Chromium, Lead, Nickel, and Zinc were
<br />found in both soil samples associated with Tank 2 and Lead was detected in both soil
<br />samples from Tank 1.
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