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,rte, EXECUTIVE SUMMARY Corrective Action Plan for UST Removal Former Unocal Station 0123 1034 Central A�enue Tracy California I i Unocal Corporation intends to remove two empty 550-gallon capacity underground fuel storage tanks (USTs) which remain at the northern edge of the property located at 1034 Central Avenue in Tracy, California. The USTs are located beneath ihe 11th Street sidewalk, approximately 20 feet east of Central Avenue. The USTs were used by Unocal from approximately 1921 through 1950 and contained gasoline. The site was previously occupied by a Unocal service station from 1920 through the 1950's. The site is currently owned by Wells Fargo Bank N.A., and is used as an asphalt-paved parking lot for the adjacent Bank of America building. It is anticipated that the site will remain a parking lot following completion of the UST removals. The USTs will be removed by way of excavation into the sidewalk right-of-way. The approximate area of the proposed excavation will measure 10 by 15 feet. The estimated depth of the excavation will be 9 feet, as measured from the existing sidewalk grade. If petroleum hydrocarbons are present within soils exposed in the excavation, Unocal may perform additional (over) excavation to remove these impacted soils. Because groundwater occurs at approximately 10 feet it is anticipated that the maximum depth of excavation will be approximately 12 feet. The resulting excavation should have an approximate dimension of 15 feet long, 10 feet wide and 12 feet deep. Soil samples will be collected at the base of the excavation to assess soil conditions following the corrective action. _ Based on the estimated total excavation volume, itis anticipated that approximately 100 cubic yards of soil will be generated from the excavation activities. The soils will be temporarily stockpiled in the central portion of the site, and completely covered by visqueen to minimize the potential for dust and odor. The stockpiled soils will be loaded directly on to trucks provided by Manley and Sons Inc., a licensed waste transporter.1 The soils will be transported to Forward Landfill in Manteca, California, a state-approved landfill facility. The maximum public concerns regarding the proposed corrective action include physical hazards associated with an open excavation, and human contact with hydrocarbon-impacted soils. Unocal will address these concerns by restricting access to the excavation with barricades, and by covering all stockpiled soils in order to minimize the potential for human contact. Upon completion of excavation in the area of the two USTs excavation will be backfilled with clean imported fill material. The backfill material will be appropriately compacted in accordance with City of Tracy specifications. All activities at this site will be overseen by the pan Joaquin County Environmental Health Division. All inquiries and/or concerns can be directed to Mr. Michael Infurna at (209) 468.3454. P