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Work Plan For UST Removal and Over-Excavation-Tosco 76 Branded Facility No. 11195 October 22, 1998 • The former waste oil UST was removed in May 1997. Petroleum hydrocarbons were not detected in the soil samples collected beneath the waste oil UST or the remote fill. • The former water supply well at the site was properly destroyed in July 1998. SCOPE OF WORK GR will collect the required compliance samples from the UST excavation and beneath the product piping and dispenser islands. Groundwater is likely to be encountered in the UST excavation preventing collection of soil samples from the base of the excavation. If petroleum hydrocarbon- impacted soil is encountered and Tosco elects to excavate the impacted soil, GR will observe the over- excavation activities and collect confirming soil samples from the base and lateral limits of the excavation. GR field methods and procedures are attached. To implement this scope of work, GR proposes the following tasks: Task 1. Compliance Sampling Three USTs, the associated product piping and dispensers will be removed by Walton Engineering, Inc. (Walton). Compliance soil samples will be collected from the UST excavation, the product piping trenches, and beneath the dispensers in accordance with the SWRCB LUFT Manual, the RWQCB Tri-Regional Board Staff Recommendations for Preliminary Investigation and Evaluation of Underground Tank Sites, and SJCPHS guidelines which specify the locations for a minimum number of soil samples to be collected upon routine UST removal. GR anticipates groundwater being encountered during UST removal and will collect a grab groundwater sample from the UST excavation. Removal and disposal USTs and related equipment, soil and groundwater sampling, and stockpiling and disposal of excavated backfill materials will be conducted according to the methods outlined in the Tank Closure Permit Application submitted to the SJCPHS on behalf of Walton. Task 2. Over-Excavation of Impacted Soil If either subjective field evidence or analytical data indicate soil beneath the site has been impacted by hydrocarbons, Tosco may elect to excavate the impacted soil. The feasibility and necessity of over-excavation of impacted soil can only be determined after UST removal and compliance sampling. Over-excavation may be necessary in, but not limited to the areas shown on Figure 2. Groundwater levels at the site will limit the depth of over-excavation to approximately 10 feet below ground surface(bgs). Based on the size of the areas defined on Figure 2, and the depth to groundwater,the potential amount of over-excavated soil is not likely to exceed 400 cubic yards. If Tosco elects to over-excavate hydrocarbon-impacted soil, GR will observe the excavation activities. Excavated soil will be screened in the field for the presence of volatile organic vapors using a photoionization detector. When possible, clean and impacted soil will be segregated during over-excavation activities. Clean soil will be reused as backfill with the permission of the 140193.04-1 2