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6.0 OVER-EXCAVATION AND PRODUCT REMOVAL The bottom of the USTs may extend to depths of eight (8) feet to twelve (12) feet below ground surface. Groundwater is expected to be encountered at a depth of 26 feet or deeper which is beyond the depth recommended for this excavation at this time. The USTs are located in close proximity to the street and public utilities thus restricting the lateral and vertical extent of the excavation, especially without engineered shoring. Subsequently, the excavation in the UST area is anticipated to extend to a depth not exceeding approximately 18 feet below ground surface immediately below the USTs as necessary. The lateral and vertical extent of the over excavation will be conducted maintaining a minimum 2:1 slope. Since the streets (S. El Dorado and 8th Streets) are close, the lateral extension of the excavations to the west and the south of the USTs will be minimal. The excavation will proceed based on visual or olfactory indications of petroleum hydrocarbons and limitations posed by property boundaries, utilities, excavation stability and/or other practical considerations. For the purposes of this workplan, the aerial dimension of the excavation is estimated to be approximately 70 feet (north-south) by 40 feet (east-west). Based on these dimensions and anticipated soil conditions ROKEN estimates that approximately 1,300 cubic yards of soil (2/3 of total volume) will be excavated and stockpiled for off-site disposal. ROKEN also anticipates that a limited amount of free product (approximately 300 gallons) in the tanks and in the immediate area of the USTs can be removed using a vacuum truck. 6.1 CONFIRMATIONSOIL SAMPLING A registered geologist is the only personnel authorized to enter the excavation for soil inspection and sampling,if necessary. Upon reaching the projected excavation limits, confirmation soil samples will be collected from the excavation sidewalls and excavation floor to verify removal of significant concentrations of petroleum hydrocarbons. Confirmation samples will be collected from the side walls and floor of the excavation at a frequency of one sample per approximately 20 linear feet or as directed by the SJCEHD inspector. ROKEN anticipates collection of approximately fourteen (14) soil samples. Each sample will be submitted to a state certified laboratory for the following analyzes: EPA Method 8260b-VOCs,TPH as Gasoline, 7 fuel additives and lead scavengers EPA Method 8015M -TPH as Diesel and Motor Oil EPA Method 6010 - LUFT 5 Metals (Cadmium, Chromium,Nickel, Lead,Zinc) After receipt of satisfactory analytical results or when physical site limits of the excavation have been reached, the excavation will be backfilled with clean fill material. Remediation of elevated concentrations of petroleum hydrocarbons remaining in soil and groundwater following this soil removal action will be addressed following completion of a remedial investigation. ROKEN will oversee the excavation and stockpiling of soil and collect soil samples for waste disposal profiles. The Contractor will excavate the soil with a backhoe and then stockpile the soil on plastic and cover the stockpiles with plastic. Areas targeted for excavation will be watered down prior to and during excavation activities as necessary to suppress dust and petroleum hydrocarbon vapors. 9