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R I� <br /> iIl <br /> Revised Proposal and Estimated Budget No. P15362.00 <br /> Ekholm Property, Escalon, CA , <br /> I� <br /> I The vapor borings will be advanced using 10-inch O.D. hollow stem augers. Soil samples will <br /> be collected at 5 foot intervals above the soil/water table interface. Two borings will be drilled <br /> in the area of the former underground gasoline storage tanks and the third vapor boring near the <br /> fuel dispenser island. These borings will be completed as 4-inch diameter vapor extraction wells <br /> for future soil remediation at the site. The proposed screened interval in the vapor extraction <br /> wells will be between 20 and 55 feet. <br /> The monitoring wells will be advanced using 10-inch O.D. hollow stem augers. Soil samples <br /> wilLbe collected at 5 foot intervals above the soil/water table interface. Two borings will be <br /> drilled in the general downgradient direction (northwest) ofi the site and one boring will be <br /> drilled in the upgradient direction. These borings will be completed as 4-inch diameter <br /> groundwater monitoring wells to evaluate the lateral extent of gasoline hydrocarbons in <br /> groundwater downgradient of the former tanks. The monitoring wells will be set at a total depth <br /> of approximately 85 feet below ground surface. <br /> Three soil samples will be selected from each boring/well and';submitted using chain-of-custody <br /> record to a State-certified laboratory for analyses of BTEX (EPA method 8020) and total <br /> petroleum hydrocarbons as gasoline (TPHG) utilizing EPA method 5030/8015. <br /> Task 5. Survey, Develop and Sample Groundlvater Monitoring Wells <br /> i <br /> Well development and sampling will consist of the following: a) survey of the top of the <br /> wellheads and measurement of depth to water in the wells to evaluate the direction and <br /> magnitude of the groundwater gradient beneath the site; b) purging and sampling of the existing <br /> and three new monitoring wells to evaluate the extent of petfoleum hydrocarbons in the first- <br /> encountered groundwater at the site. Purge water from the monitoring wells will be contained <br /> in 55 gallon drums pending laboratory analysis. If sample results indicate concentrations below <br /> State MCLS, discharge of water to the ground surface is proposed. <br /> Groundwater samples will be collected and submitted using chain-of-custody record to a State- <br /> certified laboratory for analyses of total petroleum hydrocarbons as gasoline (TPHG) and diesel <br /> (TPHD) utilizing EPA methods 5030/8015 and 3510/8015, respectively; and, benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX) utilizing EPA method 8020. <br /> j <br /> rc Task 6. Conduct a One Day Vapor Extraction Test (VET) <br /> This task includes: mobilizing and transporting the portable vapor extraction system to the site; <br /> set up of the equipment; and performing a one day VET to determine the feasibility of vapor <br /> extraction as an effective soil remediation alternative. The:�vapor extraction equipment will <br /> include a rotron blower and carbon vessels, instrumentation for measuring air flow, air velocity, <br /> air pressure, temperature, electrical current and volatile hydrocarbon vapor concentrations, and <br /> necessary piping, fittings and well head connections. <br /> ,l <br /> la <br /> Ekholm Proposal Disk ! <br /> P362-REV.2 3 ! <br /> E <br />