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vTic <br /> A S S O C I A T E S I N C . <br /> - 1 <br /> I . 5.2 Design Specifications <br /> F 5.2.1 Vapor Extraction System <br /> The proposed VES will utilize existing vapor extraction wells VW1 and VW2, two additional <br /> vapor extraction wells, a vacuum blower, and a thermal oxidizer to address the hydrocarbon <br /> impacted soil. The VES will be operated under similar conditions as the vapor extraction pilot test <br /> (VET) to achieve a similar estimated radius of influence for each well. A map showing the radius <br /> of influence and the locations of the two additional vapor extraction wells is included on Figure 11 . <br /> - Two vapor extraction wells will be advanced using a hollow stem auger equipped drill rig to depths <br /> of approximately 25 feet bgs. Drilling will be conducted by a State-licensed (C57) drilling <br /> company. A field geologist will be present to log drill cuttings and soil samples from the borings. <br /> - Descriptions of soil types encountered and sample collection intervals will be recorded on <br /> bornig/well logs. Soil samples will be collected at five-foot intervals. Each soil sample will be <br /> field screened with a FID meter or similar instrument and at least two samples fiom each of the two <br /> borings, based on field observations (i.e. odor, discoloration, FID readings), will be placed in a <br /> cooler with ice and submitted for laboratory analysis. <br /> The soil borings will be completed as vapor extraction wells . The wells will be constructed of <br /> 2-inch inside diameter schedule 40 PVC well screen and casing with approximately ten feet of <br /> 0 . 020 inch slot screened PVC from 15 to 25 feet bgs . To protect the integrity of the wells , <br /> locking , watertight well plugs will be installed on each well and a watertight wellhead labeled <br /> "monitoring well " will be concreted over each well . The top of casing of the new wellheads <br /> will be surveyed and tied into the existing wells to assess groundwater gradient and flow <br /> direction. All drill cuttings will be stored on site in 55-gallon drams pending laboratory <br /> results . <br /> Selected soil samples will be immediately placed in a cooler with ice and delivered under <br /> chain-of-custody documentation to a State-certified analytical laboratory . Soil samples will be <br /> analyzed for TPHg by EPA method 8015 ; BTEX by EPA method 8020 ; and MTBE, tertiary <br /> J butyl alcohol (TBA) , tertiary amyl ether (TAME) , di-isopropyl ether (DIPE) , and ethyl tertiary <br /> butyl ether (ETBE) by EPA method 8260 . <br /> Based on the removal rates of petroleum hydrocarbons observed during the VET (about twelve <br /> pounds per day per one well), thermal oxidation was selected as the method off-gas abatement. <br /> Removal rates will be the greatest during the first several months of operating the system and will <br /> exceed the allowable emission limit without off-gas treatment. The thermal oxidizer will be used <br /> until the influent concentrations of petroleum hydrocarbons decrease sufficiently to use vapor phase <br /> granular activated carbon for off-gas treatment. When extraction rates decrease to less than two <br /> - pounds per day, elimination of the off-gas treatment will be proposed if the system is still in <br /> -� operation. <br /> w:\wordpro\62596\reports\irp.doc 6 <br />