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VATIC <br /> A S S O C I A T E S I N C . <br /> I Subsurface piping will direct extracted vapor from the wells to a nearby remediation compound. <br /> Components of the VES located in the remediation compound will include the following: a vapor <br /> ( I extraction blower that will extract vapor from the wells through the subgrade piping; a flow <br /> I - indicator that measures extracted airflow; a condensate separator to remove entrained droplets of <br /> moisture; a thermal oxidizing unit; associated piping, control valves, pressure gauges, flow meters, <br /> k instrumentation and controls; and a contained remediation system to preclude public access. Based <br /> I on ATC' s experience at similar sites and the results of the pilot tests, a 200-250 clm thermal <br /> oxidizer would be sufficient to operate the vapor extraction component of the system and remediate <br /> the off-gas. The vacuum blower on the unit would create a maximum vacuum of 16 inches of <br /> mercury and an airflow rate of 100 standard cubic feet per minute. The thermal oxidizer on the unit <br /> would operate at a temperature of approximately 1400 degrees Fahrenheit and have a destruction <br /> efficiency of 95 % to 99%. A process and instrumentation diagram for the VES is shown on Figure <br /> 12, <br /> 5.2.2 Groundwater Air Sparging <br /> The proposed groundwater AS system will utilize two new air sparge wells and a compressor to <br /> address the hydrocarbon impacted groundwater. The AS system will be operated under similar <br /> conditions as the pilot test although with the use of properly designed sparge wells, the pressure <br /> l 1 required to achieve similar air flows may be lower. The AS system will be operated using <br /> l 1 individual wells in sequence with on-line vapor extraction wells to control migration of the <br /> groundwater plume. The wells will be constructed of 2-inch schedule 40 PVC and will be screened <br /> from approximately 37 to 40 feet bgs. A map showing the radius of influence and the locations of <br /> the two additional air sparge wells is included on Figure 13 . <br /> Two air sparge wells will be advanced using a hollow stem auger equipped drill rig to depths of <br /> approximately 25 feet bgs. Drilling will be conducted by a State-licensed (C57) drilling company. <br /> i 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 /> boring/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 from 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 /> l - I The soil borings will be completed as air sparge wells . The wells will be constructed of 2-inch <br /> inside diameter schedule 40 PVC well screen and casing with approximately five feet of 0 . 020 <br /> inch slot screened PVC from 35 to 40 feet bgs . To protect the integrity of the wells , locking , <br /> 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 drums pending laboratory <br /> results . <br /> w:\wordpro\62596\reports\3rp.doc 7 <br />