Laserfiche WebLink
' GeotagicafTec(nics Inc. • • Page 3 <br /> Feasibility Study Work Plan <br /> ProjectNo.425.2 <br /> August 17,2000 <br /> ' of a vapor extraction recovery system. The addition of air into the aquifer also aids in <br /> increasing the rate of natural degradation. <br /> 1 Vapor extraction is the process of drawing a vacuum on the vadose zone to produce an air <br /> flow through the subsurface, which removes volatile compounds from the soil and soil pore <br /> spaces through evaporation and concentration gradient diffusion. Typically the extracted air <br /> is treated using thermal destruction (a thermal oxidizer or internal combustion engine) or <br /> granular activated carbon. <br /> The design of the system is dependent on site-specific geology, depth to groundwater and <br /> contaminant type. A generalized plan for pilot testing and system installation is included in <br /> Appendix E. A discussion of system requirements and site-specific concerns are presented <br /> below in Sections 2.2.1 and 2.2.2. Appendix C gives the list of technical references used in <br /> this assessment. <br /> The cost to perform this type of remedial operation is quite expensive. A preliminary cost <br /> evaluation shows that for this work outlined in Appendix E is approximately $180,000. <br /> ' Before this work could be implemented, detailed unit costs for this work would be developed <br /> and pre-approval by the Fund would be obtained. <br /> ' 1. Air-sparging/vapor extraction pilot test <br /> 2. Installation and effectiveness testing of the air-sparging/vapor extraction system <br /> 3. Operation, maintenance, and monitoring of air-sparging/vapor extraction for one year <br /> 4. Groundwater monitoring for one year <br /> 5. Supervision <br /> 6. Reporting <br /> ' 2.2.1 Air Sparging System Requirements <br /> The following items are commonly noted in the literature as being requirements for Air <br /> Sparging to be effective for site remediation: <br /> ' 1. Air sparging should be limited to sites that exhibit course grained, homogenous geology. <br /> Fine grained and/or heterogeneous geology will prevent the upward migration of the air <br /> and can cause lateral spreading of contaminants. The coarse grained unit to be sparged <br /> ' cannot be overlain by a finer grained unit. <br /> Technology Overview Report, Air Sparging, 1996, Ralinda Miller, Ground-Water <br /> Remediation Technologies Analysis Center <br /> ' • How to Evaluate Alternative Cleanup Technologies for Underground Storage Tank <br /> Sites: A Guide to Corrective Action Plan Reviewers, 1995, USEPA Office of <br /> Underground Storage Tanks <br /> ' . Groundwater Pollution Control Program Guideline 96, 1998, Wyoming Department <br /> of Environmental Quality Water Quality Division <br /> • Air Sparging for Site Remediation, 1994,Robert E. Hinchee <br />