ARCHIVED REPORTS_FEASIBILITY STUDY AND CORRECTIVE ACTION PLAN

Home Browse Search

5.3.2.2 FEASIBILITY AND COST EFFECTIVENESS CRA's October 30, 2009 AS/SVE Pilot Test Report and Feasibility Study Addendum presented the results of the AS/SVE pilot test. The pilot test data demonstrates that AS is technically feasible based on the following: Air (19 standard cubic feet per minute at 12 pounds per square inch) was successfully introduced into the zone of contamination. • The distribution of air extended up to 15 feet from the injection well in all directions as evidenced by induced pressure, groundwater mounding, and/or increasing dissolved oxygen (DO) and oxidation-reduction potential (ORP) levels. • A spike in hydrocarbon vapor concentration at the time of AS breakthrough suggests that AS volatilized hydrocarbons and increased mass removal. However, hydrocarbon vapor concentrations decreased to lower levels during the test. It is uncertain whether source material was limited and/or reduced or AS flow was diluting the hydrocarbon vapor concentrations. • An increase in SVE flow also corresponded with AS breakthrough. The SVE pilot test data,DPE pilot test data, and historical SVE system data indicate that SVE is technically feasible, but its effectiveness is limited by the shallow groundwater table. TPHg vapor concentrations and mass removal were higher during DPE testing of well MW-37 than during AS/SVE testing of OW-2/MW-22. However, well MW-37 is closer to source material than the AS/SVE test wells. Lastly, AS/SVE is expected to be less effective for TPHd (in comparison to TPHg) due to higher boiling points of the compounds found in the TPHd range. Based on the results of the pilot test,CRA moved forward with AS/SVE implementation with the concurrence of the Central Valley Water Board. CRA completed the system design and solicited contractor bids for construction services and vendor bids for major equipment. Select figures from the AS/SVE design plan set are included as Appendix E. Due to the logistics of working around the existing terminal infrastructure and the electrical service source locations, two separate systems covering the three source areas was deemed the best design approach. Completion of permitting is estimated to cost approximately $25,000. Based on bids,the contractor and equipment vendor prices are approximately $300,000 and $292,000, respectively. Trenching and installation of horizontal SVE wells will result in removing approximately 920 tons of soil. Transportation and disposal costs are approximately 241729(33) 18 CONESTOGA-ROVERS&ASSOCIATES