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Mr Michael Infurna August 23, 2005 Page 2 1 ' groundwater circulation well technology Groundwater recirculation wells are discussed at http //www epa gov/swertiol/download/reined/gwcirc pdf and the technology is currently in use at the EPA LEHR Superfund site in Davis, ' California Ms Susan Tiinm is the Regional Water Quality Control Board regulator for this site and she approved use of the technology Ms Timm can be reached at (91 G) 464-4657 ' Additionally,we attach Chapter 4 0 of EPA's Analysis of Selected Enhancements for Soil Vapor Extraction in Exhbit A That document describes the technology ' and concludes, "Dual-Phase Extraction provides a means to accelerate removal of nonaqueous phase liquid (NAPL) and dissolved groundwater contamination, remediate capillary fringe and smear zone soils, and facilitate removal of vadose ' zone soil contaminants" We agree with the County that the remediation technology for this site should address MtBE, as well as the other petroleum hydrocarbons present at the in the soil and groundwater at the Site The ART web site ' -,vww artinwell com) does include at least two case studies that included MtBE These studies are attached in Exhibit B One site indicated a reduction of MtBE from 1,500 micrograms per hter (gg/L) to 200 µg/L in 84 days of operation The Isleton study indicated an MtBE reduction of 42,000 gg/L to 9 1 µg/L in about one year of operation EHD Page 1, paragraph 4 "The Plan did not include a proposal for additional CPT borings I BC The Work Plan includes work necessary to begin remediation activities in the shallow water bearing zone that has been vertically and horizontally characterized Because Mr Tarditi has limited resources available for this site at any one time, ' work is phased to accommodate progress At this time, after almost ten years of investigation and monitoring, he wishes these resources be directed toward mass removal of the source area Mr Tarditi intends to further investigate the deeper water bearing zone in a future phase EHD Page 1,paragraph 5, hne 1 "Of particular concern to EHD, the State Water Resources Control Board (SWRCB), and the Central Valley Region Water Quality Control Board (RWCQB) is the placement of long screen intervals in wells at contaminated underground storage tank (UST) sites " ' BC: We understand and agree with the County that long-screened wells must not intersect separate water-bearing zones so there is no potential for cross- contamination The pilot test as proposed will not result in cross contamination P\28000\128253- I&1 1 rucking SN'E\5JC Rc�pomc doc