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Mr Michael Infuma. August 23, 2005 Page 3 ' EHD Page 2,paragraph 1 "EHD cannot properly evaluate the ART technology as to being necessary and adequate for corrective action on this site Optimal and unfavorable site conditions for ART should be identified and this site ' evaluated with regard to those site conditions To date, no single technology has been demonstrated to be appropriate for all sites " BC This Work Plan outlines the recommended SVE pilot test A remediation pilot test is conducted to determine if the remediation technology is feasible, and if feasible, determine the parameters needed to engineer the system component design Brown and Caldwell commits to addressing the County long-term concerns relative to system effectiveness in a pilot test report EHD Page 2, paragraph 2 "Please demonstrate that the known site conditions ' justify the expectations for a successful application of ART technology to this site Without this justification, EHD will not permit well installations with screened intervals grater than 20 feet and `vapor well' screens to be placed in the saturated zone The proposal must be deemed adequate and necessary [Health & Safety Code section 25296 10(c)(3)] prior to EHD permitting the ART technology and well design to be installed and tested Without EHD approval, only multiple, single-casing and shorter screened interval, separate SVE and AS well casings will be permitted to be installed" 1� BC. Again, the Work Plan describes scopes of work for SVE and AS pilot tests Pilots tests are necessary to determine if SVE and AS are feasible remediation applications for the site If all the pilot tests indicate that ART technology is infeasible then the long screen remediation well may still be used for groundwater extraction and/or other remediation purposes EHD Page 2, paragraph 3, line 1 "EHD concurs that SVE may be effective in reducing the impact of the MtBE in the vadose zone down to ground water, but questions the design of the AS system utilizing existing MW-1 EHD is unsure how the sparged air will reach the vadose zone through the finer-grained material in the upper saturated zone and the lower unsaturated zone The CPT logs 1 through 5 generally show an interval of high pore pressure between 65 and 70 feet bgs This unit may provide a barrier to vertical migration of injected air" BC The Work Plan proposes that MWA be used as an air sparge point for a pilot test because it can be used as cost-effective means to determine if oxygen levels increase in adjacent monitoring and remediation wells and, if so, determine the engineering parameters necessary for final system design Brown and Caldwell has successfully used existing monitoring wells for AS pilot tests in dozens of UST • sites for ARCO, as well as other sites 1' 11\28000\128253 'I&l Trucking ,V] \sJC RcSpon,c doc