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r <br /> ConocoPhillips/Bill Borgh Page 2 <br /> 16470 Cambridge Drive August 6, 2008 <br /> Lathrop, CA <br /> This plan should incorporate a phased response approach to the formation of any <br /> undesirable byproducts (Cr[VI], bromate, or bromide) from the ozone injection and may <br /> be included as paragraphs in the pilot test work plan. <br /> The contingency plan should detail how the system will be modified to produce less <br /> ozone as a first response if the byproducts of concerned are formed. An additional <br /> response, if this method was unsuccessful, could be either pulsing the injection to other <br /> sparge wells or shutting down the injection process completely while continuing to <br /> monitor the ground water for attenuation of the byproducts. <br /> If monitoring the ground water indicates that the byproducts are not attenuating <br /> adequately, then an additional response such as ground water extraction may be <br /> needed. You may include other contingency methods if these suggestions do not <br /> completely address potential system responses. <br /> The EHD has concluded that additional monitoring wells should be placed north of MW- <br /> 6 and the houses in the down-gradient direction. During discussions with your <br /> consultant, two additional monitoring wells were proposed for installation in the parking <br /> lot north of the site. The locations seem adequate. Please finalize the details for the <br /> installations and include them in the work plan to conduct the field pilot test. These new <br /> wells should be included with the points monitored in the field pilot test to determine if <br /> unwanted byproducts of degradation are being formed and, that if formed, that they are <br /> attenuating adequately. <br /> Although your consultant concluded that the ozone sparging process would destroy <br /> hydrocarbons in the subsurface and not volatilize them, the CVRWQCB has <br /> recommended that a soil vapor investigation be included in the pilot test. Please include <br /> the installation of multiple shallow soil vapor probes in the field pilot test work plan at the <br /> north end of the parking lot near the borders of the private houses and to the east and <br /> northeast, near the other buildings that are close to the contaminant source. <br /> The EHD will review the field pilot test work plan and comment. Ultimately, the <br /> CVRWQCB will review the results of the pilot test for WDRs and advise the EHD. You <br /> will be notified by the EHD if additional testing or WDRs are required or if the September <br /> 18, 2007 Revised Corrective Action Plan can be implemented. <br /> Please submit a copy of the San Joaquin Valley Unified Air Pollution Control District <br /> (SJVUAPCD) authority to pilot test the system and the authority to construct and <br /> authority to operate permits for the ozone and air sparge systems as soon as they are <br /> issued. <br /> The installation of any onsite additional sparge wells for the pilot test may be done under <br /> the existing EHD permit if the work is done by WDC drilling and completed before <br /> February 20, 2009. A change in the drilling contractor will require a new EHD boring <br /> permit application and fee to be submitted and processed. A permit application, fee, <br /> 16470 Cambridge Drive BST impl SVE+ozone CML 8-6-08.doc <br />