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CES <br /> - � SER s <br /> PUBLICN JOAQUIN COUNTY m' <br /> SA .:. <br /> ENV�ONMENTAL HEALTH DIVISION <br /> .D., <br /> M.P.H., Acting Health Officer <br /> Ernest M. Fujimoto, M <br /> 445 N. San Joaquin Street • P.O. Box 388 • Stockton, CA 95201-0388 <br /> (209) 468-3420 <br /> DPY <br /> JOHN WEBER <br /> C M WEBER ENTERPRISES INC JUN10 1994 <br /> 3757 COLLEGE AVE <br /> SACRAMENTO CA 95818 <br /> RE: Weber Point <br /> SITE CODE: 2436 <br /> 141 North El Dorado Ave <br /> Stockton CA 95202 <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) <br /> has completed review of the "Air Sparge Installation Proposal" dated May 19, 1994 <br /> prepared by Aegis. PHS/EHD has the following comments for your consideration. <br /> The proposal included the installation of air diffusers in MW1-MW4, RW1, and RW2. <br /> The purpose of the sparging system was stated to promote natural biological activity in <br /> soils and groundwater by raising the dissolved oxygen content. The system would be <br /> monitored by measuring dissolved oxygen content prior to start-up and during purging. <br /> The vacuum levels would also be measured at start-up to ensure no vapor migration is <br /> occurring. The existing vapor extraction and groundwater extraction systems would <br /> continue to operate at their present level. Groundwater samples would be collected four <br /> weeks after start-up of the air sparge system to assess progress and ensure no adverse <br /> plume migration. <br /> PHS/EHD has the following concerns regarding this proposal: <br /> 1) All on site groundwater wells, with the exception of MW5 are planned to <br /> be upgraded to air sparging wells. If air diffusers are installed on all these <br /> wells, there will not be a down gradient unaffected well to monitor the <br /> migration of the plume. Additionally, there are no vapor extraction wells in <br /> the vicinity of these wells to capture migrating vapors. PHS/EHD <br /> recommends that until the system's performance has been evaluated that <br /> MW4, RWl, and RW2 not be used for air sparging. <br /> 2) The current vapor extraction treatment system is comprised of activated <br /> carbon filters in series. Breakthrough occurs frequently, which results in <br /> system down time until the carbon is replaced. PHS/EHD indicated in <br /> correspondence dated February 25, 1994 a concern that the treatment <br /> system may not be adequately sized to handle the concentrations of <br /> contaminants removed from the subsurface. <br /> A Division of San Joaquin County Health Care Services <br />