Laserfiche WebLink
' SEG R '017 Ki 'oreWo d, <br /> INTERNATIONAL 3017 o Cordova, <br /> Ftoaq Suite 100 <br /> S E C O R INCORPORATED Rancho, --0400 a,ECA 95670 <br /> 918-881-0430 Fu <br /> 0Q <br /> February 14, 2003 6 � <br /> vv � <br /> Mr. Michael Infurna <br /> San Joaquin County Public Health Services <br /> Environmental Health Division Q <br /> 304 East Weber Avenue, Third Floor <br /> Stockton, California 95202 <br /> RE: Notice of Intent to Prepare Conceptual Site Model <br /> Former Chevron Service Station 9-4054 <br /> 2103 Country Club Boulevard <br /> Stockton, California <br /> LOP Site Code 1780 <br /> SECOR Project No.: 77.CH.94054.00 <br /> Dear Mr. Infurna: <br /> SECOR International Incorporated (SECOR), on behalf of Chevron Environmental Management <br /> Company (Chevron), presents this letter to notify the San Joaquin County Public Health Services, <br /> Environmental Health Division (PHS-EHD) of SECOR's intention to prepare a comprehensive <br /> conceptual site model (CSM), including evaluation of the two adjacent local oversight program (LOP) <br /> sites, Boulevard Automotive Service (Boulevard) at 2151 Country Club Boulevard and Kwikee Foods <br /> (Kwikee) at 2081 Country Club Boulevard, as well as the Chevron site. SECOR intends to prepare <br /> the CSM for submittal to PHS-EHD by April 30, 2003. The objective of the CSM would be to <br /> establish the potential commingled nature of the dissolved petroleum hydrocarbon plumes <br /> emanating from the three sites. <br /> Terra Vac, Chevron's remediation contractor, operates a dual vapor extraction (DVE) and air <br /> sparging (AS) system at the Chevron site. DVE is the process by which groundwater and soil vapor <br /> are removed from the subsurface under high vacuum as a combined liquid stream. Terra Vac <br /> suspended DVE operation in December 2002 due to seasonal high groundwater elevations, as they <br /> had during previous high water periods. Bioventing, consisting of intermittent, low flow operation of <br /> the AS system, will continue to be performed by Terra Vac at the Chevron site in the interim. Terra <br /> Vac anticipates that DVE operation will resume in July 2003 once groundwater elevations have <br /> decreased sufficiently to allow effective removal of petroleum hydrocarbons using DVE. <br /> However, Chevron is concerned about resuming DVE operation without further evaluation of the <br /> effects of groundwater extraction. Chevron believes the three plumes were essentially commingled <br /> prior to commencement of DVE operations at the Chevron site in 2000. Recent groundwater <br /> monitoring and sampling data suggest to Chevron that historic groundwater extraction activities at <br /> the site have contributed to the migration of petroleum hydrocarbon impacts from the Boulevard and <br /> Kwikee sites onto the Chevron site. Chevron suspects that resumed operation of DVE will create <br /> further commingling of the plumes. The CSM will evaluate the nature and extent of impacts at each <br /> of the three sites and will include hydrogeologic modeling to determine the effect of past and future <br /> groundwater extraction. Prior to the resumption of DVE, and based on the results of the CSM, <br /> Chevron will re-evaluate the remedial strategy for the site, particularly if the CSM indicates the three <br /> plumes are commingled. <br /> I:\Chevron\94054\Correspontlence\CSM Intention Letter.tloc <br />