Laserfiche WebLink
'k�J31 , <br /> yah ornia Ronal Wat if <br /> Quality Antrol B <br /> Peter M. Central V pard �- <br /> Rooney Region _ <br /> Secretoryjar p• e <br /> ErrvJronm¢ntai Sacramento Main Oice <br /> §� <br /> Internet Address: htp://W,Z.'So rcb,c4. ov/—m <br /> Protection 3443 Routier Road,Suite A,Sacramento, 9cb5/home.html <br /> `4'C • Cali 95837-3903 �� - Ed J.Schnabel <br /> Phone(916)255-3000•FAX(916)255-3015 i,:• �j? Choir <br /> 23 July 1998 / <br /> Mr, W.T. Nickerson <br /> Unocal Asset Management Group <br /> 2121 North California Blvd., Suite 250 <br /> Walnut Creek, CA 94596 <br /> REVIEW OF DOC <br /> FACH,ITy) 05 NORTH BROADWAY ERN FARM SERVICE (FORMER pEGRO/B <br /> VENUE,STOCKTON,SAN TOA REA <br /> I have reviewed the 28 April 1998 First Quarter 1998 QIJIlV COUNTY <br /> Work Plan for Installation ofMonitoring Well Al'W Quarterly Monitoring Report and the 1 June 1998 <br /> PureGroBrea Facility) 8 12 for the Western Farm Service <br /> 26 March 1998 RiskAssessmen Workplan tBroao <br /> way Avenue in the Office of Environmentan. Also, alth submitted your <br /> (OEHHA) for review. OEHHA has completed its review of the health risk assessment Hazard <br /> Assessment <br /> detailed in the enclosed memorandum. OEHHA finds the work plan acceptable with specific comments <br /> to be addressed in the health risk assessment. The following are my comments. <br /> OEHHA states on page five in comment number two,referring to Section 6.0 Exposure Assessme <br /> the work plan, that it has asked professionals from the Department of Toxic Substances nt of <br /> Control e <br /> review the models proposed to be used. The model proposed for transport leaching from soil to <br /> groundwater is SESOIL, and one parameter that SESOIL does not account for is the downward <br /> migration of vapors to groundwater. This must be considered when making any interpretation of vapor <br /> migration using SESOIL. <br /> The data in the quarterly monitoring report show the concentrations of 1,2-dichloropropane, nitrate, and <br /> dibromochloromethane detected in well MW-8 increase as the depth to water in well MW-8 increases. <br /> Trends such as these must be explained in subsequent reports and considered when evaluating potential <br /> remedial alternatives. <br /> The work plan proposing another well downgradient of ell MW-9 is approved. ropriate permits <br /> for this work are to be obtained from the local agencies be ore r c e in <br /> L <br /> �/Z �✓ <br /> California Environmental Protection Agency <br /> ��Recycled Paper <br />