Laserfiche WebLink
ENVIRONMENTAL HEALTH DEPARTMENT <br /> ° u c SAN JOAQUIN COUNTY <br /> Donna K' Heran,R.E H S Unit Supervisors_ irector 304 East Weber Avenue, Durd Floor Carl Boman, It E H S <br /> Al Olsen,R E H S Stockton, Calzforma 95202-2708 Mike Huggins,R E H S,R D 1 <br /> Program Manager <br /> Douglas W Wilson R E H S <br /> Telephone 209 458-3420 <br /> Laurie i#.Cotulla,R E H S P � � Margaret l.agorro,R E H S <br /> Fax (209) 464-0138 Robert McClellan,R FH S <br /> Progrmn��Ianager Mark Barcell os,R E H S <br /> DARIN ROUSE SEP 0 3 2003 <br /> I EXXONMOBIL REFIRING AND SUPPLY COMPANY <br /> PO BOX 4032 <br /> CONCORD CA 94524-4032 <br />' RE Former Exxon Retail Site 7-3942 SIT$ CODE 2231 <br /> 4444 North Pershing Avenue <br /> Stockton CA <br /> San Joaquin County Environmental Health Department (EHD) is the lead agency providing the <br /> oversight of the investigation and cleansp of releases from underground storage tanks <br /> (UST) within San Joaquin County EHD has a contract hath California State Water <br /> Resources Control Board (SWRCB) to conduct an UST corrective action program <br /> EHD has completed reviewing the Feasibility Study and Work Plan for Well Installation <br /> submittal prepared by ETIC on behalf of Exxonmobal and has the following comments <br /> I 1 The deep monitoring well (MW) proposed off site to define the vertical extent <br /> of soil and groundwater contamination in the down gradient flow direction is <br /> approved in concept Please submit a well permit application, a Work Plan <br /> . (WP), and an $89 00 fee for EHD ret.aew and permit issuance When the permit <br /> I is issued, well installation can begin <br /> 2 MWs SW-1 and SN-2 are in the area of the unauthorized release on site They <br /> have well screens from 40-45 feet bgs and have evidenced ground water <br /> contamination approximately 20 feet below the current static water table <br /> These Mgrs have been recently added to the sampling schedule and should remain <br /> I on a quarterly monitoring and sampling schedule To define the vertical extent <br /> of contamination in the source area, a deep ground water investigation is <br /> required to define the limits of contamination <br /> 3 The adsorbed or dissolved contaminant masses for soil or ground water have not <br /> been estimated When the vertical limits in soil and ground water <br /> contamination have been defined, you are required to calculate and report <br /> these contaminant masses To date, only remediation system removal mass has <br /> been reported but the estimated residual mass has not <br /> 4 Due to the apparently large contaminant mass caused by the unauthorized <br /> release and the high contaminant concentrations in ground water, EHD cannot <br /> approve passive remediation, or natural attenuation, as the remedial choice <br /> for corrective action at this site Passive natural attenuation will not <br /> restore groundwater qual-ty in a reasonable amount of tame Therefore, ESD <br /> recommends an active remedial technology for corrective action EHD recommends <br /> a pilot study be conducted to evaluate low-flow rate ozone sparging at this <br /> site The study should also evaluate contaminant migration and/or destruction <br /> and any modification of ground water flow direction as a result of the ozone <br /> sparing <br /> If you have any further questions regarding this matter, please contact Harlin Knoll at <br /> (209) 468-3442 <br /> Donna Heran, REHS, Director <br /> Environmental Health Division <br /> I Harlin Knoll, Senior REHS Nuel C Henderson <br /> LOP/Sate Mitigation Unit IV LOP/Site Mitigati S � <br /> cc �C-Ted aures L L Barton �1 SEP 1 2003 <br /> TIC-Ted Moase U s <br /> Bank of Stockton-Rick Correia - <br /> Brooke Burkae k _ _ <br />