Laserfiche WebLink
a <br /> ) <br /> San Joaquin County <br /> °U �o Environmental Health Department DIRECTOR ° <br /> S 'I <br /> 600 East Main Street Donna Heran, REH�l <br /> Stockton, California 95202-3029 PROGRAM COORDINATORS <br /> Robert McClellon, REHS <br /> �. <br /> Jeff Carruesco,REHS, RDI <br /> KFoley, REHS- <br /> a ...... a� Website: wwwsjgov.org/ehd <br /> CippR - Linda <br /> Turkatte, REHS <br /> Phone: (209) 488-3420 . `� �0.•t� <br /> Fax: (209) 464-0138 l <br /> I <br /> January 133 2011 { <br /> James M. & B. Langston <br /> 1416 Ironwood Place 1 <br /> Manteca, CA 95336 <br /> Subject: Former Langston's Arco LOP Case#: 1503 f <br /> 15615 S. Seventh St. CUF#: 00367 EEE <br /> Lathrop, CA 95330 Geotracker ID#: T0607700406 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed <br /> Revised Feasibility Study Report (FS) dated August 10, 2010, which had been <br /> submitted to Geotracker. 'The submittal of the FS was a condition of the Physiochemical <br /> and Microbiological Evaluation Work Plan approval letter issued by the EHD on January <br /> 8, 2010. <br /> The FS discussed and evaluated the data collected during the March 2010 groundwater <br /> sampling event conducted on monitoring wells EW-1, MW-2, and MW-5. Based on the <br /> data collected during this event, your consultant concluded that the existing bacteria in '+ <br /> the subsurface would benefit from the addition of oxygen, the dissolved contaminant ` <br /> plume is stable, and the site should be considered for no further action (site closure). <br /> The EHD has researched the soil and groundwater data collected to date for this site ` <br /> from the first and second generation monitoring wells, the numerous soil borings, and I <br /> the data from the soil samples collected during the soil excavation in the mid-1990s in <br /> order to verify if current site conditions warrant a low-risk site closure determination. <br /> Initial groundwater samples from the first monitoring well installed in 1993 (MW-1) <br /> contained 180,000 micrograms per liter (ug/1) total petroleum hydrocarbons as gasoline <br /> (TPHg). Additionally, benzene was present in the groundwater samples from MW-1 at <br /> 17,000 ug/I during this same event. Since that time, the original four monitoring wells ,e E <br /> were destroyed under permit, the site underwent contaminated soil removal, and seven <br /> new monitoring wells, one extraction well, and two dual phase extraction (DPE) wells <br /> have been installed. ;`Wells EW-1, DPE-1, and DPE-2 continue to be impacted by . <br /> elevated concentrations of TPHg in shallow groundwater beneath the site. The last <br /> groundwater sampling data submitted to Geotracker was for the event conducted on <br /> June 14, 2010. TPHg was detected at 30,000 ug/I in EW-1, 14,000 ug/I in DPE-1, and <br /> 19,000 ug/I in DPE-2. The highest benzene concentration during this sampling event, <br /> 34 ug/I, was detected. in the groundwater sample from well DPE-2. Plume t <br /> concentrations vary over a wide range, but overall appear to be reasonably stable. <br />