Laserfiche WebLink
PUBLIC '"HEALTH SERVICES <br /> POU 1!y <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION y: , X <br /> Ernest M. Fujimoto, M. D., M.P.H., Acting Health Officer •`. <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 <br /> 209/468-3420 APR Q' 7 l;,st <br /> _J <br /> PAUL SUPPLE BRETT HUNTER <br /> ARCO CHEVRON <br /> PO BOX 6549 PO BOX 6004 <br /> MORAGA CA 94570 SAN RAMON CA 94583-0904 <br /> RE: ARCO#2133 - 2908 West Benjamin Holt Drive <br /> Chevron#9-4275 - 2905 West Benjamin Holt Drive <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) held a meeting on <br /> March 27, 1996 to discuss groundwater plume migration originating from the ARCO and Chevron sites. <br /> PHS/EHD has prepared a summary of the meeting for your information. The meeting was attended by the <br /> following: <br /> Paul Supple ARCO Brett Hunter Chevron Aaron O'Brien Geraghty and Miller <br /> Margaret Lagorio PHS/EHD Mary Meays PHS/EHD Joel Coffman Brown and Caldwell <br /> Ed Formosa City of Stockton Steve Misner Brown and Caldwell <br /> ARCO 1995 Release <br /> The Unauthorized Release Report submitted on July 12, 1997 for the northern pump island line leak <br /> indicated that the release was detected on July 11, 1995 during a product line test and that the discharge <br /> was stopped on July 12, 1995. However, the leak occurred some time during the second quarter 1995 <br /> because on June 1, 1995 a release was indicated by the floating product observed in monitoring well, E- <br /> 10, during routine groundwater monitoring. Floating product had not previously been observed in E-10. <br /> Approximately 40-50 gallons of gasoline product was recovered from E-10 by hand bailing. A free <br /> product skimmer was installed, but was subsequently removed because it proved ineffective. Free <br /> product is no longer observed in E-10, but the resultant dissolved plume has migrated off site. <br /> Co-mingled Plumes <br /> The ARCO contaminated groundwater plume has migrated and mingled with the Chevron contaminated <br /> groundwater plume. <br /> PHS/EHD indicated in correspondence to ARCO dated August 14, 1996, that based on available <br /> information there was not clear demarcation between the Chevron and ARCO plumes. The basis of this <br /> determination was the groundwater sample results obtained by the ARCO monitoring well, BHD-1, located <br /> on the Chevron property. <br /> PHS/EHD evaluated Chevron's quarterly report recently submitted, and has further determined that <br /> ARCO's contaminated groundwater plume has mingled with Chevron's contaminated groundwater plume. <br /> Prior to September 24, 1996, the results obtained from Chevron's monitoring well, MW9, evidenced low <br /> concentrations of petroleum hydrocarbons; however, following September 24, 1996 the concentrations of <br /> gasoline constituents including methyl tertiary butyl ether(MTBE) increased significantly. Chevron's MW9 <br /> is located in the southeast corner of the station in a downgradient position from the ARCO station. <br /> City of Stockton Wells #10 and #2 <br /> We discussed the construction of the Municipal Well #10 located just northeast of the intersection of <br /> Plymouth Road and Benjamin Holt Drive which was drilled in May 1967 to 355 feet below ground surface <br /> (bgs). The well is steel cased and is perforated between 295 - 315 and 333 - 353 feet bgs with a 55 foot <br /> grout seal. The City of Stockton indicated that the well was officially listed as an active well and is tested <br /> pursuant to Department of Health Services requirements. The well is used infrequently because it <br /> produces significant quantities of sand. <br /> A Division of San Joaquin County Health Care Services <br />