ARCHIVED REPORTS_XR0002180 - Laserfiche WebLink

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ENVIRONMENTAL HEALTn DEPARTMENT SAN JOA QUIN COUNTY G� Unit S+rpen l surs Donna K Hcraii,%t E El S304 East Weber Avenue, Third Floor Carl Borgntan R E lit S Dopeau+ R4rkc IIuggms R C]d S R 17 1 y� Al Olsen,R E.,H S Stockton, California 95202-2708 Douglm W Nilson R E H S ' �9irxQR • PrrogrQ+Jr Mu►rnscr Telephone (209) 468-3420 Margarci Lagono R E 14 S Laurle A Colull%R E 11 S Fax (209)4G4-0138 Robtri McClellon,R E H S Probia+�+�llnrrager Mark Barccllo%,R 1:11 S FEB 14 ?_05 KEN HILLIARD KENDALL YOUNG 7-ELEVEN INC YLY LLC PO BOAC 711 720 YORK STREET DALLAS TX 75221-0711 SAN FRANCISCO CA 94110 RE 7-Eleven Store #32262 SITE CODE 1505 2360 Grant Line Road Tracy CA 85376 San Joaquin County Environmental Health Department (SJClEHD) has begun review of Results of Srte Assessment Remedial Feasibility Testing and Site Conceptual Model(Report)dated September 30,2004, prepared on your behalf by Secor International Incorporated (SECOR) and has the following comments The Report includes documentation of the continued assessment of the lateral and vertical extent of the petroleum hydrocarbon contamination in soil and groundwater,feasibility testing of two remedial alternatives, and a site conceptual model (SCM) The site assessment discussed in the Report included the advancement of two cone penetrometer test(CPT)borings for investigation of the vertical extent of contamination, and the installation of three additional shallow monitoring wells for investigation of the lateral extent of contamination Two discrete grab groundwater samples were collected at each CPT location The sample collected from the onsite CPT-1 at 60 feet below surface grade(bsg)was reported to contain 69 micrograms per liter(lag/1)total petroleum hydrocarbons (TPH)as gasoline, and 0 74 µg11 methyl tertiary butyl ether(MtBE) SECOR noted that the chromatogram appeared to indicate that this detection of TPHg was actually 2-ethyl-1-hexanol, a compound which is not a typical constituent of gasoline or diesel fuel SECOR slates that this compound is commonly associated with pipe dope However, the chromatogram was not included in the report for SJClEHD review,and research has indicated that this compound has been used as a fuel additive (Phillips 66 Superclean unleaded fuel additive), though it is most commonly used in consumer building and furnishing products, and in pesticides Please provide to SJClEHD a copy of the chromatogram, as well as documentation of which pipe dope product lists this compound as an ingredient,and an explanation of how SECOR considers it to be likely that pipe dope is the source of the detected contamination Three shallow monitoring wells, MW-7,MW-8 and MW-9 were installed to investigate the lateral extent of the shallow groundwater plume in the cross-and down-gradient directions These wells were developed and sampled on July 30,2004 Analytical results indicate that the lateral extent of the shallow plume has not been defsned The well located furthest down gradient, MW-8, contained 210 µgtl MtBE In addition, increasing concentrations of MtBE in well MW-2 Indicate that further investigation must be done to define the lateral extent of the plume towards the west FEB I u 2005 ��li a*rraaes�r�soraMls!#