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S (EC0R <br /> 7-Eleven Store#19976 <br /> Quarterly Groundwater Monitoring and Remediation Progress Report (2Q2005) <br /> August 9, 2005 <br /> Page 6 � r; <br /> u r„ <br /> GROUNDWATER SAMPLE ANALYSES AND RESULTS <br /> nl; Ngo <br /> The groundwater samples collected from MW-1, MW-1A, MW-2, MW-3, MW-5, MW-5A, <br /> MW-6, and MW-7 were analyzed for TPHg, BTEX, and the fuel oxygenates MtBE, tert-butyl ' <br /> alcohol (TBA), diisopropyl ether (DIPE), ethyl-tert-butyl ether (EtBE), and tert-amyl-m ethyl klu <br /> ether (TAME) by Environmental Protection Agency (EPA) Method 8260B Due to a clerical <br /> error, MW-4A was not sampled during the second quarter 2005 MW-4A will be added to a�'r <br /> future quarterly sampling events beginning with the third quarter 2005 event scheduled for <br /> August 16, 2005 The certified laboratory analytical report and chain-of-custody (COC) ' ' <br /> documentation are presented as Attachment B , <br /> Groundwater analytical results are presented on Figure 3, and are summarized in Tables 1 <br /> and 2 Hydrocarbon concentrations were generally consistent with historical data MtBE <br /> and TBA concentrations decreased significantly in MW-2 <br /> REMEDIATION <br /> Remediation conducted during the second quarter 2005 was oxygen infection into SP-1 and <br /> SP-1A <br /> On April 12, April 29, May 10, May 26, June 9, and June 20, 2005, SECOR field personnel <br /> conducted oxygen infection into on-site sparge wells SPA and SP-1A 150 ft3 of oxygen Fjp <br /> was infected into each well simultaneously (Table 4) Dissolved oxygen concentrations <br /> were measured before and after the infection event in monitoring well MW-2 (Table 5) The r <br /> greatest D O concentration increase observed in MW-2, located adjacent to SP-1 and SP- <br /> 1A, was from 5 6 milligrams per liter (mg/L) to 38 7 mg/L on April 29, 2005 SECOR will <br /> continue biweekly to monthly oxygen infection during the third quarter 2005 Copies of the <br /> field notes and laboratory analysis are presented in Attachment C a <br /> PURGE AND RINSATE WATER DISPOSAL <br /> Water generated during well sampling and equipment cleaning is pumped into a SECOR <br /> truck-mounted water tank The water is transferred into properly labeled 55-gallon drums n a <br /> and stored on-site The drummed non-hazardous petroleum hydrocarbon contaminated <br /> water is transported quarterly by Belshire Environmental to DeMenno Kerdoon in Compton, ' <br /> California, for disposal ; <br /> �F <br /> ATTACHMENTS <br /> Figures <br /> r � <br /> Tables n, <br /> Attachment A— Monitoring and Sampling Field Notes <br /> Attachment B—Certified Laboratory Analytical Reports and Chain-of-Custody Documentation P � <br /> Attachment C—Oxygen Infection Field Notes <br /> cc Ms Vicki McCartney, San Joaquin County, Environmental Health Department lin <br /> Mr James Barton, California Regional Water Quality Control Board, Central Valley <br /> Region <br /> 19976 05-2Q Report doc SECOR lntematlonal incorporated <br /> } <br /> a <br />