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S E C 0 R 7-Eleven Store#19976 Quarterly Groundwater Monitoring and Remediation Progress Report(1Q2005) May 4, 2005 Page 5 ' 0 10 pound of TPHg was removed in sod vapor during the 22-hour test No recordable amount of benzene or MtBE was removed during the test On November 23, 2004, an additional SVE test was conducted on monitoring well MW-2 Based on the sod vapor samples collected during the five hour test, approximately 1 79 lbs of TPHg was removed No recordable amounts of benzene or MtBE were removed during the test On March 15, 2005, SECOR submitted a Work Plan for 02 Sparge Well Installation to the SJCEHD This work pian details the proposed installation of three oxygen injection wells to improve the remediation at the site MONITORING AND SAMPLING PROCEDURES The depth to water was measured to within 0 01 feet bgs in monitoring wells MW-1 through MW-7, MW-1A, MW-4A, and MW-5A from the top of casing (TOC) using a water level indicator Dissolved oxygen concentrations were also measured in each well using a YSI Model 550A dissolved oxygen meter equipped with a down hole sensor NN,11nor A u)4+mw1i A , Well purging and sampling equipment was thoroughly cleaned prior to purging and s�1 sampling each well The sampling procedure for each well included measuring the water level and checking for the presence of liquid-phase hydrocarbons (LPH), using either an electronic indicator and a clear Teflon® bailer or an oil-water interface probe Wells not containing LPH were purged of approximately three casing volumes of water (or to dryness) using a submersible pump or bailer The equipment and purging methods used for the current sampling event were noted on the field data sheets shown in Attachment A During purging, temperature, pH, and electrical conductivity were monitored After purging, water levels were allowed to recover to 80% of the original levels prior to collection of the water sample Groundwater samples were collected using a disposable Teflon`s bailer, placed into appropriate EPA-approved containers, labeled, logged onto chain-of-custody documents, and transported on ice to a California state-certified laboratory Copies of the field notes are presented in Attachment A GROUNDWATER SAMPLE ANALYSES AND RESULTS The groundwater samples collected from MW-1, MW-1A, MW-2, MW-3, MW-5, MW-5A, MW-6, and MW-7 were analyzed for TPHg, BTEX, and the fuel oxygenates MtBE, tert-butyl alcohol (TBA), diisopropyl ether (DIPE), ethyl-tert-butyl ether (EtBE), and tert-amyl-methyl z°�4 ether (TAME) by Environmental Protection Agency (EPA) Method 8260B In addition, annual sampling and analysis for 1-2-dichloroethane, 1,2-dibromoethane, methanol, and ethanol was conducted The certified laboratory analytical report and chain-of-custody (COC) documentation are presented as Attachment B Groundwater analytical results are presented on Figure 3, and are summarized in Tables 1 and 2 Hydrocarbon concentrations were generally consistent with historical data REMEDIATION Remediation conducted during the first quarter 2005 was oxygen injection into SP-1 and SP-1A 19976 05-10 Report doc SECOR International incorporated