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S ESC ® R
<br /> 7-Eleven Store#19976
<br /> Quarterly Groundwater Monitoring and Remediation Progress Report(1Q2004)
<br /> June 3, 2004
<br /> Page 4
<br /> On May 27, 2003, one sal sample was collected under the northern fuel dispenser, and a second
<br /> sample was collected beneath the product line during a fuel system upgrade The soil samples
<br /> collected beneath the dispenser and fuel delivery piping did not contain concentrations of TPHg,
<br /> BTEX, or fuel oxygenates above laboratory detection limits On June 9, 2003, three 10,000-gallon
<br /> double-walled fiberglass USTs were removed from the excavation and hauled offsite
<br /> On June 9 and 19, 2003, a total of six UST confirmation soil samples (T1 N-15' through T3S-13')
<br /> were collected in native soil underlying the ends of the three USTs (Figure 2) at approximate depths
<br /> of 12 to 15 feet bgs during the second UST replacement event at the site TPHg, BTEX, and fuel
<br /> oxygenates were not detected at concentrations above laboratory detection limits in two of the six
<br /> sod samples collected beneath the USTs Benzene and TPHg were reported in the soil samples
<br /> collected beneath the north ends of two USTs (T1 N, T2N) at maximum concentrations of 0 0087
<br /> mg/kg and 9 3 mg/kg, respectively MtBE and TBA were reported at maximum concentrations of 3 3
<br /> mg/kg (T1 N@13') and 18 mg/kg (T3N@13'), respectively
<br /> Between June 23 and July 7, 2003, Glacier Environmental Services installed two new double-walled
<br /> fiberglass USTs one 10,000-gallon premium unleaded gasoline UST, and one 15,000-gallon regular
<br /> unleaded gasoline UST, and associated piping and dispensers (Figure 2) In order to accommodate
<br /> the new 15,000-gallon UST, Glacier excavated approximately 288 cubic yards of sod, expanding the
<br /> UST pit to the west The excavated soil was disposed of at Forward Inc landfill
<br /> . MONITORING AND SAMPLING PROCEDURES
<br /> The depth to water was measured in monitoring wells MWA through MW-7, MWAA, MW-4A, and
<br /> MW-5A from the top of casing (TOC) using a water level indicator to within 0 01 feet bgs Dissolved
<br /> oxygen readings were also collected from each well using a YSI Model 550A dissolved oxygen meter k
<br /> equipped with a down hole sensor
<br /> Well purging and sampling equipment was thoroughly cleaned prior to purging and sampling each
<br /> well The sampling procedure for each well included measuring the water level and checking for the
<br /> presence of liquid-phase hydrocarbons (LPH), using either an electronic indicator and a clear
<br /> Teflon® bailer or an oil-water interface probe Wells not containing LPH were purged of
<br /> approximately three casing volumes of water (or to dryness) using a submersible pump or bailer
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<br /> The equipment and purging methods used for the current sampling event were noted on the field �� 1
<br /> data sheets included in Attachment A During purging, temperature, pH, and electrical conductivityaJ
<br /> were monitored in order to document that these parameters were stable prior to collecting samples �
<br /> After purging, water levels were allowed to recover to 80% of the original levels prior to collection of
<br /> the water sample Groundwater samples were collected using a disposable Teflon® bailer, placed
<br /> into appropriate EPA-approved containers, labeled, logged onto chain-of-custody documents, and
<br /> transported on ice to a California state-certified laboratory Copies of the field notes are included in
<br /> Attachment A
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<br /> GROUNDWATER SAMPLE ANALYSES AND RESULTS
<br /> The groundwater samples collected from MWA through MW-7, MW-1A, MW-4A, and MW-5A were
<br /> analyzed for the presence of TPHg, BTEX, and the fuel oxygenates MtBE, tert-butyl alcohol (TBA),
<br /> diisopropyl ether (DIPE), ethyl-tert-butyl ether (EtBE), and tert-a myl-m ethyl ether (TAME) using
<br /> Environmental Protection Agency (EPA) Method 8260B The certified laboratory analytical report
<br /> and chain-of-custody documentation are presented as Attachment B
<br /> 19976 44-10 Report doc SECOR International Incorporated
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