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S E C 0 R
<br /> In April 2001, Gettler-Ryan, Inc (GR) conducted a subsurface investigation at the site,
<br /> which involved the drilling of eight Geoprobe soil borings (six off-site and two on-site),
<br /> and one on-site cone penetrometer test (CPT) probe Analytical results of selected soil
<br /> samples collected during the CPT investigation were reported by the laboratory as not
<br /> detected (ND) for total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene,
<br /> ethylbenzene, xylenes (BTEX), MtBE, ethanol, tert-butyl alcohol (TBA), di-Isopropyl
<br /> ether (DIPS), ethyl tert-butyl ether (ETBE), 1,2-dichloroethane (1,2-DCA), tert-amyl
<br /> methyl ether (TAME), and ethylene dibromide (EDB) Analytical results for groundwater
<br /> samples from the Geoprobes were reported as ND for all analytes in samples B-3, B-5,
<br /> B-6, B-7 and B-8 Sample B-1 contained MtBE at 90 parts per billion (ppb) and DIPE at
<br /> 2 8 ppb Sample B-2 contained only MtBE at 15 ppb Sample B-4 contained MtBE at
<br /> 11 ppb Sample CPT-1, collected at 75 feet below ground surface (bgs), contained
<br /> MtBE at 120 ppb and 1,2-DCA at 23 ppb
<br /> On August 8, 9 and 10, 2001, GR installed three off-site and one on-site groundwater
<br /> monitoring well (MW-8 through MWA 1) Analytical results for sod samples collected
<br /> from well borings MW-8, MW-9 and MW-10 were reported as ND for all analytes Soil
<br /> sample MWA 1-14, collected at 14 feet bgs, contained 1 7 parts per million (ppm) of
<br /> MtBE Analytes were reported as ND in groundwater samples collected from wells MW-
<br /> 8, MW-9 and MW-10 The only analyte detected in groundwater was MtBE In well MW-
<br /> 11 at a concentration of 110 ppb (EPA Method 8260)
<br /> Between December 3 and 7, 2001, SECOR International Incorporated (SECOR)
<br /> . performed a dual-phase extraction (DPE) event at the site The DPE test was performed
<br /> on wells MW-3 and MW-7 over a 110-hour period Flow rates during the test varied from
<br /> 10 90 to 33 41 cubic feet per minute (cfm), and vacuum rates vaned from 24 to 25 $
<br /> inches of mercury (in Hg) Over the course of the five-day event, SECOR reportedly
<br /> removed a total of 0 pounds (Ibs) of TPHg, 0 01 lbs of benzene, and 6 64 lbs of MtBE
<br /> The amount of hydrocarbons removed is based on laboratory samples collected during
<br /> the test SECOR determined that the vacuum radius of influence was between 36 and
<br /> 60 feet Approximately 20,830 gallons of groundwater were extracted during the DPE
<br /> event Based on the low mass removal achieved with this test, SECOR concluded that
<br /> DPE is not an effective remedial alternative for this site ;
<br /> On April 23, 2002, the SJCEHD expressed concern with high concentrations of TBA in
<br /> MW-3 and MW-7 On May 9, 2002, GR confirmed high concentrations of TBA in the
<br /> wells (over 200,000 micrograms per liter or µg/Q, and attributed the raised
<br /> concentrations to MtBE metabolism The SJCEHD required on July 22, 2002, that
<br /> groundwater samples collected from MW-3 and MW-7 be analyzed for the full scan of ;
<br /> analytes by EPA Method 8260 The SJCEHD stated that if MtBE metabolism was
<br /> occurring in the vicinity of MW-3 and MW-7, then other degradation constituents should
<br /> be detected by this analytical method GR began sampling MW-3 and MW-7 for the full
<br /> scan of analytes by EPA Method 8260 during the first quarter 2003
<br /> In December 2002, GR installed monitoring wells MW-12 and MW-13, sparge points SP-
<br /> A through SP-H, SP-J, and SP-K, and drilled two CPT probes (CPT-2 and CPT-3) to a
<br /> maximum depth of approximately 140 feet bgs The CPT rig was equipped with an
<br /> onboard computer system that provided a real time analysis of the subsurface
<br /> iconditions The CPT device created a lithologic log of the boring by comparing the CPT
<br /> tip resistance to sleeve friction on the CPT cone Groundwater samples were collected
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