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GRO, benzene, and MTBE were reported in wells VW-3 and VW-5 GRO and benzene were also
<br /> reported in wells MW-4 and MW-8, and benzene and MTBE were also reported in well VW-6 The highest
<br /> concentrations of GRO (2,900,000 pg/L) and benzene (12,000 µg/L) were reported in well MW-4, and the
<br /> highest concentration of MTBE (180 pg/L) was reported in well VW-3 1,2-DCA (520 pg/L) was reported
<br /> in well MW4, and ethanol (950 µg/L)was reported in well VW-5 TBA, TAME, DIPE, ETRE, or EDB were
<br /> not reported in any of the upper zone wells Analytical results for the fourth quarter 2005 are generally
<br /> consistent with previous quarters GRO, benzene, and MTBE analytical data for the samples collected on
<br /> December 19, 2005, are presented in Figure 5 Analytical data were submitted to the State Water
<br /> Resources Control Board as required by AB2886 The electronic delivery receipt is attached in Appendix
<br /> C
<br /> Lower Water Bearing Zone Sand Zone 2
<br /> During the site visits conducted during the fourth quarter 2005, a product sheen was found in well MW-1,
<br /> and free product was measured in well MW-15 at thicknesses ranging from 0 33 and 0 40 feet
<br /> Approximately 10 gallons of product/water mixture were manually bailed during the fourth quarter 2005
<br /> from wells MW-1 and MW-15 Approximately 205 gallons (MW-1) and 35 gallons (MW-15) of
<br /> product/water mixture have been manually bailed to date Product thickness measurements and volumes
<br /> of liquid bailed are summarized in Table 1
<br /> At the time of the fourth quarter 2005 monitoring event, groundwater levels had decreased between 0 19
<br /> and 0 44 feet in wells MW-10 and MWA 5, and increased between 0 09 and 0 35 feet in wells MW-1 and
<br /> MW-12 since the previous monitoring event (September 19, 2005) Depth-to-water measurements were
<br /> normalized to mean sea level (MSL) and used to construct a groundwater elevation contour map
<br /> (Figure 4) Wells that contained less than 1 foot of water are interpreted to be dry and are indicated as
<br /> "dry" on Figure 4 Groundwater flow was generally to the east at an average gradient of 0 032 ft/ft
<br /> . Groundwater flow has been to the southeast, east-southeast, and east during previous quarters
<br /> GRO and benzene were reported in wells MW-10 and MW-12 The highest concentrations of GRO
<br /> (54,000 pg/L) and benzene (12,000 µg/L) were reported in well MW-12 1,2-DCA (37 pg/L) was reported
<br /> in well MW-10 MTBE, TBA, TAME, DIPE, ETBE, EDB, or ethanol were not reported in any of the lower
<br /> zone wells Analytical results for the fourth quarter 2005 are generally consistent with previous quarters
<br /> GRO, benzene, and MTBE analytical data for the samples collected on December 19, 2005, are
<br /> presented in Figure 5 Analytical data were submitted to the State Water Resources Control Board as
<br /> required by AB2886 The electronic delivery receipt is attached in Appendix C
<br /> Domestic Well
<br /> GRO, BTEX, MTBE, TBA, TAME, DIPE, ETBE, EDB, 1,2-DCA, or ethanol were not reported above
<br /> method detection limits in the domestic well GRO, benzene, and MTBE analytical data are presented in
<br /> Figure 5 These analytical results for the fourth quarter 2005 are consistent with historical data
<br /> System Description
<br /> Soil Vapor Extraction System
<br /> The Solleco 500 cfm SVE system consists of a 500 cfm rated thermal oxidizer with a 40 hp liquid ring
<br /> blower Upon system start-up (May 16, 2005), petroleum hydrocarbon laden soil vapors were extracted
<br /> from wells VW-1, VW-3, VW-4, VW-8, VW-14, MW-2, MW-8, and MW-9 using the 40 hp blower package
<br /> capable of producing up to 28 "Hg vacuum The extracted soil vapors were abated in the thermal oxidizer
<br /> prior to discharge to the atmosphere The SVE system has a built-in hour meter that is used to determine
<br /> the operational uptime Sample ports (influent, system-influent, and effluent) are designated to collect air
<br /> samples The results of the air samples are used to calculate the destruction efficiency of the system
<br /> K\Bp-Arco for URS\6100\Quarterly\2005\Arco_6100-4Q05 doc STIz/17U5
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