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<br /> 5 Stratus prepared and submitted a Site Conceptual Model on October 3, 2002 Based on the
<br /> conclusions of the Site Conceptual Model, Stratus prepared and submitted a Work Plan proposing
<br /> additional assessment activities
<br /> WORK PROPOSED FOR NEXT QUARTER(First 2003)
<br /> 1 Stratus will continue to remove floating product from well MW-1 on a weekly basis, monitor free
<br /> product thickness in selected wells, and remove floating product when necessary
<br /> 2 At the request of PHS/EHD, Stratus will measure the depth-to-water in all vapor extraction and
<br /> monitoring wells during the first quarter 2003 Wells with measureable water will be purged Those
<br /> wells that recharge sufficiently will be sampled during the first quarter, the more slowly recharging
<br /> wells will be sampled during the following sampling event without prior purging
<br /> 3 Stratus will sample select vapor extraction and monitoring wells The onsite water supply well will
<br /> also be sampled The next sampling event is tentatively scheduled for March 2003 Groundwater
<br /> samples will be analyzed for total petroleum hydrocarbons as gasoline (TPHG), benzene, toluene,
<br /> ethylbenzene, total xylenes (BTEX), tertiary butyl alcohol (TBA), methyl tertiary butyl ether (MTBE),
<br /> di-isopropyl ether (DIPE), ethyl ternary butyl ether (ETBE), tertiary amyl methyl ether (TAME), 1,2-
<br /> dichloroethane (1,2-DCA), and ethanol using USEPA Method 82608
<br /> 4 Upon approval of the previously submitted Work Plan, Stratus will implement offsite access in order
<br /> to implement the proposed assessment activities
<br /> DISCUSSION
<br /> In wells MW-3 through MW-6, MW-8, MW-9, VW-1, VW-2, VW-3, VW-5, VW-10 through VW-14, and
<br /> VW-20, there was less than 1 foot of water column in the well, the water in these wells does not appear to
<br /> be formation water, therefore the wells were not sampled Wells MW-7, VW-7, VW-8, VW-9, and VW-16
<br /> through VW-19 were dry The groundwater in wells screened within the upper water-bearing zone (MW-2,
<br /> VW-4, and VW-6) were measured at depths between 35 39 and 59 50 feet below top of well casing
<br /> (TOC) Well VW-4 bailed dry during purging Groundwater in well MW-1 (screened in the lower water-
<br /> bearing zone) was measured at 105 37 feet bgs These data are similar to groundwater data from
<br /> previous quarters
<br /> During quarterly monitoring activities on December 22, 2002, a product sheen was observed in wells
<br /> MW-1, VW-1, and VW-4 During the weekly visits to the site, product was measured in well MW-1 at
<br /> thicknesses ranging from a sheen to 0 16 feet thick During each site visit, free product in the well was
<br /> manually bailed, and placed in properly labeled DOT-approved drums pending disposal Approximately
<br /> 22 gallons of a mixture comprised of free product and water was bailed from well MW-1 during the fourth
<br /> quarter 2002, and 81 gallons of product/water mixture have been bailed to date
<br /> During the fourth quarter 2002 sampling event, TPHG and benzene were detected in the groundwater
<br /> samples collected from wells MW-2 and VW-6 The highest concentrations of TPHG (20,000 pg/L),
<br /> benzene (8,600 pg/L) were detected in well VW-6 MTBE (310 pg/L) was detected in well VW-6
<br /> Toluene, ethylbenzene, xylenes, or other fuel oxygenates were not detected in either of the wells
<br /> Petroleum hydrocarbons or fuel oxygenates were not detected in the sample collected from the domestic
<br /> well These data are similar to chemical analytical data from previous quarters TPHG, benzene, and
<br /> MTBE analytical data for the samples collected on December 22, 2002, have been plotted in Figure 3
<br /> Laboratory quality assurance notations are summarized in Table 4
<br /> P\13P-Arco for URS\6100\Quarterly\2002\Arco_6100_4Q02 doe 5TKA TUS
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