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A S S O C I A T E S I N C <br /> of petroleum hydrocarbons Quarterly monitoring and sampling of the groundwater monitoring wells on <br /> site was initiated in October 1991 <br /> In September 1993, RESNA supervised the advancement of a boring that was subsequently completed as <br /> groundwater monitoring well MW-6 (Figure 2) Soil encountered during drilling was monitored for <br /> organic vapors using a PID No evidence of soil contamination was noted Analytical results of <br /> groundwater samples indicated only toluene was detected, at a concentration of 38 micrograms per liter <br /> (ug/1) <br /> In August 1995, due to infiltration of organic debris in groundwater monitoring well MW-4, Smith <br /> Environmental Technology Corporation destroyed well MW-4 by overdrilling the PVC casing and sandpack <br /> with 8-inch diameter hollow-stem augers Smith also supervised the advancement of a boring for <br /> groundwater well MW-4R to replace well MW-4 (Figure 2) Analytical results of the soil samples collected <br /> from the boring for monitoring well MW-4R indicated that petroleum hydrocarbons were detected only in <br /> the sample collected from 6 5 feet bgs <br /> In January and February 1996, SECOR advanced ten soil borings at the site Soil samples and grab <br /> groundwater samples were collected from the borings No total petroleum hydrocarbons as gasoline <br /> (TPHg), total petroleum hydrocarbons as diesel (TPHd), total petroleum hydrocarbons as motor oil <br /> (TPHmo), methyl tertiary butyl ether (MTBE), or benzene, toluene, ethylbenzene, or total xylenes <br /> (BTEX) constituents were detected above reported laboratory detection limits in any of the soil samples <br /> analyzed with the exception of soil boring SB2 Low concentrations of benzene, toluene, and total <br /> xylenes were detected in the soil sample collected from SB2 at 3 5 feet bgs Trace amounts of free <br /> product were observed in the water samples obtained from borings SB 1, S132, and SB26 Groundwater <br /> samples collected from borings SB26, located between the restaurant and store buildings, and SB1 and <br /> SB2, located between the levee and the store, contained elevated concentrations of petroleum <br /> hydrocarbons MTBE was detected in the water sample collected from boring SB26 at 130 ug/1 The <br /> water samples from SB 1 and SB2 were not analyzed for MTBE <br /> In July and August 1999, ATC advanced ten soil borings (Figure 2) to evaluate the extent of petroleum <br /> hydrocarbons and trace amounts of free product detected by SECOR Soil borings advanced along the <br /> levee, hydraulically upgradient and southwest of the location of the former USTs and the current AST <br /> location, contained elevated concentrations of TPHg, TPHd, and MTBE The extent of impacted soil <br /> was defined and generally extended along the backside of the levee, west of the store The areal extent <br /> was approximately 200 feet in length and 65 feet in width and was limited to depths between 5 and 15 <br /> feet bgs Additionally, MTBE impacted soil extended eastward, between the store and office building <br /> The groundwater plume was located generally along the eastside of the levee, west of the store <br /> Concentrations were highest in the boring adjacent to the former and current product lines The extent of <br /> TPHg in groundwater was not fully defined to the west and south but samples indicated that the borings <br /> in those directions were near the edge of the plume <br /> In April 2001, ATC drilled one soil boring to 30 feet bgs and converted the boring into groundwater <br /> monitoring well MW-7 (Figure 2) Well MW-7 is located between the levee and the on-site store where <br /> elevated petroleum hydrocarbons were detected during the previous investigations TPHg, benzene, ethyl <br /> benzene, and total xylenes were detected at 60, 1, and 2 9 milligrams per kilogram (mg/kg), respectively <br /> in the soil sample collected at 5 feet bgs MTBE was detected at concentrations of 56 and 41 mg/kg in <br /> the soil samples collected at 5 and 10 feet bgs, respectively MTBE was detected in water samples <br /> w 1625141reportslstatusreport doc 2 <br />