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<br /> mg/kg TPH-cr, 37 mg/kg TPH-d, and a trace concentration of toluene (0.0058 mg/kg). There
<br /> were no detectable concentrations of the remaining BTEX compounds; including benzene.
<br /> I Boring BB-81, northwest of BB-82, contained 70 mg/kg TPH-cr and 31 mg/kg TPH-d, BTEX
<br /> compounds were not detected. Laterally,it is bounded by BB-80, BB-83,BB-144/BB-190, and
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<br /> BB-160/BB-191, in which no hydrocarbons were detected. Vertically,Area B1 extends no
<br /> deeper than approximately 9 feet, as seen in the analytical results for BB-175. No hydrocarbons
<br /> were detected in groundwater from this area.
<br /> 6.2.2 Area B2
<br /> Area B2 (Figure 4a)is centered on boring BB-94 and BB-176,which contained up to I 10,000 mg/kg TPH-cr, 7,600 mg/kg TPH-d, and no detectable BTEX to a depth of approximately 10
<br /> feet. This area is defined to low to non-detectable concentrations of TPH-cr and TPH-d in
<br /> borings BB-93,BB-95, BB-145/BB-192,BB-161/BB-193. Vertically, TPH is defined to low to
<br /> non-detectable results at a depth of 14 feet in boring BB-176.
<br /> A groundwater sample along the alignment in Area B2 contained TPH-cr at 9,100 µg/L, TPH-d
<br /> at 7,100 µg/L,with no detectable benzene, and a maximum of 30 µg/L of the remaining BTEX
<br /> constituents. Impacted groundwater is defined laterally to a maximum TPH of 200 µg/L(TPH-
<br /> Id)by BB-192 and BB-193.
<br /> • 6.2.3 Area B3
<br /> Area B3 (Figure 4a)is centered on the former pipelines' alignment between BB-107 and BB-16,
<br /> with the highest petroleum hydrocarbon concentrations in BB-1 and BB-5,with a maximum
<br /> TPH-cr of 67,000 mg/kg and a maximum TPH-d of 17,000 mg/kg. No benzene was detected in
<br /> this area; up to 2.7 mg/kg of the remaining BTEX constituents (xylenes) were present. Impacted
<br /> soil is laterally defined to a maximum of 50 mg/kg TPH by BB-17,BB-106, BB-116,BB-117,
<br /> BB-146 though BB-150, and BB-162 through BB-166. The vertical extent of hydrocarbon
<br /> impact extends to exhibits a sharp decrease between at depth 9 to 11 feet and 15 feet. Below 15
<br /> feet, TPH concentrations are no greater than 280 mg/kg TPH-cr, and 75 mg/kg TPH-d.
<br /> I Within Area 3, groundwater was collected from 12 borings. Groundwater at BB-177 contained
<br /> 1,000 µg/L TPH-cr and 590 µg/L TPH-d. No benzene was detected in groundwater, though low
<br /> concentrations of the remaining BTEX components (maximum 3.2 µg/L) were present. Lateral
<br /> I and downgradient groundwater from the area of B-177 contained either no or only low
<br /> concentrations of TPH (maximum 250 µg(L TPH-d in boring BB-178A), with a trace amount of
<br /> I toluene in BB-179. Thus,TPH-impacted groundwater does not appear to extend beyond 25 feet
<br /> off of the former pipelines' alignment.
<br /> 6.2.4 Area B4
<br /> Area B4 (Figure 4b) is centered on BB-19 and BB-20 and is bounded by BB-18, BB-22, BB-23,
<br /> and BB-151. The central borings contained up to 3,600 mg/kg TPH-cr and 900 mg/kg TPH-d.
<br /> ITPH concentrations in the lateral borings are no greater than 47 mg/kg. TPH in soil appeared to
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