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Ms.Lori Duncan
<br /> CAM B R I A September 9,2005
<br /> 2003 Site Conceptual Model (SCM): Cambria submitted a Site Conceptual Model/Site
<br /> Investigation Work Plan on October 3, 2003. In the SCM, Cambria recommended installing a
<br /> well downgradient of the USTs, installing a deep groundwater monitoring well, and performing
<br /> dual-phase extraction(DPE) and SVE in the former UST complex.
<br /> 2004 Well Installation: During February 2004, Cambria installed one shallow off-site well
<br /> (MW-12) in the parking lot east of the site and one deep on-site well (MW-13). No TPHg,
<br /> BTEX, or fuel oxygenates were detected in well borings MW-12 and MW-13. Soil results from
<br /> MW-12 indicate that subsurface soil across Pacific Avenue east of the existing UST complex is
<br /> not impacted by gasoline constituents. Cambria's April 9, 2004 Site Investigation and First
<br /> © Quarter 2004 Groundwater Monitoring Report details this investigation.
<br /> 2004 Interim DPE: During a 5-day period in June 2004, Cambria performed DPE using well
<br /> VEW-2 and SVE using well VEW-1. Cambria estimates that approximately 200 pounds of
<br /> vapor-phase TPHg and 2.31 pounds of vapor-phase benzene were removed from wells VEW-1
<br /> and VEW-2 during the course of this interim remediation. In addition, 3,486 gallons of
<br /> groundwater were extracted from VEW-2, removing approximately 3.49 pounds of liquid-phase
<br /> TPHg and 0.12 pounds of liquid-phase benzene from the subsurface. Cambria's February 9,2005
<br /> Interim Remediation Report further describes these activities.
<br /> Groundwater Monitoring Program: There are currently six on-site groundwater monitoring
<br /> wells (MW-1 through MW-4, MW-13 and VEW-2), one on-site SVE well (VEW-1), and eight
<br /> off-site groundwater monitoring wells (MW-5 through MW-12). VEW-2 was originally installed
<br /> as an SVE well, and well MW-13 is screened deeper than the other wells. Wells MW-1 through
<br /> MW-8, MW-12, MW-13, and VEW-2 are sampled quarterly, well MW-9 is sampled semi-
<br /> annually during the first and third quarters, and wells MW-10 and MW-11 are sampled annually
<br /> during the third quarter. Well VEW-1 is dry.
<br /> During the second quarter 2005 sampling event, TPHg was detected in wells MW-4, MW-6,
<br /> MW-7, MW-8, MW-12, and VEW-2 at concentrations ranging from 140 to 100,000 ppb. The
<br /> laboratory noted that the TPHg reported for wells MW-6 and MW-8 did not match their gasoline
<br /> standard. Benzene was detected in wells MW-3, MW-4, MW-6, MW-7, MW-8, and VEW-2
<br /> from 0.52 to 2,100 ppb. MTBE was detected in wells MW-4, MW-12, and VEW-2 at
<br /> concentrations of 11, 29, and 1.4 ppb, respectively. 1,2-dichloroethane was detected in wells
<br /> MW-12 and MW-13 at concentrations of 94 and 0.65 ppb, respectively. Wells MW-9, MW-10,
<br /> and MW-I1 were not sampled this quarter.
<br /> Cambria presents well and boring construction data in Table 2, historical soil data in Table 3,
<br /> historical groundwater investigation analytical data in Table 4, and historical groundwater
<br /> monitoring data as Attachment A.
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