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ATC Associates Inc.
<br /> \vim/ 1117 Lone Palm Avenue, Suite 201
<br /> Modesto, California 1
<br /> 209-579-222-2221
<br /> ASSOCIATE S I N C . Fax: 209-579-2222
<br /> in boring SB-14 generally attenuated rapidly with depth. Borings SB-12, SB-13, and SB-15 did
<br /> not contain detectable concentrations of TPHg, TPHd, or BTEX. No oxygenate fuel additives,
<br /> including 1,2-dichloroethane (1,2-DCA) and ethylene dibromide (EDB) were detected in any of
<br /> the soil samples above laboratory method detection limits. Dissolved petroleum hydrocarbon
<br /> constituents were detected at moderate to elevated concentrations in the groundwater samples
<br /> collected from borings SB-13 and SB-14, located near well MW2. The groundwater sample
<br /> from boring SB-11 contained relatively low concentrations of TPHg, TPHd, benzene, and
<br /> ethylbenzene. Groundwater samples collected from borings SB-12 and SB-15 did not contain
<br /> detectable concentrations of TPHg, TPHd, or BTEX, or oxygenate fuel additives.
<br /> The last record of periodic sampling of the monitoring wells occurred in May 2001. On
<br /> November 14, 2001, the SJCEHD staff and the Central Valley Regional Water Quality Control
<br /> Board (CVRWQCB) staff met, to review the soil and groundwater assessment data for the site.
<br /> The SJCEHD and the CVRWQCB staff agreed that additional work was necessary to reduce
<br /> contaminant mass and clean up the impacted groundwater.
<br /> In correspondence dated November 20, 2001 to Toledo Holdings Inc., the SJCEHD required
<br /> that a work plan be submitted to determine the feasibility and cost-effectiveness of at least two
<br /> remedial alternatives by January 20, 2002.
<br /> In correspondence dated July 15, 2008, the SJCEHD directed the sampling of monitoring wells
<br /> at the site by August 15, 2008 and uploaded into Geotracker by September 15, 2008. A
<br /> subsequent letter was sent dated March 31, 2009.
<br /> During sampling activities on June 15, 2009, ATC was unable to locate monitoring well MW7 as
<br /> it appeared to have been paved over. ATC recommended in its Monitoring Report, June 15,
<br /> 2009 Monitoring Event, C&R International Sales Inc., 2403 Navy Drive, Stockton, California,
<br /> LOP Site Code: 2023, dated August 27, 2009, that the well be located and abandoned.
<br /> A subsequent phone discussion with the SJCEHD concurred with this recommendation. The
<br /> well was located and uncovered by site personnel of C&R during the week of October 5, 2009.
<br /> ATC technicians then examined the well to determine whether it could be returned to service or
<br /> if it had sustained damage that would have required its destruction. The well was found to be
<br /> serviceable. Consequently, the well was purged and sampled and the analytical results were
<br /> detailed in a report dated February 19, 2010. In this report, ATC recommended to evaluate the
<br /> site for closure as a low risk closure site.
<br /> In correspondence dated June 4, 2010, the SJCEHD agreed with ATC's recommendation to
<br /> evaluate the site for closure as a low risk closure site. The SJCEHD directed additional actions
<br /> as part of the evaluation. The required actions included the completion of a soil vapor intrusion
<br /> study to be completed in the fourth quarter of 2010.
<br /> Soil gas study activities were conducted at the site between November 2010 and February
<br /> 2011. Three soil gas sampling points (SG1, SG2, and SG3) were installed at the site on
<br /> November 19, 2010. These points were initially sampled on December 2, 1010; however, the
<br /> data was not reliable due to elevated detections of the leak check compound 1,1-difluoroethane.
<br /> The soil gas sampling points were re-sampled on February 7, 2011, after replacing the
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