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#w` Additional Groundwater Investigation Report
<br /> CSUS Multi-Campus Regional Center
<br /> August 19,2003
<br /> Page 2
<br /> On December 28 and 29, 2000 Condor conducted a limited soil and groundwater investigation utilizing
<br /> Geoprobe® direct push technology at the site. Condor prepared. the Preliminary Investigation and
<br /> i Evaluation Report (PIER), dated February 7, 2001, describing the results of.the-. work. Laboratory
<br /> analytical results of the soil and groundwater samples and field observations indicated that petroleum
<br /> hydrocarbons were present in site soil and groundwater down to the approximate,total depth of the
<br /> investigation (36 feet below grade). Based on the results of the investigation, Condor recommended the
<br /> installation of three CPT borings to investigate the site geology, three direct push boings to collect soil
<br /> samples, and three Hydropunch borings to collect discrete groundwater samples at depths to be.
<br /> determined by the results of the CPT borings. The purpose of the borings was to continue with evaluation
<br /> of the vertical and horizontal distribution of petroleum hydrocarbon impacted soil and'groundwater at the
<br /> site. Condor also recommended the installation of three groundwater monitor wells to establish the
<br /> groundwater gradient and to monitor the concentrations of petroleum hydrocarbons in site groundwater.
<br /> In addition, Condor recommended the completion of a sensitive receptor survey within a radius of 2,000
<br /> feet of the site to investigate the potential for receptors that may be impacted by petroleum hydrocarbons
<br /> in the groundwater.
<br /> In a letter dated April 4, 2001 to Mr. Cliff Bailey of CSUS, Ms. Dot Lofstrom of the SJCEHD concurred
<br /> with the recommendations contained in the PIER. At the request of Mr. Rosso, Condor:prepared the Work
<br /> Plan - Additional Soil and Groundwater Investigation, dated October 5, 2001. The proposed work
<br /> included the installation of CPT borings, direct push borings, and monitor wells, and the completion of a
<br /> sensitive receptor survey to identify potential sensitive receptors within a 2,000-foot..radius of the site.
<br /> The work plan was approved by Ms. Rebecca Setliff of the SJCEHD in a letter dated November 14, 2001
<br /> to Mr. Cliff Bailey of CSUS.
<br /> The approved work was conducted in November and December 2001. Findings of the Work were
<br /> described in the Additional Soil and Groundwater Investigation and Monitor Well Installation Report,
<br /> dated January 11, 2002, prepared by Condor. Results of the work indicated that site soil contamination
<br /> was fully investigated but that groundwater contamination was not. Groundwater contamination was
<br /> present down to the total depth of the investigation (approximately 81 feet below the ground surface) and
<br /> was present at the Iateral bounds of the area investigated; particularly to the east, in the direction of the
<br /> groundwater gradient indicated by an initial monitoring event. The sensitive receptor survey indicated.the
<br /> presence of several potential receptors, but no wells within close proximity to the site':that had not been
<br /> previously destroyed.
<br /> The January 11, 2002 report recommended quarterly groundwater monitoring, additional lateral and
<br /> vertical groundwater characterization, and soil over-excavation. The soil over-excavation was a suggested
<br /> remedial alternative that was most likely to result in rapid mitigation of site contamination. In a letter
<br /> dated April 26, 2002 to Mr. Bailey of CSUS, Ms. Setliff of the SJCEHD agreed with the monitoring and
<br /> additional groundwater investigation portion of the recommendations, but requested the evaluation of the
<br /> feasibility of at least two remedial options for the site.
<br /> Condor has conducted Eve quarterly monitoring events at the site (December 2001;'!June, September,
<br /> December, 2002; and March 2003); field activities included measurement of water levels and collection
<br /> of water samples from the three monitor wells,MW-1, MW-2, and MW-3. The quarterly monitoring data
<br /> indicate that groundwater conditions at the site have remained relatively static. Monitor well MW-1 is
<br /> located up gradient of the contaminant plume, and, to date, no petroleum hydrocarbonconstituents have
<br /> been detected in the groundwater samples collected from MW-1. Toluene and 1,2-dichloroethane (1,2-
<br /> DCA) have consistently been detected in the groundwater samples collected from monitor well MW-2;
<br /> Benzene, ethylbenzene, total xylenes, total petroleum hydrocarbons quantified as gasoline (TPH-G),
<br /> diesel (TPH-D), and motor oil (TPH-MO) were also detected in the groundwater samples collected from
<br /> CONDOR
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