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Until GHD took over the project in 2011, no additional subsurface investigation work had been conducted at the site since 1997. GHD performed soil boring and monitoring well installation activities in accordance to Winzler& Kelly's August 2011 Workplan for Subsurface Investigation, approved in the CVRWQCB's August 25, 2011 letter. On December 13, 14, and 19, 2011, and February 29, 2012, Winzler& Kelly/GHD supervised the installation of three groundwater monitoring wells (MW-2, MW-3, and MW-4)and two temporary soil vapor sampling points (SV-1 and SV-2) in order to investigate the vertical and lateral extent of petroleum hydrocarbon impacts to soil and groundwater at the site. Groundwater samples were collected from MW-2, MW-3, and MW-4 after initial well development on December 19, 2011. Locations of the new monitoring wells are shown on Figure 2. Groundwater was encountered between 27 and 28 feet bgs with initial flow moving towards (calculated in December 2011 and February 2012) the north at a relatively moderate gradient of 0.010 feet per foot(f ift). Relatively low concentrations of petroleum hydrocarbons in soils were encountered in newly installed monitoring well/boring MW-2, located adjacent to one of the former USTs in the center of the property (Figure 2). In the soil sample collected from MW-2 at 41 feet bgs, concentrations of total petroleum hydrocarbons as gasoline(TPH-G) and ethyl benzene were detected at 21 milligrams per kilogram (mg/kg) and 0.0024 mg/kg, respectively. Each of the six soil samples collected during this investigation had low concentrations of total lead ranging from 3.5 to 5.2 mg/kg, and are likely background concentrations. Groundwater samples collected from the newly installed monitoring well MW-2 had concentrations of TPH-G detected at 3,500 micrograms per liter(Ng/L), TPH-D at 1,400 pg/L, BTEX up to 260 pg/L, methyl tert-butyl ether(MTBE) up to 28 pg/L, and 1,2-Dichloroethane(1,2-DCA) at 2.3 pg/L. Monitoring wells MW-3 and MW-4 had very low concentrations of TPH-D (below detection limits) up to 44 Ng/L, BTEX up to 1.9 pg/L, and MTBE up to 1.4 pg/L. Groundwater samples were previously analyzed to determine if the identified dissolved lead is organic. EPA Test Method HML 939M is a specific test that isolates tetramethyllead (TML) and tetraethyllead (TEL), the compounds used as anti-knock additives in gasoline from inorganic lead using organic solvents. The analytical laboratory reported dissolved organic lead was below the laboratory's RDLs for MW-2, MW-3, and MW-4; therefore, the reported dissolved lead is not from anti-knock additives typically used in gasoline products. Additionally, two soil-vapor samples were collected (SV-1 and SV-2)to assess vapor intrusion. The results for SV-1 detected xylenes at a very low concentration of 11 micrograms per cubic meter(Ng/m3), and chloroform at 18 pg/m . The xylenes soil gas concentrations were below the California Human Health Screening Levels (CHHSLs) for residential land use of 3.19 E+5 pg/m3. Chloroform is not listed in the CHHSLs; however, it was below the San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) Environmental Screening Levels (ESLs) (November 2007) of 4.6 E+2 pg/m3 for residential land use and can be a laboratory contaminant. Chloroform is not suspected to be from the contaminants of concern at the site. Groundwater was originally anticipated to flow in a westerly direction (CVRWQCB conversations 2009); however, groundwater has been calculated to consistently (seven events) flow to the north. Recent groundwater sampling during the fourth quarter 2013 indicated that groundwater samples collected from MW-2 remain impacted with petroleum hydrocarbons (TPH-G, weathered gasoline constituents, BTEX, MTBE, and fuel oxygenates) consistent with historical concentrations that could be a risk to the health and safety of the public. The site constituents of concern do not appear to be attenuating at the MW-2 03009-10017-37110 2 of 6 March 2014