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CAMBRIA <br /> collected from SB-15 did not contain detectable levels of TPHg, BTEX, or fuel oxygenates <br /> delineating the southern portion of the site Grab groundwater samples collected from SB-16 did <br /> not contain detectable levels of TPHg, BTEX, or fuel oxygenates providing groundwater <br /> delineation to the northwest of the site Grab groundwater samples collected from SB-18 <br /> contained TPHg, benzene, and xylenes at low levels, but did not contain detectable levels of fuel <br /> oxygenates <br /> 1,2-DCA was detected in grab groundwater samples collected from each boring at concentrations <br /> ranging from 2 7 to 470 ppb The highest 1,2-DCA concentrations found during this <br /> investigation were from boring SB-18, located on the northern side of East Fremont street <br /> Cambria evaluated the groundwater elevation data from the deep screened wells and compared it <br /> to the groundwater elevation data for the adjacent shallow screened wells to determine if there is <br /> an upward or downward vertical groundwater gradient beneath this site The vertical gradient <br /> was found to be upwards at the S-1/S-1-85 well cluster and at the S4/S4-83 well cluster The <br /> vertical gradient was found to be downward at the S-31S-3-84 well cluster Additional <br /> groundwater monitoring data will need to be collected to further evaluate the nature of the <br /> vertical gradient at this site <br /> Groundwater contour maps were prepared for both the shallow groundwater wells and the deeply <br /> screened wells The groundwater flow direction in the shallow groundwater zone was <br /> determined to be predominantly northerly with an approximate hydraulic gradient of 00005 <br /> The deep groundwater zone groundwater flow direction was to the west at an approximate <br /> hydraulic gradient of 0 01 <br /> RECOMMENDATIONS <br /> Cambria recommends that the newly installed groundwater monitoring wells be added to the <br /> quarterly groundwater monitoring program for this site Additional groundwater monitoring data <br /> (at least one hydrologic cycle) needs to be collected from these newly installed wells to be able <br /> to evaluate concentration trends at depth Once sufficient data has been collected we can make a <br /> determination as to whether additional wells are needed or if sufficient data exists to prepare a <br /> Problem Assessment Report for this site <br /> 0797 7 <br />