Laserfiche WebLink
AOC Work Plans <br /> groundwater in August 1990 via seven groundwater monitoring wells;two additional monitoring <br /> wells were subsequently installed by URS Corporation(URS)in 2004. To petroleum <br /> hydrocarbons as diesel has been detected in groundwater samples collecte over 14 years of <br /> monitoring(1990 through 2004)at a maximum concentration of 0.44 mg/L, which is above the <br /> general RWQCB cleanup level of 0.064 mg/L. <br /> In addition to TPHd,low levels of 1,2-dichloethane(1,2-DCA)have been lso detected in <br /> monitoring wells during the monitoring of the former tank area. Historic ,2-DCA concentrations <br /> have ranged between 1.4 and 40 micrograms per liter(µg/l-),above the California Department of <br /> Health Services(DHS)maximum contaminant level of 5 µg/L . OnFebruaryl8,2005,URS <br /> submitted Additional 1,2-DCA Investigation and Site Conceptual Model and Second Quarter 2004 <br /> Groundwater Monitoring Report,Former American Forest Products Facility, 2801 West Lane, <br /> Stockton, California(URS, 2005a)to the PHS-EHD and RWQCB. This r rt detailed the results <br /> of groundwater monitoring for the period between June 2003 and June 20(4,the installation of the <br /> two additional monitoring wells(one in a deeper water bearing zone)and presented a Site <br /> Conceptual Model. Based on the results of the additional monitoring and nstallation of two <br /> additional monitoring wells,URS concluded the following: <br /> • Corroborate data collected from the newly installed wells and prei bus borings indicate <br /> onsite sediments consist of interbedded clays, silts,and fine sands The fine sands are local <br /> and discontinuous. <br /> • During the dry season,the groundwater direction is north;howevc r,during the rainy <br /> season the direction is irregular <br /> Draft <br /> KB61125 workplan-ESC MACTEC Engineering and Consulting, Inc. 17 <br /> September 28,2005 <br />