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Moore Truck Lines -4 - 25 May 2012 <br /> 3400 Newton Road <br /> Stockton, San Joaquin County <br /> gravelly sand, sand and silt described from 77'bgs to 85' bgs, and clay, clayey silt, and <br /> silt from 85' to 103' bgs, the maximum extent of investigations. Depth to groundwater <br /> varied from 53' bgs (February 2000) to 71' bgs (August 2002), and also varied from <br /> 60' to 63' bgs in 2011 Groundwater flow direction, which has varied in all directions, <br /> was predominantly towards the northeast through 2008, and varied from northwest to <br /> west in 2011. The groundwater gradient varied from 0.001 to 0.007 ft/ft. <br /> Residual Mass Calculation <br /> In 2004, the consultant estimated remaining TPI-Ig mass in soil as 1,749 lbs. Less than <br /> 1 Ib. of TPI-Ig and MTBE remain in groundwater. <br /> Public Participation <br /> Public participation was conducted from 30 September 2011 to 30 October 2011 with no <br /> adverse comments. <br /> Summary and Recommendations <br /> Moore Truck Lines has complied with all of the requirements in the Regional Board staff <br /> letters and directives. Residual soil and groundwater contamination pose minimal risk <br /> to sensitive receptors, human health, or other beneficial uses of groundwater in the <br /> area. Based on the stable plume with very limited but well defined vertical and lateral <br /> extent of pollution, lack of threats to sensitive receptors from groundwater, soil and soil <br /> vapor intrusion, and compliance with the tasks of Regional Board directives, no further <br /> action is warranted for the Site. Staff recommends closure of this Site. The required <br /> public participation comment period was conducted from 30 September 2011 to <br /> 30 October 2011 with no adverse comments. All monitoring wells (MW-1 through <br /> MW-8) were properly destroyed on 8 May 2012. The RP and the San Joaquin County <br /> Environmental Health Department concur with case closure. <br /> Attachments: Figure 1: Site General Location Map <br /> Figure 2: Site Plan <br /> Figure 3: Groundwater Elevation Map <br /> Figure 4: TPI-Ig Isoconcentration Lines in Soil <br /> Figure 5: Extent of Soil and Groundwater Contamination <br /> Table 2: MW-1 Groundwater Monitoring Results <br /> Graph 1: Time to Reach WQGs MTBE at MW-1 <br /> Graph 2: Time to Reach WQGs TPI-Ig at MW-1 <br />