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Soil and Groundwater Investigation Report <br /> Tracy Byron Road Project May 2008 <br /> the EPA non-mandatory Secondary Maximum Contaminant Level of 500 mg/L for TDS, which is based <br /> ' on aesthetic (taste and odor)and technical (staining and corrosion)characteristics (EPA, 2008). <br /> 6. CONCLUSIONS AND RECOMMENDATIONS <br /> ' SAIC reviewed the findings of this and previous site investigations along the West Byron Road corridor <br /> and concludes and recommends the following: <br /> ' • Boring SB-37 on APN 209-260-20 is located at the delineated southeastern (up-gradient)extent <br /> of an affected area(Figure 3a). <br /> • Boring SB-38 on APN 209-260-20 is located at the delineated southern (up-gradient)extent of an <br /> ' affected area(Figure 3a). <br /> • Borings SB-39 and SB-40 on APN 238-070-02 and SB-41 on APN 238-070-06 are located at the <br /> ' delineated southern (up-gradient)extent of an affected area(Figure 3b). <br /> • To fully delineate the extent of affected soil and groundwater to the south and up gradient of <br /> SB-19,proposed boring SB-42 should be moved to and advanced on APN 238-080-04 <br /> ' (Figure 3c), where soil and groundwater samples should be collected and submitted for analysis <br /> of the COCl. <br /> • To fully delineate the extent of affected soil and groundwater to the south and up gradient of <br /> ' SB-23,proposed boring SB-43 should be advanced on either APN 238-050-06 or 238-050-09 <br /> (Figure 3c), where soil and groundwater samples should be collected and submitted for analysis <br /> of the COCs. <br /> ' • To fully delineate the extent of affected soil and groundwater to the southeast and up gradient of <br /> SB-33, proposed boring SB-45 should be advanced on APN 238-570-13 (Figure 3d), where soil <br /> ' and groundwater samples should be collected and submitted for analysis of the COCs. <br /> • The up-gradient extent of soil and groundwater was defined at monitoring wells MW-2 and MW- <br /> 3 during a site investigation on the Calderon's General Store property(Geological Audit Services, <br /> ' 1995);therefore, advancement of proposed step-out boring SB-44 south of boring SB-25 <br /> suggested in SAIC's 2004 work plan is not necessary. <br /> • The proposed apartment complex at the northeast comer of Lammers Road and Feteira Way in <br /> ' Tracy is unlikely to be impacted by affected soil and groundwater from the OVP, as it is up <br /> gradient and approximately 1,300 feet away. <br /> ' 7. REFERENCES <br /> Condor, 2001. Chevron Pipeline Easement Environmental Assessment Report, Mountain House <br /> California. November. <br /> ' DWR, 2003 updates Bulletin 118.California's Groundwater-Bulletin 118, Update 2003. October. <br /> EPA, 2004. Region 9 PRGs Table.http://www.epa.¢ov/recion9/wastetsfund/pratindex.html#pr tg able. <br /> October. <br /> —, 2008.National Secondary Drinking Water Regulations <br /> http://www.epa.gov/safewater/contaminants/index.html#sec. May. <br /> Geological Audit Services, 1995. Site Summary Report, Calderons' General Store, 12750 West Byron <br /> Road, Tracy, California. March. <br /> Geomatrix, 2005. Technical Approach to Site Evaluation and Decision Making, Historical Pipeline <br /> Portfolio, Central Valley Region. February. <br /> ' 7 <br /> .2AURLI <br /> From Science to Sol tws <br />