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Soil and Groundwater Investigation Report
<br /> Catellus Property September 2006
<br /> or potential sources of drinking water. The WQOs include numeric limits for constituents of concern
<br /> under the following criteria: Chemical Constituents(which require compliance with California drinking
<br /> water Maximum Contaminant Levels and generally prohibit adverse effects on beneficial uses), Toxicity
<br /> (which prohibits toxic chemicals in toxic amounts),and Tastes and Odors(which prohibit nuisance
<br /> conditions). The lowest, most conservative ESL or WQO concentration was used.
<br /> Laboratory analytical testing detected constituents of concern,at concentrations exceeding the lowest
<br /> ESL or WQO,in the following groundwater samples:
<br /> • TPHd: SB-1 (900 µg/L), SB-9(290 µg/L), SB-13 (660 µg/L), SB-14(860 µg/L), SB-16(2,900
<br /> pg/L), SB-18 (6,300 gg/L.), SB-19(560 µg/L),and SB-20(510 gg/L);
<br /> • PAHs: chrysene in SB-13 (0.45 µg/L);benzo(a)anthracene(0.86 µg/L),benzo(a)pyrene(0.51
<br /> gg/L),benzo(b)fluoranthene(2.0 gg/L),benzo(g,h,i)perylene(1.1 µg/L),benzo(k)fluoranthene
<br /> (0.67 gg/L),chrysene (1.7 µg/L),dibenz(a,h)anthracene(0.26 gg/L),and indeno(1,2,3-cd)pyrene
<br /> (0.89 gg/L)in SB-16;and anthracene(1.1 pg/L),benzo(a)pyrene(0.62 µg/L),
<br /> benzo(g,h,i)perylene(5.4 gg/L),chrysene(3.4 gg/L),dibenz(a,h)anthracene(0.68 gg/L),and
<br /> indeno(1,2,3-cd)pyrene(1.3 pg/L)in SB-18.
<br /> During the logging of soil samples,petroleum-affected soil was observed in borings SB-5, SB-6, SB-8,
<br /> and SB-15. In accordance with the CTA,no groundwater samples were collected from these borings for
<br /> laboratory analyses. The groundwater of these borings is also considered to be affected.
<br /> Based on groups of contiguous borings in areas with constituents of concern present at levels above ESLs
<br /> and WQOs,three plumes of affected groundwater were noted:
<br /> • A small North Plume,encompassing boring SB-1 and adjacent areas located near the Tracy Pump
<br /> Station project;
<br /> • A Central Plume,encompassing borings SB-5,SB-6, SB-8,and SB-9; and
<br /> • A South Plume,encompassing borings SB-13 through SB-16 and SB-18 through SB-20.
<br /> Up gradient and down gradient of the North,Central,and South plumes(and the OVP and the TAOC
<br /> Pipeline),the lateral extent of affected groundwater is undefined.
<br /> Laboratory analytical results for the SB-20 sample,which was collected to delineate the vertical extent of
<br /> affected groundwater,indicate 510 µg/l,TPHd in groundwater,a level above the ESL/WQO of 100 µg/L.
<br /> Although PAHs were detected,none exceeded an ESL or WQO,and no BTEX were detected in this
<br /> sample.
<br /> For more information regarding the delineation of affected groundwater,refer to the Appendix F,
<br /> Affected Soil and Groundwater Delineation Worksheet.
<br /> Of the 10 water wells identified by the search of DWR files,the following are of potential concern due to
<br /> their proximity to the site and shallow screened interval:
<br /> • The well at 14821 W. Grant Line Road(Map ID No. 22),which is approximately 50 to 100 feet
<br /> from the affected groundwater at soil boring SB-1 and screened from 124 to 144 feet bgs;
<br /> • The well at 15355 W. Grant line Road(Map ID No. 15),which is approximately 200 feet from
<br /> the affected groundwater at soil boring SB-1 and screened from 260 to 280 feet bgs;and
<br /> • The well at the northwest corner of W. Grant Line Road and Lammers Road(Map ID No. 18),
<br /> which is approximately one-quarter of a mile down gradient from the site and screened from 85 to
<br /> 100 feet bgs.
<br /> 6 From Science to Solutions^
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