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Site Assessment Proposal Frontier Transportation Doc # 101501 October 15, 1997 TPH as diesel at 1 ,200 ,ug/L with no detectable concentrations of BTEX (Benzene, Toluene, - Ethylbenzene, and Xylene). On November 7, 1995, San Joaquin County Environmental Health Division, Mr. Steven Sasson, requested a work plan to assess the extent of soil and groundwater j contamination beneath the northern excavation, the dispenser island, and the product lines. In August of 1996, six vertical soil borings (B- I , B-2, B-3 , MW4RA, MW- IRB, and lMW-2RA) and one angle boring (B-4) were advanced to depths between 10 . 5' and 12. 5 ' below grade (bg) to assess subsurface conditions near the northern excavation by Twinning - Laboratories, Inc. In addition, two hand augers (S- 1 and S-2) were advanced to T bg to assess subsurface conditions beneath the dispenser and product lines and three groundwater monitoring -_ wells, MW- 1 through MW-3 , were drilled to approximately 25' bg to assess the subsurface water beneath the site (See Figure 2, Site Layout Map) . Initial subsurface water was encountered at 10 . 5 ' bg. Soil sample results are presented in Table 2. j TABLE 2 : 1996 Site Assessment Soil Sample Results (mg/kg) U Boring Depth TPH-g TPH-d B T E X MTBE l B- I 6' <1 ,0 NA 0.045 ND ND 0.005 0.096 J 11 ' 330 NA 1 .5 0.87 2.8 0.86 <1 :25 -i B-2 6' 5.6 NA 0.21 0.079 0.009 0.044 30. 5 I 9.5' 17200 NA 14.4 17.3 37 . 5 190 19. 8 U B-3 6' <4.0 NA 0.08 <0.02 <0.02 <0.02 0. 91 -� 11 ' 11200 NA 5 .8 6.9 28.6 76.8 7 . 9 B-4 6. 8' 34 NA <0. 125 0.30 0. 15 0.79 15 10.2' 15300 NA 21 . 5 40.4 29.8 89.0 110 MW- IRA 10' 540 NA 8.7 45. 8 16.7 70. 1 19.9 _ MWARB 10' 530 NA 7.2 22.8 20 45. 1 10 MW-2RA 10' 340 NA 3.23 4. 13 7.54 27.9 <6.25 MW-2 11 ' 104 NA 0. 14 0.29 1 .6 3.2 <0.625 - MW-3 11 ' 340 NA 3 .8 3.5 8.6 27 14.2 S-1 3' ND ND ND ND ND ND 0.089 S-2 ND ND ND ND ND ND 0. 19 bLs 10 10 1 0.005 1 0.005 1 0.005 1 0.005 2 I