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Remedial Action Plan
<br /> Frontier Transportation
<br /> June 17, 2004
<br /> Page 6
<br /> 15' to 40' bgs in MW- 13 . The soil sample results indicate that the band of shallow
<br /> impacted soil extends from T to 9' bgs and was limited to borings B- 1 through B-4 and
<br /> MW- 13 . Furthermore, the lateral extent of TPH-g, BTEX, and MTBE in soil collected
<br /> l from 9 .5' to 12' bgs was now limited to B- 1 , 13-2, B-3 , B-4, B-6, MW- IRA, MW- 1RB,
<br /> _ MW-2RA, MW-2, MW-3 , MW-3R, and MW- 13.
<br /> l Further delineation was requested by the PHS/EHD and performed in June 2003 . 7
<br /> One monitoring well (MW- 14) was advanced to 40' bgs. Soil sample analysis identified
<br /> MTBE at 5' and 10' bgs (See Appendix A) . The soil sample results indicate that shallow ) 11 V'S
<br /> impacted soil extends from 4' to 9' bgs and was primarily identified in the pattern formed
<br /> by borings 134 through 134, B-6, MW- 13 and MW- 14. Furthermore, the lateral extent of
<br /> TPH-g, BTEX, and MTBE in soil collected from 9 .5' to 12' bgs was increased to that area
<br /> bounded by B- 1 , B-2, B-3 , B-4, B-6, MW- IRA, MW- IRB , MW-2RA, MW-2, MW-3 ,
<br /> MW-3R, MW- 13 and MW- 14.
<br /> In January 2004, an additional subsurface delineation was performed at the
<br /> request of the PHS/EHD. Four monitoring wells, MW- 15 through MW- 18, were
<br /> advanced from 20' to 40' bgs. Soil sample results identified mostly MTBE with trace
<br /> TPH-g. No BTEX was detected in the soil (See Appendix A). MTBE was detected aslei
<br /> follows :
<br /> • Monitoring well MW- 15 identified MTBE at 10', 15' and 35 ' bgs .
<br /> • Monitoring well MW- 16 contained MTBE at 15 ' bgs.
<br /> -� • Monitoring well MW- 17 identified MTBE at 15' and 20' bgs.
<br /> • MW48 identified MTBE at 10' and 15 ' bgs.
<br /> IIIIS
<br /> The soil sample results indicate that shallow impacted soil extends from 4' to
<br /> bgs and was defined by borings B- 1 through B-4, B-6, MW- 13 and MW- 14.
<br /> Furthermore, the lateral extent of TPH-g, BTEX, and MTBE in soil collected from 9.5 ' to
<br /> i 12' bgs was now extended to B- 1 , B-2, B-3 , B4, B-6, MW- IRA, MW- IRB, MW-2RA,
<br /> MW-2, MW-3 , MW-31? MW- 13 , MW- 141 MW-15, MW46, MW47 and MW- 18 .
<br /> The shallow impacted soil region starts from 4' bgs, as identified by soil samples
<br /> collected from the 2002 excavation, and ends at the capillary fringe at approximately 9'-1
<br /> bgs. The deep impacted soil region starts at approximately 9' bgs and ends at 15' bgs
<br /> (assumption) within the saturated zone. However, soil samples collected from
<br /> monitoring wells MW- 17 and MW- 15 identified impacted soil at 20' and 35 ' bgs. The
<br /> estimated areas of impacted soil were defined by existing soil sample results . The
<br /> estimated mass of adsorbed petroleum hydrocarbons were calculated as follows :
<br /> Extent of Impacted Soil (best case)= 180 feet x 105 feet x 8 feet thick (9 to 17' bgs)/27 It .(
<br /> = 5,600 yds3
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