ARCHIVED REPORTS_XR0004473 - Laserfiche WebLink

Home Browse Search

C ISite Conceptual Model • Frontier Transportation June 30, 2003 ' IPage 5 The soil sample results indicate that the band of shallow impacted soil extends from 4"to 9' bg and was exclusively limited to bonngs B-1 through B-4,and MW-13 Furthermore, the lateral extent of TPH-g, BTEX, and MTBE in soil collected from 9 5' to 12'bg was now limited to B-1, B-2, B-3, B-4, MW-IRA, MW-IRB, MW-2RA, MW-2, MW-3, MW-3R, and MW-13 't�-�, Concentrations of TPH-g, BTEX, and MTBE were plotted along A-A' and B-B' to conceptualize the extent of impacted soil within the geologic framework of the site (See Appendix D) Note that concentrations were collected years apart C / Based on the soil sample results, it is estimated tha 500 yd of shallow impacted and 2,390 yd of deep impacted soil remains in place (See A endix D for extent of impacted soil) The shallow impacted soil region starts from 4' bg, as i ntified by soil samples collected from ' the 2002 excavation, and ends at the capillary fringe a approximately 9' bg The deep impacted soil region starts at approximately 9'bg and ends at 1 ' bg (assumption) within the saturated zone The estimated areas of shallow and deep impacted soil were defined by existing soil sample results The estimated mass of adsorbed petroleum hydrocarbons were calculated as follows r Extent of Impacted Shallow Soil = 60 feet x 60 feet x 5 feet thick(4 to 9' bg)/27 ft' = 670 yds' Extent of Excavated Impacted Shallow Soil = 30 feet x 30 feet x 5 feet thick/27 ft3 = 170 yds3 Extent of Impacted Shallow Soil Left in Place = 670 yds3- 170 yds3= 500 yds' rExtent of Impacted Deep Soil = 105 feet x 105 feet x 5 feet thick (9 to 14' bg) + 0 5(70 feet x 80 feet x 5 feet)/27 ft3 = 2,560 yds3 r Extent of Excavated Impacted Deep Soil = 30 feet x 30 feet x 5 feet thick/27 ft3 = 170 yds3 Extent of Impacted Deep Soil Left in Place = 2,560 yds3- 170 yds3= 2,390 yds' rThe shallow soil impacted soil exists primarily in heterogeneous clays and the deep impacted soil exists within the saturated zone Heterogeneous clays and saturated soil are the r main factors limiting the effectiveness of soil vapor extraction Excavation would be the most _ effective remedial action based on site subsurface conditions r5.0) EXTENT OF GROUNDWATER CONTAMINATION Historical groundwater data has identified dissolved TPH-m in monitoring well MW-3 5 s r exclusively Maximum concentrations of dissolved TPH-m were identified in MW-3 as 33,000— µg/L in January 2000 using EPA method 8015 modified In January 2000, the well cover for h MW-3 was destroyed allowing oily surface water to infiltrate the well BEII concludes that the ` damaged well cover caused the increase in TPH-m in MW-3 from November 1999 to May 2000 9 r r r