2007-11-20_REVISION - M1982015 (14)

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indications, excavation was discontinued. A confirmation soil sample was collected when it appeared petroleum contamination was no longer present. Soil samples were ' submitted to Origins Laboratories in Denver, Colorado, by courier for rush analysis (1-2 hour results) to assist in confirming removal of petroleum-impacted soil and excavation determinations. The samples were analyzed for BTEX by EPA Method 82608. Confirmation soil samples were submitted for analysis as lateral excavation neared ' station markers in 25 and/or 50 foot intervals depending on the volume and characteristics of the soil encountered. The SHT remedial excavation ranged in depth from 3 to 12 feet below the ground surface (bgs). The excavation ranged from ' approximately 10 to 16 feet in width. The laboratory soil results are shown on Table 2C. The laboratory reports are included in Appendix 4. The extent of the excavation and sample locations are presented on Figure 5. ' If soil was encountered that measured greater than 1,000 ppm on the PID, samples were collected for rush BTEX and toxicity characteristic leaching procedure (TCLP) analysis to verify that material was not hazardous and could be transported to the ' special waste landfill. Excavating was discontinued in these areas until the laboratory results were available. A chronological summary of these activities follows. ' February 13, 2007 - Began removal of soil stabilized with cement along the entire length of the SHT. Soil screening and sampling was not performed as samples were collected on February 3, 2007 (See Table 2B). Due to cold ' conditions, soil was freezing in the bottom of the dump trucks and some could not be unloaded at the landfill. E-21 and GeoCon personnel began lining trucks using 6-mil plastic sheeting. E-21 and GeoCon excavated and disposed of 731 cubic yards (43 truckloads) of soil at the Allied Tower Road Landfill. February 14. 2007 - Completed removal of cement stabilized soil from SHT. Began excavating sidewall and bottom soils in SHT at sm 19+00 (far west end). ' Petroleum impacts were evident in soils. Excavated laterally approximately 8 feet from the centerline of the SHT and to a depth of approximately 6 feet. Collected confirmation samples and submitted for analysis. Sample SHT 19+00 CL@7' and 19+75 CL@10' screened very high for VOCs. Excavating in this ' area was discontinued until laboratory confirmation was received. Benzene was 7.73 mg/Kg in SHT 19+00 CL@7' and sample was submitted for TCLP analysis for 19+75 CL@10'. Excavated and disposed of 1,071 cubic yards (63 ' truckloads) of soil the Allied Tower Road Landfill. Februarv 15, 2007 - Moved to far east end of the SHT to start excavating at ' 22+90. Discovered pocket of highly contaminated soil at 22+90. Submitted sample for rush analysis 22+90 6NCL@6'. The sample screened at 1,089 ppm on the PID and laboratory benzene concentration was 45.3 mg/Kg. Other hot sample was collected from 22+90 CL@5'. Discontinued excavating in this ' location and moved to 22+50. Discovered another hot pocket at 22+00 5SCL@6'. Submitted for lab analysis and discontinued excavating in that area. Excavated from 22+00 to 21+00. Soil impacted but PID screening and lab ' concentrations well below action level. A deep pocket of slurry was encountered between sm 19+00 and 20+00. This portion of the SHT was excavated wider and deeper by GeoCon personnel at the time of the emergency response activities to allow for more storage of slurry until the eastern portion of the SHT could be excavated. During excavation in this area, PID measurements were increasing to levels ranging from 1,200 ppm to 2,000 ppm. The excavated material was more liquid and contained a very strong hydrocarbon odor. This 4