(Notes Re: 5/24/11 Revisions) The Tier 2 soil pathways were re-evaluated as a result of the post soil excavation soil sampling activities completed in March of 2011, following the Work Plan dated 1/26/2011, and subsequently approved by the IDNR in a letter dated 2/3/2011. All historic soil samples located within the area of excavation and all replacement soil samples approved in the Work plan were ''ignored'' in the revised Tier 2 and all new soil samples were added and used in the evaluation. Soil sample percentage reductions were applied for 12/3/2009 soil sample locations B-13 and SS3 using the percent reduction at the soil source (SBMW16R).


The soil source width/length values were re-evaluated because of the ignored and new soil data. Please note that we did not use the maximum soil source width/length value generated for TEH(WO) because the software produced an erroneously large estimation of the source width and length due to a lack of definition data and low results of existing data. There have been no historic exceeding soil action levels at the site for TEH(WO). The BTEX source width/length values were used considering that benzene and ethyl benzene are the only chemicals of concern for the subject site.

The results of the post soil excavation samples indicate a lower contamination concentrations than those detected from soil sampling completed as reported in the 10/18/2010 SMR/Tier 2/OE Report. Considering the soil source (and other soil sampling locations that resulted in high or low risk classification for soil vapor and soil leaching to groundwater vapor pathways and receptors), a soil plume submergence evaluation was completed and is provided in Appendix 1 of this SMR. Remaining receptors to address are the PGWS and the black plastic (PB) water main.

Soil and groundwater plume contour maps include the plastic water line evaluation concentrations that became effective on 9/29/2010, since a new RBCA software version with these criteria have not been released at this time of this report.


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(Notes Re: 5/24/11 Revisions) The Tier 2 soil pathways were re-evaluated as a result of the post soil excavation soil sampling activities completed in March of 2011, following the Work Plan dated 1/26/2011, and subsequently approved by the IDNR in a letter dated 2/3/2011. All historic soil samples located within the area of excavation and all replacement soil samples approved in the Work plan were ''ignored'' in the revised Tier 2 and all new soil samples were added and used in the evaluation. Soil sample percentage reductions were applied for 12/3/2009 soil sample locations B-13 and SS3 using the percent reduction at the soil source (SBMW16R).


The soil source width/length values were re-evaluated because of the ignored and new soil data. Please note that we did not use the maximum soil source width/length value generated for TEH(WO) because the software produced an erroneously large estimation of the source width and length due to a lack of definition data and low results of existing data. There have been no historic exceeding soil action levels at the site for TEH(WO). The BTEX source width/length values were used considering that benzene and ethyl benzene are the only chemicals of concern for the subject site.

The results of the post soil excavation samples indicate a lower contamination concentrations than those detected from soil sampling completed as reported in the 10/18/2010 SMR/Tier 2/OE Report. Considering the soil source (and other soil sampling locations that resulted in high or low risk classification for soil vapor and soil leaching to groundwater vapor pathways and receptors), a soil plume submergence evaluation was completed and is provided in Appendix 1 of this SMR. Remaining receptors to address are the PGWS and the black plastic (PB) water main.

Soil and groundwater plume contour maps include the plastic water line evaluation concentrations that became effective on 9/29/2010, since a new RBCA software version with these criteria have not been released at this time of this report.


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