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' Item 6) -This item referzed to the thickness of a geosynthetic liner for a site repository. No <br />geosynthetic liner is to be used for the revised treatment plan. Instead, a clay liner will be used in the <br />case that some material is found to have more than 10 mg/Kg 2,4-D, as is described in Item 2. <br />' Item 7) -This item largely concurs with the conclusion that it is unlikely that the wash plant <br />sediments contain contamination. The sediments in the stormwater retention and process water pond <br />' consist of fines produced by all operations on the site and runoff sediment from the entire operation <br />azea. These sediments sit in a shallow basin under strong aerobic conditions. Also, the fines from the <br />washing of the original minus 3/4 road base (feedstock) pile are only a small fraction of the total pile <br />material. <br />Nevertheless, B&B commits to sampling the storm water retention basin following a rain event at <br />least one time over the upcoming year. This sample will be tested for Diesel, 2,4-D, Bromacil and <br />Dicamba according to the methods described on Page 22 of the original SAP produced by Dames and <br />Moore. If no weed killers are found in concentrations of concern in the initial sample, no further <br />sampling of the retention basin water will be made. It should be kept in mind that any diesel range <br />petroleum hydrocarbons could be present from normal activity on the site, given the frequent use of <br />heavy machinery and trucks in the area. <br />' B&B also concurs that the wash plant sediments will need to be addressed if hi t levels of <br />contamination aze found in the soil under the original minus 3/4 feedstock pile or the minus '/: inch <br />' roadbase pile. We strongly believe that this is unlikely. <br />Item 8) - B&B commits to the installation of one shallow well for ground water sampling down- <br />gradient ofthe original minus 3/4 feedstock pile. B&B also commits to sampling the Eagle river <br />upstream and downstream. See Figure 1 for the proposed sampling locations. Lab analysis will be <br />' conducted as previously described on Page 22 of the SAP. <br />' Item 9) - We have done considerable investigation into the possibility of dioxin being produced as a <br />result of thermal degradation of 2,4-D from that material placed into the kiln for asphalt production. <br />There is a perception that since 2,4-D contains chlorine, dioxins could have formed as a result of the <br />' heating. <br />The following information is supplied to demonstrate that sampling of the bag house dust for dioxin <br />' is both unnecessary and potentially misleading. <br />Two groups of compounds are of concern when referring to the term dioxins: <br />' I) polychlorinated dibenzo(p)dioxins (dioxins) <br />2) polychlorinated dibenzofurans(furans) <br />Together, the two groups of chemicals are referzed to as PCCD/F. <br />