SITE INFORMATION AND CORRESPONDENCE 1995-2004

Home Browse Search

James L. Tjosvold, A October 5, 1999 Page 4 Thus,the necessity to amend a ROD (or RAP)hinges on the degree to which a significant change in a remedy can be construed to constitute a fundamental change to that remedy, considering the changes to scope,performance and cost. EPA offers some guidance as to what may be considered a significant, but not fundamental, change in its Guidance on Preparing Superfund Decision Documents: The Proposed Plan, The Record of Decision, Explanation of Signif cant Differences, The Record of Decision Amendment, Interim Final, July, 1989, OSWER Directive 9355.3-02. Significant changes to a remedy are described as generally incremental changes to a component of a remedy that do not fundamentally alter the overall remedial approach. EPA offers examples of a 50 percent increase in waste volume,with an attendant increase in cost, or the substitution of carbon adsorption for air stripping as a groundwater treatment measure, as examples of significant,but not fundamental, changes to a remedy. In its guidance, EPA also provides as an example of a fundamental change to a remedy the situation where an innovative technology will not meet the human health and environmental protection remediation goals set forth in the ROD, and where the lead agency determines that a more conventional technology, such as thermal destruction, should be used at the site. EPA's guidance describes such fundamental changes as being no longer reflective of the selected remedy in the ROD. The proposed change at the PG&E Stockton site is notfundamental in nature; rather, it is at most a "significant change"within the meaning of federal and state guidance. The significance of the proposed changes to the Stockton site remedy should be evaluated in light of each of the factors set forth in the EPA CERCLA regulations: scope, performance and cost. Each of these factors is considered separately below: Scope The fundamental nature of the Stockton remedy is excavation and off-site disposal of soils which could contribute to an exceedance of beneficial use protective limits established for groundwater underlying the site. That fundamental nature will remain unchanged by PG&E's proposed modifications. Substitution of a thermal drying/thermal oxidation process,with offsite asphalt road base use, for the originally envisioned asphalt batch process specified in the RAP is a significant change, but does not, in itself, amount to a fundamental change to the RAP. (Bear in mind that, in evaluating the significance of proposed changes, comparisons should be made to the original RAP, which had undergone full notice and community input,rather than to an approved modification to the remedy outside of the RAP process.) EPA's guidance supports the substitution of one treatment measure over another as being the type of change which may be considered significant,but not fundamental,as in the example of carbon adsorption substitution for air stripping. None of the descriptors that define"scope"( i.e.,the area, extent, reach or