SITE INFORMATION AND CORRESPONDENCE_FILE 1

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sparge system, with respect to active sparge points and sparge duration, would be modified in order to optimize volatilization and biodegradation. 5.4 Alternative Evaluation Technical, institutional, environmental safety, and economic criteria were used to evaluate the alternatives. Because some remedial alternative elements were common to both alternatives (i.e., complete downgradient plume definition), only the characteristic elements were consid- ered during the evaluation process. It was determined that Alternative 1 is the most feasible for long-term application. An assumption of this selection is that the extent of dissolved hydrocarbons downgradient of the site is minimal due to the limited nature of the release and the relatively low concentrations of dissolves detected on site. In the case that plume delinea- tion uncovers conditions which would require additional evaluation regarding remediation an addendum to this CAP would be prepared. Alternative 1 was chosen on the following basis: Technical. Technical criteria considered included: short- and long-term effectiveness; reduction in the toxicity, mobility, and volume of affected media; and implementability. With regard to implementability, Alternative 1 is favored because implementation is not expected to significantly disrupt the site, or the community. In terms of effectiveness, Alternative 2 is anticipated to be incrementally more effective in the short-term. The benefit that ranked Alternative 2 above Alternative 1 in the short term was the increase in short-term effectiveness associated with the higher mass reduction rate. It should be noted that the benefit described for the short-term may be superficial in the long-term. Since plume degradation appears to be occurring naturally and migration is minimal, application of Alternative 2 over the long-term would provide little benefit over that provided by Alternative 1 (Alternative 2 isnot expected to significantly decrease the remediation lifespan associated with Alternative 1). It was determined that both alternatives allow for a similar degree of reduction in toxicity, mobility, and volume of hydrocarbon-affected media. Given the discussion above, Alternative 1 was ranked over Alternative 2. Institutional. It is anticipated that implementation of either alternative would be consistent with applicable, relevant, and appropriate requirements; however, community acceptance of the heavy construction associated with Alternative 2 may be weak and the complexity of compliance would be higher than for Alternative 1. Additionally, Alternative 2 would require more resource commitment from the regulatory community. Because of these factors, Alter- native 1 was ranked above Alternative 2 with respect to institutional criteria. Human Health and Environmental Protection. Both alternatives would provide protection of human health and the environment; however, when compared to Alternative 1, imple- 3201357B/CAPREV 1 14 June 29. 1995