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8.0 SELECTION OF A RECOMMENDED REMEDIAL ACTION ALTERNATIVE AND PRELIMINARY WORKPLAN 8.1 Selec&ion of 4 Recommended Remedial Ac i n Alternative A qualitative rating for each criteria and the present worth cost estimate for each Final Candidate Alternative is summarized in Table 8-1. Each alternative was assigned an overall score calculated in a two step process. First, each of the rating criteria are assigned a score from 1 to 5 (see Section 7) . The individual criterion scores are then summed to give the alternative score shown at the bottom of the table. The relatively high overall rating given to each alternative reflects the ' belief that risks associated with site contaminants are minimal, even under the No-Action Alternative. Alternatives 7 and 8 received the highest overall scores of 61 and 62, respectively. Both of these alternatives require the excavation of all on-site soils containing greater than 10,000 ppm TPH, but differ in the method of treatment. Alternative 8 involves disposing of the excavated soils at an off-site Class I landfill, while Alternative 7 involves on-site bioremediation of the excavated soils. Both alternatives received high technical feasibility scores and both are expected to significantly reduce the potential for adverse environmental or health impact. The primary difference between the two alternatives is cost. The cost of implementing Alternative 8 is twice that of Alternative 7 due to the high cost of off-site disposal. Given the belief that both alternatives will significantly reduce the ' potential for adverse environmental or health impact, and the relatively non-tonic nature of diesel fuel, we recommend Alternative 7 as the preferred remedial alternative. This alternative combines the benefits of removing approximately 50 percent of the leaked diesel fuel with a reasonable cost. r ti 8-1 GGA/0209b/276a