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adding nutrients to a small portion of the treated water as it is injected into the underground <br /> aquifer. These nutrients will cause TCE, PCE, and other organic contaminants that are <br /> underground to break down into nontoxic compounds. Altemative 4 uses the same number <br /> of extraction wells and air strippers as Alternative 3. An additional four wells to inject the <br /> nutrient-rich treated water have been added to make a total of 38 injection wells. Pilot testing <br /> would be needed to demonstrate the effectiveness of this alternative. A similar cleanup <br /> strategy has been accepted at another Superfund site. This alternative would include <br /> monitoring of the groundwater and would be implemented for 45 years. The estimated costs <br /> for the EPA-mandated 30-year period are: <br /> Pilot Tests Cost $200,000 <br /> Monitoring Costs $1,734,300 <br /> Capital Costs $3,868,800 <br /> Annual O&M Costs $366,000 <br /> 5-year Performance Evaluation $83,500 <br /> (performed at end of years 5, 10, <br /> 15, 20, 25, and 30) <br /> Present Worth Cost for 30 years $11,312,900 <br /> EVALUATION OF ALTERNATIVES <br /> The alternatives described above were evaluated using the nine EPA criteria that follow. <br /> 1. Overall protection of human health and environment <br /> 2. Compliance with applicable or relevant and appropriate requirements (ARARs), <br /> which are (1) the federal and state standards applicable to the chemicals of concern <br /> and remedial actions at DDRW-Tracy, and (2) federal and state standards that, <br /> while not directly applicable to the site, address problems and situations similar <br /> enough that their use is suited to the site. <br /> 3. Long-term effectiveness and permanence <br /> 4. Short-term effectiveness <br /> 5. Reduction of toxicity, mobility, and volume through treatment <br /> 6. Implementability <br /> 7. Cost <br /> Q-8WD43.1(90380C)\12 12 M1 0 0 892114 2 <br />