ARCHIVED REPORTS_REVISED FEASIBILITY STUDY 2000

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• 7hx3dwe11&Ro110 vapor recovery wells is reportedly approximately $150,000. Long term operations and maintenance costs are not known. Bioremediation of soil is generally of low to moderate cost, especially when done in situ. Soil below the water table can be treated by injecting oxygen, air, or nutrients into the soil. Soil above the water table can be treated by sparging air or oxygen. Injection/sparge wells typically cost$2,000—$5,000 each, not including specific injection equipment,blowers or gases and nutrients. Typical on-site bioremediation systems of a size suitable for OU 2 parcels cost from $50,000 to $200,000. Operations and maintenance costs range from $25,000 to $75,000 per year. The No Action estimated cost is low. Long-term groundwater monitoring is often required for this alternative. Typical annual monitoring costs are $500—$1,500 per well, depending on analytical requirements. • 4.3 Groundwater Remedial Alternatives Initial Screening The initial screening for groundwater remedial alternatives produced five general response actions (Tables 6 and 7). No remedial actions for groundwater are planned for OU 1, as groundwater has not been impacted at OU 1. Alternatives for OU 2 were evaluated in light of the on-going remedial action at Parcel 16, and the past actions at Parcels 15 and 21. Remediation goals for groundwater are typically set at drinking water standards, or Maximum Contaminant Levels (MCLs). As of this writing, cleanup goals for groundwater have not been set for the OU 2 parcels, although representatives of SJCEHD have stated that MCLS are the initial target. Experience has shown that attaining MCLs is often impractical or impossible, and that alternative cleanup goals are generally developed after a remedial action has been attempted. It • is likely that this will be the case for the OU 2 properties. Cancer risk-based and non-cancer 32 25970318.PGS 15 November 2000