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m /L for toluene 0 7 m /L for g , g o ethylbenzene, and 1 750 mg/L for xylenes No MCLS were established for TPHg or TPHd Summary of Evaluated Remediation Alternatives Remediation alternatives which have been discussed in the FRP and/or this addendum include vapor extraction, vapor extraction with passive air Inlet wells, and vapor extraction with groundwater extraction Each of these alternatives are technically feasible. Vapor extraction has been shown through a vapor extraction field test to be feasible and would act to reduce petroleum hydrocarbon contaminants in the soil Vapor extraction will also tend to reduce the dissolved constituents in the groundwater as well, though to an unknown degree The estimated cost to design a treatment system, Install the instrumentation, piping, blowers, and off-gas abatement device associated with a vapor extraction system at the site is $30,000 to $60,000 Operational costs would Include permitting, system start up and evaluation testing, routine monitoring and sampling, routine maintenance and repairs, preparing site status reports, and project management Operational costs would be expected to be approximately $12,000 to $16,000 per year The estimated time frame for remediation of soil using vapor extraction is 1 to 3 years It is unknown whether or not vapor extraction alone would successfully reduce groundwater contaminants to below site cleanup goals Passive air Inlet wells are sometimes used in conjunction with vapor extraction, particularly to establish a boundary for the targeted area However, based upon the relative Isolation of the site and the apparent limited extent of soil and groundwater contamination, the addition of passive air inlet wells would have minimal benefit for this site The estimated cost for the installation of passive air Inlet wells and associated controls is $10,000 to $30,000 The results of a groundwater pumping test performed at the site indicates that a radius of influence can be exerted from existing monitoring well RW-1 which would largely encompass the contaminant plume However, extensive case studies have shown groundwater extraction to be a relatively inefficient, albeit widely Implemented, technology for groundwater remediation The estimated cost to install the instrumentation, piping, pumps, and treatment device associated with a groundwater extraction system at the site Is $40,000 to $70,000 Operational costs would include permitting, system start up and evaluation testing, routine monitoring and sampling, routine maintenance and repairs, preparing site status reports, and protect management. Operational costs would be expected to be approximately $15,000 to $20,000 per year The estimated time frame for remediation of groundwater using groundwater extraction is 2 to 5 years • 98009-IO/FRP-ADD doc