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Mr. Russell F. Chapin, Sr. <br /> November 15, 1995 <br /> Page 5 <br /> EXTRACTION SYSTEM <br /> We recommend installing an internal combustion engine unit equipped with a 15 kW <br /> generator unit which will increase the throughput capability of the engine. It is our judgment that <br /> the site could make use of an internal combustion engine for a period not likely to exceed 6 to 12 <br /> months, after which it would be appropriate to replace the engine with a blower extraction unit <br /> using activated carbon as the primary emissions control method. The timing of the switch to <br /> blower and carbon filters will be made when projected utility and carbon costs for the blower <br /> system are less than fuel and utility costs associated with the engine units. All remedial <br /> equipment will be designed to be easily transported or stored. <br /> OPERATE AND MAINTAIN SYSTEM <br /> The system will be operated and maintained at minimum monthly intervals with quarterly <br /> reports of system performance. <br /> INTERIM VERIFICATION SAMPLING <br /> Progress sampling was requested in the request for bid, which was to consist of drilling <br /> soil borings and evaluating selected soil and/or groundwater samples. We do not recommend <br /> this procedure. Careful monitoring of the system inlet concentrations for hydrocarbons and other <br /> parameters such as oxygen should allow reasonably accurate estimation of the site status without <br /> un-necessary site disturbance by drilling and sampling operations. <br /> VERIFICATION SAMPLING <br /> Verification sampling is proposed to consist of collection and analysis of samples from <br /> drive-point sampling, a quick and cost-effective way of collecting undisturbed soil and <br /> groundwater samples. The method involves hydraulically pushing a 2-in probe to collect <br /> samples The method also has the added advantage of producing no drill cuttings and minimizing <br /> site disturbance. We should be able to generate 8 to 12 or more penetrations within a day. We <br /> expect that this should be sufficient to evaluate subsurface conditions at the site. <br /> 4058-P3 <br /> LUSH GEOSCIENCES <br />