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' Former Manna Pro Site Page 3 <br /> Project No 207 3 <br />' Remedial Feasibility Study <br /> 1996, GTI conducted pilot level fieldwork to evaluate several remedial options The GTI <br />' report concluded that a combination of vapor extraction and groundwater pumping offered <br /> the most attractive option for remediation of the gasoline plume at this site <br />' Up until April of this year, a total of eleven groundwater monitoring wells, three observation <br /> wells, and one combination groundwater and vapor extraction well have been constructed on <br /> or near the Manna Pro site In April of 2000, Geo-Please Environmental drilled and <br />' constructed a 97 foot deep monitoring well intended to investigate the vertical distribution of <br /> gasoline hydrocarbons In addition, a pilot scale remedial pilot test was completed The pilot <br /> test work consisted of testing soil vapor extraction and simultaneous vapor extraction with air <br />' spargmg The pilot test required construction of a 55-foot deep air sparge well, a 50 foot <br /> deep vapor extraction well, a 50 foot soil boring backfilled with Oxygen Releasing <br />' Compound (ORC) and two 30 foot air monitoring well, which were also installed at this time <br /> The pilot test was documented in the report of July 31, 2000, which was cited above <br />' Groundwater Technologies Inc (GTI) estimated that over 31,000 pounds (13,600 kg) of <br /> gasoline are present in the subsurface Over the past several years, groundwater monitoring <br /> data have been collected from 14 monitoring, extraction, and observation wells situated <br />' through and around the contaminant plume The available data suggests that the contaminant <br /> plume is stable and has not migrated off of the Property except in a small area to the west <br /> under El Dorado Street The continued high levels of gasoline and aromatic hydrocarbons <br />' (especially benzene) in groundwater samples collected from on-site wells, however, suggest <br /> that natural attenuation is not adequately mitigating the groundwater plume <br /> 1.2 Scope of Work <br /> This feasibility study represents an attempt to evaluate all work completed at the site to date, <br />' and to assess which of four potential remedial methods is most likely to effectively mitigate <br /> the gasoline impact to the groundwater The work documented in this report consists of the <br /> following tasks <br /> 1 Estimate the vertical and lateral distribution of hydrocarbons including <br /> g <br /> volumetric estimated of the residual contaminant mass This task was <br /> undertaken for the purpose of verifying and updating the previous GTI <br /> estimate <br /> 2 Using all data from the recent pilot test, the previous GTI pilot test, <br /> groundwater monitoring information, and other past site characterization <br /> reports, evaluate the feasibility and cost effectiveness of four methods of <br /> remedial action <br /> 3 Suggest the most appropriate remedial method based upon the distribution of <br /> hydrocarbons, and the information gathered from the two pilot tests <br /> 2937 Veneman Ave,46240 Geo-Phase Environmental Inc Phone(209)569-0293 <br /> Modesto, CA 95356 Fax(209) 569-0295 <br />