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5 <br /> w <br /> E <br /> Com site Quotation for Likely Scope of Work <br /> • Install three borings (3 wo/Diesel @ $2,650) $ 7,950 <br /> • Install and Convert three borings to monitor wells (3 w/Diesel @ $4,865) $14,595 <br /> • Complete one soil and groundwater investigation report $ 6.905 <br /> Total Estimate $29,450 <br /> Com2gsite Ouotation for Maximum Scope of Work <br /> + Install six borings and convert to wells <br /> (3 w/Diesel @ $4,865) $14,595 <br /> (3 wo/Diesel @ $4,380) $13,140 I <br /> • Complete one soil and groundwater investigation report 16,205 <br /> Total Estimate $34,640 j <br /> WESTON would like to note that even though the costs estimated above are per the GASI work <br /> plan, the estimates are probably lower than what will actually be encountered in the field due <br /> to the unrealistic estimate of the depth to water contained in the GASI scope of work. i <br /> WESTON is currently working on a project reasonably close by and the well depths required <br /> may be up to 108'. It should also be noted that the GASI plan would convert :soil borings to <br /> monitoring wells if hydrocarbons were found at 30 feet bgs, which may be as much as 40 feet <br /> 1 above groundwater. Making the decision to convert to wells at a depth of 30 feet is premature <br /> because there could be a significant thickness of clean soil between 30 feet and groundwater <br /> which would negate the need for well installation. <br /> SECTION 2 - PROPOSED ALTERNATE APPROACH <br /> Although WESTON has retained the major elements of the previous scope, our alternate <br /> approach contains several modifications to the field program which will increase efficiency and <br /> reduce the potential for unnecessary cost growth for the initial phase of the project. Specifically, <br /> if evidence from the soil borings indicates groundwater has been impacted by hydrocarbon, a <br /> maximum of three monitoring wells will be installed on the site to evaluate the groundwater <br /> conditions, regardless of the number of borings which may show hydrocarbon concentrations at <br /> 30'. Additionally, there is no guarantee that conversion of soil borings to monitor wells will I <br /> Place the monitor wells in the best probable location. Typically, wells are sited to provide site <br /> coverage based on probable groundwater direction, location of source areas, and site constraints, <br /> not upon whether or not the soil is contaminated in a particular borehole. Based on WESTON's <br /> 4, experience with the EHD on similar sites, three wells will provide adequate analytical and t ! <br /> groundwater gradient data to meet EHD requirements and there would be no advantage to <br /> installing more than three wells at this stage of the project. <br /> Also, it should be noted that the boring and monitoring well depths proposed under the previous <br /> work scope are probably not sufficient. Based on the most recent groundwater data published <br /> by the Sall Joaquin County Flood Control district, groundwater beneath the site,is expected to <br /> ,= bt encountered at a depth of at least 70 feet below the surface. This depth would require well <br /> ' 1 dePths of at least 85 feet, with 90 feet preferred in order to account.for future drops in the water <br /> the <br /> ...�� kwtl due to drought. <br /> .�W <br />