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YY � <br /> r' <br /> f= ' <br /> J- <br /> F <br /> f <br /> 1 �a <br /> Harding Lawson Assoclates <br /> sem+ III. COST EVALUATIONS OF SELECTED REMEDIAL ALTERNATIVES <br /> It <br /> Technical and cost aspects of remediation alternatives for <br /> i' ground water and soil are discussed in this section and recommen- <br /> dations are made for optimal remediation methods for the site. <br /> A. Gro ound Water <br /> 1. Fai-:sive horizontal extractions st - <br /> em This alternative <br /> involves placing a French drain downgradient of the zone where <br /> ground water contains levels of hydrocarbons above clean-up ; <br /> levels. This system would be installed in trenches separate from <br /> those used for soil-ventin <br /> f <br /> ry g. We anticipate that the drain would <br /> L be no deeper than 10 feet and <br /> 1 p approximately 125 feet long, .and . <br /> f would be located alongthe northern and eastern sides of the t <br /> xU, building. Estimated cost of such a drain ranges from $25,000 to <br /> .i $35,000 dollars. <br /> 2 Active horizontal extractions stem - This alternative <br /> involves placing horizontal ground-water extraction <br /> drains below , <br /> r 4 vapor extraction wells and in the <br /> i . same trenches. A suction pump <br /> 17. would be. used to assist in withdrawing hydrocarbon-laden ground <br /> sr: <br /> water and help prevent - <br /> ground water from...being .drawn.-into the <br /> :r f ..... ._....._ ......_ _._ <br /> soil-venting system It is estimated that the co <br /> i <br /> sts for ; <br /> installing this system would range from $25,000 to $35 000. <br /> 3 Off_sit disposal Given a <br /> _ I <br /> f" projected average monthly <br /> ' yield. of 100 gallons from a passive drain Off-site disposal of . <br /> ' the water costs . per. <br /> could range :to .between $3,000 and $4,000 <br /> month. Costs may also vary somewhat among dis Deal <br /> BE <br /> a -� p companies. <br /> 22 <br /> 4 <br /> Ell oil <br /> � 5 <br /> 5 <br />