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a rr a e <br /> Du Pont Bio5-pitenis <br /> Page 37 <br /> August 10, 1989 <br /> Job No. 211-71-6 <br /> Ground water remediation alternatives are presented because significant Levels of gasoline <br /> constituents were detected in the ground water at the site. Physical containment is not consider:':: <br /> practical because the contaminants may have migrated off-site and because of the very high <br /> _. constructions costs associated with containment. <br /> The feasibility of in-situ biodegradation in the saturated zone would require additional studies to <br /> define the necessary parameters for successful treatment. Pecause ground water at the site has a <br /> fairly gentle gradient, in-situ biodegradation may be a viable option but will require extensive <br /> monitoring. We are presently pursuing this treatment option but believe it would be successful <br /> only after the free product has been removed. <br /> Ground water extraction.�3nd treatment by air-stripping is a proven technology that may be readily <br /> designed and implemented. We presently favor this approach because free-floating product is <br /> present in three of the monitor.n, wells and because it is a relatively quick and inexpensive method <br /> for ground water cleanup. We propose to install at least two extraction wells; one outside of the <br /> 4 free-product area for use during the pump test and for ground-water extraction. The other well will <br /> be a 75-foot deep extract:an welt (4 to 6-inch diameter) to be located in the vicinity of monitoring <br /> well MW-17 as shown. on the Site Plan, Figure 2. This well would extract and treat both <br /> hydrocarbon-contaminated ground water and free product with the use of a free-p:oduct skimming <br /> pump. The Iocation of additional extraction wells (if any) wculd be determined after analysis of <br /> pump test results. The system would be designed to handle anticipated flow rates of 2 to 10 gallons <br /> per minute. A rough cost breakdown of the major system constructi,h costs are as follows-. <br /> -- Engineering Design and Specifications $18,000 <br /> Installation of Initial Extraction Well $7,000 <br /> _ Pump and Purification Unit (Installed) $50,000 <br /> Pump Test and Analysis $10,000. <br /> Site Restoration (Pavement Repair, etc.) $4,000 <br /> Permits 4 000 <br /> TOTAL $93,000 <br /> J <br /> ,1 <br />