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'• 18 July 2002 <br /> AGE-NC Project No 96-0254 <br /> ' Page 10 of 17 <br /> I5 2 6 Feasibility <br /> A limited feasibility study for in-situ bioremediation has been performed at the site in November <br /> 1999 Microbiological analysis of soil samples indicated thatpopulations of indigenous hydrocarbon- <br /> degrading bacteria constitute a low proportion of total microbiological population at the site, <br /> furthermore, the total microbiological population is low Results of the microbiological and <br /> physicochemical analysis are included in Appendix B <br /> The low concentrations ofhydrocarbon-degrading bactena at the site maybe due to the elevated soil <br /> ' pH(10 0-10 4),high concentrations of potassium(172 ppm)and low concentrations of nitrogen In <br /> addition, if high concentrations of pesticides or fumicides are present at the site, they could have a <br /> biotoxic effect on some bacteria <br /> ' The total colony units(CFU)of the bacteria and the chemical composition of the soil at the site are <br /> low for bioremediation without the inoculation of additional microbes and nutrients If <br /> ' bioremediation is chosen as the method of remediation,additional soil samples should be collected <br /> and analyzed for physicochemical properties necessary for effective bi oremediation The results will <br /> be used to evaluate the need for nutritional enhancement, if necessary, to facilitate effective <br /> '• biodegradation <br /> I5 2 7 Estimated Costs For In-situ Bioremediation <br /> I The cost for in-situ bioremediation will vary,depending upon the volume of moculum required and <br /> the number of remediation wells to be inoculated, in addition, longer-chain hydrocarbons (diesel) <br /> in the vicinity of the former USTs will probably require a longer remediation period Generally,the <br /> ' initiation cost for in-situ bioremediation will range from$35,000 to $75,000 Weekly and monthly <br /> monitoring generally costs between $10,000 to $20,000 annually, soil borings to monitor <br /> bioremediation progress typically averages $5,000 to $10,000 annually Total costs for <br /> e bioremediation of soil at the subject site is estimated to be between $50,000 and $110,000 <br /> ' 5 3 MONITORED NATURAL ATTENUATION <br /> Natural attenuation, or passive bioremediation, is a remedial alternative that relies on natural <br /> I processes to degrade hydrocarbons Biodegradation is the most important natural attenuation <br /> mechanism No additional bacteria or nutrients are added to the soil Essential nutrients required for <br /> biodegradation are commonly present naturally in the subsurface, however, where high <br /> ' concentrations of hydrocarbons are present, nutrients may be consumed before hydrocarbon <br /> • remediation is complete <br /> IAdvanced GeoEnvimnlnentnl,Inc <br /> I <br />