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' 28 April 1995 AGE-NC-95-4103 Page 10 of 11 ' There is considerable variation in the types of microbes used by different remediation consultants for bioremediation The microbes are cultured and selected for their ability to degrade petroleum ' hydrocarbons They are microaerophilic and facultatively anaerobic, and therefore abundant oxygen is not necessary for the process to occur No exotic forms of oxygen (such as hydrogen peroxide or liquid oxygen) are needed A small blower delivering atmospheric air to the ' subsurface at a rate of 2 to 5 psi per well can be used to enhance air flow and maintain the oxygen content during the process This may result in unwanted dehydration of the soil, but dehydration can be prevented by monthly injection of distilled water to each well ' The microbes are also tolerant to a wide range of soil conditions For instance, pH can range from 4 to 9 5 and elects ical conductivity has little or no effect unless sodium lex els reach greater than ' 5% on a weight basis ' 5 3 3 INOCULATION WELLS Due to the limited lateral extent of soil contamination at the site and the high permeability of the ' unsaturated zone, the radius of influence of remedial well V\V-1 should be adequate to remediate all of the soil contamination It should not be necessary to install additional inoculation wells, but it may be necessary to re-inoculate VNV-1, if subsequent confirmatory sampling indicates that remediation is pioceeding slowly or bacterial counts are low V\V-1 is screened to \\ithm 10 feet of the pi esent water table, it is therefore pi obable that the bacteria will reach the groundwater ' Inoculation of VXV-1 will therefore result in partial remediation of the saturated zone ' 5 3 4 (MONITORING ACTIVITIES - After inoculation, the inoculation »ell and groundwater monitoring well IMNN'-1 should be ' monitoi ed by monthly field nleasui ements of of garlic vapors, cai bon dio%ide, and o\\gen Quarter ly monitor ing activities should include collection of air samples from each monitoring and ' inoculation well for quantitative analysis of cai bon diomde, which is a by-product of li}drocarbon degt adation At least one boi ing should also be drilled to collect soil samples for laboratory analysis of petroleum hydrocarbons and bacterial populations 1 ' 5 3 5 DURATION Duration and cost ai e dependent on the volume of soil to be remediated, the number of inoculation and monitoring wells and events, the average concentrations of contaminants and nuts cents, and the temperature and permeability of the soil Theoi etically, the radius of influence of the inoculation well should increase rapidly at first, then gradually decline as the affected