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20 March 1996 AGE-NC Project No 95-0130 Page 14 of 23 molecules 6 3 2 NUTRIENT REQUIREMENTS AND TOXICITY [ The bacteria require certain essential nutrients, which are usually available in native soil If supplemental nutrients are needed, the quantities and concentrations are generally very low, comparable to the quantities and concentrations utilized in fertilizer for light agricultural use There is considerable variation in the types of bacteria used by different remediation consultants for bioremediation The bacteria are selected and cultured 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 Exotic forms of oxygen (such as hydrogen peroxide or liquid oxygen) generally are not needed Free oxygen does increase the metabolic rates of reaction in the bacteria 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 oxygen concentrations during the process This may result in unwanted dehydration of the soil, but dehydration can be ameliorated by monthly infection of distilled water to each well The bacteria are also tolerant to a wide range of soil conditions For instance, pH can range from 4 to 9 5 and electrical conductivity has little or no effect unless sodium concentrations exceed 5% on a weight basis However, based upon physicochemical analysis of soil samples from the TFS site, environmental biotoxicity problems may be present at the site Additional analysis of soil samples at the site will be required to implement an in-situ bioremediation program Furthermore, it is likely that supplemental nutrients would have to be applied at the site to encourage biodegredation 6 3 3 INOCULATION WELLS The effective radius of influence of inoculation wells is typically 15 feet, depending upon several factors including well construction and soil type Extraction wells VW-1 through VW-3, as well as monitoring wells MW-1, MW-2, MW-3, and MW-5 could be utilized for inoculation However, approximately 20 additional inoculation points would have to be installed to cover the impacted soil plume Temporary inoculation wells could be installed for inoculation without the installation of additional permanent wells A greater radius of influence is usually obtained for ground water inoculation, since ground water movement can assist the bacterial migration 6 3 4 MONITORING ACTIVITIES Following inoculation, both inoculation and groundwater monitoring wells should be monitored for