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c <br /> r t t <br /> I ' 14 11 <br /> XNovember 1995 <br /> AGE-NC Project No 95-0121 <br />' Page 12 of 20, ; <br /> 1 <br /> There is considerable vanation,in the types of bacteria used by different remediation consultants for <br /> bioremediation The bacteria are cultured and selected for thea,ability to degrade petroleum ,,, <br /> hydrocarbons They are microaerophilic and facultatively anaerobic, and therefore abundant oxygen <br />' is not necessary for the process to occur No exotic forms of oxygen (such as hydrogen peroxide or <br /> liquid oxygen)are needed Free oxygen does increase the metabolic rates of reaction in the bacteria <br /> A small blower delivering atmospheric air to the subsurface at a rate of 2 to 5 psi per well can be used r <br />' to enhance air flow and oxygen concentrations during the process This may result in unwanted <br /> dehydration of the soil, but dehydration can be ameliorated by monthly injection of distilled water to <br /> each well <br /> The bacteria are also tolerant to a wide range of soil conditions For instance, pH can range from 4 <br /> to 9 5 and electrical conductivity`has little or no effect unless sodium concentrations exceed 5% on <br /> a weight basis <br /> 6 3 3 INOCULATION WELLS <br /> The effective radius of influence of inoculation wells is typically 15 feet' Extraction wells EW-1, VW- <br /> 1 and VW-2 can be utilized for soil inoculation However, approximately 5 additional inoculation <br /> point would have to!be installed to cover the impacted soil plume Temporary points could be <br /> I installed for inoculation without the installation of,additional wells Existing monitoring wells and <br /> EW-1 can be used for inoculation of ground water A greater radius of influence is usually obtained <br /> for ground water inoculation, since ground water movement can assist the bacterial migration <br /> However, additional ground water inoculation points would also be needed ^ <br /> I I <br /> 6 3 4 MONITORING ACTIVITIES ; <br /> After inoculation, the inoculation wells and groundwater momtonng wells should be`momtored for <br /> several months by periodic field measurements of organic vapors, carbon dioxide, and oxygen ' <br /> Ground water samples,should be collected and analyzed for petroleum hydrocarbons,to monitor <br /> progress of the remediation Quarterly monitoring activities should include the installation of soil <br /> rboring to monitor bacterial populations,, nutrient availability and soil remediation progress If <br /> monitoring indicates areas of slow remediation, additional inoculations may be required <br /> f ' <br /> I t <br /> t 1, JI <br /> 6 3 5 DURATION <br /> 1 <br /> Duration and cost fare dependent on the volume of soil too be remediated, the number of inoculation <br /> and monitoring wells and events, the average concentrations of contaminants and nutrients, and the <br /> ' I <br /> r „ I <br /> I h <br /> i n <br /> a , t <br />