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r- <br /> 18 July 2002 <br /> AGE-NC Project No 96-0254 <br /> Page 14 of 17 <br /> degrade hydrocarbons and spread-laterally by migrating and reproducing, creating an advancing <br /> remediation front <br /> i6 2 1 Nutnent Requirements And Toxicity <br /> The bacteria are not tolerant to a wide range of ground water conditions For instance, pH should <br /> ' range from 6 to 8 5 In addition, the possible presence of high concentrations of pesticides or <br /> f imicides at the site may have a biotoxic effect on some bacteria <br /> The microbes require certain essential nutrients that are commonly available in ground water If <br /> supplemental nutrients are required, such as nitrogen and phosphorus as ammonium phosphate in <br /> ' liquid phase,the quantity is usually very low However,a Waste Discharge Permit is required by the <br /> RWQCB for the injection of nutrients into ground water <br /> ' Typically,the microbes utilized inbioremediation are aerobic and usually require additional oxygen <br /> to supplement dissolved oxygen concentrations in ground water Generally, several air spargmg or <br /> in-well aeration sources are sufficient to provide the necessary oxygen In some cases, addition of <br /> '• hydrogen peroxide is beneficial <br /> ' 6 2 2 Monitoring Activities <br /> After inoculation,the inoculation wells and ground water monitoring wells should be monitored for <br /> several months by periodic field measurements of organic vapor, carbon dioxide, and dissolved <br /> oxygen concentration Ground water'samples should be collected and analyzed for petroleum <br /> ' hydrocarbons,bacteria] populations and nutrient availability Ifmonitonng indicates areas of slow <br /> remediation, additional inoculum and/or nutrients may be required <br /> 623 Feasibility Studies <br /> A limited feasibility study for in-situ bioremediation of the ground water at the site was performed <br /> in January 2002 Microbiological analysis of an impacted water sample indicated that populations <br /> of indigenous hydrocarbon-degradmgbactena constitute 29%ofthe total microbiological population <br /> ' at the site, and that some degree of contaminant biodregradation is likely to be occurring The <br /> contaminant biodegradation is moderate to high due to high levels of nitrogen and phosphates The <br /> rate of contaminant biodegradation may be stimulated by the addition of nutrients into the ground <br /> Iwater Results of the microbiological and physicochemical analysis are included in Appendix D <br /> Advoaced G"Envvonmental,Inc <br />