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1 <br /> ' 01 June 1999 <br /> AGE-NC Protect No 95-0137 <br /> Page 22 of 26 <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 in bioremediation are aerobic and usually require additional oxygen <br /> ' to supplement dissolved oxygen concentrations in ground water Generally, several air sparging 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 3 2 Monitoring Activities <br /> ' After inoculation the inoculation wells andound water momtonn wells should be monitored for <br /> gr g <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, bacterial populations and nutnent availability If monitoring indicates areas of slow <br /> remediation, additional inoculum and/or nutrients may be required <br /> ' 6 3 3 Feasibility Studies <br /> A limited feasibility study for in-situ bioremediation of the ground water at the site has been <br /> ' performed Microbiological analysis of an impacted water sample indicated that populations of <br /> indigenous hydrocarbon-degrading bacteria constitute 5 2% of the total microbiological population <br /> at the site, and that some degree of contaminant biodregradation is likely to be occurring The <br /> ' contaminant biodegradation is slow due to low levels of nitrogen and phosphates The irate of <br /> contaminant biodegradation may be stimulated by the addition of nutrients into the ground water <br /> Results of the microbiological and physicochemical analysis are included in Appendix C <br /> 1 <br /> 6 3 4 Duration <br /> 1 <br /> Cleanup durations for to-situ bioremediation will vary, depending upon specific site characteristics <br /> However,an 18 to 36 month treatment period is commonly achievable Since dissolved hydrocarbon <br /> concentrations at the site are low, a cleanup period as short as 18 months may be possible <br /> Advanced GeoEmironmental,Inc <br />