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07 November 2004 <br /> AGE-NC Project No 96-0232 <br /> Page 8of11 <br /> 4 3 IN-SITU BIOREMEDIATION/BIOENHANCEMENT <br /> Bioremediation involves the introduction of hydrocarbon-degrading microbes or supplemental <br /> nutrients to enhance naturally-occurring bacteria,through wells into the ground water The microbes <br /> degrade hydrocarbons and spread laterally(and vertically)by migration and reproduction <br /> Hydrocarbon-degrading microbes are able to metabolize hydrocarbons and assimilate the resulting <br /> organic chemicals into biomass for reproduction and growth Typically,the light-end hydrocarbons <br /> are degraded first, followed by heavier compounds <br /> 4 3 1 Nutrient Requirements And Toxicity <br /> The microbes require certain essential nutrients that are usually 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 /> CRWQCB for the infection of nutrients Into ground water,furthermore,the CRWQCB has been very <br /> reluctant to Issue Waste Discharge Permits <br /> Typically,the microbes utilized in bioremediation of groundwater are aerobic and commonly require <br /> additional oxygen to supplement dissolved oxygen concentrations in ground water Generally, <br /> several air spargmg or in-well aeration sources are sufficient to provide the necessary oxygen <br /> However, in some cases the addition of hydrogen peroxide or other oxygen source is necessary <br /> 4 3 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 oxygen Ground <br /> water samples should be collected and analyzed for petroleum hydrocarbons,bacterial populations <br /> and nutrient availability If monitoring indicates areas of slow remediation, additional inoculations <br /> may be required <br /> 4 3 3 Feasibility Studies <br /> Feasibility studies have not been performed at this site However, results of many bioremediation <br /> pilot tests conducted by AGE at similar sites in Lodi and Stockton (i e Geweke Land Development, <br /> 16 South Cherokee Lane, Lodi CA) indicate that lighter petroleum hydrocarbons, such as MTBE, <br /> are more readily biodegraded than longer-chain (heavier) hydrocarbons, such as diesel fuel <br /> Advanced GeoEnvironmental,Inc <br />