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' 01 June 1999 <br /> AGE-NC Project No 95-0137 <br /> Page 14 of 26 <br /> ' influence is usually obtained for ground water inoculation, since ground water movement can assist <br /> the bacterial migration However, additional vadose zone inoculation points would be needed <br /> Temporary inoculation points or soil borings could be utilized <br /> 5 3 4 Monitoring Activities <br /> ' After inoculation,the inoculation wells and ground water monitoring wells should be monitored over <br /> a period of several months through periodic field measurements of organic vapor, carbon dioxide, <br /> ' and oxygen concentrations Quarterly or semi-annual monitoring activities should include the <br /> installation of soil borings to collect soil samples to monitor bacterial populations, nutrient <br /> availability and soil remediation progress If monitoring indicates areas of slow remediation, <br /> additional inoculation or addition of nutrients may be required <br /> ' 5 3 5 Duration <br /> Duration (and cost) is dependent on the volume of soil and water to be remediated, the number of <br /> inoculation and monitoring wells,the average concentrations of contaminants and nutrients, and the <br /> temperature and permeability of the soil Theoretically,the radius of influence of the inoculation well <br /> ' should increase rapidly at first, then gradually decline as the affected volume increases and the <br /> bacteria encounter decreasing hydrocarbon concentrations toward the margins of the hydrocarbon <br /> plume Shorter-chain hydrocarbons are typically consumed first and longer-chain hydrocarbons later <br /> Remediation at sites with similar soil composition typically takes between 12 and 48 months <br /> 5 3 6 Feasibility <br /> A limited feasibility study for in-situ bioremediation has been performed at the site Microbiological <br /> ' analysis of a soil sample indicated that populations of indigenous hydrocarbon-degrading bacteria <br /> constitute a low proportion of total microbiological population at the site, furthermore, the total <br /> microbiological population is low <br /> ' The low concentrations xa ons ofhydrocarbon-degrading bacteria at the site may be due to the elevated soil <br />' pH (9 4), high concentrations of potassium (728 ppm) and low concentrations of nitrogen, both <br /> oxidized and reduced High concentrations of pesticides or fumicides at the site, if present, could <br /> have a biotoxic effect on some bacteria The total colony units (CFU) of the bacteria and the <br /> chemical composition of the soil at the site are low for bioremediation without the inoculation of <br /> additional microbes and nutrients Results of the microbiological and physicochemical analysis are <br /> included in Appendix C <br /> Advanced GeoEm rronmenial,inc <br /> r <br />