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' 15 June 1999 <br /> • AGE-NC Project No 98-0450 <br />' Page 14 of 27 <br /> collection of confirmatory soil samples to momtor bacterial populations,nutrient availability and soil <br /> ' remediation progress If monitoring indicates areas of slow remediation, additional inoculations or <br /> nutrient injection may be required <br /> 4 3 4 Feasibility <br /> ' Soil samples for the determination of in-situ bioremediation activity at the site have been collected <br /> at the site <br /> Samples were analyzed for physicochemical properties to evaluate nutrient levels, biotoxicity, and <br /> microbial activity for bioremediation effectiveness As presented Section 4 2 4, due to relatively <br /> ' high clay-content and suggested low intrinsic permeability of site soil, enhanced in-situ <br /> bioremediation may not be an adequately effective remedial alternative (Appendix E) <br /> xnaiyucat results of soil samples submitted for physicochemical analysis and microbiological <br /> enumeration indicate that there were measurable microbe activity at the site The lack of <br /> biodegrading bacteria may be due to the presence of biotoxic compounds in the subsurface at the <br /> site, such as metals, caustic materials or pesticides Adequate concentrations of necessary nutrients <br /> for microbe growth and minimal sustenance were present in the soil at the site, however the pH of <br /> ' the soils analyzed were above the optimal ranges for microbial rowth <br /> ' 4 3 5 Duiation <br /> Duration (and cost) of in-situ bioremediation are dependent on the volume of soil to be remediated, <br /> ' the number of inoculation and monitoring wells, the average concentrations of contaminants and <br /> nutrients, temperature and the permeability of soil Theoretically, the radius of influence of the <br /> inoculation well should increase rapidly at first, then more slowly as the affected volume increases <br /> ' and the bacteiia encounter decreasing hydrocarbon concentrations toward the margins of the <br /> hydrocarbon plume Shorter-chain hydrocarbons are typically consumed first and longer-chain <br /> ' hydrocaibons later Remediation at sites with similar soil compositions typically takes between 24 <br /> to 36 months <br /> ' - 3 4 3 6 -Estimated Cost- - <br /> ' The cost for in-situ bioremediation will vary, depending upon the volume of inoculant and nutrients <br /> . required, the number of remediation wells to be inoculated and the duration of bioremedial activity <br /> Generally, the initiation cost for in-situ bioremediation will range from $35,000 to $75,000 <br /> Adianccd GcoEn{Ironrncnia1,Inc <br />