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Selective Enumerations - Represents only those microorganisms, which are capable of specifically degrading the target contaminant Percentage Degraders - This number represents the percentage of selective organisms capable of degrading the target contaminant when compared to the heterotrophic/general I population If a given sample had 100 general organisms and 15 selective organisms, it would be stated that the sample had a 15% degrader population All references to microbial counts are expressed in Colony Forming Units (CFU's) per gram of soil tines 105 Example if the heterotrophic count was 5 2 and the selective count was 52 this would mean that there were 520,000 microbes per gram of soil in the given sample, but only 52,000 of these microbes are capable of degrading the _contaminant of concern Following each comparison will be a number in parenthesis which represents the overall percentage ofmicrobe�iich are capable of-biodegrading the contaminant of concern The previous example would have had ( 10) following the selective count referring to the fact that 10% of the total population of microbes could remediate the contaminant of concern As a general rule of thumb, 20% of the total microbial population capable of degrading the contaminant with adequate nutrient levels could be considered acceptable depending on contaminant concentration 1 All microbial enumerations were performed by taking sample dilution's and inoculating them onto 50% Plate Count Agar for heterotrophic/general microbial growth, and 50% Bushnell-Haas Agar media supplemented with gasoline for selective microbial growth All media was prepared at site specific pH and incubated at 30°C for six days A single dilution for all samples was conducted in triplicate, with the results being reported as an average of the three Prior to beginning the studies, background samples were analyzed from locations within ' the plume (VE-1 @ 25' and VE-1 @ 40') and outside of the plume (SB14 @ 25' and SB 14 @ 40') The samples within the plume yielded very low recoveries of both heterotrophic and selective microorganisms These samples contained what would appear to be adequate levels of nutrients for bioremediation to occur The samples outside of the established plume had increased levels of both heterotrophic and selective microbes over inside the plume however they would also be considered below what ' would be acceptable for remediation, they contained increased levels of both nitrate and ammonium nitrate The increased levels of nitrate outside of the plume vs inside the plume could indicate that the nitrate is not being utilized because there is no contaminant to remediate The increased levels of ammonium nitrate could indicate that anaerobic remediation is occurring ' L ects o Nutrient Au mentation on Microbial Growth This study's were performed over a 21-day period, and conducted to comparatively ' evaluate the effects of nutrient supplementation on microbial kinetics This study involved samples from location VE-1 taken at a depth of 25 feet from the site This study was undertaken to determine if nutrient levels at the site may be a contributing factor in ' limiting microbial growth and biodegradation, and to determine what effect nutrient augmentation would have on microbial growth