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5. BIOREMEDIATION <br />' Aar stripping of VOCs by the UVB system as the primary treatment process for the removal of <br /> petroleum hydrocarbons in the contaminated soil and groundwater The current work plan also <br />' recommends monitoring microbial activity, along with several physical and chemical parameters <br /> which may limit this activity The goal as to maintain the indigenous microbial population in an <br /> active state such that the kinetics of petroleum hydrocarbon biodegradation in the contaminated <br /> soils and aquifer are enhanced <br /> 5.1 MICROBIAL ENUMERATION AND ACTIVITY <br /> 5.1.1 Heterotrophic Plate Counts <br /> The enumeration of viable cells an soil samples provides a measure of the overall microbial <br /> activity and biodegradation potential After being extracted from soil using an aqueous solution, <br /> viable cells can be grown on an appropriate heterotrophic growth medium under aerobic <br />' conditions The number of colony forming units (CFU) that can be counted at a particular <br /> dilution represents the number of viable cells in the sample Typically, the counts from active <br /> soil are in the range of 106 to 108 CFU (colony forming units) per gram of soil This method, <br />' which as referred to the heterotrophic plate count, may be limited by the inability of some <br /> indigenous forms to grow on the given medium <br /> 5.1.2 Epifluorescence Microscopy <br /> This analysis measures the total number of bacteria present in a given sample It will always <br />' exceed the heterotrophic plate count After an appropriate stain is applied, bacteria an soil <br /> samples will fluoresce when excited by light Metabolizing cells can be distinguished from <br />' non-metabolizing cells by this method A comparison of heterotrophic plate counts and <br /> epifluorescence counts provides indirect evidence of the degree of aeration in the subsurface <br /> Since volatile organic hydrocarbon biodegradation as primarily an aerobic process, at as desirable <br />' to maintain an essentially aerobic microbial community <br /> 5.2 AMENDMENTS TO IMPROVE MICROBIAL ACTIVITY <br />' The UVB system will provide an aerobic environment by adding oxygen to the soil and <br /> groundwater through aeration Other physical and chemical parameters which may limit <br />' microbial growth and activity include nitrogen, phosphorus, soil moisture, and pH If these <br /> parameters should become Iimiting, appropriate amendments will be introduced to the <br /> subsurface <br />' WP61 73942 WP10%TX 5 10 <br />