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15 February 2000 <br /> AGE-NC Project No 98-0448 <br /> Page 20 of 33 T <br /> (See Section 6 0) Therefore, the estimated cost to remediate the site utilizing excavation techniques <br /> would be between $107,200 and $160,800 This dollar amount does not include the financial losses <br /> that Sierra Lumber would mcur due to the disruption of day to day business operations, warehouse <br /> building demolition and warehouse building repairs <br /> I8 3 IN-SITU BIOREMEDIATION <br /> Acceptance of this treatment technology within the regulatory community has grown recently, due' <br /> to documented successful remediation of petroleum-hydrocarbon contaminants at numerous sites <br /> in California <br /> 8 3 1 Principles <br /> For in-situ bioremediation,hydrocarbon-degrading bacteria are propagated in a liquid medium and <br /> infected into impacted soil via inoculation wells screened through or into the hydrocarbon-impacted <br /> soil If ground water has been impacted, strategically located ground water monitoring wells can be <br /> used for inoculation Once in the contaminant plume, the bacteria metabolize hydrocarbons and <br /> spread laterally and vertically by migrating and reproducing, creating an advancing remediation <br /> front <br /> Hydrocarbon-degrading bacteria metabolize hydrocarbons and assimilate the material into biomass <br /> for reproduction and growth, and release water and carbon dioxide as waste products The light-end <br /> hydrocarbons are typically consumed first, followed by "heavier" hydrocarbon molecules <br /> 8 3 2 Nutrient Requirements and Toxicity <br /> The hydrocarbon-degrading bacteria require certain essential nutrients, which are usually available <br /> in native soil If supplemental nutrients are needed, the quantities and concentrations are generally <br /> very low, comparable to the quantities and concentrations utilized for light agriculture <br /> There is considerable vanation in the types of bacteria used by different remediation consultants for <br /> bioremediation The bacteria are cultured and selected for their ability to degrade petroleum <br /> hydrocarbons They are microaerophilic and facultatively anaerobic, and therefore abundant oxygen <br /> is not necessary for the process to occur }Exotic forms of oxygen (such as hydrogen peroxide or <br /> liquid oxygen) are usually not required However, free oxygen does increase the metabolic rates of <br /> the bacteria A small blower delivering atmospheric air to the subsurface at a rate of two to five scfm <br /> Advanced GeoEnvironmental,Inc <br />