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I18 July 2002 <br /> • AGE-NC Project No 96-0254 <br /> IPage 8of17 <br /> The cost for excavation, treatment/disposal and backfilling would probably be between $150 and <br />' $200 per cubic yard, depending upon hydrocarbon concentrations Total costs for excavation and <br /> treatment or disposal, plus permitting fees, could therefore approach $112,500 to $150,000 <br /> I5 2 IN-SITU SOIL BIOREMEDIATION <br /> Local acceptance of this treatment technology by the regulatory community has grown recently,due <br /> to documented success for remediation of petroleum hydrocarbon contaminants at a number of sites <br /> in California and elsewhere However,the CVRWQCB has been reluctant to issue discharge permits <br /> required to inject bacterial inoculum and/or nutrients into the subsurface <br /> I5 2 1 Principles <br />' Hydrocarbon-degrading bacteria metabolize hydrocarbons and assimilate the resulting organic <br /> chemicals into biomass for reproduction and growth,and release water and carbon dioxide as waste <br /> products The light-end hydrocarbons are typically consumed first, followed by "heavier" <br />' hydrocarbon molecules <br /> For to-situ bioremediation, hydrocarbon-degrading bacteria are propagated in a liquid medium, <br /> which is then injected into inoculation wells screened in the interval of contamination If ground <br /> water has been impacted, strategically located ground water monitoring wells can be used for <br /> inoculation Once in the contaminant plume,the bacteria metabolize and degrade hydrocarbons and <br /> spread laterally and vertically by migrating and reproducing, thereby creating an advancing <br /> remediation front <br /> I <br /> 5 2 2 Nutrient Requirements And Toxicity <br />' The hydrocarbon-degrading bacteria require certain essential nutrients, which are commonly <br /> available in native soil If supplemental nutrients are needed, the quantities and concentrations are <br /> generally very low,comparable to the quantities and concentrations utilized for light agricultural use <br /> There is considerable variation in the types of bacteria used by different remediation consultants for <br /> I 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 /> Iliquid oxygen) are usually not required <br /> • <br /> Advanced GeoEnvironmental,Inc <br />