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I16 August 20' 0'1 <br /> AGE-NC Project No 97-0312 <br /> Page_9 of 20 ' 1 <br /> 7 1 3 Estimated Costs For Excavation <br /> f <br /> Once excavated, Impacted soil could be treated on-site oratransferred to an off-site disposal or <br /> I recycling facility Replacement backfill material must be Imported if off-site disposal is chosen <br /> Based upon limited site space, it is unlikely that on-site treatment would be acceptable The cost for <br /> excavation, treatment/disposal and backfilling would likely be between $80 00 and $100 00 per <br /> cubic yard, depending upon actual hydrocarbon concentrations encountered during excavation <br /> Therefore,based on the estimated volume of 10,157 cubic yards,the estimated cost to remediate the <br /> site utilizing excavation would be between$812,600 and$1,015,700 assuming no special excavation <br /> techniques or shonng are^required <br /> 7 2 IN-SITU BIOREMEDIATION <br /> Currently, acceptance of this treatment technology within the regulatory community is not certain <br /> due to the inconsistent remediation results for petroleum-hydrocarbon contaminants at numerous <br /> sites in California <br /> 7 2 1 Principles <br /> For in-situ bioremediation,hydrocarbon-degrading bacteria are propagated in a liquid medium and <br /> injected into impacted soil via inoc,uldUon weils screened Lhrougli or intim Lire Iiydrocdrbon-Impacted <br /> soil If ground water has been impacted, strategically located ground water monitonng 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 /> Ifront r <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 /> 7 2 2 Nutrient Requirements and Toxicity <br /> S F 4 <br /> Hydrocarbon-degrading bacteria require certain essential nutrients, which are usually available in <br /> native soil If supplemental nutrients are needed,the quantities_and concentrations are generally very <br /> low, comparable to the quantities and concentrations utilized for light agriculture There is <br /> considerable variation 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 /> � ' f <br /> Advanced GeoEnvironmental,Inc <br /> I '` 1 <br />