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n, » <br /> 4 <br /> u <br /> J <br /> 28 February 1997 <br /> AGE-NC Protect No ,95-0144, A <br /> tPage 9 of 20 <br /> ' <br /> of overburden soil, and would also be difficult below'a depth of 18 feet due to saturated flowing v r <br /> sand ; <br /> Once excavated, the impacted soil is generally stockpiled on-site for treatment or transported for t' <br /> disposal If soil, is treated on-site and the hydrocarbon concentrations can be reduced to <br /> concentrations set by the lead agency or to non-detectable concentrations, the soil can be used to <br /> backfill the excavation If the hydrocarbon-impacted soil is disposed of off-site, material must be <br /> , <br /> , imported to backfill,the excavation , <br /> The primary disadvantage of excavationes the disruption to a site Since the site is currently not in <br /> use, no other operations would be disturbed Other disadvantages include air pollution control <br /> concerns, backfilling and compaction costs <br /> 5 2 3 ESTIMATED COSTS FOR EXCAVATION <br /> At the subject site, impacted soil could be excavated with traditional equipment Approximately 200 <br /> cubic yards of soil would have to excavated from the former location of UST No 1 and i <br /> approximately 750 cubic yard of soil would have to be excavated from former location of UST No <br /> 8 location Very little "clean"overburden soil would need to be removed , <br /> Once excavated, the soil will then be treated on-site or transferred to an off-site disposal facility <br /> Replacement backfill material must be imported if off-site disposal is chosen Space is available for <br /> on-site'treatinent of excavated soil However, permitting would be required for on-site treatment of <br /> ' impacted soil The cost for excavation, treatment/disposal and backfilling would likely be between <br /> $80 00 and $120,00 per cubic yard, depending upon hydrocarbon concentrations Total costs for <br /> excavation and treatment or disposal could therefore approach $100,000 00 <br /> ' 53 IN-SITU BIOREMEDIATION <br /> u Acceptance of this treatment technology by the regulatory community has grown recently, due to <br /> documented success for remediation of petroleum hydrocarbon contaminants at a considerable , <br /> number of sites in California and elsewhere <br /> F„ 5 3 1 PRINCIPLES <br /> For in-situ bioremediation, hydrocarbon-degrading bacteria are propagated in a liquid medium, <br /> which is then infected into inoculation wells screened through the interval of contamination If' <br /> F <br />