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Remedial System Enhancement Plan—Former Tosco(Unocal)Service Station No 6981 <br /> August 8,2001 <br /> CONCLUSION The current catox VES is no longer effective The VES can be <br /> optimized by utilizing activated carbon to abate the air stream in <br /> place of the existing catox unit <br /> Option#5__In-Situ Biodegradation and/or Oxidation <br /> COST Unknown <br /> TIME FRAME Medium to long term <br /> ADVANTAGES "1) Effective for moderate dissolved levels of groundwater <br /> contamination <br /> 2) Natural biodegradation rates may be enhanced by introduction <br /> of nutrients and/or oxygen, if warranted <br /> DISADVANTAGES 1) Potentially slow process, <br /> 2) Difficult to control distribution <br /> 3) Unknown results for MtBE <br /> 4) Unknown cost <br /> CONCLUSION Potentially a feasible remedial technique for this site,by introduction of an <br /> oxidizing agent such as Fenton's Reagent to source areas following application of other <br /> remedial techniques Fenton's Reagent is an oxidant that works on contact Based on the <br /> distribution of hydrocarbons at the subject site,many injection points would be required <br /> I <br /> Option#6--Ozone Microsparging(C-Sparge') <br /> Ozone microsparging is a process where ozone in air is'introduced into the groundwater <br /> through specially designed sparge points to create small `microbubbles' As these <br /> r microbubbles rise within the column of water, they strip VOCs from the groundwater Low <br /> flow rates (2-6 cfm) are used Upon entering the microbubbles, the VOCs are rapidly <br /> oxidized Any ozone not consumed in the direct reaction with hydrocarbons rapidly <br /> decomposes to oxygen This has an added benefit of stimulating the natural biological <br /> degradation <br /> COST Low to medium. <br /> TIME FRAME Short term for impacts on or near the site,longer for off-site impacts <br /> ADVANTAGES 1) Relatively low equipment, operating and maintenance costs <br /> 2) Contaminants treated in-situ <br /> 3) Natural biodegradation rates may be enhanced by introduction <br /> of oxygen <br /> 4) C-Sparge has shown the ability to decrease MtBE <br /> concentrations <br /> 5) Minimal impact to site operations <br /> 140124 10 5 <br /> I <br />