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b Kam ginng Uses of ORC on Other Sources of Contamination The first applications of ORC were for the treatment of BTEX and other light petroleum hydrocarbon fractions.Its use has now expanded to the treatment of heavier fractions such as home heating oil and certain polycyclic aromatic hydrocarbons(PAHs).More recently,ORC has been used to bioremediate the highly mobile and problematic gasoline oxygenate MTBE and has been applied to sites impacted with dhloroaromatics, nitroaromatics and some of the lower. order chlorinated aliphatics that can be treated aerobically—most notably vinyl chloride. Methyt Tert-Butyl Ether (MTBE) Vinyl Chloride MTBE complicates remediation and closure of properties The presence of oxygen stimulates the degradation ofvinyl contaminated with BTEX and other fuel hydrocarbons chloride and is the basis upon which ORC has been shown because it is highly soluble and does not readily retard on to effectively treat this contaminant The metabolism of vinyl the aquifer matrix. Other complexities with this compound chloride may proceed via two possible oxygen-demanding have limited the use of mechanical treatment methods in processes(direct substrate oxidation and/or co-metabolism). favor of maim aerobic bioremediation of MTBE,which can The accelerated bioremediation of vinyl chloride has been be enhanced by oxygen and specifically by ORC. demonstrated several times and published. It is useful to note that Regenesis played a recognized In one such sample ORC soda were used in a recirculat. industry role in demonstrating the importance of oxygen in ing well system as a polishing step to the anaembic treatment MTBE bioremediation.Since 1997,we have provided several of the parent product TCE.After 110 days the avenge con- reports in the literature of positive field remediation results centrations of VC in three monitoring wells declined 47 per. with ORC barriers and source treatments.We also sponsored cent(Lewis,R R,et al. 1998).In another example,ORC slurry original work at universities and private research laboratories was injected throughout a contaminated plume(racy,D.P., that elucidates key microbiological aspects of MTBE biore- 1998).Residual vinyl chloride concentrations were effectively mediation. Many other reports, parallel and subsequent to remediated after natural attenuation had stalled. Con- the Regenesis findings, now clearly define the value of oxy- centrations in areas of the plume that had not been so treated gen in the remediation of MTBE. The best summaries to increased.Based on the results,the existing mechanical control date of the field and laboratory work, that includes com- systems were shut down in favor of an ongoing ORC treatmrnt. pendiums of site management strategies to which the Regerimis work has contributed,can be found in Koenigsberg Complex Organic Mixtures Featuring et 21., 1997 and Stocking et al. 1999. Nitroaromaties and Chloroaromaties The uppermost aquifer beneath a chemical plant contained Home Heating Oil residual concentrations of nitrochlorobenzene from a tank Releases of heating oil,kerosene and diesel from residential car spill, as well as pre-existing levels of other organic com- storage tanks have become an increasing and costly problem pounds including nitroaniline and chloroaniline.The aquifer and the use of excavation and/or mechanical remedies is consists of low permeability clays and silts, and produces often physically or economically unfeasible. Also, by their only a few gallons of groundwater per day from a shallow residential nature these contaminated sites are more likely to recovery well previously installed for remediation.Soil removal impact receptors. Fortunately,the use of ORC is a low cost was the principle mechanism to treat the tank car spill. passive option as cited in the following example. Subsequently, recovery of residual groundwater contamina- A 550-g2llon UST was excavated from a residential site tion has been ineffective for more than 10 years due to low in Middlesex County, New Jersey. The UST was located aquifer yield,and the recalcitrant nature of the contaminants. immediately adjacent to the foundation of the residence and The ORC was injected into the six foot thick aquifer in a additional remedial excavation could not be performed grid pattern covering approximately 900 square feet. After without undermining the foundation. Groundwater moni- seven months the accelerated aerobic bioremediation poten- toting revealed a TPH concentration of 6,605 ppb (11g/I),so tial was demonstrated. Levels of nitroaniline and chloroani- 60 pounds of ORC was injected in three borings. After 5 line were reduced 95%and 83%respectively.Other contam- months, the TPH was non-detect (ND); subsequent sam- inane reductions at the site include nitrochlorobenzene pling confirmed the result (74%),chlorobenzene (64%)and naphthalene(91%). L.a Lr-rlif.11ti}M„a K OA Mw"F 1111.flees MI/Vdn1 Tm�war T.d..imn Wl 11{YI.2 4 II&P G�OK.Tai.PD.11*.Vwfl OJuJ.N�..r W rMs I�waa d hwa,..vs#kl).1f.4w14 P.�r.++.Fa 0K•su1w.ti IG.dpb.t S..Ik Kaw�xA 1fn.Ex—rb—M 1191,11,%-11.-x..ep SWS C M,kf'.11 rk M. WKF�Im.III—lades d1MslHry'eMu,wl DI- e*v Umik ft it V % 1q 1111