Subsurface remediation in the urban environment is often hampered by space restrictions, numerous underground utilities, as well as significant amounts of “urban fill” comprising soils, resulting in heterogeneous soil textures.  At a warehouse facility in New York City, a shrinking plume of groundwater contamination did not attenuate to regulatory standards due to a stubborn “hot spot” of high BTEX concentrations.   Traditional remedial technologies (air sparging/SVE, excavation, pump and treat) were not selected due to space restrictions, safety concerns, cost, and site hydrogeology. Monitored natural attenuation can be an effective and inexpensive remediation strategy at petroleum release sites mainly due to intrinsic bioremediation.  However, microbial degradation of organic contaminants like aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylenes (BTEX), methyl tert-butyl ether (MTBE), diesel, fuel oil, and other hydrocarbons in groundwater is usually limited by the availability of electron acceptors.  The addition of oxygen release compound is one way to enhance aerobic degradation by autochthonous microorganisms in the subsurface.   This paper presents field evidence for the biological degradation of dissolved phase BTEX compounds under enhanced oxidizing conditions using ORC^®.   A program of oxygen-releasing compound application was designed and performed at the site, and included the on-going monitoring of basic indicators of attenuation.  Initial monitoring and sampling results obtained six weeks after ORC^® was applied, indicated BTEX concentrations decreased approximately 98% to concentrations below regulatory guidance levels.  Benzene, in particular, decreased one order of magnitude, to a concentration below guidelines, for the first time in ten years of quarterly sampling.  With approximately 90% of the work scope completed, the cost for this program totaled approximately $70,000.