Operations at an active wood treating facility in Mississippi resulted in a ground-water plume of semivolatile organic compounds (SVOCs)-- pentachlorophenol, naphthalene, and 14 other compounds--greater than 500 m in length and 150 m in width. The lead regulatory agency agreed that limited active remediation likely would be adequate to support a dominant monitored natural attenuation remedy. Three subsurface regions along the centerline of the plunging plume are areas of concern due to elevated ground-water impacts. To address these three areas of dissolved-phase contamination, a coupled chemical oxidation and enhanced aerobic bioremediation (chem/bio) pilot testing strategy was developed and initiated with a bench-scale treatability study during the winter of 2006-2007. The results of the treatability study led to the estimation of specific application requirements and potential field-scale effectiveness for two remediation products manufactured by FMC Corporation: PermeOx(r) Plus and Oxygen BioChem (OBC)(tm). A thick sequence of alluvium lies beneath the site, coarsening with depth at 12 to 34 m below ground. Total detected SVOC concentrations in soils exceeded 500,000 ug/kg. Soil oxidant demand tests were conducted in addition to long-term destruction removal efficiency tests. OBC was used to promote sequential chemical oxidation via alkaline activation of sodium persulfate and enhanced biodegradation via slow oxygen release. PermeOx(r) Plus, an engineered calcium peroxide product for timed oxygen release, also provides alkalinity to activate the persulfate in OBC. Additionally, PermeOx(r) Plus was tested separately to evaluate the potential for enhanced bioremediation of the full-strength soils and ground water. After 64 days of treatability testing, OBC application resulted in 23% and 40% reductions in total SVOCs in soil and ground water, respectively. After 94 days, undiluted SVOC reductions for soil and ground water amended with PermeOx(r) Plus were 70% and 71%. Despite significant chemical loading required by the highly contaminated soil and ground water, only a temporary one-log depression in overall viable biomass as measured by phospholipid fatty acid analysis was observed, and in all cases the microbial population rebounded with an advantageous shift in the specific types of microorganisms. A pilot test of one year's duration involving the three areas of concern commenced May 2007. If significant contaminant reductions are observed during the pilot test period as a result of chemical oxidation and subsequent aerobic bioremediation, then additional limited treatment may be pursued. Once active treatment is terminated, the project team expects that anaerobic conditions will reestablish. Paper at http://www.esaa-events.com/remtech/2007/pdf/Paper29.pdf