The study was undertaken to evaluate in-situ soil bioremediation processes, including degradation and detoxification, for wood preserving and petroleum refining wastes at high concentrations in an unacclimated soil. The soil solid phase, water soluble fractions of soil, and column leachates were evaluated. A mutagenic potential assay (Ames assay) and an aqueous toxicity assay (Microtox(TM) assay) were used to evaluate detoxification; high performance liquid chromatography was used to evaluate chemical concentration and degradation for eight polynuclear aromatic hydrocarbons (PAHs). The group of noncarcinogenic PAHs studied demonstrated greater degradation, ranging from 54-90% of mass added for the wastes; the carcinogenic group of PAHs studied exhibited degradation ranging from 24-53% of mass added. Although no mutagenicity was observed in waste/soil mixtures after one year, Microtox(TM) toxicity was observed in water soluble fractions and in leachate samples. Integration of information concerning degradation of hazardous constituents with bioassay information represents an approach for designing treatability studies and for evaluating effectiveness of in-situ soil bioremediation. When combined with information from waste, site, and soil characterization studies, data generated in treatability studies may be used in predictive models to: evaluate effectiveness of on-site soil bioremediation; develop appropriate containment structures to prevent unacceptable waste transport from the treatment zone; and design performance monitoring strategies. (Copyright (c) 1990 ISWA.)