Laboratory experiments were conducted to evaluate the potential for in situ biodegradation in the contaminated groundwater aquifer at the Hoe Creek underground coal gasification site. Experiments were performed in electrolytic respirometric cells under simulated environmental conditions. An orthogonal, fractional factorial design was used to evaluate the effects of the following factors on phenol degradation: nutrient dose, amount of bacterial inoculum, temperature, light conditions, and substrate concentration. Microorganisms native to the environment were used as the inoculum, and phosphorus was used as the nutrient. The amount of inoculum introduced and the nutrient dose were found to have a positive effect on phenol degradation. Temperature changes from 15{degree}C (59{degree}F) to 25{degree}C (77{degree}F) had no significant effect. The light conditions (fluorescent or dark) also had no significant effect on phenol degradation. Higher concentrations of substrate required increased amounts of oxygen for biodegradation. 24 refs., 1 fig., 4 tabs.