During the course of operation, a now-abandoned wood preserving facility located in Pensacola, Florida, released PAH compounds to the groundwater. Much of the contaminant plume resides at and above 100 ft below ground surface (bgs). The contaminated groundwater flows east under a railroad switching yard, limiting access and treatment options. In situ enhanced bioremediation with injection of oxygen to stimulate indigenous bacteria and form a biological treatment zone was selected for dissolved-phase remediation. Horizontal directional drilling (HDD) beneath the railroad switching yard was proposed for initial pilot testing of the biosparge remedy. A bundle of three wells comprising different construction materials and slot configurations was installed in the double-ended HDD bore. Well screen materials included stainless steel with longitudinal slots and air-diffusion system HDPE in which microslots open and close depending on pressure of the injection medium. Specialized HDD well installation techniques included a steel carrier casing, grouting pipes, and biopolymer drilling fluid. The final well construction was 1,450 ft long and set at 100 ft bgs. A limited number of downgradient monitoring wells were installed to gauge the performance of the HDD well bundle during two oxygen injection pilot tests. Overall, the pilot tests indicated that the HDD well screens provided excellent biosparging capabilities. Concerns for full-scale treatment include potential occlusion of the well slots.