Horizontal Interceptor Well T he University of Minnesota retained the firm of Peer LOCATION: Engineering to find a solution to problems being created Minneapolis, by the infiltration of contaminated groundwater into an Minnesota underground library archive. Following analysis of subsurface geological conditions and an evaluation of required perform- ENGINEERING FIRM: ance criteria, the firm recommended installation of a hori- Peer Engineering zontal interceptor well in the limestone bedrock above the Bloomington, mined underground storage area. The horizontal interceptor Minnesota well was installed by drilling a 460-foot-long horizontal bore- hole using directional drilling technology. Precise measuring CLIENT: instruments and drill motor controls were utilized to main- University of tain a trajectory within twelve inches of a predetermined path Minnesota along the entire borehole length. The well was finished with a stainless-steel well screen and well casing. CONTRACTOR: The well is withdrawing 38,000 gallons a day of contami- Layne Christensen nated groundwater from the bedrock above the underground Company space. The groundwater is treated by filtration and granular carbon prior to discharge. The interceptor well has reduced PROJECT COST: contaminant infiltration by more than 80% and has success- $600,000