A backfilled trench containing low-level radioactive waste was grouted with a particulate grout. The accessible void volume of the waste zone was estimated to be 20% or 28 m³, but 30.6 m³ of grout was injected into the trench. Part of the grout forced a path outside the trench. The water permeation into the trench from monitoring wells was reduced by two orders of magnitude. Site characterization and monitoring costs were outside the scope of this paper, so the only costs presented are the grouting costs. The grout costs only $0.055/L; but most of the cost was in manpower, 1220 man-hours for this demonstration.