This mitigation project spanned over 1,700 linear feet of road in Glenrock, Wyoming. Because historic coal mine workings were found as shallow as 65 feet immediately below the highway, the risk for additional subsidence remained high. This existing public hazard prompted the Wyoming Abandoned Mine Lands office and Brierley Associates to immediately prioritize and mitigate injecting a high-mobility grout to allow for maximum permeation within the highly rubblized zone. To prevent road closures and traffic hazards, all drilling and grouting was performed from the highway shoulder angled directly beneath the road, requiring a high level of precision. A total 3,400 cubic yards of grout was injected in 92 borings, with over 9,100 linear feet drilled.