In 2018, DA Smith (formerly Agapito Associates, Inc. Field Services)
drilled three 5-inch-diameter, high-angle core holes into the mine roof to facilitate backfilling of a natural void located above the Maiden Rock Mine. Holes were drilled up to 93 feet deep into the void. Work was performed beneath a steel canopy to protect against heat-driven slaking of the sand roof. Holes completed with 4-inch flush-coupled casing. DA Smith and Fairmount personnel installed special-purpose rubber hoses through the casing for pumping sand into the void.