Lead, SD

Long-Baseline Neutrino Facility (LBNF)

South Dakota Science & Technology Authority


The project is located inside the former Homestake Goldmine in Lead, South Dakota. The facility includes two large, seven-story-tall cryogenic vessel caverns (each approximately 475 feet long x 65 feet wide x 92 feet high [145 m x 20 m x 28 m]); a central utility chamber (approximately 624 feet long x 64 feet wide x 37 feet high [190 m x 19.5 m x 11 m]); and construction of associated access drifts, ancillary spaces, and a ventilation shaft. LBNF will create a high-intensity neutrino beam at Fermilab in Batavia, Illinois, and send it through the earth more than 800 miles (1,287 km) to the detector caverns. 

Neutrinos have minuscule but nonzero mass and can pass through ordinary matter nearly undisturbed. Studying them is expected to lead to insights into the particles that existed in the initial stages of the universe. 

Fast Facts
  • Dominant rock structure is complex foliation developed through repeated metamorphic events
  • Approximately 800,000 tons (725,748 metric tons) of rock excavated
  • Approximately 1 mile (1.6 km) underground to the excavation site
  • More than 30,000 rock bolts installed

Scope of Work

Delve Underground provided geotechnical engineering, preliminary design, final design, and construction support for an underground particle detector for the LBNF project. Delve Underground executed a site exploration program, performed geologic mapping, managed an in situ stress testing program, performed laser scanning of existing underground drifts, and performed time-dependent movement assessments to collect detailed data on the site conditions and develop an accurate 3D model to evaluate rock movement and rock behavior during and after excavation. 

Delve Underground developed and helped execute an underground test blasting program to develop parameters to design full production blasts that limit vibration and air overpressure impacts to existing operating laboratory space within the work areas. Delve Underground also led the geometric design of adit junctions; evaluation of construction sequencing and impacts; and the development of the Geotechnical Data Report, Geotechnical Interpretive Reports, and Geotechnical Baseline Report.

Challenges & Innovations

The project encountered variable rock behaviors from foliated rock and high in situ stress, and complex drift intersections, large span drifts, and caverns. Delve Underground used laser scanning to support the design, 3D equipment clearance modeling, test blasting program, and the Geotechnical Baseline Report.