When particle physicists look to solve the fundamental mysteries of the universe, they build deep underground. When they need to protect the massive structural caverns housing those complex experiments, they depend on advanced industrial coatings. Ultimate Linings is proud to highlight its role in a groundbreaking large scale fire-rated polyurea project for the Deep Underground Neutrino Experiment (DUNE), hosted by Fermilab at the Sanford Underground Research Laboratory in Lead, South Dakota.

To secure the massive caverns supporting this international research initiative, specialty contractor Hartman Walsh coated approximately 250,000 square feet of vertical and overhead rock faces. This massive engineering project utilized Ultimate Linings’ specialized fire-retardant polyurea system, FR-263, to deliver an elite tier of containment and structural protection.

Project Snapshot & Metrics

Achieving Safety in a Large Scale Fire-rated Polyurea Project

Securing a structural excavation located 4,860 feet below the surface presents unique safety and environmental challenges. The deep-earth caverns feature ceilings soaring more than 90 feet overhead. During the initial mining phase, the surrounding natural rock was mechanically stabilized using rock pinning systems and wire mesh, followed by a foundational shotcrete lining.

Under the immense subterranean pressures inherent to deep mining, micro-shifts in the rock can cause shotcrete to crack, splinter, and fall. In a facility filled with delicate scientific equipment and active research personnel, falling debris poses an unacceptable risk.

Fermilab specifiers determined that a high-build elastomeric membrane was the ideal solution to encapsulate the walls and ceilings. This thin spray liner acts as a structural catch-net, utilizing its remarkable tensile strength and elongation properties to hold loose fragments in place. Because the application occurred in a confined underground environment, strict fire performance metrics were non-negotiable, making this a highly specialized large scale fire-rated polyurea project.

Material Specification: FR-263 Polyurea

The engineered specification required a comprehensive multi-layer layout to achieve long-term concrete protection over the clean, dry shotcrete substrate. The installation team executed a precise, heavy-duty formulation rollout:

• Primer Phase: Crews applied 3,000 gallons of a high-performance epoxy primer system to secure the initial bond to the shotcrete.

• Polyurea Membrane: Applicators built out a 5mm thick barrier using 25,000 gallons of Ultimate Linings FR-263 fire-retardant polyurea.

Beyond core containment and fire safety, the material choice offered a major environmental benefit for the workforce. The polyurea system was custom-pigmented bright white. In a cavernous space of this magnitude, the white coating significantly increased light reflectivity, brightening the workspace and optimizing day-to-day operational visibility for the subterranean crews.

Extreme Subterranean Logistics and Application

Executing a six-month project a mile beneath the earth’s surface requires absolute logistical precision. Because environmental conditions deep underground remain completely stable, weather was not a factor; however, physical space constraints were severe.

Every piece of heavy machinery, including massive 120-foot boom lifts, had to be completely disassembled to fit inside the tight 5-foot by 14-foot mine elevator. Once lowered nearly a mile down, the machinery was meticulously reassembled by the crew. To keep multiple construction trades moving safely during daytime hours, the application teams worked exclusively on a night shift from 4:00 PM to 2:00 AM, six days a week. Mine personnel transported chemical totes to the project level during off-hours to ensure the raw materials were never exposed to freezing temperatures at the surface.

To handle the heavy fluid dynamics of the 5mm elastomeric barrier, the contractor deployed specialized high-pressure equipment. Two Graco Reactor HXP-3 units paired with 410 feet of heated hose were utilized to mix and spray the fast-curing polyurea, while a Graco King E-MAX XT unit handled the initial epoxy priming phase.

Safety rigging was extensive. While actively spraying, crew members wore 3M full-face respirators, full Tyvek spray suits, hard hats, and heavy-duty safety harnesses. Even when not spraying, anyone entering the cavern zone was required to wear high-visibility vests, long sleeves, a hard hat with an attached light, and a mandatory self-rescuer breathing apparatus.

North American Manufacturing Capabilities

A project of this scale cannot afford supply chain disruptions or batch inconsistency. Fermilab and Hartman Walsh selected Ultimate Linings not only for the advanced engineering of FR-263, but for the company’s robust domestic manufacturing footprint.

Operating out of a state-of-the-art 302,000-square-foot complex in Lebanon, Tennessee, Ultimate Linings houses its corporate offices, an advanced innovation center, and high-volume chemical manufacturing lines under one roof. To fulfill the massive volume requirements of the DUNE megastructure, the plant scaled up its production lines to ensure a continuous, uninterrupted material pipeline to the job site.

From its origins in 1989 as a dedicated provider of polyurea truck bedliners to its modern status as a global leader in protective industrial coatings, Ultimate Linings continues to advance the science of polyurea chemistry for the world’s most demanding infrastructure environments.

As Feautured in Spray Foam Magazine:

Read Article: https://www.sprayfoammagazine.com/foam-news/one-mile-below-earth/4714