Wildfire-Hardening an Emergency MSE Retaining Wall on US 101 near Cook Valley

Winter storms took out part of US 101 near Cook Valley. After the Department of Transportation rebuilt the slope with a 14-foot-tall, 2,500-square-foot retaining wall, NanoTech coated its timber facing with Wildfire Shield, so a future fire would not undo the repair.

In early 2023, heavy winter storms saturated the slopes above the South Fork Eel River. A major slip out collapsed parts of the southbound lanes of U.S. 101 near Cook Valley. To keep traffic moving, the Department of Transportation set up one-way traffic control with round-the-clock monitoring while geotechnical drilling and soil-nail stabilization were mobilized on site.

As part of the emergency response, the Department of Transportation let an expedited contract for a permanent fix. It included a 14-foot-tall, 2,500-square-foot welded-wire MSE retaining wall. Cesaretti designed it, Granite Construction built it, and it went in next to the failure area to stabilize the slope and restore long-term roadway support. NanoTech then coated the wall's timber facing with Wildfire Shield to protect the new structure against the corridor's wildfire risk.

Project at a glance

An emergency repair in a fire-prone canyon

The slip out took out lanes of a critical north-coast highway. The Department of Transportation stabilized the slope and rebuilt with a welded-wire MSE wall faced in timber lagging. The South Fork Eel River canyon is remote, heavily forested and wildfire-prone, so a freshly rebuilt emergency structure faced in combustible timber needed protection, or a future fire could undo the work.

Two hazards in the same corridor

This stretch of canyon carries two threats at once: storm-saturated slopes that slide, and wildfire. Hardening the timber facing with a passive coating answered the second hazard right after the first one was handled.

Why the timber facing needed protection, and how the coating works

Timber lagging on an MSE wall is exposed, combustible and structurally relevant. Under radiant heat and flame it ignites and chars, and intumescent coatings only react once heating starts, which can be too late to stop ignition.

A passive barrier that needs no activation energy

Wildfire Shield is non-sacrificial and works from the moment it cures. Its patented ICP technology pairs high emissivity, high reflectivity and low thermal conductivity to reflect and re-radiate heat and slow its path into the wood, forming a high-temperature thermal barrier with no flame spread and no smoke development (ASTM E84 Class A, 0/0).

In testing witnessed by Department of Transportation personnel, coated timber lagging was held under a direct propane-torch flame for 20 minutes while the thermocouples behind the coating stayed near ambient.

Wildfire Shield applied to the new wall's timber facing

NanoTech-guided applicators coated roughly 2,500 square feet of timber facing across the 14-foot-tall wall. They cleaned and moisture-checked the substrate, then built Wildfire Shield up in passes to the specified dry-film thickness, following the lagging across the full height of the wall.

What the coating system delivered

• Class A fire protection on the wall's exposed timber facing (ASTM E84, 0/0)

• Passive, non-sacrificial protection with no activation energy

• Resilience added to a critical emergency repair on US 101

• Protection built to last across repeated fire events when maintained

• A water-based coating suited to a sensitive river canyon

• Backed by NanoTech's 10-year material warranty

Two hazards, one corridor.

The remote canyon that produced the storm-driven slope failure on US 101 is also wildfire-prone, which made passive fire protection a natural complement to the emergency slope repair.

An emergency repair, now fire-hardened

The rebuilt 14-foot wall came away with its timber facing under Class A passive fire coating. That protects the investment in the emergency slope repair and keeps a key north-coast highway link resilient against the corridor's wildfire risk.

What this means for your team

The same outcome reads differently depending on your role. Here is what this project means for the people who own, specify and apply fire-protection coatings.

For DOT structural & fire-protection engineers

Wildfire Shield gives specifiers a documented, independently tested alternative to defaulting to concrete for fire-exposed wooden infrastructure. It is verified to ASTM E84 (Class A, 0/0), plus E119, E162 and E662, and it came through a 20-minute direct flame-impingement test on timber lagging witnessed by Department of Transportation personnel. That is the kind of evidence it takes to qualify a non-traditional material with confidence.

For DOT district managers & budget authorities

Coating in place, or shop-applying off-site, preserves existing timber lagging instead of replacing it with costlier concrete or steel. Wildfire Shield is non-sacrificial and is built to protect the structure across repeated fire events when the system is maintained, so it stretches mitigation budgets across more lane-miles while keeping crews and traffic moving.

For bridge & highway contractors / applicators

Wildfire Shield is sprayed or rolled with common equipment and conforms to the geometry of timber lagging, abutments and fences, with no jacketing or fabrication required. On-site or off-site shop application removes seasonal and just-in-time bottlenecks, and NanoTech's certified-applicator training and supervision keep DOT-specified work on schedule.

Wildfire Shield technical specifications

Wildfire Shield is a water-based, non-sacrificial fire-mitigation coating built on NanoTech's patented Insulative Ceramic Particle (ICP) technology. Key published properties are summarized below; confirm project specifics against the current Technical Data Sheet and SDS.

Frequently asked questions

Can Wildfire Shield be applied to timber on an MSE or welded-wire wall?

Yes. The coating follows and protects the timber-lagging facing no matter what structural wall system sits behind it, including welded-wire MSE walls.

How is Wildfire Shield different from intumescent fireproofing?

Intumescent coatings have to be triggered by fire. They char and swell only after the substrate begins to heat, so the wood can ignite before the coating activates, and the char can give off smoke and toxicity. Wildfire Shield is non-sacrificial and works the moment it is applied. Its mix of high emissivity, high reflectivity and low thermal conductivity reflects and re-radiates heat and slows the heat that reaches the wood, with no flame spread and no smoke development (ASTM E84 Class A, 0/0).

Can the coating survive more than one fire?

Yes. Because it is non-sacrificial, Wildfire Shield is designed to protect the underlying structure through repeated wildfire events when the coating system is inspected and maintained. NanoTech recommends yearly inspections for wear, cracking or damage, and worn areas can be touched up by overcoating rather than fully replaced.

How hot can Wildfire Shield withstand?

It withstands direct flame exposure up to 3,272°F (1,800°C). In testing witnessed by Department of Transportation personnel, coated timber lagging was held under a direct propane-torch flame for 20 minutes while the thermocouples behind the coating stayed near ambient.

Is it safe and environmentally responsible?

Wildfire Shield is water-based and non-toxic, with no reportable VOCs and no toxic runoff or leaching, and it is not classified as hazardous for supply or use. It cleans up with water and suits sensitive settings such as national parks and the wildland-urban interface.

Related resources

From NanoTech Materials

• Wildfire Shield product page

• Fire Protective Coating System overview

• Wildfire mitigation applications

• Industries we serve

• Resource library and case studies

• Request a quote or join the certified-applicator network

External references

• CAL FIRE (California Department of Forestry and Fire Protection)

• ASTM International fire-test standards

Talk to NanoTech about wildfire protection

Protecting timber lagging, bridges, utility poles, fences or homes in a wildfire-prone area? Talk to NanoTech about Wildfire Shield, or join our certified-applicator network. Call (888) 296-6266, email [email protected], or visit our contact page.

About NanoTech Materials. NanoTech Materials is a Houston-based materials-science company developing advanced coatings for energy efficiency and fire protection. Its Fire Protective Coating System, including Wildfire Shield, is built on patented Insulative Ceramic Particle (ICP) technology to protect critical wooden infrastructure and high-value assets from wildfire, buying time and saving lives.

_{© 2026 NanoTech Materials. All rights reserved. Performance data summarized from NanoTech technical documentation (TDS, SDS, Application & Technical Manual) and the Wildfire Shield Project Portfolio; confirm project-specific details and current published values with a NanoTech representative.}