Fairmont Hot Springs, BC sits at the base of two steep mountain creeks—Cold Spring Creek and Fairmont Creek—where intense rainfall can send refrigerator-sized rocks, soil, water, and logs rushing downhill with devastating speed and force. These creeks drop rapidly from rugged terrain, producing both debris floods (fast surges of water carrying sediment) and debris flows (concrete‑like slurries capable of pushing boulders through homes at speeds over 40 km/h). Between 2000 and 2020, residents endured repeated events that damaged property, closed highways, prompted evacuation alerts, and created a persistent sense of uncertainty.

In response to these risks, the Regional District of East Kootenay (RDEK) launched a project to design and construct a mitigation structure capable of protecting life and reducing economic losses. The solution needed to operate as a “system‑within‑a‑system,” addressing high‑magnitude debris flows and more frequent debris floods.

In 2025, McElhanney delivered an innovative mitigation solution designed to reduce these hazards. Working in close collaboration with BGC Engineering, Gygax Engineering Associates, and regulators, the multidisciplinary team advanced a project with no established Canadian design standards, regulatory framework, or recent precedent for debris‑flow mitigation at this scale. Drawing on international best practices and adapting them to BC’s terrain realities, the team developed a bespoke design and review approach accepted by provincial regulators.

The resulting roller compacted concrete (RCC) slot barrier—the largest for debris‑flow mitigation in Canada—works with a debris‑settling basin and creek diversion system to form an integrated, low‑maintenance mitigation suite. Together, these elements set a precedent for guidance and design criteria and marked a transformative moment for the community: a record‑setting, life‑saving piece of infrastructure that reduced debris‑related life‑safety risks to acceptable limits.

To meet RDEK’s objectives, McElhanney brought together a multidisciplinary team of geoscientists, and civil, hydrotechnical, and structural engineers, supported by BGC Engineering’s (BGC) geohazard and geotechnical specialists and Gygax Engineering Associate’s (GEA) structural expertise. Early hazard and risk investigations benchmarked Cold Spring Creek conditions against international standards and comparable BC communities. These investigations confirmed the scale of the threat and strengthened the case for investment, enabling successful grant applications that secured 98% of capital funding.

No provincial standards existed for this type of infrastructure, so the team developed new design criteria informed by global best practices from Europe, Hong Kong, and Japan and guided an independent review panel and provincial regulators through the framework.

Next, the team evaluated multiple mitigation options and selected the RCC slot barrier for its reliability, durability, fast construction, and cost‑efficiency. Hydrotechnical modelling and geotechnical analyses refined the design and validated its effectiveness against dynamic debris‑impact loads.

The approach integrated comprehensive permitting, including Water Sustainability Act licensing, Fisheries Act review, Indigenous engagement with Ktunaxa and Secwépemc Nations, and landowner approvals resulting in a collaborative, technically sound, and community‑centered design.

Delivered on budget and within grant funding and regulatory timelines, the Cold Spring Creek Debris Flow Mitigation project transformed a high‑risk community into one better prepared for intensifying climate‑driven storms. The durable RCC barrier and supporting works now protect residents, infrastructure, and essential services from debris floods and flows, providing long‑term safety and resilience for Fairmont Hot Springs.