McCabe Creek Culvert Replacement

Water resources

What began as a sewer pipe replacement became a full redesign of the culverts and channel at McCabe Creek. Roaring Fork Engineering provided hydrology, hydraulic design, and construction-phase engineering on a small, constrained site.

This project began as the replacement of a sewer pipe crossing beneath McCabe Creek. During design, Roaring Fork Engineering found that the pipe ran beneath two large culverts that also needed replacement, and our study showed both were severely undersized for appropriate flood flows. The scope expanded to include redesigning the culverts and the channel section, and protecting the new sewer pipe from erosion during floods.

Challenges & highlights

The site was small, flood magnitudes through the culverts were high, and the surrounding land was private property, which limited how much could be disturbed. Our team balanced total site disturbance against the need for greater flood resilience. Unmarked gas utilities and a sewer line in a different location than expected required field changes during construction.
The existing FEMA floodplain mapping and hydrology for the area dated to roughly the 1970s. We performed new hydrology work using modern methods to determine more realistic flood magnitudes for the site.

The results

The culverts were installed successfully, and the town was pleased with the outcome. To balance disturbance with resilience, the crossing was designed as a low-flow crossing, which allows floodwaters to pass over the roadway during extreme events without eroding or damaging the road. This approach is uncommon, and it was feasible here because the road is a public road with relatively low traffic.

Location: Pagosa Springs, CO

Project started as a sewer crossing replacement; design revealed two severely undersized culverts above the pipe
Scope expanded to culvert and channel redesign and erosion protection for the new sewer pipe
New hydrology replaced FEMA mapping and flow estimates from roughly the 1970s
Crossing was designed as a low-flow crossing so floodwaters pass over the road without damaging it
Unmarked gas utilities and a misplaced sewer line required field changes during construction
Culverts were installed successfully and the town was pleased with the outcome

Infrastructure that lasts

Whether you’re planning a new development, upgrading public infrastructure, or improving community systems, our team is ready to help bring your project from concept to completion.