Upper Ingram Gulch

Project Information

Upper Ingram Gulch Channel Restoration

Fourmile Watershed Coalition
Gold Run, Boulder County, CO – 2020

Project Owner

Fourmile Watershed Coalition

Project Amount

$749,896

Project Date

January 2020 – April 2021

Project References

Maya MacHamer
Watershed Coordinator

Fourmile Watershed Coalition
1740 Fourmile Canyon Drive
Boulder, CO 80302

303.817.2261

fourmilewatershed@gmail.com

Paul Kos, PE
Project Engineer

Stantec
2000 South Colorado Blvd Suite 2-300
Denver, CO 80222

303.570.9163

paul.kos@stantec.com

About the Project

The Ingram Gulch drainage consists of approximately 286 acres of land, of which approximately 270 acres were severely disturbed by wildfire in 2010. Following the fire, severe flooding and debris flows occurred in both 2011 and 2013 which significantly affected the Ingram Gulch channel and the downstream drainage Gold Run Creek causing significant damage to homes and infrastructure. The key feature of the stream channel is the steep gradient, which is typically greater than 10%. Sinuosity is essentially non-existent. Erosion of the channel side slopes has undercut the valley walls which are unstable regardless of the flow conditions. The unstable slopes continue to erode, and sediment transport is enhanced during high flows. Vegetation is minimal along the riparian corridor. Fire and flood impacts have exposed and destabilized legacy mine waste piles throughout the watershed. Fine sediment and waste rock are continually mobilized into downstream waterways. Soil samples from the piles include elevated levels of arsenic, zinc and chromium among others and can contribute to water quality impairments. Frontier was contracted to excavate and haul 2,000 CY of mine waste to areas outside of the drainage and cover, cap, and revegetate the waste piles. After the mine waste was removed, a step-pool steep mountain bedform channel was constructed utilizing engineered bedding and boulders. Boulder toe walls with willow stakes were installed at the toe of unstable slopes. Upland slopes were stabilized through grading, topsoil addition, coir mat, seeding and installation of 5,000 plantings to minimize erosion under a wider range of conditions and promoting the regrowth of vegetation so that Ingram gulch is more resilient under high flow conditions.