North Michigan Creek Dam Rehabilitation

Walden, Colo.


Submitted By: SEMA Construction Inc.

Owner: Colorado Parks and Wildlife

Lead Design Firm: Gannett Fleming

General Contractor: SEMA Construction Inc.

North Michigan Creek Reservoir and its surrounding facilities are among the main recreational attractions at State Forest State Park. The reservoir was formed in the mid-1960s with construction of a 65-ft-high earthen dam, which has experienced uncontrolled seepage at its right abutment for nearly 50 years. Despite multiple attempts to mitigate the problem with shallow drain lines and other measures, safety required a full rehabilitation of the dam.

The strategy called for installing a granular drainage blanket collection system, removal and replacement of a 275-ft-long concrete service spillway, reconstruction and rehabilitation of the outlet works system and installation of dam safety instrumentation. More than two dozen design innovations—including different approaches for construction of seepage collection embankment zones and earthwork material management and utilization—helped reduce cost, optimize constructibility and increase the dam’s life cycle and performance.

The team also was able to streamline what had been a multiphased approach into a single construction package that could be completed in a single season. That yielded savings so that the owner could increase the scope of rehabilitation, provide facility enhancements and fund safety improvements at other dams. Still, the process posed risks and challenges, including working at a remote site with limited services, a short construction season, high-altitude weather conditions and COVID-19 precautions.