CS23B - Concurrent Session 23B: North Michigan Creek Dam: Breathing Life into Aging Infrastructure Through Alternative Project Delivery

Since 2016, North Michigan Creek Dam (NMCD) had been operated under a storage restriction due to unfiltered seepage emanating on the right abutment. This presentation includes a case study documenting the lessons learned while both exploring alternatives to address dam deficiencies, and implementing a new Alternative Project Delivery Method called Construction Manager/General Contractor (CM/GC). Among the project risks included a remote location, high altitude, challenging site conditions, and a spillway that activated each spring.

The CM/GC Method was utilized to balance cost with overall Risk reduction of the facility. In addition, through the use of early contractor involvement afforded by the CM/GC Method, the owner was able to minimize construction risk for itself and the construction contractor. The CM/GC Method included the development of an Integrated Project Team (IPT) comprised of the owner, design engineer, contractor, independent cost estimator, and state dam safety regulator. Each entity in the IPT worked together in its respective role to execute a successful delivery that was both on time and under budget.

The construction completed in 2022, and was a FIRST for Colorado Department of Natural Resources delivered through the CM/GC Method. The project also received ENR’s 2022 Water/Environment Project of the Year Award for the Mountain States Region. The project removed the existing concrete spillway, non-functioning seepage system, and the low level intake structure, and replaced these features with structural improvements designed to meet current dam safety standards and state-of-practice. A filtered chimney drain was designed and installed using an “innovation” that was proposed during the CM/GC predesign phase to save time and cost, and to minimize construction risk. The filtered seepage collection system continued under the newly installed concrete chute spillway. The existing low-level CMP outlet was lined with a cured-in-place pipe, and included the installation of a filter diaphragm through trenching to limit the required excavation. The project also included a new intake structure and concrete grade beam to protect against the site’s heavy ice loading. Reservoir instrumentation provides an early warning system. The CM/GC Method is estimated to have saved one year and approximately $2.5 million.

NMCD is a 53-ft-high earth embankment dam located at elevation 8933 feet. It has a normal storage capacity of 1,267 acre-feet. NMCD is owned and operated by Colorado Division of Parks and Wildlife for recreational use and fishing. The dam is located in State Forest State Park along the Medicine Bow Mountains in Colorado.