R&M Through the Years: Hydroelectric Project Feasibility and Development Studies

April 25, 2019

In celebration of R&M’s 50th anniversary, we are taking a look back at the projects over the last five decades that made R&M into the firm it is today. This month we take a look at a couple hydroelectric projects in which R&M helped determine the engineering and economic feasibility of hydroelectric development during the 1980s.

The hydroelectric facility at Bradley Lake.

Alaska has enjoyed a long and rich history with hydroelectric power. High energy costs, abundant resources and a strong standard for renewable generation have led to an abundance of hydroelectric facilities in the state. There are nearly 50 operating utility-scale hydroelectric projects throughout Alaska, many of which were developed in the early 1900s. These facilities produce about 21% of the State’s electrical energy in a year, versus about 10% in the Lower 48, and are, by far, the largest source of renewable energy in Alaska.

R&M has been involved in several of these efforts to develop new hydroelectric facilities. This includes the Bradley Lake and Susitna River Hydroelectric Projects, in which R&M conducted numerous studies to determine the feasibility of developing facilities at these locations during the 1980s.

Bradley Lake Hydroelectric Project

Map of the proposed locations for the various facilities at Bradley Lake.

Bradley Lake has long been recognized as having significant potential to provide hydroelectric power to the Kenai Peninsula and along the railbelt. A project to develop a hydroelectric facility at the lake was originally authorized by Congress in 1962 but, due to lack of funding, did not move forward until the Alaska Energy Authority (AEA) assumed responsibility for the project in 1982. The project ramped up at that point, with preliminary plans and field investigations starting that same year.

R&M was heavily involved with the development of the Bradley Lake Hydroelectric Project, providing geotechnical investigations, surveying and civil engineering design of ancillary features. Project components included an access road, construction camp, airstrip, barge access facility, materials sites and the dam facility, which consisted of a concrete-faced, 170’ high rockfill dam with a 19,000’-long power tunnel conducting water to an above-ground powerhouse.

Today, the facility at Bradley Lake is the largest hydroelectric facility in Alaska and provides 5-10% of the annual railbelt electric power needs.

R&M continues to provide support to AEA to maintain the project in compliance with Federal Energy Regulatory Commission requirements regarding dam safety and performance monitoring. This includes periodic inspection of the Dam and Diversion facilities for operation and performance, and engineering design/supervision of remedial repairs and maintenance for water diversions and control facilities, power tunnel and diversion tunnel gate testing, and visual inspection of the main dam and spillway structures.

Susitna Hydroelectric Project

Susitna River

The Susitna River was another area identified early on as having significant potential for a high producing hydroelectric facility. Feasibility and engineering studies to develop a facility on a remote section of the river, upstream of Devils Canyon, as an alternative energy source for the railbelt region of Alaska commenced in the 1980s. As part of this effort, R&M provide surveying and mapping, right-of-way (ROW), hydrologic, geologic, geotechnical and preliminary civil design services for airstrip location, access road and feasibility studies.

Due to the remoteness of the proposed dam site, an airstrip was needed to serve the resupply and emergency needs of the base camp supporting the field studies and feasibility analysis. R&M was involved in determining the best location for this remote airstrip, providing data gathering, siting, construction costing, feasibility analysis and preliminary design. Unique aspects included gathering weather data and forecasting, assuring FAA compliance for air carrier airfields and locating the airstrip as close to the base camp as possible.

Access Route Alternatives

A transportation corridor was also needed to provide access to the area for construction of the proposed dam and other necessary facilities. R&M researched and documented the ROW status of the potential corridor route and facilitated ROW acquisition for the access corridor. The firm also studied possible road or rail alignments, identifying three major transportation corridors with several alternatives.

Other studies and tasks conducted by R&M included terrain mapping, various surveys, regional flood frequency, hydrologic studies, hydraulic modeling, borehole instrumentation monitoring, aquatic habitat assessment, glacial lake temperature and sediment studies, meteorologic data collection, and ice studies.

Because of the environmental and social concerns associated with this project, special care had to be taken to make the project as compatible as possible with the environment and with the needs of the people affected.

The project is currently on hold as Governor Bill Walker vetoed the construction of the dam in 2016 for environmental and economic reasons.

A Strong Future for Hydroelectric Projects

With more than more than 365,000 miles of rivers and 33,000 miles of coastline, there are abundant locations available to support hydroelectric facilities. The need for low cost power and fuel in many areas of the state is also a driving factor in developing clean, reliable energy. For these reasons, hydroelectric power is an ideal renewable energy resource for Alaska and development of hydroelectric facilities will continue to be a focus throughout the State for many years to come.

Next month, we will take a look at the details of a new water transmission line in Anchorage designed by R&M during this same decade.