The US City of Aspen has applied for a ‘conduit exemption’ to the Federal Energy Regulatory Commission (FERC) which, if approved, would allow the city to develop the planned Castle Creek hydroelectric project without a licence as the scheme could use existing infrastructure.

Aspen City Council voted last spring to move forward with the construction of a pipeline that will allow for safe drainage of Thomas Reservoir above the Castle Creek Valley. By delivering water from the reservoir via the pipeline, or conduit, to the Castle Creek hydroelectric plant, the City can take advantage of water for hydropower generation while providing needed flood protection to properties downhill of the Thomas Reservoir.

“We know to the public this looked like putting the cart before the horse… building a pipeline before having FERC approval,” said Phil Overeynder, director of utilities and environmental initiatives. “However, even if FERC doesn’t approve the hydro project, we need this pipeline for safety purposes alone, while being optimistic that it will serve dual purposes if and when FERC does approve a hydro use.”

A 2007 vote by Aspen citizens overwhelmingly supported the Castle Creek hydroelectric project, with more than 70% of the public voting for it.

“The City has been working with consultants on the hydro project ever since the 2007 voter approval,” Overeynder said. “During their work, the consultants discovered the need for a pipeline to safely drain Thomas Reservoir, citing changes in engineering practices and safety measures from when the reservoir was built in the 1960s.”

The consultants also recommended that because of the need to create a conduit to safely drain the reservoir, the City could be eligible for a conduit exemption for the hydro project based on federal laws and regulations.

A conduit exemption can be a more expeditious, less expensive way to bring a hydro project online than a new hydro license application with FERC. The environmental requirements are stringent for a conduit exemption. Although an environmental impact statement (EIS) or environmental assessment (EA) may not be required, the same topics are included in exemption review as are required for analysis under an EIS or EA.

As part of the FERC application, Aspen has consulted with the Colorado Division of Wildlife on the hydro project since July of 2008 and has received input from the public and interested parties such as Trout Unlimited, the Roaring Fork Conservancy, Wilderness Workshop, and the U.S. Forest Service.