Hydro project goes underground

A lot has changed in the four-plus years since Black Canyon Hydro, a hydropower development firm, began talks about a proposed power plant on the North Fork of the Snoqualmie River. Two things, though, Black Canyon’s intentions to pursue the project, and affected residents’ opposition to it, have stayed consistent.

A lot has changed in the four-plus years since Black Canyon Hydro, a hydropower development firm, began talks about a proposed power plant on the North Fork of the Snoqualmie River. Two things, though, Black Canyon’s intentions to pursue the project, and affected residents’ opposition to it, have stayed consistent.

A handful of residents, mostly from the Ernie’s Grove neighborhood, shared their concerns about the project at the July 13 Snoqualmie City Council meeting. Citing property rights and environmental concerns, they urged the city to use its influence to stop the project.

Concerns raised by citizens and local government have already changed the project.

Black Canyon’s initial proposal, for a 25-megawatt-capacity plant, included a seven-foot inflatable dam at the intake, a powerhouse 2.4 river miles downstream and a 150-foot tailrace to return water to the stream.

Chris Spens, a project engineer for Tollhouse Power, a holding company for the Black Canyon project, said that based on community feedback, both  in initial meetings in 2011 and subsequent communications, the project team revised their plans to make as much of the project as possible underground.

“I think the overwhelming sentiment from Ernie’s Grove is they want the least change possible, the least visual presence,” he said.

The current version of plans for the Black Canyon plant feature, instead of a dam, a “roughened channel,” or stone lip that will divert up to 900 cubic feet per second of water from the river to a fish-screened, 8-foot-diameter intake pipe that drops 450 feet to an underground powerhouse to produce electricity. Once through the powerhouse, the water, powered only by gravity, flows 8,600 feet and back into the river via the 200-foot, 12-foot-diameter tailrace, 1,000 feet upstream of the nearest house in Ernie’s Grove.

“All of that water standing in that vertical pipe is creating pressure, which provides the energy,” Spens said.

Snoqualmie’s water source

No other part of the system is pressurized Spens said, which is important since the project is near the Canyon Springs aquifer.

“Canyon Springs is one of the significant sources of water for the city,” said Russ Porter. “It’s a historical source. It’s a gravity system, there’s only chlorine treatment and it’s a very high quality, so it’s kind of your best and cheapest water.”

Porter, a water engineer with Gray and Osborne, was speaking to the Snoqualmie City Council at its July 13 meeting, to present his review of the recently published groundwater study conducted by Black Canyon.

The study was made to project the impact of the power plant construction and operation on Canyon Springs, Porter said, because “one of our biggest concerns was the hydrology of the groundwater at Canyon Springs was not real well known…. At the time we did this, we thought that perhaps the river recharged the aquifer in this area.”

The study suggested that Canyon Springs, among several area streams, drew water from a much larger area than they had projected, Porter said, adding, “The river may still have a contribution, but it’s probably not significant.”

Snoqualmie has three water sources, and although it uses only about 25 percent of the water it had rights to from Canyon Springs last year, Porter said he was going to recommend changes to increase the Canyon Springs draw, “because it’s the most cost effective.“

Porter noted that his review focused on groundwater impacts, and although the aquifer had a larger supply area than originally thought, the Black Canyon project could still have an effect on the water in Canyon Springs. The aquifer recharge area narrows in the same area that Black Canyon engineers are proposing to place the intake for the power plant, he said, and “there could be impact on water volume and quality.”

He recommended requesting additional geotechnical studies and downstream monitoring on the project, if it goes forward.

Protected river

Snoqualmie Watershed Coordinator Janne Kaje also had concerns about the project, which he said King County officials shared. Among them were environmental effects — because of its short distance, the project would not trigger a minimum in-stream flow requirement, and the protected status of that reach of the river.

Although it’s not a Wild and Scenic River, the North Fork has been designated a protected area by the  Northwest Power and Conservation Council “since the 1980s because of its outstanding fish and wildlife value…” Kaje said.

Protected status doesn’t mean that hydropower projects can’t be implemented there, he said, but it does mean the Federal Energy Regulatory Commission (FERC) has to give strong consideration to the impact of those projects.

“The definition of a protected area means that putting hydro there would create impacts that can’t be mitigated,” Kaje said. “It’s such an outstanding resource in the area, that the impacts can’t be mitigated.”

Regarding the question of in-stream flows, Spens said the project would take only excess water from the river, and “there wouldn’t likely be any operation from about mid-July to about mid-September, due to natural low flows.”

To residents concerned about the possibility that his company might exercise eminent domain for some property acquisition as well as temporary and permanent access rights across several properties, he said he understood their concerns, and “We as a company have never used (eminent domain) before, and we’ve never had to use it…. it’s not something that we want to do.”

Comments are still being accepted on the groundwater report, through Aug. 9.

After the comments are received, FERC will determine if all of the investigation is complete.

Spens said that Black Canyon next plans to hold meetings with various property owners, and hopes to submit a draft license application by Dec. 1 of this year.

That application would undergo a 90-day review, and Spens estimated that the company would take two to three months to process the information from the review, before submitting the final license application in June or July of 2016.

For more information, or to submit comments, visit www.ferc.gov and search for Black Canyon Hydro, or project number: 14110.