Cascade Renewable Transmission project introduced to FSEC; applicants outline 100-mile underwater line and environmental safeguards

Chris Hocker, a member of the Cascade Renewable Transmission (CRT) project team, presented the project Thursday night to the Energy Facility Site Evaluation Council, describing “about a 100 mile high voltage transmission line, of which a little more than 80 miles will be under the bed of the Columbia River” and about 19 miles buried on land. He said the system would transmit roughly “1,100 megawatts of energy.”

The project team described technical approaches intended to limit impacts. Hocker said river entry and exit would use horizontal directional drilling (HDD) so the cable is brought underground rather than by open trench. The marine installation would employ a barge and a jet or hydro plow to form a narrow (about 2-foot-wide) trench in sediment, lay the cable bundle, and allow most sediment to resettle. He said typical burial depth would be “10 to 15 feet below the sediment.”

The presentation placed the project in regional context: Hocker and the applicant argued the line would relieve growing east–west and north–south transmission bottlenecks, help Washington and Oregon reach clean-energy mandates and improve grid resiliency. The applicant also highlighted prior marine projects operated by its partners, noting the firm’s lines “have been operating very well” for years and citing experience with New York–New Jersey and San Francisco installations.

Council members pressed the team on specific risks. Blake Nelson asked whether the sample cable included casing; the applicant confirmed the sample “is the casing,” said the conductor core is copper, there are metal shields, and an outer synthetic protective skin. Nate Pamplin asked how the 1,100 MW sizing was chosen; the applicant said sizing is a tradeoff of available technology and economics and that doubling capacity would require additional, separately installed cables.

Members of the public asked about operations and environmental risk. Ken Benningfield asked how much maintenance the San Francisco line required; the applicant said, aside from rare anchor strikes, the submerged lines have not required maintenance and that most maintenance occurs at converter stations. Clark County staffer Brian Mattson asked what would happen if an anchor strike exposed the cable; Hocker said the system is buried deeply, anchor strikes are rare, and that damage is repaired by splicing replacement cable and that operations would shut down “in a fraction of a second” to prevent electrical hazards to wildlife.

On thermal effects and contaminants, the applicant said it modeled thermal dissipation and that heat dissipates through sediment so there is “no change” to the overlying water column at scale. Regarding disturbed contaminants such as PCBs and mercury, the team said routing avoided “surface contamination” and that sediment-transport modeling indicates little downstream transport; they said limited sampling around Bonneville did not find contaminants at the sampled locations.

The applicants said construction would take roughly 36–42 months, in-river work would be scheduled seasonally to avoid fisheries impacts, and that permitting will involve multiple state and federal agencies, including the U.S. Army Corps of Engineers. Hocker said the team expects to file the application in the fourth quarter of this year and emphasized multi-agency coordination and tribal outreach.

What happens next: the CRT team will continue multiagency review, additional technical studies and public outreach; council staff and the applicant will post application materials and supporting studies to the FSEC project page, and public comment remains open through the online comment portal for the posted window.