What to know about hydropower cable installation in the Hudson River
July 17, 2024
Ben Foster, Legal Intern
If you spend time around the Hudson River this summer you may notice large vessels installing cables along the bottom of the river as part of the Champlain Hudson Power Express (CHPE) project.
Here’s what you need to know about the project:
What is the Champlain Hudson Power Express project?
CHPE is an approved energy transmission development designed to bring 1,250 MW of hydropower generated in Canada to New York City. Construction on the line began in late 2022, and is scheduled to continue until mid-2026, when it is expected to go live.
The project involves laying two five-inch-diameter cables underground or underwater along a 339-mile route stretching south from the U.S.-Canada border down through Lake Champlain (for 96 miles), the Hudson River (for 89 miles), and the Harlem River (for 6.3 miles). The line will end at a converter station currently being built in Astoria, Queens.
On June 20, 2024, the Public Service Commission approved CHPE’s environmental management and construction plan for the Hudson River cable installation segment of the project, officially paving the way for construction and cable installation work to begin in the Hudson River.
Riverkeeper’s Role
Riverkeeper has worked tirelessly to minimize CHPE’s impact on the Hudson River Estuary. We helped to establish an Environmental Trust Fund to offset potential environmental impacts, negotiated key changes to the project route to avoid PCB hotspots and the designated Significant Coastal Fish and Wildlife Habitat at Haverstraw Bay, and ensured the project includes appropriate construction windows and compliance studies. Riverkeeper will monitor construction to ensure it adheres to all relevant laws and regulations, and continue to advocate for the protection and preservation of the Hudson River and our communities.
Where will the cables be located in the Hudson River?
The transmission cables will be buried in two distinct sections, totaling approximately 89 miles:
- The first segment (~67.5 miles) begins in the Hamlet of Cementon, Town of Catskill, and ends in the Town of Stony Point.
- The second segment (~21.6 miles) begins in the Hamlet of Congers, Town of Clarkstown, and ends at the mouth of the Harlem River.
Importantly, in response to Riverkeeper’s advocacy, the transmission cables will temporarily exit the Hudson River in the Town of Stony Point to avoid the protected habitat area at Haverstraw Bay. Haverstraw Bay is a major spawning, nursery, and wintering area for various fish species, especially for the endangered shortnose and Atlantic sturgeon.
Hudson River Route Overview [2]
How will the cables be installed in the Hudson River?
Installing the cables in the Hudson River will happen in four stages over the next two years.
1. Pre-Lay Mattress Installation
Because there is lots of infrastructure already in the Hudson — such as electric, gas, and telecommunication lines — the CHPE project was required to install concrete pads, called mattresses, to protect these existing utilities. These four-feet thick concrete mattresses were installed over roughly 50 locations in the Hudson River between 2023 and 2024 to form barriers between the utility and CHPE lines.
Arrangement of Pre-lay Mattresses Over Existing Utility [3]
2. Pre-Lay Grapnel Runs (PLGR)
The second step of the project involves running a “grapnel,” a barbed hook, along the bottom of the river in order to remove surface and shallow buried debris, such as fishing lines or abandoned wire, that might otherwise obstruct the installation of the cables.
Grapnel runs will begin at Cementon and be performed along the entire route, except at the intersections between the cable lines and at public water intakes. This work is expected to be completed between August and September of 2024.
Grapnel Tools [4]
3. Cable Installation
After the grapnel phase, large cable-laying vessels will be used to install the cables in the Hudson River.
The Ariadne, the Primary Cable-Laying Vessel [5]
The cables will be buried under the riverbed in a single pass using a towed burial tool called a jet plow. The jet plow uses high-powered streams of water to carve a trench and simultaneously lay cable. The cables will be buried at least seven feet below the sediment as required by CHPE’s permits from the US Army Corps of Engineers issued in 2015.
Jet Plow Operation [6]
The cable installation work on the first section of the project (Cementon-Stony Point) is anticipated to begin in August 2024 and be completed in September 2024, with construction on the second section (Congers-Harlem River) running from September 2025 to October 2025.
4. Post-Installation Activities
Once the cable is laid, CHPE will perform any additional actions necessary to guarantee cables are properly buried and protected. These actions include using machines and divers to ensure cables are buried to the proper depth and installing additional concrete mattresses for protection where CHPE is unable to bury the cables to the required depth.
When can construction take place?
Construction in the Hudson River can only take place during specific times selected to minimize impacts to endangered and threatened species. CHPE can perform underwater construction only from July 1 to January 14, with additional restrictions in certain locations:
CHPE Project Timeline [7]
How will cable laying work affect recreational use of the Hudson River?
The cable laying process will not have a significant impact on recreational use of the Hudson River, but some portions of the project may present potential hazards to boaters.
Divers will be in the water at various stages of the project. To ensure diver safety, boaters should be alert for diver down flags, and must reduce speed and maintain a safe distance from vessels flying such flags.
Diver Down and International Code of Signals Alpha flags. Reduce speed and maintain a safe distance from vessels flying these flags.
Additionally, when possible boaters should maintain a 500-foot distance from the cable-laying vessel and reduce speed to minimize wake. When crossing the path of the vessel, boats should try to pass in front (on the south side) to limit the potential for any conflict with the cable line laid off the stern.
For a more complete discussion of Riverkeeper’s role and a timeline of key events, please see our campaign page.
For questions or concerns related to the cable installation, contact CHPE at publicoutreach@chpexpress.com or click here.
Riverkeeper protects and restores the Hudson River, and safeguards drinking water supplies through community partnerships, science, and law. Our core programs improve water quality, restore habitat for an abundance of life, and address the impact of climate change on our waterways. Founded in 1966 as the Hudson River Fishermen’s Association, Riverkeeper became the model for more than 320 Waterkeeper organizations around the world and helped establish globally-recognized standards for waterway and watershed protection. We continue to work toward the goal of a swimmable, fishable, and drinkable Hudson River for all. Learn more, get updates, and support our work by visiting https://www.riverkeeper.org.
1. TDI CHPExpress, Route Maps, chpexpress.com, https://chpexpress.com/project-overview/route-maps/ (last accessed July 8, 2024).2. CHPE Hudson River Marine Segment Cable Installation, Environmental Management and Construction Plan, Narrative (May 2024) https://chpexpress.com/wp-content/uploads/2024/04/Hudson-Cable-Install_Seg-19B_EMCP-Narrative-Revised-5.31.2024-REDACTED.pdf.3. CHPE Hudson River Marine Segment Cable Installation Environmental Management and Construction Plan, Appendix 6-A: Methodology Statement for Post-Lay and Remedial Mattress Placement, Figure 2 Indicative Arrangement of Pre-lay Mattresses Over Existing Utility (April 2024) https://chpexpress.com/wp-content/uploads/2024/04/Hudson-Cable-Install_Seg-19B-EMCP_App-6-A-Methods-for-Post-Lay-and-Remedial-Mattress-2.pdf.4. CHPE Hudson River Marine Segment Cable Installation, Environmental Management and Construction Plan, Appendix 5-A: Hudson River Cable Installation Methodology, Figure 7-1 Grapnel Tools Which are Planned to be Utilized (April 2024), https://chpexpress.com/wp-content/uploads/2024/04/Hudson-Cable-Install_Seg-19B-EMCP_App-5-A-Hudson-River-Cable-Installation-2.pdf.5. https://www.assogroup.com/asso-subsea-to-install-the-champlain-hudson-power-express-submarine-cable-system-in-the-hudson-river/6. CHPE Hudson River Marine Segment Cable Installation, Environmental Management and Construction Plan, Appendix 5-A: Hudson River Cable Installation Methodology, Figure 2 Simultaneous Lay and Burial Operation (April 2024), https://chpexpress.com/wp-content/uploads/2024/04/Hudson-Cable-Install_Seg-19B-EMCP_App-5-A-Hudson-River-Cable-Installation-2.pdf7. TDI CHPExpress, Construction Progress, chpexpress.com, https://chpexpress.com/construction-progress/ (last accessed July 8, 2024).
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