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Overview


Proposed Route

Underground in an existing corridor, underwater to Boston 

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Overview


Proposed Route

Underground in an existing corridor, underwater to Boston 

Detailed route information

The Maine Power Express is a proposed 315 mile, 1000MW HVDC transmission line, comprised of two 5" cables that will be 100% buried in an existing energy corridor and underwater from Searsport, Maine to Boston, Massachusetts. Details below include:

  • The Origination point (northern AC to DC Converter Station) site in Haynesville, Maine
  • The 115 mile terrestrial portion, located within the existing Searsport-Loring Corridor ("SL-ROW")
  • The Searsport Land-to-Sea transition point at the Mack Point Marine Intermodal Cargo Terminal
  • The 200 mile subsea route from Searsport to Boston
  • The route within Boston Harbor
  • The southern DC to AC Converter Station at the Massport Conley Terminal
  • The K Street Substation interconnection point with ISO-NE

Landowners abutting the SL-ROW can contact the Maine Power Express development team at info@mainepx.com or by calling (207) 762-5000.

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Haynesville


Northern DC Converter

Haynesville, Maine

Haynesville


Northern DC Converter

Haynesville, Maine

Northern DC Converter - Haynesville, ME

Northern DC Converter Site Options - Click on image to expand.

The Maine Power Express Development Team has secured an Option on one of two sites in the southern Aroostook County town of Haynesville for the location of the northern DC Converter. This is the area where the existing 345kV "MEPCO" line runs parallel to the existing Searsport-Loring Corridor ("SL-ROW"), in which MPX holds the rights to install new transmission facilities. The SL-ROW is situated between the MEPCO and Route 2A. Recently, SunEdison constructed the 115kV Oakfield Generator Lead to deliver power from the 148MW Oakfield Wind Farm to a substation in Chester, ME. In addition, EDP Renewables ("EDPR") has proposed a 345kV Generator Lead from their proposed 250MW "Number Nine" Wind Farm to a new substation in Haynesville, interconnecting with the MEPCO. EDPR intends to utilize the existing "Bridal Path" right-of-way, owned collectively by Emera Maine and Central Maine Power, for their transmission generator lead. The bridal path is currently undeveloped and there are other proposals which intend to use it for other purposes. 

This is a very efficient location for a DC Converter and collection point for new wind resources. The existing "Bridal Path" and the existing SunEdison right-of-way provide a convenient path to reach the northern MPX DC Converter. And proximity to the MEPCO provides the opportunity to import Canadian wind and hydro resources over the existing 345kV transmission line which holds 1000MWs of transfer capacity. Furthermore, the ample acreage, and non-producing farm land surrounding the area presents an opportunity for large-scale solar installations. 

MPX worked with the Maine-based James W. Sewall Company to identify and work with landowners to secure an option in this area. In addition, MPX worked with TRC and ISO-NE on the interconnection with Canada via the MEPCO line. 

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SLROW


Underground Transmission

Utilizing an existing energy infrastructure corridor

SLROW


Underground Transmission

Utilizing an existing energy infrastructure corridor

Searsport-Loring Corridor

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The Maine Power Express will be buried in 115 miles of the existing 200 mile long, 50 foot wide, Searsport-Loring Corridor ("SL-ROW"). The SL-ROW is a continuous easement corridor, or "right-of-way", that was first created by the U.S. Air Force in the 1950's for the installation of a 6" pipeline to deliver jet fuel from Searsport to the Bangor International Airport and the former Loring Air Force Base.

Currently, Bangor Gas is using the existing pipeline for natural gas distribution in the Bangor-to-Lincoln area, with plans to expand south to Searsport.

The SL-ROW has been partitioned into five lanes for the potential installation of a new natural gas pipeline in Lane 1 and/or construction lay down, and the Maine Power Express HVDC transmission lines in Lanes 4 & 5. 

Lanes: 1) Construction lay down area 2) Existing 6" pipeline 3) LDA non-energy use 4) 1000MW HVDC Transmission Line 5) 1000MW Transmission Line Expansion

Lanes: 1) Construction lay down area 2) Existing 6" pipeline 3) LDA non-energy use 4) 1000MW HVDC Transmission Line 5) 1000MW Transmission Line Expansion

The SL-ROW is exempt from the Maine Interagency Review Panel. It is located in Aroostook, Penobscot and Waldo counties and runs alongside route 116, 2, 2A, 1 and 1A, which provide convenient access to the corridor for construction and maintenance. 

For the terrestrial portion of the route, the transmission lines will be buried underground.  A trench approximately 4 to 5 feet deep will be installed and low thermal resistivity material will be placed at the bottom.  The two cables will typically be laid side-by-side within the trench and covered in an additional layer of low thermal resistivity material.  A protective cover of HDPE, concrete, or polymer blocks will be placed directly above the low thermal resistive backfill material.  A marker tape will then be placed 2 to 3 feet (0.6 to 0.9 meters) above the cables and soils backfilled in order to restore topography. For more on the construction of the project, see Technology and Construction

Below is a collection of images that illustrate the route from North to South for the Maine Power Express buried transmission line. 

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Searsport


Searsport, Maine

Mack Point Marine Intermodal Cargo Terminal, land-to-sea transition point

Searsport


Searsport, Maine

Mack Point Marine Intermodal Cargo Terminal, land-to-sea transition point

Subsea Route

From Searsport, the Maine Power Express will enter the ocean waters of Penobscot Bay. A state-of-the art marine vessel, built especially for laying and protecting submarine cables, will be utilized during the submarine cable installation. The cables will be laid from the vessel onto the seafloor and are subsequently buried for protection utilizing either water-jetting (jet plow) or ploughing techniques. Water-jetting techniques will be utilized wherever feasible (i.e., soft sand seafloor), otherwise ploughing techniques will be required. The jet plow uses jets of pressurized sea water from water pump systems on board the cable vessel to fluidize seafloor sediments, creating a narrow trench within which the cable system can be laid. The cables settle via gravity into the trenches then the fluidized sediments quickly settle around the cable after the plow has passed. The seafloor naturally returns to pre-construction contours.

The proposed submarine cables will be buried beneath the seafloor for protection against mechanical damage from, but not limited to, fishing gear and ship anchors. Burial depths may vary along the cable route based on conditions or existing infrastructure that are identified. Where existing conditions do not permit burial (e.g. bedrock, infrastructure), the cables will have a protective cover (e.g. concrete mattresses, rip rap, grout mattress) or other protective armoring.  Where the MPX Project crosses existing infrastructure, it is anticipated the submarine cable will be laid atop the existing infrastructure and covered for protection.

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Searoute


Subsea Route

200 miles, Searsport to Boston

Searoute


Subsea Route

200 miles, Searsport to Boston

Detailed Route Maps

Installation techniques include Hydraulic Directional Drilling, jet burial and laying the cable on the seabed where approved. The path out of Penobscot Bay is under study and will take into consideration existing cable crossings, shipping channels, fisheries, sensitive areas, shipwrecks, and will be coordinated with the harbor masters and the Army Corps of Engineers. Below is a collection of preliminary maps illustrating the subsea route from Searsport to Boston. This route will be coordinated with all necessary state and federal regulatory agencies, lobstering associations and other key stakeholders. 

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Massport


Southern DC Converter

Massport Conley Terminal, Boston, Massachusetts

Massport


Southern DC Converter

Massport Conley Terminal, Boston, Massachusetts

southern dc converter station - massport

The southern DC Converter Station for the Maine Power Express will be located at the Massport Conley Terminal in Boston, MA. Massport and MPX have a Letter of Intent for a 5.5 acre site, less than one mile from the K Street Substation Interconnection Point. 

From the 5.5 acre DC Converter Site, MPX will employ HDD to install a 345kV AC line underground to the K Street Substation. MPX holds ISO-NE queue position #506 with details available here. The System Impact Study is fully funded and currently underway. 

Maine Power Express

  • Diverse Clean Energy Resources
  • 115 Miles underground
  • 200 Miles underwater
  • Delivering to the heart of the load center