N.J. Utility Turns Switch On Billion-Dollar Rewire
For years, electrical transmission constraints in the crowded corridors of northern New Jersey were obvious. One indicator was that capacity prices in the region—what is paid to insure electric generation is available when needed—were consistently among the highest in the PJM Interconnection, the organization that runs the wholesale power grid for the state and all or part of 12 others.
The fix would seem to be simple: upgrade the transmission lines. But nothing is simple when working with live electricity and when the job runs right through one of the most densely populated regions on the Eastern Seaboard.
The service territory of utility Public Service Electric & Gas (PSE&G) runs in a north-south axis right through that densely populated part of the state, from the New York-New Jersey border along the Hudson River counties and across to the Delaware River, the Pennsylvania border and the municipalities of Trenton and Philadelphia.
PJM assigned construction responsibility for the first phase of the Bergen-Linden transmission corridor upgrade project to PSE&G in late 2013. The $1.2-billion project calls for replacing existing 138-kV transmission lines with 345-kV lines in a corridor that extends about 22 miles from Ridgefield in Bergen County just south of the George Washington Bridge to Bayonne, then under Newark Bay into the city of Elizabeth south of Newark Liberty International Airport and south again to Linden.
The project includes 20 circuit miles of 345-kV double circuit overhead conductor to replace existing 138-kV double circuit overhead cables. Underground, the project calls for 20.5 circuit miles of new 345-kV conductor and 6.2 circuit miles of reconductored cable. Circuit miles are equal to geographic miles or pole miles. For double circuit transmission lines, such as these, the number of circuit miles is twice the pole or geographic miles.
The project skirts marshland, crosses rivers, highways, bridges and a bay. It goes through seven municipalities in Bergen, Hudson, Essex, and Union counties, including Ridgefield, North Bergen, Jersey City, Bayonne, Newark, Elizabeth and Linden.
In the end, the project will increase the transmission capacity in the region as mandated by PJM and improve power quality by enhancing system redundancy and hardening assets, says Chuck Tkachuk, PSE&G project director. He says the 138-kV lines being replaced were installed in the 1920s.
The first step in tackling the project— and perhaps the most complicated—was the planning stage, begun “two or more years in advance of construction,” says Albert Cretella of Burns & McDonnell, PSE&G’s program manager for the project.
The schedule was driven by PJM’s determination of when and where reliability issues are expected to occur on the transmission system. PSE&G’s planning department and energy system operation center then worked with PJM to assess how issues could be addressed within the time frames needed to procure equipment and materials.
The project calls for the installation of 45 transformers; each can take up to one year to deliver. To avoid bottlenecks and spread out the fulfillment risk, PSE&G ordered transformers from several different sources, including manufacturers in Europe, Mexico and South Korea.
Another important aspect of project planning is permitting. Permits are required from an alphabet soup of public-sector regulators. Federal agencies include the U.S. Environmental Protection Agency, Federal Aviation Administration, U.S. Army Corps of Engineers, Coast Guard, U.S. Fish & Wildlife Service and Amtrak. Within New Jersey, state transportation and environmental protection agencies must clear the project, as well as the N.J. Sports and Exposition Authority and N.J. Transit. At the local level, permits had to be secured from a host of county and municipal boards and departments. To date, the project has received more than 300 permits, and PSE&G anticipates 100 more will be needed.
In addition to managing the large amount of information needed for the project, other challenges include determining the construction sequence at each of the switching stations to safely remove the old equipment and replace it with new equipment while keeping the lights on for PSE&G customers. PSE&G and PJM agreed that a three-phased approach would best address the issues and allow adequate time for equipment procurement and construction.
The first phase encompasses the northernmost section of the project from the Bergen to the Marion stations in Ridgewood and Jersey City. It calls for installation of 345-kV overhead lines in the Hudson-Bergen/Marion-Bergen 230-kV and 138-kV corridors and upgrade of the Bergen, North Bergen, Homestead, Penhorn and Marion stations. Phase 1 construction started in mid-2014 and is to be completed in June.
The second phase calls for conversion to 345 kV of overhead lines from the Bayway station southeast of Elizabeth to the Linden station. Construction on that section has not begun. The anticipated in-service date is June 2017.
The third and final phase will complete the project by connecting work on the first phase from Marion south to the Bayway station. Activity involves upgrading seven miles of existing underground lines to 345 kV and installing 23 miles of new 345-kV cables underground. The new underground lines include a one-mile section that will run under Newark Bay from Bayonne west to Newark airport and south to Elizabeth. The third phase of the project runs under Jersey City and Elizabeth—New Jersey’s second and fourth most populous cites, respectively. The anticipated in-service date for completion is June 2018.
The rationale and scope for Phases 1, 2 and 3 were determined by a focus on the most critical reliability issues, which made the Bergen-Marion section first, put the Linden and Bayway switching stations in Phase 2 and the North Avenue, Bayonne and Newark airport in Phase 3, says Cretella .The third phase will take the most time to complete because work is underground, Tkachuk says. Roadways will have to be dug up and traffic diverted. The phase will involve 1.1 million sq ft of road paving and will cross four major highways, make six rail crossings and involve three bridge attachments. Work also includes 54 underground vaults, some as large as “a little house,” Tkachuk says. But the biggest challenge will no doubt come when the new lines cross Newark Bay from Bayonne to Elizabeth. Two conduits, each 6,574 ft long, will be drilled 120 ft under Newark Bay using horizontal directional drilling. “It is cutting-edge stuff,” Tkachuk says—and to the best of his knowledge, the longest continuous 345-kV cross-linked polyethylene (XLPE) trenchless cable installed in North America.
The PSE&G team considered other methods of stretching the cable across the bay, but it is a heavily trafficked body of water that would make laying cable from a ship or trenchless deposition more problematic. LS Cable & Systems will supply and install the cable for the underwater section under a $57-million contract. The South Korean company says it will manufacture the cable in a continuous length of more than 7,000 ft, which will “require well-planned logistics for transportation and special care and handling of large reels at the site.”
The drilling job is being contracted out to New Jersey-based contractor J. Fletcher Creamer & Son. The drilling job will be done by Southeast Directional Drilling of Casa Grande, Ariz., which has a “verbal award” from Fletcher, says Todd Barton, Southeast president.
The job calls for drilling two side-by-side holes under the bay. They are not the longest tunnels that have been drilled, but the diameter—36 in.—is quite wide, says Barton. He estimates the job will take about eight months.
When completed, the underground phase of the Bergen-Linden project will have pulled 60 miles of XLPE cable and workers will have made 162 cable splices. # While the Bergen-Linden third phase has the challenge of underground work, its first phase—the Bergen-Marion section now under construction—shows the difficulties of working with an electrical system. Work involves two adjacent rights of way, one for the 138-kV lines and one for the 230-kV line.
The project calls for the 138-kV lattice towers to be deconstructed. To take one down, a crane is attached to the top and supports the tower as it is cut “in a controlled manner,” Tkachuk says. As sections are cut loose, they are lowered to the ground where another contractor cuts the dismembered pieces “like you would with scissors” and removes them as scrap, he says.
A key requirement of the Bergen-Linden project is to maintain electrical service for all customers while the backbone of the grid in that area is being replaced. To do that, the system must be modeled to determine electrical flows during the construction phases. Before a 138-kV tower is deconstructed, the electric load is shifted to the 230-kV circuits during the outage. Lines must be taken out of service in sections so no customers lose service. “It is all about coordination and communication,” Tkachuk says.
As the roughly 90-ft-tall lattice structures are taken down, they are replaced with monopole structures that will carry the new 345-kV lines. PSE&G is using monopoles because they are quick to install, have a small footprint and are less expensive, Tkachuk says. The project calls for erection of 92 monopoles, averaging 165 ft in height, with the tallest, 245 ft, installed where the corridor crosses the New Jersey Turnpike. In some marshy areas where the soil does not have too much cobble, PSE&G is using vibratory caissons that can sink 20-ft sections of 8-ft-dia sleeves into the ground without drilling. They are sunk about 70-80 ft deep. Once foundations are set, monopoles are bolted into place in 50-ft sections.
Varying geography, infrastructure and other conditions make a complicated job more challenging, including “unexpected constraints put on the project by outside agencies,” Cretella says. The time-consuming work requires attention to detail. Workers do not take down or put up live cables, but energized equipment is involved in the job, making safety paramount. Tkachuk says the 30 people on his team so far have worked 1 million man-hours—even as construction on the challenging underground section has yet to begin. When the job is finished, it will have taken about 3.25 million man-hours, he estimates.