GSRP Boosts Grid Reliability in Northeast
For many multi-million-dollar power projects, challenges are expected, especially for those that cover large areas. But for the $678-million Greater Springfield Reliability Project (GSRP), the challenges started in 2007, before work even began.
The project, which spans 39 corridor miles and runs through Massachusetts and Connecticut, required the team to go through many regulators to site and permit the project. "We felt we had two separate projects where we had to go through the same process with one team," says Jerry Fan, vice president of Burns & McDonnell, the general contractor on the project.
The project is one of four related transmission jobs proposed as part of Northeast Utilities' $1.5-billion New England East-West Solution (NEEWS) Program.
Construction, which broke ground in late 2012, involved installing 726 new transmission structures and 13 new or rebuilt substations and switching stations.
Officials say the four projects—GSRP, the Interstate Reliability Project, Central Connecticut Reliability Project and Rhode Island Reliability Project—are needed to solve problems with the region's transmission system to meet national and regional reliability standards and provide adequate power.
In Massachusetts, GSRP included 23 miles of new 345-kV overhead transmission lines, three major substation upgrades and two new switching stations. To accomplish this, the team first built access roads and crane paths because existing roads were too narrow for equipment to pass through. About 32.6 miles of new or rehabilitated roads were required.
The team drilled shaft foundations—which were some of the largest ever built for the owner—so that transmission structures up to 130 ft tall could be erected. The largest of these foundations was 11 ft in diameter and 70 ft deep. Lastly, the wires and cables for the overhead transmission lines were strung.
The 2014 Best Projects judging panel took special note of the project's roadway construction and its complex foundations.
"At any given time [during the wire stringing], the team was constructing one of the 13 substations," Fan says. "This required a lot of coordination."
Collaboration efforts on GSRP included the program management approach, which gave Northeast Utilities flexibility and a single source of accountability from design through construction. Also, Burns & McDonnell coordinated with transmission line contractor PAR Electrical Contractors Inc. as well as station contractors Manafort Brothers and Bond Brothers, in addition to more than 16 specialty contractors.
"At peak construction, there were over 600 people working," Fan says. "And there was not a single lost time accident on the job" for a project that took more than 2.9 million hours of labor to complete.
"The safety seemed exemplary for this category," one judge said.
"That's almost unheard of in the transmission and distribution business because it's such a high-risk industry," Fan says. "It was a huge accomplishment."
Project permitting was delayed by about nine months for the development of mitigation plans for neighboring resources. The schedule was truncated by about a year, but to accommodate for the delay, the team resequenced overhead and substation construction activities so that work in upland areas could start shortly after receiving siting approvals, Fan says.
Helping to drive the overall project schedule was the completion of the drilled shaft foundations, which were individually designed following a geotechnical survey that tested the subsurface soil for structural safety.
Just two or three shaft foundations had to be relocated, but a lot more would have been if the surveys hadn't been done, Fan says.
But perhaps the biggest challenges were planned and unplanned power outages. Besides the 703 planned equipment and line outages associated with the project, Superstorm Sandy and the Blizzard of 2013 caused numerous outages. As a result, all labor was at times focused on restoring that power, Fan says.
While the severe weather also affected productivity, line work was accelerated when conditions were favorable. The estimated $718-million project was finished on time and $40 million under budget.
To mitigate the impact of the 703 planned equipment and line outages, the team built the 345-kV line along the same centerline as an existing 115-kV line. It also rebuilt or reconductored existing 115-kV lines on the rights-of-way, Fan says.
Outage restrictions prohibited taking 115-kV lines out of service long enough to complete the rebuilding of the entire line. Thus, the team either removed an old de-energized line or temporarily modified one of the existing 115-kV lines to allow for construction of the new line. Once constructed, the 345-kV line was used as a temporary path for the existing 115-kV circuits to provide service to customers, Fan says. Once service was established, the 115-kV lines were rebuilt.
"There was a lot of back and forth to minimize service interruption and maintain service," Fan says.
Fan says the team's major areas of focus were safety, community relationships and environmental compliance. This included stormwater control processes to prevent runoff into nearby wetlands.
That was a problem for the substations, many of which were located on undesirable land with challenging terrain. They were often hit with microbursts of up to 4 in. of rain at a time. A host of methods including infiltration galleries, rain tanks and dry well infiltration systems were designed and used to proactively plan for water runoff.
Also, the project was done around sensitive areas including wetlands, threatened and endangered species' habitats, cultural resources and sanctuaries. Burns & McDonnell worked closely with the Massachusetts Dept. of Transportation, the Massachusetts Dept. of Environmental Protection (MADEP) and the Massachusetts Historic Commission to ensure protections.
The team completed extensive resource mapping along project areas. The mapping data was then used by both substation and overhead engineering staff to refine the project design, including relocating overhead structures and substation footprint to minimize impacts to resource areas.
The project team, in close consultation with the MADEP Natural Heritage Endangered Species Program, also developed several conservation management plans to establish protective measures. These included implementing time-of-year restrictions in which construction activities were prohibited within threatened and endangered species habitats during active breeding season as well as using radio transmitters to track Eastern box turtles. This enabled the team to confirm that the turtles were not within construction areas.
While the project had many challenges, it also had its share of goals. For example, according to Paul Williams, lead engineer for Burns & McDonnell on the project, one of those goals was to accomplish bulk power station (BPS) conversion. This means having separate primary and backup electrical control and protection systems in place to maintain a high level of reliability and reduce the outage risk at the stations. The new 345-kV is more efficient and could be engineered as BPS-compliant, but the existing 115-kV wiring needed to be upgraded to this standard, with conversion occurring one circuit at a time.
The end result was the establishment of primary and backup systems that will help with reliability needs while also protecting expensive equipment components from failures during unplanned events.
The main goal of the project, however, was to bring reliable and affordable electricity to the region, Fan says. "With demand growth, these types of [reliability] projects are the main reason there are no brownouts or blackouts in the region," he says.
"To meet the demand for electricity in the region, reliability projects such as GSRP help improve the bulk power supply system to withstand electric short circuits or the unanticipated loss of power system components without interrupting power delivery to utility service areas," Fan adds. These projects will also "improve the regional bulk power supply system's ability to reliably meet electrical demand during periods of peak power use."
The project succeeded in delivering more reliable and cost-effective power to the area, while ultimately strengthening the region's electrical grid, Fan says. One judge called the project "magnificent and power/energy efficient with significant challenges."
Owner Northeast Utilities
General Contractor/Lead Design Firm/Program Manager Burns & McDonnell
Transmission Line General Contractor PAR Electrical Contractors
Station Electrical Construction & Testing McPhee Electric/E.S. Boulos/EPS/American Electric Testing/SM Electric
Station Civil Contractors Manafort Brothers/Bond Brothers
Environmental Monitoring AECOM
Landscape Design & Construction Distinctive Tree/Eastern General/Running Brook Farms/BL Cos.
Access Construction & Vegetation Management Northern Land Clearing/Supreme Industries
Public Outreach Subcontractor Watkins Strategies
Archeological & Survey Subcontractors UMASS/VHB