To keep the customers connected to a secure and reliable source of electricity, the Duquesne Light Co. (DLC; Pittsburgh, Pennsylvania, U.S.) invested US$500 million in its transmission and distribution system. While DLC's infrastructure has served customers well for decades, some components are nearing the end of their useful operating lives. This is especially true of facilities located in numerous underground residential distribution (URD) systems dating back to the early 1970s, such as the Bon Meade plan in the Pittsburgh suburb of Moon Township.
DLC tackled the URD rehabilitation project as part of a multimillion-dollar infrastructure improvement program currently underway throughout its 800-sq-mile (2072-sq-km) service territory in southwestern Pennsylvania. DLC became aware of the need for the rehabilitation two years ago while systematically analyzing circuits that carry electricity across Allegheny and Beaver counties. With customer complaints higher than normal because of more frequent and longer outages, DLC sent out a scout team that lifted every manhole cover in the plan to survey the equipment. The company also surveyed more than 50 other aged developments as part of the investigative process. Workers discovered the collapse of numerous transformer vaults caused by age, moisture, lawn chemicals, road salt and the occasional run-in with vehicle tires, because many of the vaults were located next to the curb. Much of the equipment had been installed in the early 1970s and had only a 30-year life expectancy.
DESIGNING THE PROJECT
Rebuilding the Bon Meade network was a high priority for DLC. Although customers tend to understand an occasional outage, customer satisfaction suffers when service is interrupted more than twice a year.
As with all the projects in DLC's infrastructure improvement program, the scout team's results followed a well-defined implementation process. The local service center manager reviewed the Bon Meade survey results, and the company's planning department added the findings to the schedule of projects for consideration. The planners then set the targeted projects on the schedule and forwarded the general project description to the engineering department.
Engineering this project was a major undertaking. The assigned engineer and technician were responsible for designing a replacement project as well as creating an optimal design. To accomplish this task, they evaluated the existing design in an attempt to limit the amount of new primary wire to eliminate potential exposure while maintaining reliability. DLC also engineered its plans to ensure every transformer was part of a loop system. This design principle allows the crew to isolate any device or piece of cable while maintaining service to the remainder of the plan and reduce circuit footage within the plan by about 30%. This was no easy task when you consider having to replace cables in existing conduit and determining how to tie it all back together.
With these general plans in hand, the project manager, engineering supervisor and design technician met with the Moon Township municipal engineer to find the limits of the streets' rights-of-way and determine whether utility easements existed. All the streets in the plan had an additional utility easement behind the sidewalk except for two. Rather than securing the right to install equipment on private property, DLC opted to relocate the sidewalk in front of the transformers at those two locations.
ENGAGING THE COMMUNITY
Once these rights-of-way issues were resolved, and a more detailed plan was drawn up, DLC invited more than 500 neighborhood residents to a community meeting. Community presentations are not uncommon for these types of projects, but in this situation, DLC felt a meeting was especially important because the new equipment would be pad-mounted, replacing sight unseen vaults, and placed behind the sidewalk, in the residents' yards or about 13 ft (4 m) behind the curb.
As work on the project started, DLC established work schedule parameters that prohibited scheduled outages before 8 a.m., with power restored no later than 4:30 p.m. on a daily basis. The team scheduled work on Monday through Thursday, so as to not conflict with the customers' weekend plans. A telephone hotline and a special section of the company's website kept customers informed of the schedule. DLC updated the hotline and website at 5 p.m. daily with precise information as to which house numbers would be affected by the following day's outages. Crews also posted signs with the hotline number at each entrance of the residential plan.
The team kept disruptions to a minimum while working on the project. The on-site supervisor told the crew members that as ‘guests’ in that neighborhood, they should not leave trash lying around, not have music playing, and be courteous to each and every resident. The homeowners understood DLC's need to interrupt service to safely replace equipment, and without their cooperation and patience, this difficult work could not have been completed within the allotted time frame.
While the year-long project, completed in October 2006, seemed to move along without many problems, DLC did face an unusual situation with one of the plan's residents. When customers were notified via mail of the pending outages, the letters specifically asked of any critical medical concerns. Unfortunately, one customer who is a quadriplegic didn't notice this section of the letter and failed to notify customer service that the loss of the electric power would be a major issue. Thinking quick on their feet, crews installed a single-phase generator tied into the customer's meter base and the problem was solved.
GOING THE EXTRA MILE
The Bon Meade rehabilitation project provided a key benefit to customers by upgrading the prior equipment from in-ground non-loadbreak. This required de-energizing major portions of the residential plan to establish safety clearances to the new equipment, which is aboveground loadbreak technology. DLC uses a 23,000-V distribution system, but has the ability to sectionalize a potential problem quickly and efficiently to enhance customer satisfaction.
The crew replaced a total of 43,000 ft (13,106 m) of primary cable in the existing flexible conduit. The conduit in many locations was crushed, and the team needed to excavate it to repair the damaged portions. Deteriorated external concentric neutrals on the cables also made it challenging to extract existing wire from the conduit, and in some locations, required unanticipated excavation.
In addition, crews replaced 65 submersible transformers with new pad-mounted URD transformers and installed 25 fiberglass above-ground sectionalizing enclosures, replacing electrical elbows previously located in underground vaults.
To make the equipment less noticeable, yet allow for proper operation, the crew adhered a sticker with specific instructions on where greenery can be planted on each pad-mounted transformer. DLC also used quality replacement topsoil and reseeded the areas that were excavated. DLC's efforts didn't go unnoticed. By going above and beyond, DLC helped to make the neighborhood a better place to live for the plan's residents.
John Khalil has been employed at Duquesne Light Co. for 34 years and served in numerous engineering and customer account positions prior to becoming a project manager. John, who is responsible for the rehabilitation of existing aged plans, also manages about 80 new residential developments a year, from first contact with the developer, to the completion of utility construction.
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