By Kathleen Davis, associate editor
In October of last year, Anaheim Public Utilities unveiled Park Substation, the first underground electric substation in the United States. The substation is nestled below the city’s Roosevelt Park, a two-acre facility that serves the East Anaheim neighborhood.
The 100-MVA electric distribution station has the capacity to serve 25,000 residential customers and uses gas-insulated switchgear (GIS), which allowed Anaheim to reduce the required space for the substation to approximately 30 percent of a conventional station design. (According to Anaheim Public Utilities and its technology partner on the project, Siemens, the use of this type of switchgear and substation design is more common in Europe and Japan).
“I am pleased to see Anaheim continue its transformation into a city of the 21st century with the completion of this innovative project,” Anaheim Mayor Curt Pringle told an audience of more than 100 invited guests that included city and utility leaders, project team members, as well as local residents and business owners. “With this new technology, we will be able to build substations closer to where we need them, in spaces that are considerably smaller than their predecessors and within enclosures such as buildings or underground.”
The design-build team for Park Substation is a joint venture consisting of three companies: Siemens (supplier of the GIS equipment), Turner Construction (a general contracting firm) and BETA Engineering (a specialty electrical engineering firm).
Design Details from Siemens
“The GIS supplied is a 69-kV, 40-kA rated equipment,” Tony Cutillo, Siemens’ manager of business development for AIS/GIS substations, said. “We supplied our HIS (highly integrated switchgear) style of equipment for two major reasons: one the customer requested outdoor GIS even though the station was indoor, and second, due to the fact that the substation was located underground, headroom would be a major issue to the size of the station.”
He added, “In this manner [of GIS], a lower profile is attainable.”
We discussed a number of project details with Cutillo, including safety-because that is often a major hurdle with substation construction and public acceptance. Our basic question: How safe is an underground substation?
“Very safe,” Cutillo said. “All of the design meets or exceeds national standards including seismic requirements.”
And, in the end, although the project breaks new ground-literally-it wasn’t all that difficult to change from the traditional above-ground installation to one nestled under the topsoil.
“The major change involved in this station was the elimination of any heat build up due to the operation of transformers in an enclosed area,” Cutillo said. “Therefore, the cooling system employed is very sophisticated.”
According to Cutillo, all other items were standard outdoor equipment.
And, of course, the smaller footprint that the GIS equipment gave to the project helped a lot when it came to size and scope.
“By using GIS equipment you automatically shrink the footprint of a substation by almost 70 percent,” Cutillo said. “A standard AIS (air-insulated switchgear) substation would have required a great deal more real estate. The heat dissipation would have been much larger as well, necessitating not only larger areas but more cooling equipment, therefore more costs.”
From Siemens standpoint-the manufacturing side-the project ran approximately 18 months from design to turnover to the City of Anaheim. The biggest hurdle for their process was an unexpected one: rain. Lots of rain. As it was described among residents and newscasters, a “100-year” rain. This complicated the process of moving the ground. Therefore, a different support structure had to be implemented post-design work.
But, otherwise all went well, including the concrete pour of the roof, where the project participants laid out 875 cubic yards in a single day.
However, Cutillo doesn’t believe that the underground work on this substation made it particularly more difficult than a traditional above-ground structure-just different, with a few unique requirements. For example: an emergency hatch was required for the underground substation, but the design needed to blend into the overall park design. Also, the cable ducts were somewhat unique and required close coordination, according to Cutillo. And, the design of the fire suppression system using HFC125-as well as the air handling system-had to be closely coordinated to comply with both national codes and city requirements.
Overall, Cutillo sees the possibility of many more underground substations, based on the project’s success.
“This could have a very significant impact based on the amount of interest we have seen from other utilities around the country,” he said. “It allows utilities to revisit their initial plans knowing there are feasible alternatives that can be implemented to tackle their demand needs as well as their customer needs.”
The $19.5 million project is expected to be a benchmark prototype for other utilities, not only in California but across the nation. All circuits into and out of the station are underground, including 10 circuit miles of underground cable installed on Santa Ana Canyon Road, while another 5 miles of existing overhead lines are being converted to underground. An additional 8 circuit miles are underground on other streets.
But, more important than the future is what the Park Substation has accomplished in the present.
“Not only does [the Park Susbstation] allow for growth in a very highly residential neighborhood of Southern California, but it also provides a two-acre park environment for the use of all residents. It is the local consumer who has received the greatest benefit of this facility.”
From Anaheim’s Perspective
In December, Utility Automation & Engineering T&D spoke about the project with Jafar Taghavi, the manager responsible for the system planning division and major capital project management for the Anaheim Public Utilities Department, and Keith Tieszen, a project manager in the system planning division. The first question we asked was what prompted them toward this unique underground design.
“We anticipated community opposition to a conventional open-air substation, particularly at the primary site, located adjacent to and overlooked by existing single-family homes,” Taghavi said. “The primary site was city-owned and had been designated as a possible park or library. The location offered ideal street frontage for expanding our electrical distribution circuits to serve existing and future electrical system load. The topography of the site (approximately 25 feet above street level) prompted our investigation and research into using GIS technology and installing the substation below ground.”
Considerable research was conducted with input from various suppliers of the gas-insulated technology, according to the utility, revealing at least two installations in Europe (one in Spain and one in Switzerland) where substations were placed below ground. This inspired them to move forward with their own below-ground project.
Once the design was decided and the project got under way, everything ran fairly smoothly, according to project manager Tieszen.
“This project marked the first time that a design-build process was used by Anaheim Public Utilities for a project of this magnitude,” he said. “The bidding, evaluation and award went well.”
Like Cutillo, Tieszen mentioned the overwhelming rains, which, he commented, “resulted in extensive use of shoring as a precaution prior to excavation for the underground building.” Tieszen and Cutillo agree that Mother Nature was the biggest hurdle for this project.
Interestingly enough, the public reaction to the project wasn’t a hurdle at all-something surprising to probably all utility managers trying to put substations into various communities across the U.S.
“Public reaction was positive from the very beginning,” said Taghavi. “Once it was clear that Park Substation would not be visible, would be quiet and would enhance the surrounding neighborhood by providing additional community green space, the only issues revolved around the actual design of the park. The community was encouraged to give us input on the park design and suggestions were included in the final design.”
Keeping the public informed was key to keeping them on board with the project, Taghavi added. The utility utilized flyers and even personal visits for just this purpose.
The project itself has been “in the works” since the second and third quarters of 2003, when the preliminary investigation of GIS suppliers and the preparation of a request for qualification began. Community meetings on the topic fired up in the fourth quarter of that year with the request for bid coming in at the start of 2004. Construction began in the second quarter of 2005 and was completed in the third quarter of last year, with the dedication of the facility falling into the fourth quarter of 2006.
According to Anaheim, the lessons learned on this project will be applied to future projects for the utility.
“At present, a 230/69-kV, GIS substation is being constructed at the city’s Utilities Service Center (USC),” said Tieszen. “This can be accomplished at the USC because of the greatly reduced space requirement for GIS installations. In another project, the required replacement of Anaheim Substation also will use GIS technology. Plans call for the entire substation to be placed in a new building designed to complement the historical architectural themes of the downtown neighborhood.”
He added, “Anaheim Public Utilities has chosen this technology for all future substations because of its invisibility and acceptance by the community, plus reduced land requirement.”
“Without a doubt, Park Substation has been our most gratifying distribution system project,” Taghavi said. “Both from a utilities department and a personal perspective, this has been a more-than-expected win-win for the city and the community. We have received numerous compliments from the local community, from businesses and from other utilities-both local and from across the United States.”
Glendale Installs Largest GIS Station in N. America
Gas-insulated substations are apparently all the rage on the West Coast. Glendale Water & Power (GWP), a municipal utility located in southern California, recently completed the installation of the largest GIS Station in North America, according to the utility. The project cost approximately $20 million and took 21 months to complete. The GIS is a 69-kV sectionalized double bus switchgear which replaced an existing non-sectionalized air insulated 69-kV switch rack.
The new GIS has seventeen 69-kV bays of double breaker and breaker-and-half arrangements on two 3150 amp double buses. The buses can be sectionalized using two 3000 amp circuit breakers. In all, the GIS has 42 circuit breakers that serve GWP’s Grayson Generating Plant, Air Way switching station, and four distribution substations. Spare positions are designed for future expansions.
The new GIS with associated disconnect switches, ground switches, control house, and other ancillary equipment occupies a 150-foot-by-65-foot area. It replaces the air insulated switch rack that occupied 70 feet by 205 feet of real estate, thus saving 4,600 square feet of valuable land that can be used for future expansion of GWP’s electrical system.
The GIS project was a turn-key design-build contract. ABB Inc., the primary contractor, provided the engineering and construction design and supplied the GIS station. The GIS station was fabricated in Germany. ABB Inc. subcontracted with Henkels and McCoy for the civil construction and power line work and with Miron Electric for the assembly and installation of the GIS and the supervisory and control wiring of the station.
The project started Aug. 18, 2004, with completion originally set for summer 2006 and a budget of $19.8 million. It was completed ahead of schedule on May 16, 2006, and under budget with a final cost of $18.7 million.