Portland General Electric: building out its largest infrastructure project downtown in 50 years
PGE is building new infrastructure to support Portland's growth in the largest energy infrastructure project downtown has seen in 50 years.
Construction began this fall replacing 60-year-old equipment by adding the new Marquam Substation and upgrading the underground power lines along Southwest Naito Parkway and First Avenue that serves much of downtown and the South Waterfront.
The new substation and power lines will make electricity service even more reliable, strengthen the downtown grid and replace the old equipment with smart technology. The Marquam project — including the Tilikum Crossing transmission lines and the SW Portland underground distribution lines — is the biggest set of PGE improvements to the downtown Portland power grid in at least 50 years.
Phase 1 cost $62 million for the substation, and phase 2 — approved this January — is projected to cost $19 million for the power lines underground and across the river, bringing the project total to $81 million.
"We're replacing the substation over by OMSI, which has cables under the river," said Ezra Richards, PGE engineer and project manager on the site. "Some cables are under the sediment, some are over. Some could be washed away, or some could be buried."
The cables beneath the Willamette, which bring power to much of downtown, are up to 60 years old.
"If the cable fails, then it's a very expensive project to replace a cable," Richards said. "It serves downtown — our system doesn't have just one source downtown, but if there's an outage, it could temporarily affect several blocks. It wouldn't be long-term outages, but it creates a strain on the system if those cables are out for a long period of time."
The new project strings the cables across the river via Tilikum Crossing instead.
"We planned ahead and asked them to build a conduit into the bridge," Richards said. "It comes out over here, crosses through Moody (Avenue) and wraps into the substation."
PGE is adding approximately 1.5 miles of new underground distribution cable and just under 1 mile of underground transmission (higher voltage) cable.
"Transmission cables at high voltage are very costly to bury, and we can't build over (the overpasses) easily," Richards said.
"It's all for the sake of increased reliability for downtown customers," said Stan Sittser, external communications at PGE.
There are currently 50 people performing construction activities at or around the Marquam Substation, not including engineering, supply chain or project management responsibilities.
Constructing the substation
In the late 1800s, the site used to be a tannery, which burned down. Then it became an imitation marble foundry which supplied many of the facades for downtown. Later, it became a hotel, which also burned down, before finally becoming the site of the Greyhound bus garage in 1931.
It's a great site for the PGE substation partly because it's beneath the I-405 overpass to the Marquam Bridge and other residential and commercial developers weren't as interested.
"Because it's central to downtown, and available land," Richards said. "It will serve downtown Portland to the west of the Willamette from here north, and also serve Marquam Hill and the South Waterfront."
But before PGE could begin to build, they first had to spend two years cleaning up contaminants.
"There were significant environmental hazards on-site we had to remediate," Richards said. "Some of that (cost) was included in the purchase price."
There's also a huge retaining wall on the south side of the site, holding up the steep streets of the Lair Hill neighborhood that back to old homes and new apartments.
"We removed the building, but part of it was a retaining wall," Richards said. "We left one part of the wall there and built this wall."
In the underground vault, a cement stronghold with groups of holes and color-coded wires are in the walls.
"All these tubes are filled with gas breaking the arc, stopping electrons from jumping," Richards said. "The conduit pipe in Tilikum Crossing, this is where it comes out. These pipes are continuous all the way across Tilikum — and one for fiber."
Richards said once the cables are wired through, the large basement will be half filled with them — and that it's the largest vault he's ever seen.
"We're going to pull the cable through this," Richards said, gesturing to a group of holes in the wall farthest from the stairs. "They're heavy and it's not a perfectly straight path. We'll put tape through, then pull through a larger wire too heavy to pull by hand: we'll lube the cable with a jelly, have one truck push and one pull reels of cable."
The pushing truck will be above ground, over the vault, because it won't fit inside.
Among the disconnected cable pieces of all sizes littering the site, there are also long strands of copper.
"The copper cable is groundwire. We attach copper wire to all the metal all around," Richards said. "If there's an electronic charge and somebody touches metal, the copper takes that down into the ground so nobody will be electrocuted."
The project experienced some security challenges with damage and break-ins, with the suspects being people living on the Interstate 5 slopes in tent villages — who also probably lit the dumpster fire behind the International School a few weeks ago. From up along Naito Parkway, tents are visible behind the PGE site.
PGE used a tunnel boring machine to create four 48-inch wide tunnels out under the 405.
"In 1920-30 there were homes through here," Richards said. "When they built the freeway, they didn't remove everything: we hit foundations. We sent a man with a saw inside the 48-inch tube to cut out rebar."
Half the conduits cross up First Avenue, tracing it for three-quarters of a mile, and the other half — about 25 or so conduits — do the same along Naito Parkway.
"There are all kinds of existing infrastructure we have to weave between," Richards said, pointing to the spray paint codes in the asphalt. "Red paint indicates lights, blue utilities in the ground."
His team excavated 20 feet down so the new cable can travel across the street, and built a shoring system within a very narrow space, weaving it all among 15 other utilities already installed in the roadways.
"Where we're excavating there's the MAX line and the streetcar, so we have to bring all the cables underneath, and jack and bore underneath," Richards said.
PGE is digging five to 10-foot deep trenches along Naito Parkway and First Avenue. They also had to avoid historic trees, so they have to put the vaults in the streets instead.
To help the community navigate the traffic impacts, Sittser organized an outreach campaign that includes electronic reader boards along the impacted streets, door-to-door information officers, a mailer, an email update service and outreach to residents and neighboring businesses.
One company along Naito Parkway is a recording studio, and while it's pretty noise-proof, the vibrations of the machinery could mess with its ability to do business. Sittser's outreach program found them and was able to organize the timing to fit both the studio's and PGE's needs.
The International School is located on the next block, and recently built a new building. Among other challenges, the school was worried the PGE project's vibrations could cause harm to their new build.
"In the assembly of the GIS, if dust gets in, it could create a flash," Richards said. "We had to work with them to avoid dust getting in."
PGE also installed a machine on their building to calculate the vibrations, which resulted in a count that wouldn't even hurt a 100-year-old building.
"This is the biggest infrastructure downtown in 50 years, and it needs an outreach program to match," Sittser said.
The three state-of-the-art transformers are separated by firewalls to protect from risk of fire, because the site doesn't provide enough space to spread them out safely. Then there's the switchgear that breaks up all the power for the downtown feeder cables.
"The gas-insulated switchgear (GIS) is the heart of the substation. One cable can't serve every block, you have to have multiple spider web out into the city. The switchgear breaks it up into all little cables and sends it into the city," Richards said. "Typically, you need a large piece of ground."
That's because the electrons try to jump from the source to the package unless the switches are opened, disconnecting them from their path. Because the voltage is so high, the electrons can jump farther — that's the spark you see when you unplug something in your house, but with the voltage multiplied by 1,000.
"We didn't have the space with the high voltage to create space as it breaks and opens, and the electrons try to jump," Richards said. "The GIS has a property that doesn't allow electrons to jump: inside all these tubes are switches that break arcs. You can attach a camera — people working want to see whether it's open or closed, so the crews feel comfortable working on it."
Building up Portland's smart grid
The substation takes the high-voltage power, which is more efficient to transport over distances, and steps it down to a lower voltage usable by businesses and households before spider-webbing it out across downtown.
"The power you take in at your house is a lower voltage than the power taken from one place to another," Richards said. "We have to step it down as it gets closer to your house."
The substation's high voltage transformer is a 115 KV Transformer — that's 115,000 volts. A household socket uses 120 volts in the U.S.
"The transformers were just installed a few weeks ago," Richards said. "PGE is a summer-peaking utility now — the highest powers are used in summers now — as heat is being produced, fans blow cool air to keep temperatures down."
Apparently, Portlanders use more A/C in the hot months than heating during the long winters these days. If the system overheats, it could have caused power outages during the heat wave last August.
"The grid is getting smarter, the sprinklers are now remote control," Sittser said. "Two-thirds are able to do remote control to keep them cooler. This is state-of-the-art, built to the highest possible standards."
The site currently has huge foundations where steel poles will be set up where the power coming into the substation will go back up and out to the city.
"There's a control center for everything that happens. This communicates with the downtown office so we know what's happening — it's super high-tech monitoring," Richards said. "Each wire has a vocation engineering team designing it for protection and the control station for the substation."
The project's timeline is slated to be between nine months and a full year, with completion slated for fall 2018.
"The smart grid is built one power line at a time," Sittser said. "When different elements can talk to each other, deliver information and power both ways, ultimately it gives customers what they want: an intelligent grid, that's the goal."
By Jules Rogers
Reporter, The Business Tribune
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PGE Marquam Substation
Southwest Water Avenue and Sheridan Street
Owner/developer: Portland General Electric
Subcontractors: Black & Veatch Construction, Inc.
Loy Clarke Pipeline
Nexans industrial wire & cables
Wilson Construction Company
Gonzales Boring and Tunneling