When a hospital’s primary mission is keeping people healthy, what happens when a power plant gets sick? That was the situation that faced the Milwaukee Regional Medical Center (MRMC) when it’s circa 1950 coal-fired power plant needed critical upgrades as well as conversion from coal to natural gas.
1. The Milwaukee Regional Medical Center campus sits on 250 acres, and is home to hospitals, medical offices, and clinics, in an area on the city’s west side. Courtesy: The Boldt Company
The 250-acre medical campus (Figure 1) is home to hospitals, medical office buildings, and clinics, and is located in a busy area on Milwaukee’s west side. Five primary tenants of the complex formed a consortium to address the plant’s deficiencies, an important task because the plant provided heat and chilled water for all the campus’ buildings. The consortium had to decide whether the campus would continue to be the power customer of a utility, or whether it should purchase the plant and have direct control over the expansion and renovation needed to answer future campus growth. Purchasing the plant ensured ongoing reliability.
“Our ownership allowed for the campus to control the reconstruction to meet our critical needs for redundant production and distribution capability while ensuring continuity of service during the project,” said Mark Geronime, vice president of operations for MRMC Thermal. “The acquisition has been a complete success and the campus is exceeding their goals for increased reliability and efficiency as well as significantly reduced environmental impact.”
The group acquired the plant and created MRMC Thermal in April 2016, then assessed the state of the plant. The structure and assets within it were aged, and did not provide emergency backup or redundancy. Before updating the main plant, they needed to build a transitional plant to support the medical campus during construction. Energy production/distribution for the campus was treated as a core, critical asset and MRMC Thermal established objectives for the plant to include:
■ Evaluating improved economics for steam and chilled water production
■ Building physical redundancy by bi-furcating plant steam and chilled water production assets
■ Utilizing cleaner combustion technology to develop improved environmental emissions
■ Assessing lean construction principles for delivery of a thermal plant project
The organization hired The Boldt Company and project manager Jay Ehrfurth, a veteran of power plant construction and the former chief power plant engineer for the state of Wisconsin.
“The medical complex needed ultimate reliability for their thermal sources,” Ehrfurth said. “Every piece of equipment and plant design was created with N+1 redundancy so the team’s solution was to bifurcate the plant.” Construction and engineering crews proposed dividing the plant into two main sections each supplying chilled water and steam production. But before any demolition and reconstruction could start, the campus needed a transitional thermal source.
2. The North Plant at the site is now part of the permanent plant arrangement. It was originally designed as a temporary site, housing the boilers and auxiliary equipment for the boilers, with the thought that once those items were no longer needed they could be returned and the building would become a storage site and warehouse for the complex. However, as design moved forward, the building became a permanent fixture to house two boilers (expandable to four), with additional water treatment equipment so it could be a “self-sustaining” plant. Courtesy: The Boldt Company
The nine-acre site of the plant allowed room to build what’s known as the North Plant (Figure 2), a facility housing four, 70,000 pound-per-hour steam generating gas boilers. A 700-foot pipe bridge transported steam to the main plant’s distribution tie-in points and took treated water back to the transitional plant. And all of it was built in less than nine months.
“To get the transitional plant up and running we rented the boilers—I knew it was an option and I knew it could be done quickly,” Ehrfurth said. “It’s a little like leasing a car.”
After construction was completed, the transitional plant was upgraded to handle two permanent boilers and water treatment facilities.
Demolition and Renovation
Once the North Plant was operational, demolition began on the coal boilers, coal ash handling equipment, electrostatic precipitators, and stacks in the original buildings. Crews from Boldt, Burns and McDonnell Engineering, and NV5 Engineering soon realized there was no legacy institutional knowledge about the facility.
“There were diagrams, but they weren’t up to date,” Ehrfurth said. “We were mapping out the systems with Grunau Mechanical and Staff Electric team members as we were isolating operating elements and planning renovations.”
Construction crews operated in a collaborative environment using Boldt’s Integrated Lean Project Delivery (ILPD). This process combines up front collaboration between all parties with the waste-reducing lean principles and is designed for uninterrupted workflow and an increase in value-add activities. Crews relied on rigorous standard process, visual controls, and collaborative communication of the production plan on a daily and weekly basis.
Demolition and renovation called for:
■ Three steam-driven turbines were removed and the turbine hall was renovated.
3. Construction crews lift one of the facility’s boiler units. The team removed four coal-fired boilers and replaced them with two gas-fired boilers during the construction phase. Courtesy: The Boldt Company
■ Four boilers were removed and replaced with two new boilers (Figure 3).
4. Construction crews lift one of the facility’s chiller units. Three new chillers and three chilled-water pumps were added to the facility. Courtesy: The Boldt Company
■ Three new chillers (Figure 4) and three chilled-water pumps were added, and six turbine-driven prime movers were converted to electric motors and variable frequency drives (VFDs).
■ A new three-cell cooling tower was erected to handle the condenser water off the new chillers.
■ New office space, locker facilities, and control rooms were added.
Demolition was carefully planned as Boldt crews took apart the giant boilers and supporting structures brick by brick. The three coal boilers were five stories tall with three-inch-thick steel drums, each four feet in diameter. Crews used torches to cut the boilers apart and scrapped the steel to steadily deconstruct the decades-old structure.
For construction crews, the challenge was always providing N+1 redundancy during all phases of construction to provide adequate steam or chilled water to fully functioning hospitals and clinics. “It was like a dance, we had to continually match capacity and provide backup before we took any one process offline,” Ehrfurth said. “We had to ensure that temperatures in operating rooms were sufficiently cool during surgeries, or provide adequate heat to hospital rooms during winter.” To further manage operations, construction crews did boiler renovations in summer months and chiller renovations in winter.
You Can’t Get There from Here
One challenge in construction was the plant was physically located 800 feet from the campus—across one of the busiest highways in the state of Wisconsin. Expanding the distribution system (see sidebar) for additional capacity and better performance called for adding 5,100 feet of chilled water piping and 3,100 feet of steam piping. But crews could not dig up the congested highway used by as many as 30,000 vehicles (including emergency vehicles) each day. Interrupting traffic was not in the construction plan.
A Cleaner and More Flexible Facility
The Milwaukee Regional Medical Center (MRMC) has said the elimination of coal and conversion of its plant to natural gas reduced greenhouse gas emissions by about 50%. Redundancy at the site was created through construction of a second plant, which provides a continuous supply of critical service, with two independent thermal sources and on-site alternate fuel backup. Reliability was improved through investment in plant and distribution infrastructure to enhance an uninterrupted, consistent source of thermal service.
The members of MRMC Thermal are:
■ Froedtert Memorial Lutheran Hospital
■ Children’s Hospital of Wisconsin
■ The Medical College of Wisconsin
■ Blood Center of Wisconsin
■ Milwaukee County Behavioral Health
Some pertinent statistics about the project include:
■ 7,500,000 square feet of conditioned space
■ 22 buildings representing five customers
■ 4 miles of steam and condensate lines
■ 4 miles of chilled-water piping
■ 2,500 feet of steam tunnels
■ Peak chilled-water demand: 17,100 tons
■ Peak steam demand: 217,000 lbm/hour
■ Largest chilled water line: 42-inch HDPE and 36-inch PCCP
■ Largest steam line: 24 inch (15 psi) and 12 inch (135 psi)
“The highway was new and there was a six-year moratorium on excavating,” Ehrfurth said. “We couldn’t open cut, so we opted for horizontal boring to run the pipes under the highway. Conventional wisdom indicates open cutting is the most economical, but when you add crews to flag traffic flow, re-route traffic, and do the actual work, directional boring was the best option,” he said.
Before work started, crews used computers to plot a path for the boring and collected soil samples to ensure the tunnels would not collapse during construction. “There’s a lot of upfront engineering to make sure a plan like this was safe to execute,” Ehrfurth said.
Crews bored holes 54 inches wide and 35 feet under the highway, for about 750 feet, to carry the 42-inch diameter piping. In several places, crews dug open trenches and laid in trench boxes and steel plates overhead so traffic could proceed while crews worked. The sections of pipe were thermally fused to make one continuous run and it took 10 to 12 hours to pull the pipe the entire distance under the highway. Most of the road work was done overnight and on weekends, when traffic in the area was lighter.
The facility’s construction began in March 2015, and the new plant was in full service by August of 2018, with the work done on time and under budget. Decisions made early in the design and planning phase enabled the construction and engineering team to achieve all its milestones.
—This article was written by staff of The Boldt Company, an Appleton, Wisconsin-based construction services firm.