University rebuilds on-site power plant, switching from coal to gas
By Jay Ehrfurth, The Boldt Company
What do billions of dollars’ worth of research, football games, government shutdowns, police escorts and dry ice have to do with a university’s heating plant? As it turns out, everything.
A wide range of challenges must be overcome during power projects. Some involve emissions issues or crowded urban sites-others have tight schedules or are hit with adverse weather conditions.
The Charter Street Heating Plant rebuild project that The Boldt Company and project joint-venture partner AMEC recently completed at the University of Wisconsin–Madison faced them all and more.
|The University of Wisconsin Madison Charter Street Heating Plant is near student housing, urban development, sporting venues and a rail line. The plant was recently rebuilt, converted to run on natural gas instead of coal and expanded. Photo courtesy: The Boldt Company|
The Charter Street plant is a true tri-generation plant; steam produced by the plant (at 1.2 million pounds per hour) generates 10 MW of electricity, runs through campus to heat the university’s facilities and drives compressors to create chilled water (with a capacity of 26,000 tons). Sitting on a postage stamp-size, brownfield site surrounded by a bustling urban area, the large on-site Charter Street plant is just one of two power plants run by the university to serve its more than 43,000 students and 330-plus buildings, a task so critical that the plant can never afford to go offline for any extended
A prolonged outage could result in devastating scenarios. Freezers housing delicate research materials shut down and a professor loses his life’s work. A doctor can’t proceed with a life-saving operation when her facility’s power is cut. Student services cease.
That means taking the plant offline for a massive rebuild project is simply out of the question, which is one of the many challenges the Boldt and AMEC team faced when the university selected it as engineer-procurement-construction (EPC) contractor to convert the then coal-powered Charter Street plant to run on natural gas, expand the facility and update the plant’s equipment and controls.
The massive rebuild and conversion project features the addition of four 225,000-lb./hr. natural gas/fuel oil package boilers and a 70,000-sq.-ft. plant expansion to accommodate the new boilers and additional equipment.
Other elements of the project include:
- Water treatment equipment installation
- Upgrades to feed water and condensate collection systems
- New air compressors
- Upgrade to digital controls for both campus heating/cooling plants
- Electrical system upgrades and additions
- New 13.8-KV switchyard
- Fire protection for the existing plant and expansion
- New six-cell, 50,000-GPM cooling tower
- Construction of a new control room
Powering through challenges
The set of challenges facing the project team were both unique and diverse.
One of the main project challenges for the owner, UW–Madison and state of Wisconsin Department of State Facilities (DSF), was simply the sheer size of the undertaking.
The $250 million project budget was the largest in the owner’s history and the project contract was the first to be delivered on for the owner through the EPC process.
Since the rebuild of the plant is meant to last 50-plus years, the EPC process was chosen to allow flexibility within the project to select work and equipment bids based on cost and value, instead of just cost alone, as is normally the case under the state’s standard design-bid-build contracts.
As the EPC contractor, the Boldt and AMEC team was responsible for procurement, which allowed the team to receive bids and then discuss different options with the owner and assess them for value. This allowed the owner to spend money on the best project options in terms of value, not low bid alone, to reach the highest level of quality possible for the project within its budget.
The owner also didn’t have the available staff resources that were needed to manage the project from an internal standpoint, so it hired P3M as its owner’s engineer. (P3M is a joint venture created for this project and made up of Power Engineers Collaborative, Pöyry, Middough and Potter Lawson.) With Boldt leading the project planning and delivery effort, its project joint-venture partner AMEC doing the engineering work and P3M producing conceptual drawings and schematics, the owner was able to successfully navigate the EPC process and manage the project with just a few of its own staff members.
|Boldt employees oversee the rotation of one of the plant’s new boilers prior to its installation, which was part of converting the plant to run on natural gas instead of coal. Photo courtesy: The Boldt Company|
Detailed planning key to success
High-quality preconstruction planning and scheduling are important for any project, but the unique characteristics of the Charter Street plant rebuild required an especially rigorous level of precision and detail:
Since the plant is vital to supporting the campus, the project needed to be completed without shutting down the facility. There was also a main utility high-pressure gas line and high-voltage lines that ran directly through the main construction zone.
The project would run through all of Wisconsin’s seasons-meaning the project team had to plan for both sweltering heat and frigid cold. Temperatures during the course of the project ranged from more than 100 degrees Fahrenheit to less than minus 15 degrees Fahrenheit.
The project schedule was aggressive and deadlines had to be met to meet campus steam and chilled water needs.
The 3.3-acre project site is surrounded by urban development, student housing, a main artery into campus, a main rail line and sporting venues the Kohl Center and Camp Randall.
An intricate plan of 20-plus phases was used to ensure the plant remained operational throughout the project. Each phase was linked through the building of one new component so that one existing component could be replaced and torn down without impacting the plant’s operations. In addition, the main high-pressure gas line and overhead high voltage lines that ran directly through the site were relocated before the project began.
The main weather challenges involved removing existing boilers during summer and tearing down and building a cooling tower during the winter. The boiler work was planned for summer, when demand for steam is lowest and likewise, the cooling tower work was scheduled for winter, when there is little need for chilled water services.
In addition to making safety the number one priority as always, a number of unique solutions were employed to deal with the congested project site, including:
The project site is bisected by one of the main streets on campus, so it could almost never be closed for construction because of its use by emergency vehicles, public transportation vehicles and students. To work around that busy passage, a transfer bridge was built over the street that could be used for project foot traffic, storage and as a laydown area. It also provided a safe space over the road for cranes to traverse picks over. The bridge was removed when the project was completed.
Because of limited lay-down space, “just-in-time” deliveries were central to keeping the project on schedule. Using this scheduling tool, every material delivery was planned for precisely the time at which each material would be needed. This requires a very coordinated execution of the project schedule, but keeps lay-down areas open and reduces costs and waste due to lost time waiting for materials or waiting for space to open up for materials.
The height of the project’s crane tower was made high enough to allow it to clear a large chimney on the site (which was eventually removed). There is also a rail line on the site, above which cranes are not allowed to operate, so the crane’s swing radius was locked in order to avoid that area.
Every sports game or other event that would impact the project was meticulously built into the schedule and planned for by the project team. For example, the project team made sure roads were open for sporting event traffic and did not schedule overtime work on Saturdays when there were home UW Badgers football games.
Extensive planning was conducted for crane picks. For example, a detailed pick plan was created for the installation of a new deaerator. The large deaerator had to be installed in the existing boiler plant, which is located more than 80 feet past the facility’s façade. Putting the 84-ft., 134,000-lb. component into position was akin to picking up a submarine and sliding it into place over one’s head. To accomplish the installation, an extensive scaffolding system was built next to the facility, which the deaerator was placed on by a crane. A rail system and steel supports replaced an existing coal bunker next to the scaffolding and inside the building; the rail system was used to slide the deaerator from the scaffolding into its final position in the building. Execution of the plan resulted in the safe, effective installation of the deaerator and minimized the pick time and disruption to local traffic.
|A new deaerator is lifted as part of a complex pick and installation plan at the University of Wisconsin Madison Charter Street Heating Plant. Photo courtesy: The Boldt Company|
Government shutdown and midnight deliveries
It wasn’t just the construction site itself that dealt with tight spaces and complex schedules during the project though. The four massive boilers needed for the project were delivered from Nebraska and were each built as one piece. With each trailer (carrying one boiler apiece) measuring 214 ft. in length and each boiler’s dry weight tipping the scales at 240,000 pounds, delivery of the boilers was no simple task.
Due to road weight and other restrictions, the boilers took a circuitous route through five states. Additionally, shoring work had to be done on some of the culverts along the boilers’ journey and inspections needed to be performed both before and after the boilers crossed some of the roads and bridges on the route.
Outside of Nebraska, the boilers progress was impeded in Iowa due to road weight restrictions caused by significant flooding in the state. Nearing their destination, the boilers were again delayed, this time for seven days in Minnesota when the state’s government shutdown in the summer of 2011-the boilers were stuck because Minnesota state police were working on an emergency-only basis during the shutdown and were not available to support oversized-load escorts. When the Minnesota government started churning again, so did the boilers’ journey toward their Wisconsin destination.
As planned, the boilers-then joined by police escort-arrived in Madison in the middle of the night in order to minimize traffic disruption; the vehicles carrying the boilers took up most of the road and turning corners were lengthy affairs, as the vehicles and boilers cleared traffic lights and other municipal features by mere inches.
|The Charter Street power plant conversion was completed in December 2013. Photo courtesy: The Boldt Company|
Efficiency, execution and the environment
Much of what made this rebuild a success was the elimination of waste throughout the project. Using innovative Lean processes, that idea manifested itself through the prevention of both physical waste and wasted time-especially important with Boldt personnel alone putting in more than 475,000 hours of work on the project.
The project team repurposed as many materials as it could in order to add in additional value to the project without additional cost. For example, a large amount of grating was removed when the plant’s existing boilers were taken out, but instead of throwing the grating out, it was repurposed and installed throughout the plant to add a significant amount of extra storage area.
The new boilers that were installed greatly boosted the plant’s efficiency. The previous four boilers generated 500,000 pounds of steam, versus the 900,000 pounds of steam produced by the four new, somewhat larger and more efficient boilers.
Efficiency in communication was also very important throughout the rebuild. The project’s complex and aggressive schedule required efficient communication between Boldt, AMEC, owner UW–Madison and state of Wisconsin DSF, P3M and others involved on the project. Six-week look-aheads were one tool used to achieve that. Everyone involved in the project gathered to coordinate work detailed in each look-ahead to ensure that the execution effort was well defined and understood before any work began. This reduced the need for any rework and also helped keep the project on schedule and on budget. Effective communication lines were also invaluable during the commissioning, startup and turnover phases of the project, which all required close coordination between each of the parties involved.
Environmental topics were another significant focus area of the project. Aside from changing the plant’s fuel source from coal to natural gas, the project also diverted waste from landfills by recycling at a rate of 86.8 percent, dealt with environmental remediation issues, reduced the plant’s emissions, increased its energy efficiency and set up the facility to meet new maximum achievable control technology industry regulations.
The Charter Street Heating Plant had been operating as a coal-fueled plant since the late 1950s before its conversion to natural gas. Over the years, chemicals had contaminated soil on the site and coal dust coated the entire facility. In addition, many of plant’s old control valves operated with mercury switches and the facility contained significant amounts of lead paint and materials containing asbestos. Identifying the environmental hazards and implementing appropriate related procedures early was key to successfully dealing with the project’s environmental issues.
Since it can be flammable and unhealthy to inhale if disturbed, the coal dust presented a safety concern to workers on the site. Dry ice blasting and large vacuum systems were used to physically remove the coal dust-a more effective method than sandblasting. In addition, extra fire blankets and fire extinguishers on site, as well as fire watches, were used to mitigate the fire hazard. Additional personal protective equipment, such as respirators and Tyvek suits, were also used to keep everyone on the project safe and healthy.
As for the other contaminant issues, an environmental remediation company removed contaminated soil, the old mercury control valves were identified and safely removed before any work began and another company completed asbestos abatement and the removal of lead paint.
Those and other environmental aspects of the project have led to the project seeking Leadership in Energy and Environmental Design (LEED) certification from the U.S. Green Building Council. The project is currently aiming for the “gold” level of LEED certification and would be one of the only university power plants in the U.S. to achieve it.
Jay Ehrfurth is director of project development, power and industrial for The Boldt Company. He is a registered professional engineer with more than three decades of experience in project management, project engineering, supervision and training, operations and maintenance, air permitting and quality assurance.
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