Optimizing Oak Creek
September 1, 2007
The year 2010 will be a huge year for the Oak Creek coal-generating power plant in southeastern Wisconsin--both physically and figuratively. By that year the Oak Creek Power Plant will have two new 615-megawatt generating units, a new coal storage facility, a new water intake and cooling system, and a new 550-foot chimney. It’s all part of Wisconsin Energy Corporation’s (We Energies) “Power the Future” campaign to meet increasing energy demands with more efficient, reliable and environmentally sound power plants. At a cost of $2.2 billion, it is the biggest private construction project in the state’s history, and will employ 2,500 craftworkers at peak of construction.
At the helm of the project is Bechtel Power Company, a global engineering, construction and project management company based in San Francisco. It is not only Bechtel’s largest-ever lump sum turnkey project, but it requires the company’s surveyors and engineers to triumph over extraordinary engineering challenges, says Francis Canavan, Bechtel’s public affairs manager.
To support the mechanical complexities of the Oak Creek project and to give field crews the connectedness and efficiency they need to meet deadlines, Bechtel chose integrated survey and 3D machine control technology from Trimble (Sunnyvale, Calif.) for its technological foundation.
“The Trimble GPS equipment and S6 Total Station instrument are a tremendous help,” says Mark Anderson, a Bechtel field engineer who has been using Trimble equipment on construction sites for 12 years. “With this technology as our foundation, all of our construction pieces to date have fit.”
The Case for Oak CreekHeadquartered in Milwaukee, We Energies oversees four natural gas-fueled stations, six coal-fueled stations, two nuclear units, 13 hydro dams and two wind turbines, with 88 new wind turbines under construction. The company serves more than 1.1 million electric customers in Wisconsin and Michigan’s Upper Peninsula and more than 1 million natural gas customers in Wisconsin. Twenty percent of that energy production capability comes from the Oak Creek Power Plant.
Situated 10 miles south of Milwaukee and sprawled out over 1,000 acres of land along the shores of Lake Michigan, Oak Creek contains five generating units that combined produce more than 1,150 megawatts of electricity. One unit alone measures approximately 300 feet long, 200 feet wide and 280 feet high. Able to store 900,000 million tons of coal onsite (think 900,000 million one-ton trucks), anywhere from 5,000 to 10,000 tons of coal will run through its 20 pulverizers every day, each of which can crush 33 tons of coal per hour. Around 700,000 gallons of Lake Michigan water are used every minute to convert exhaust steam from the turbine back into water for reuse and then returned to the Great Lake.
According to Barry McNulty, We Energies’ media relations manager, Oak Creek was a natural candidate to put We Energies’ “Power the Future” plan into action. It is an existing brownfield site (the company wouldn’t need to develop on green space) and has access to cooling water, and existing transmission and rail networks. Launched in 2000, the plan’s overall objective is to both reduce emissions systemwide by more than 65 percent while increasing electricity generation by 50 percent by 2013. Emissions at the Oak Creek site will be reduced by more than 60 percent. With approvals in place, Bechtel began construction in June 2005; to date, the crews are on schedule for its first set of deliverables.
That efficiency, says Bechtel’s Lead Project Surveyor Doug Wooley, has been enhanced by their use of Trimble’s Connected Site approach, a technology model that seamlessly manages diverse data streams from different tools, processes and techniques to help users reduce rework, increase productivity, utilize assets more efficiently, accelerate design updates and improve planning cycles.
“We are able to monitor and manage individual project areas in real time, giving us the flexibility to quickly respond to design changes,” Wooley says.
Managing the MassivenessBechtel assigned Hoffman Construction Company, based in Black River Falls, Wis., the preparation of the construction footprint for Oak Creek’s expansion, an immense earthworks project that began in July 2005.
Crews had to move approximately 6 million cubic yards (4,587,329 cubic meters) of earth--enough to build the Great Pyramid at Giza almost twice--to create the construction footprint. All of the dirt remained onsite and was used to create berms to screen the neighbors and community from construction activities.
The massive operation was brought down to manageable size with the aid of advanced GPS and 3D grade control technology that Hoffman Grade Foreman Allen Johnson says enabled crews to stay connected in the field and with Bechtel surveyors. With both Hoffman and Bechtel teams using comparable Trimble GPS equipment, the same controller units and the same Trimble construction data prep software, supervisors and managers could streamline field and design data integration to better plan work schedules and ensure operations were running efficiently. Improved efficiency began, in fact, before their Caterpillar (Peoria, Ill.) graders even made their first cut, says Dan Labus, Hoffman project surveyor.
Because Bechtel provided Hoffman with initial ground control and a topographic survey based on Trimble technology, surveyors could readily integrate that data into their Trimble TSC2 Controller for their Trimble SPS780 GPS Site Positioning Systems. This provided them with the initial information to accurately lay out the project parameters. Bechtel also electronically sent the first set of 3D design models, which were imported into both Trimble’s Terramodel visualization software and SiteVision Office data prep software. These models helped workers to visualize and analyze the site and to prepare the data for use in the field with Trimble GPS rovers and Trimble GCS900 Grade Control Systems. The ability to understand the site topography and the overall view of the end product at the outset of the project allowed Hoffman personnel to better map out high priority areas, delegate equipment and assign crews before their Caterpillar D6 and D8 bulldozers and 14G and 140H graders put a blade in the ground.
Adding Machine ControlTypically, Hoffman grade foremen have relied on their rovers to lay out their projects and verify grade accuracy and position. The Oak Creek project introduced them to machine control in the form of the Trimble GCS900, a 3D earthmoving grade control system that allows operators to view design surfaces, grades and alignments inside the cab. Though the initiation of the Trimble GCS900 ushered in new field techniques for Hoffman crews, Johnson says they were welcomed changes.
“Normally, I use a rover to lay out stakes and verify grade,” he says. “With grade control there is a lot less staking involved, freeing you up to better manage and control a wider area. One foreman could take care of several different grading operations with the confidence and security that the grade-control dozers equipped with Trimble Grade Control Systems were guaranteeing our needed accuracy. The rovers then became like a second supervisor.”
Both the GPS data and the data from Hoffman’s five machines with grade control were continually integrated into the Trimble TSC2 Controller throughout the day, allowing supervisors to better monitor work progress and operators to see the bigger picture of the overall project. The integrated, streamlined data handling coupled with real-time field data management also enabled Hoffman and Bechtel to quickly adapt to design changes and revise work priorities with confidence.
“The ability to integrate our field and design data in real time enhanced our superintendents’ ability to plan for the next day or next week with much more confidence,” Labus says. “We could also keep everyone--supervisors, laborers, operators and Bechtel personnel--better informed.”
Connectivity for CrewsConnection and integration have also been operative words for Bechtel’s crews since arriving on the scene in August 2005. Because they could readily interface with Hoffman’s field data, Bechtel teams wasted no time getting in the dirt. To ensure all project contractors would benefit from the same efficiency, they used their Trimble 5800 GPS rover unit to create a single reference station network for site control and calibration to provide a unified coordinate system. From there, the daily ritual began of updating the design and fieldwork data, delegating work assignments, performing layouts and setting control points, verifying craftwork, and performing both topographical and structural as-built surveys.
Faced with the need to build two new boiler units--one to be operational in 2009, the other in 2010--along with a new coal handling facility, water intake system, chimney and 16 miles of new railway track, the magnitude of the project set in quickly. Bechtel’s Anderson says that the integration of innovative survey technology and software has helped them to build and maintain a well-orchestrated assembly line of mini projects.
“The GPS and total station equipment has helped us to be far more productive and cover a lot more ground with fewer people,” he explains. “The GPS allows us to go anywhere onsite at a moment’s notice and get to work immediately. The survey controller software has enabled us to cut our calculation time for layout coordinates by seventy-five percent. And having both data sets integrated into one controller allows us to quickly verify the quality of our work, monitor our progress and adapt to frequent changes.”
The latter asset has been particularly beneficial to Bechtel in meeting the challenges presented by the new coal handling facility.
The coal storage shed will be supported by a network of more than 14,000 feet of conveyor belts--stretching about 54 to 84 inches wide and up to 1,300 feet long--that will feed coal into the two boiler units. To position the new facility and the conveyor system, surveyors used the cable-free Trimble S6 Total Station along with the Trimble TSC2 and TCU controllers to set up a survey monument baseline around the site. When they began to lay out the foundation for the facility, they hit their first challenge.
The entire coal-handling area is set askew, so traditional staking where northing, easting and elevation coordinates are used (which would normally require surveyors to calculate every point needed to lay out any footing or bolt that will be placed along that line) was not feasible. However, functionality in the Trimble Survey Controller software not only allowed surveyors to handle the facility’s angles, it erased the need to physically calculate the significant number of points needed to accurately lay it out, Wooley says.
“With the reference line function in the Trimble software, you only need to give it a beginning point and an end point and it will automatically calculate that line and stake it out for you,” he explains. “For example, I can have a start point on the ground and an end point 1,300 feet away and several hundred feet in the air. It will automatically calculate that line and provide you with the elevation of any point along that line. I can then lay a footer at a specific station (distance point) along that line and it will automatically calculate its slope and elevation.”
After prevailing over the layout, surveyors then discovered that mounting some of the conveyor system would take ingenuity as well, particularly for the long conveyor belt that will attach to the existing plant at an elevation point of 300 feet. Placing that belt required the installment of a 21,000-ton crane with a 500-foot boom. However, the crane sits 300 feet from where the conveyor belt needs to be mounted so surveyors had to lay out the position of the crane (it needed to be built onsite) and then stake out piles to support the crane as it maneuvered its heavy load weight. Teams drove piles for four weeks to support the crane.
Despite these engineering adventures, Bechtel is still on schedule to deliver the completed coal-handling facility--the first project deliverable--to We Energies this fall.
Small Details in the Big PictureBy the end of 2007, the Oak Creek plant will have its new water intake system, another element that has required a few extraordinary engineering feats. The system will provide more than 2.2 billion gallons of cooling water per day (that could fill approximately 3,332 Olympic-sized swimming pools) to both the new and existing plant. To fulfill this massive distribution system, Bechtel teams have overseen construction of four 12-foot diameter steel-lined intake shafts drilled about one mile offshore Lake Michigan. These down shafts will then connect to a 27-foot-diameter intake tunnel that is being bored about 200 feet below the bed of the lake. The tunnel boring was completed in February 2007.
Parallel to the focus on these auxiliary systems is the dedicated effort to the primary piece of the project, the new power block. Concentrating initially on Unit 1, in January 2006 Bechtel teams used their Trimble 5800 GPS rovers to lay out the foundation work and the Trimble S6 Total Station to lay out the foundation corners for fabricating the rebar matte, erecting walls and placing the top rebar matte. Once the matte was placed, they used the Trimble S6 to lay out control lines to place bolts, conduits and piping for the craftworkers to lay their commodities and then performed as-built surveys to verify their correct placement. Concrete was then poured and the Trimble S6 Total Station helped to set grid lines to ensure that laborers put columns down in the proper location. In May 2006, steel erection began on Unit 1 and by March 2007 it had reached its full height of 280 feet. Construction on Unit 2 continues.
Though crews can now begin to see these two units take their massive shape, Bechtel surveyors were initially consumed by the small elements: the bolts.
“Bolts are one of our most critical elements on a project like this because if a bolt pattern is off, even by one-eighth of an inch, none of the pre-fabricated steel fits,” Wooley says. “Turning specific angles manually to lay features out is really laborious, but the Trimble S6 turns angles on its own. To lay out bolt patterns, we would input into the controller the point number for a specific bolt, and the instrument would automatically turn to where it should be.”
With the Trimble S6’s Direct Reflex (DR) technology that allows surveyors to take measurements at great distances without a prism, Bechtel surveyors could more easily handle the fluctuating heights of targets and measure a multitude of diverse surfaces such as conveyors, stockpiles and the ground. Wooley says that feature was particularly beneficial when constructing the new 550-foot chimney for both units because they were able to shoot high-elevation points and verify their accuracy from the ground.
Controlling the ConcertAnchoring these multiple streams of diverse activities are the Trimble TSC2 and TCU controllers that serve as the data hub to enhance productivity in the field and provide more robust back office support in updating design or drawing files. Integrated with Trimble Geomatics Office and Terramodel software, personnel can generate contour drawings and update fieldwork progress and then upload the relevant data files to the controllers to ensure teams are working with the most up-to-date information available. The ability to monitor all the different operations through the data collectors helps better direct site tasks by superintendents and stay connected to all the various pockets of work areas.
As they continue to move through challenges, Wooley says the ability to effectively and efficiently manage all the varied construction elements can be attributed to the Connected Site concept of Trimble technology.
“GPS dramatically decreases the amount of points and the time required to generate points for layout,” he says. “The Trimble S6 allows us to be very quick, mobile and precise. And the capabilities of the survey controllers enable us to readily pull up data and manipulate it in the field, greatly increasing our efficiency and keeping us on schedule.”
To view aerial shots of the Oak Creek Power Plant, visit We Energies' Power the Future website at www.powerthefuture.net/projects/ocpp_constructphotos.htm.