By Joe Stange, Helmkamp Project Manager
Stricter EPA regulations on fossil fuel power plants have led some utilities across the country to close coal-fired plants. Dynegy, a provider of wholesale power, capacity and services to utilities in six states, has instead invested in cleaner operations to reduce emissions at eight of their coal-fired plants in Illinois.
A major part of Dynegy's investment is being made at their 1,761 MW coal-fired Baldwin Station in Baldwin, Ill., where the company is installing a selective catalytic reduction system and a dry flue gas desulfurization project to reduce sulfur dioxide and particulate matter.
Once the new systems at Dynegy come online, the plant's sulfur dioxide emissions are expected to be the lowest of any coal-fired units in the state. Combined with Dynegy's earlier conversion to low-sulfur coal, these environmental investments will significantly reduce particulate matter and cut sulfur dioxide and mercury emissions by about 90 percent.
For the civil work on the dry flue gas desulfurization project at the Baldwin plant, Dynegy turned to Helmkamp Construction Co., a firm that had already been on-site for the previous 13 years. Helmkamp prepared the site, performed excavations for underground mechanical and electrical installations, and installed foundations for the baghouses, dry scrubber equipment, duct supports, support buildings, utility racks and silo foundations.
Helmkamp's 36-month, $45 million project was complex and challenging, requiring precise coordination and communications between their team and Dynegy staff as they worked within the fully operational power plant. The team also faced the challenge of a tight construction site, wedged between the plant and Baldwin Lake with little room for equipment or staging. Helmkamp constructed and maintained a haul road, which all of the contractors on the job used on a daily basis to get materials from a laydown area to the jobsite nearly half a mile away.
To sequence the installation, Helmkamp integrated the drawings for the electrical duct bank, fire protection, stormwater and underground piping into the foundation layout. This made it easier to visualize where these systems would be routed and allowed the team to install most of them while the excavation was open for the foundation installation, saving time and money.
Much of the foundation work was done during two cold, snowy and windy winters when setting the foundation and pouring concrete presented particular challenges. Because wind and ice can interfere with traditional survey markers and string lines, Helmkamp chose newer technology to prepare a precise layout of the site.
|Dynegy installs a selective catalytic reduction system and dry flue gas desulfurization unit at its 1,761 MW coal-fired Baldwin Station. Photo courtesy Helmkamp|
They used a Robotic Total Station, an instrument that yields exact measurements of distance and location, and Trimble LM80 desktop software to establish exactly where to place the 4,000 anchor bolts and 2,500 auger cast piles required for the project. As revisions were made, Helmkamp entered the data into the desktop model and then transferred it to the field for immediate implementation. By using the Robotic Total Station, the team achieved an impressive record of zero re-dos in the field.
The Robotic Total Station also was used to accurately and efficiently place the auger cast piles, which were set at an average depth of 60 feet. Even after the foundation was laid, the technology allowed the team to easily reestablish the location of piles at later points in the project.
During project excavations, the construction team discovered numerous underground obstructions that had not been shown on the drawings. Although this was the largest delay issue encountered, Helmkamp minimized delays by working directly with plant personnel to identify and relocate or remove these items.
Helmkamp poured approximately 30,000 cubic yards of concrete at Dynegy Baldwin. The lime storage and waste ash silo foundation required the largest single concrete pour, with three pump trucks in a limited access area simultaneously pouring a total of 2,200 cubic yards of concrete. The second largest concrete pour was approximately 1,300 cubic yards.
Helmkamp performed 280,000 man-hours on the Dynegy Baldwin project. They received a Zero Injuries Award from the National Maintenance Agreements Policy Committee for 57,321 injury-free self performed man-hours on the job in 2008 and the same award for 102,800 injury free work hours in 2009.
Power Engineerng Issue Archives
View Power Generation Articles on PennEnergy.com