Boldt was the general contractor on this new greenfield, 300-MW, one-on-one combined cycle power plant built by Basin Electric in South Dakota. The Boldt Company was contracted by the owner to manage and perform the construction of their combined cycle plant, which included the following work scope:
- Installation of 14,000 cubic yards of concrete foundations
- Assembly of one Nooter/Erickson HRSG’s boiler
- Assembly of one GE 7FA gas turbine and generator
- Assembly of one ALSTOM steam turbine and generator
- Assembly of 18 cell air cooled condenser
- Erection of 1,500 tons of structural steel in the main utility rack
- Erection of the pre-engineered buildings:
- Generation building
- Administration/warehouse building
- Water treatment building
- Cooling tower chemical feed building
- Installation of 97,000 linear feet of piping, 650,000 linear feet of electrical cable and 161,000 linear feet of U/G and A/G conduit
- Installation of two 75 ton cranes with 80 foot span
- 400,000 cubic yards of cut and fill
- 700 drilled concrete piles
Boldt Technical Services assisted with the lift and rigging services. For example, a Manitowoc 2250 crane with Maxer, 220 ft. main boom, 130 ft. lift radius, located on a double layer 12 inch timber crane mat, lifted HRSG modules ranging from 195,000 lbs. to 334,000 lbs. The rigging also required the use of a gantry system to lift the heavier items such as the turbines, generators and main GSU transformer which weighs as much as 575,000 lbs.
One of the most important tools of any project that directly impacts both the quality and the cost is the project schedule. Boldt joined the project team six months prior to breaking ground on this project and immediately began the scheduling process. This early involvement helped to align the engineering deliverables to support the aggressive construction surge required to get critical site and foundation work in place to avoid winter impacts. The project team tracked and maintained a detailed project schedule that included over 2500 activities including engineering, procurement and construction for this endeavor.
Project Challenges and Solutions
Like any major construction project, this undertaking had many challenges. Providing a qualified work force was one of our major challenges. To provide an experienced, well trained, quality and safe work force, Boldt chose to team up with the local unionized craft trades and sourced craft labor from a four state area to meet the needs of the project. With this support we expected to provide the owner with a quality, on time, safe and on-budget project.
The owner for this project, Basin Electric, had the foresight to place equipment orders very early for the major equipment installation. While this has advantages within the schedule, it also came with the challenge to take delivery of massive quantities of material very early in the project and provide the necessary protection prior to installation. Prior to receiving all this equipment, the project site required moving over 400,000 cubic yards of soil to prepare the 70 acre site for construction. This included the 15 acres required for laydown of the major equipment. During this critical stage of developing the site, we experienced 100 year rain events which required creative drainage solutions to keep the work progressing. The effort to mitigate the late start and overcome the weather events proved a success as the equipment started to arrive and filled the laydown area as it was being completed.
Other challenges that were expected were winter weather conditions. Plans were in place to deal with frost removal, providing and maintaining concrete temperatures within specifications, cold working conditions, equipment maintenance and snow removal for not only the site but the several miles of county roads that we were responsible to keep open to provide access for construction personnel and material deliveries. Most of all, maintaining a safe work environment was our ultimate goal.