A trio of Iowa wind farms being developed by utility MidAmerican Energy Co. promises to put Mortenson Construction to the test. That is because the projects – the 443.9 MW Rolling Hills, 29.9 MW Pomeroy and 119.6 MW Laurel – are being built simultaneously.
The build-out of the wind farms began on May 16 and requires the continuous delivery and assembly of 10 Siemens 2.3 MW turbines per week until mid to late November, says Tom Budler, MidAmerican Energy's general manager of wind development, adding that 593.4 MW will bring the company's Iowa total to 1,877 MW.
‘For the state of Iowa [the three projects] are going to mean a lot for renewables,’ he says.
In fact, besides one other smaller wind project in the state, the MidAmerican Energy projects represent the lion's share of new installed capacity in the state. Taken together, this is the largest combined project ever undertaken by Mortenson.
While Mortenson is nearly complete with the design and has started the construction of foundations, access roads and underground collection, the company plans to concentrate on turbine delivery, which underscores the importance of logistics and planning.
Some of the turbines are coming from Denmark and are arriving through the Port of Duluth, while other components will arrive from Siemens' Hutchinson, Kan., facility. Some components are also arriving from the Siemens facility in Fort Madison, Iowa, by truck.
The turbines for the Rolling Hills project will require more than 2,000 semi loads of turbine components, more than 8,000 truckloads of concrete and 110 miles of crane walks, according to Tim Maag, a vice president and general manager for the Mortenson Renewable Energy Groups.
MidAmerican Energy says that all three projects need to be completed by the end of the year. To ensure that the projects stay on schedule, MidAmerican Energy, Siemens and Mortenson are using a staging area near the site to pre-load about two turbines' worth of component deliveries per day, and then it begins all over again.
The staging calls for turbines to be shipped to the local area the day before and then unloaded for the next day, says Tom Kristensen, construction executive at Mortenson Construction.
‘We've laid out the plan as best we can, and we know that the weather is going to change,’ Kristensen says. ‘And there could be transportation issues, so the better the communication, the better we can work together.’
With rolling hills and terraces, the terrain near the turbine sites is challenging. For example, there are areas where the 16,000 WA cranes cannot operate, which requires them to be completely dismantled, trucked to the site, and re-assembled across the 140 square miles of the project.
What's more, construction at the site will be tricky due to the area's wet soils resulting from heavy rains.
‘In some spots, some drying has occurred,’ Kristensen says. ‘However, there are three particular locations on the site that may never dry. On Pomeroy, it will be an issue all the way through.’