At the Tuesday, March 22, O’Brien County Board of Supervisors meeting, O’Brien County engineer Tom Snyder reported results of a meeting he’d had with Mortenson Construction Company project managers about when work on the next O’Brien County wind farm would begin.
As part of MidAmerican Energy Company’s (MEC’s) Wind X expansion program announced on May 1, 2015, construction of its 250 megawatt (MW) O’Brien Wind Energy Project in O’Brien County is imminent. The other wind farm in the Wind X initiative is the 300 MW Ida Grove Project. Both wind farms are developed by Invenergy, built by Mortenson and transferred to MEC for operation and ownership.
MEC filed with the Iowa Utilities Board (IUB) a request on April, 30, 2015 asking the Board to consider and expedite the Wind X advanced rate making principles. In its Aug. 21, 2015 order approving the wind farms and rate making principles, the IUB set a cost cap at $1.61 million per MW. Initially, MEC had proposed a $1.638 million per MW cost cap figure.
The IUB said in its order, “This lower cap reduces the risk to customers and provides an incentive to MidAmerican to keep costs low while still providing a contingency for unanticipated changes that could increase costs above that shown by MEC’s economic analysis.”
By using the IUB $1.61 million per MW cost cap figure and multiplying it by the 250 MW O’Brien nameplate rating; this shows the net acquisition cost of this wind farm could approach $402,500,000. Adding both the 500 MW Highland and 250 MW O’Brien project costs together means an estimated investment of $1,223,200,000 that MEC will have made to build 750 MW of wind energy in O’Brien County.
When the 104 wind turbines are fully assessed at 30% 7 years after they are commissioned, the yearly property tax revenues generated from O’Brien County’s second wind farm could add another roughly $2,600,000 to county coffers.
Snyder relayed the information that Mortenson’s construction managers reported at their recent meeting. “We did meet with Mortenson about the wind farm. They gave us a schedule and timeline of their planned construction activities showing what they are looking at,” said Snyder.
The work activity schedule shows that Mortenson plans to start preparing their haul roads, the wide radius turns, access road driveway entrances and turbine site access roads on April 6th. Work on excavating the first of the 104 turbine foundations will follow 10 days later on April 14th. Mortenson plans on pouring the last of the cement foundations around July 12th.
“Mortenson will set up the portable concrete plant just off Highway 18 two miles east of Sanborn,” Snyder continued. “I think the nice thing about where the cement plant will be at is that most of the loads will use Highway 18 and then turn off onto gravel roads wherever they need to. It’ll probably help our roads out a lot.”
Turbine component deliveries aren’t scheduled to begin until after the foundation work is finished. Mortenson plans to start erecting the turbine sites on July 25th and finish assembling the last sites around October 26th. For each turbine site, 8 over-sized or over-weight loads must use the haul roads. That’s over 800 loads in all. The 312 blades will come from the Siemens facility at Fort Madison, Iowa and the 104 nacelles will come from Hutchinson, KS.
“Mortenson people said their intent is to build turbine sites west of Sanborn and north of Highway 18 in Franklin Township. They’ll work their way east and then build sites in Lincoln Township before building the last sites in Center Township southeast of Sanborn,” Snyder reported.
Snyder said Mortenson’s plan is to bring in four large Manitowoc cranes like they used last year. Two smaller cranes lift the bottom two tube sections and attach the three blades to the hub then move on to the next site. Two giant Manitowoc 16,000 cranes with 300 feet of boom will lift the top tube section and the 191,000 pound nacelle. The hub and blades are lifted as one assembly and attached to the nacelle.
Trenching in the extensive 34,500 volt underground collection system from one turbine to the next and then back to the wind farm interconnection substation will begin on May 14th. Completion of all underground power collection circuits is expected to occur around October 1st.
Work on building MEC’s MVP-3 switching substation began about a year ago when EC Source and its subcontractors began grading the new 345,000 volt facility. The switching substation will tap off of an existing MEC transmission line that was built in the 1960s. EC Source excavated and poured numerous cement foundations for the overhead high voltage structures required for this complex facility.
From this new switching substation, plans called for building a new 345,000 volt AC transmission line east to another switching substation in Kossuth County near Burt where the power line heads south to an existing MEC substation in Webster County. Most of the 650 steel transmission poles along the route are in place and construction crews have been stringing high voltage cables over the winter months.
Meanwhile, the O’Brien County Board of Supervisors approved and issued a construction permit for the O’Brien Wind Energy Project in August of 2015. MEC and Invenergy officials said at the public hearing that construction on the new wind farm interconnection substation would now be going on concurrently with the switching substation, largely because EC Source crews were already on site.
Snyder reported that a heavy modular electrical switchgear building that connects the wind farm onto the high voltage grid was due to arrive on Thursday, March 24th. Snyder said earlier that he has heavy load permits indicating that two large power transformers will soon arrive at Hartley by rail and then moved to the substation.
“It looks like Mortenson hopes to be done with everything by around November 1st,” Snyder reported to the supervisors last Tuesday.
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