Converting a piece of remote farmland to a 343-megawatt wind facility requires planning and coordination to give Lower Snake River Wind Energy Project strong footing.
Converting a portion of remote farm land to a fully functioning, 343-megawatt (MW) wind facility has its share of challenges. But Burns & McDonnell and Puget Sound Energy (PSE) are making it happen on a fast track.
PSE was the first utility in the Pacific Northwest to bring wind power, on its own, to its customers. It already has two large wind farms combining to generate 430 MW of electrical power. In late August 2009, Burns & McDonnell began providing development assistance and design for a third wind farm that will nearly double the utility’s wind portfolio.
The Lower Snake River Wind Energy Project in southeast Washington will generate 343 MW of wind power, enough to meet the electricity needs of more than 100,000 homes. Completion of the first access road in June 2010 marked the culmination of months of fast-paced, detailed and coordinated work.
“One of the things that Burns & McDonnell did was assemble all the information related to the project in the same place — who owns the land, permitting corridors, the microwave beam paths, existing roads, etc.,” Doughty says. “A constraints map with layers allows you to look at all the aspects. By tuning into these layers, you can examine the site. That has been a very useful document for us.”
A project the size of the Lower Snake River Wind Energy Project would be complex anywhere — but in this case, the location presented particular challenges. “The same conditions that make a site good for wind generation can be a harsh environment for transmission lines and structures,” says Robert Healy, Burns & McDonnell project manager.
Conditions at the site include freezing fog, rocky terrain with steep hills and, of course, high winds. Through the rugged topography, roads had to be designed 34 feet wide to walk the cranes between turbines and to carry rigs hauling 165-foot-long rotor blades, sections of towers nearly 263 feet tall and numerous other components — about 12 trailer loads for each of the 149 turbines. The shorter the roadway and the less cut-and-fill, the lower the costs — but the curves couldn’t be too sharp or the grades too steep for the enormous tractor-trailers and cranes to negotiate.
“A lot of design elements were constrained,” Doughty says. “There could be nothing steeper than an 8 percent grade, and we wanted the roads on the south side of the hill.” As project manager for PSE’s earlier wind farm projects, Doughty knew that snow and ice accumulation on north-facing slopes can be a problem for winter access.
Washington winters can also load transmission lines with up to three inches of rime ice. Monopole structures supporting transmission lines have previously shattered and fallen due to the extreme ice loading. These extreme conditions required transmission line structures to be upgraded relative to previous projects. H-frame wooden poles with heavy-duty fittings are needed to withstand the harsh conditions.
Communication and Coordination
As detailed design progressed, design teams used SharePoint to share drawings and documents with PSE so that each part of the design could be reviewed as it was issued. Weekly conference calls and monthly face-to-face meetings between design leads and management teams also ensure that information is transmitted on a timely basis. Healy travels to Seattle bimonthly to coordinate the project design with the PSE project team and to keep communication and coordination smooth.
At one point, to verify constructability of the planned transmission line and avoid cost escalation during construction, Healy and Doughty, along with a construction contractor and several other members of the team, scrambled up and down eight miles of hills — some with nearly 60-degree inclines — to trace the path of the proposed transmission line.
Doughty says PSE chose Burns & McDonnell partially because it could bring a complete range of capabilities, including the ability to perform wind resource studies, research microwave beam paths, perform civil design and provide tools such as the web-based constraints map.
“We were trying to get one company that would be able to provide all the services we would need,” Doughty says.
In tandem with PSE, Burns & McDonnell specialists in electrical engineering, transmission system design, program management, civil engineering and other areas are meeting the project challenges, small and large.
No Cow Left Behind
For example, the road design includes what will be a future county road. For Burns & McDonnell engineers familiar with design of all kinds of roads from interstate highways to local intersections, meeting the specifications for the county road was no problem. But there was a slight complication.
“There are 28 different organizations and individuals that own land on the project. We try to accommodate them as best as we can,” Doughty says. “In this case, a landowner wanted to be able to move his cattle across the public road.”
For more information, contact Robert Healy, 816-823-7102.