| Gulf Coast Wind Farm Construction: Case Study |
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The Texas Gulf Coast is a heterogeneous region spanning over 350 miles from Louisiana to Mexico. The Gulf Coast exhibits a great diversity of geography and climate. Depending on where you are along the coast, you may find yourself in a wetland, desert, chaparral, urban center, commercially viable farm or ranch land, or the beach. This geographic diversity and proximity to major population centers make the region an especially valuable source of wind power. This also means, however, that each wind project brings its own unique set of challenges. The following case study focuses on the construction challenges of Iberdrola Renewables’ Peñascal II Wind Project, which is being built by Mortenson Construction. Peñascal II boasts some of the most challenging conditions in wind power facility construction to date. From extreme heat to sand to geographical challenges, Peñascal II is testing some of the most experienced construction professionals in the industry. According to Tim Maag, VP and general manager of Mortenson Construction’s Renewable Energy Groups, “Peñascal II has required that [we] provide more innovation and tailor-made solutions than any other Iberdrola Renewables-Mortenson wind power project. This is largely because Peñascal II combines typical Gulf Coast wind power construction challenges with all the safety and logistical concerns of an extremely remote location.” The remoteness of Peñascal II was one of the first hurdles the team had to overcome. Peñascal II is located on approximately 194,000-acre ranch near Sarita, Texas, which is on the sparsely populated south end of the Texas Gulf Coast. The nearest major airport is in Corpus Christi, Texas, about two hours north of Peñascal, and the nearest highway is about 45 minutes from the site. The remote location has required construction of more than 30 miles of access roads around mesquite trees and live oak motts to make the site accessible for utility scale wind power construction. The team also had to install its own electrical generators to power construction equipment and the on-site Peñascal II office complex, which houses six office trailers for five different companies and one mobile testing lab. For the first two months of the project, computers and telephones were connected through satellite. Housing has been a major issue, requiring some workers to commute more than 70 miles to the site. The Peñascal II site typifies Gulf Coast region wind farm construction in that it displays a number of significant safety risks. During construction there may be up to 200 personnel on site, and as team member safety is top priority; a certified Emergency Medical Technician is located on site to serve as a first responder in an emergency situation. Venomous snakes and spiders in and around the project site pose a potential hazard to workers. With temperatures reaching into the 100s during the summer, special precautions must be taken to avoid heat related illnesses. As an example, the project team placed concrete for foundation installations primarily during night time hours. Construction teams continue to work multiple shifts around the clock, bringing in different crews when necessary to accommodate rapidly changing wind and weather patterns. The particular geography of the Peñascal II site has also presented interesting construction challenges. The project site is located on a mixed terrain comprised predominantly of large, moving sand dunes and chaparral close to sea level. Sandy coastal land presents a host of complex challenges for wind power construction. High winds, at times, make it difficult to move equipment, stall work, and increase safety hazards. Special safety glasses were issued with foam lining and face masks since blowing sand impairs visibility for workers. The project team had to build passing lanes on access roads because vehicles would sink into the sandy shoulders. Crane trucks required the use of additional crane mats to create a bridge over the soft soil. Aggregate had to be shipped in by rail, about 180 miles from San Antonio, since the material is not available locally. In addition to soil constraints, the area’s high water table required specially designed above ground, inverted-T foundations. Whereas a typical wind turbine foundation is excavated five to seven feet below the ground, about two feet below the ground was excavated at Peñascal II and then backfilled to create a mound condition. This created a higher final grade elevation that solved the high water table problem, but then presented new challenges for crane pads and offloading of construction materials. The proximity to the actual Gulf of Mexico also presents environmental factors typical of a coastal installation site. The salt air from the Gulf surf accelerates the rusting of any exposed metals. A large storage tent was required to limit the exposure of small, loose metal parts prior to installation. The Gulf is also famous for its strong hurricanes and other tropical storms that generate significant amounts of wind. Since Peñascal II is in a wind storm zone, a Hurricane and Flood Preparedness Plan was prepared that explains how the site will be prepared and evacuated if an emergency weather event should occur. While this article has focused on the many challenges associated with building on the Texas Gulf Coast, the region will continue to see future wind power development. Steve Cook, construction executive for Peñascal II adds, “Building wind power facilities on the Gulf Coast is as rewarding as it is challenging. Peñascal II has given our experienced team a chance to demonstrate creativity and problem solving, and in this case, we can be especially proud of each success.” Mortenson Construction Iberdrola Renewables
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The challenges of building the Peñascal II Wind Project