Fabric structures create massive hydro-electric storage facility
The world’s need for energy is overwhelming, and fulfilling that need is obviously far from easy. It is no wonder that so many different energy supplies—minerals, oil, solar, wind and water—are routinely tapped into, as no single source would be capable of sustaining our lives as we know them. Whether it involves a long-established resource or a new technology, significant effort and financial investment almost always are required to extract and utilize a given energy pipeline.
Building the infrastructure to capture and sustain certain energy sources is a daunting task in itself. Getting the necessary people and plans to come together and make a project flow smoothly and on schedule is another matter entirely.
When Manitoba Hydro, in conjunction with four Manitoba First Nations, put up the bid for its new Keeyask Generating Station on the lower Nelson River in northern Manitoba—a project expected to take approximately six years to complete—a group of contracting companies recognized how formidable the task ahead would be, and formed a joint venture to tackle the $1.4 billion job.
Bechtel, Barnard Construction and EllisDon converged to form BBE Hydro Constructors. The team is responsible for constructing a seven-unit powerhouse, building 25 km of earthen dam or dike structures, and excavating a significant amount of rock. The contract also calls for electrical and mechanical work, a concrete spillway, and construction and removal of temporary cofferdams. Once completed, the generating station will provide 440 gigawatt-hours of hydroelectricity annually. It is expected that the plant will begin generating power in 2019, with final completion slated for 2020.
A project of this magnitude requires a lot of manpower and equipment. Furthermore, the site of the Keeyask Generating Station is in an extremely isolated and remote area, about 175 km northeast of Thompson, MB, and 30 km west of Gillam, MB. The combination of the location and the need for numerous machines meant that BBE would need temporary maintenance and storage facilities on site for the duration of the project.
“Given the climate in the area and the overall scope of the job, we knew we would need buildings on location to service all the equipment and to provide general warehousing of materials,” said John Lehman, a superintendent for Barnard, which has extensive dam-building experience as part of its construction and engineering portfolio. “We solicited bids from building suppliers for two structures based on previous projects where similar sized equipment was used.”
The specification parameters for the buildings included having enough room to accommodate large construction vehicles, as well as the space to operate a large crane inside. The most important criterion was that the building interior needed to be kept above freezing temperature at all times.
“We needed to have the buildings insulated,” Lehman said. “We have our in-floor heat and radiant head inside, but the structures themselves required a certain R-value to maintain warmth in the winter months. A lot of the temporary structures in the region are fabric structures, so we mainly looked at those types of buildings, though we did consider a metal building as well.”
The storage facility has 18-ft ceilings with a peak clearance of nearly 48 ft to ensure plenty of space for shelving and large equipment. Insulated commercial steel coil doors and insulated service doors allow passage for equipment and personnel in and out of the storage structures, which are also heated to keep the interior above freezing temperatures.
Legacy Building Solutions emerged with the most competitive bid and was selected by BBE to supply two fabric buildings to support the Keeyask station construction process. To meet the established environmental parameters, Legacy added R-30 insulation with a 7.5-ounce interior fabric liner to each structure to combat the cold.
The buildings were designed using the company’s rigid-frame engineering concept, where structural steel I-beams are used instead of the open-web truss framing often used in the fabric building industry. Among the advantages of the solid beam design are straight sidewalls that maximize the usable space inside and the capability to fully customize every aspect of the building plans.
The rigid steel frame for each BBE fabric building was finished with an oxide primer for enhanced corrosion protection. Outfitted to deal with potentially difficult weather conditions, the structures each feature 3-ft overhangs with airflow in the soffit, along with icebreakers to prevent accidents or injury from snow and ice sliding off the roof. A gutter and downspout system also was added to both sides. Additionally, each building was rated to withstand 2.5-kilopascal (kPa) ground snow load and 0.39-kPa windspeed.
The vehicle maintenance building, also known as the mechanic repair shop, measures 80 by 160 ft and is used for daily maintenance or periodic service on a variety of trucks and equipment. Machines at the larger end of the spectrum for the job include huge excavators and Caterpillar 777 trucks for hauling rocks.
To account for the vehicles and other equipment coming and going from the fabric structure, Legacy equipped the building with seven large TNR rubber roll-up doors. The building also has 12 insulated service doors providing access for personnel and small equipment. The durable roof and sidewalls of the vehicle repair shop are comprised of Nova-Shield 15-ounce, flame-retardant polyethylene fabric.
The second building, measuring 120 by 150 ft, is a warehouse holding a plethora of materials and equipment to support the construction of the powerhouse and the dam structures. Along with vehicle parts and construction components, the building contains lumber, scaffolding and a variety of small equipment.
Designed to provide ample room for shelving and forklift runways inside, the building’s ceiling height is 18 ft, 3 in. high at the sidewalls, spanning to a peak clearance of 47 ft, 11 in. The structure has a pier and curb foundation 1 ft above grade, and provides edge-of-dock 25,000-lb load capacity levelers with a 78-in. plate, 15-in. bumpers and a 27-in. mechanical flip leveler. Personnel and equipment can enter through seven insulated commercial steel coil doors or 10 insulated service doors.
“Due to the overall project timeline, the buildings had to be constructed in the dead of winter,” Lehman said. “So there were certainly environmental constraints with the extreme cold, but we were able to handle that challenge. Legacy sent a technical representative to assist the local crews, and the installation went well. We had a great working relationship with Legacy throughout the entire process. They supply a very high-quality fabric structure, and we’re certainly pleased with what we’ve seen from the buildings thus far.”
Although the buildings were designed and constructed specifically for the Keeyask Generating Station project—just as BBE Hydro Constructors was formed for this single job—there is the possibility the buildings will continue to be used in the future. They can be relocated for another job or put up for sale to another company. Since the buildings could be applied to virtually any industrial application, from government to mining to warehousing, they likely will find a meaningful second life after Keeyask.
For now, BBE is happy with the structures’ role in simplifying critical aspects of its massive operation. And in the complex world of energy production, something relatively easy is more than welcome.