Since opening Feb. 28, 1995, Denver International Airport (DIA) has become the U.S.' sixth busiest airport. More than 58.3 million passengers traveled through the airport during 2016, making it one of the most active hubs in the world's aviation market.
Located on 33,531 acres, DIA has the most land area of all U.S. airports and offers nonstop service to 187 destinations throughout North America, Latin America, Europe and Asia. Owned and operated by the City and County of Denver, DIA is Colorado's primary economic engine, generating more than $26 billion annually.
In October 2011, the South Terminal Redevelopment Program was launched to enhance the airport's competitive standing as a leading global airport and increase overall passenger and aircraft-handling capacity. The $544 million new construction project encompassed building a new Westin hotel with a conference center and a Public Transit Center, including a commuter rail train connecting the hotel to the Jeppesen terminal.
Black Roofing Inc., Boulder, Colo., was selected to install all waterproofing membrane assemblies and coatings for the massive project.
Scope of work
In May 2014, Black Roofing began its work on The Westin Denver International Airport hotel and Public Transit Center.
Westin hotel
The 433,000-square-foot Westin hotel has 14 floors and 519 guest rooms and features a grand lobby with views of the mountains and airport runways, a restaurant, gym, fitness center and indoor pool. The hotel's conference center has 12 meeting rooms and three ballrooms housed under 16,000 square feet. The saddle at the hotel's center is designed to maintain sight lines to the terminal's signature peaked roof.
At the hotel's 97,000-square-foot level 5 plaza, Black Roofing workers installed a hot fluid-applied, fabric-reinforced American Hydrotech Monolithic Membrane 6125® assembly, including custom-tapered extruded polystyrene insulation and layered drainage mats. An expansion joint cover assembly with Wabo® ThermoShield (a fire barrier) also was installed between the plaza and existing terminal.
At the hotel's indoor pool on level 11, workers installed 4,000 square feet of the American Hydrotech Monolithic Membrane 6125 assembly. About 2,000 square feet of the hot fluid-applied membrane assembly also was installed at the grade-level planters at the Westin hotel's porte cochère (a covered entrance large enough for vehicles to pass through).
Extensive detailing was required to accommodate hundreds of penetrations for the pool mechanic piping and equipment. When the perimeter pool drain was installed, more than 100 penetrations were drilled to support the drain, which all had to be reflashed, including custom-made stainless-steel counterflashings and fabricating and installing a mile-long termination bar.
In addition, workers applied a NEOGARD® AUTO-GARD® FC polyurethane coating below the pool and in the pool equipment room.
Public Transit Center
The 82,000-square-foot Public Transit Center is located between the Westin hotel and DIA's Jeppesen terminal and features a 22.8-mile commuter rail line with a centralized pick-up and drop-off plaza.
On the 350-foot-long train platform, Black Roofing workers fabricated, installed and detailed more than 250 copper sweep inserts before installing 47,000 square feet of American Hydrotech Monolithic Membrane 6125, including extruded polystyrene insulation with layers of drainage mats, on the concrete platform and transit's main area.
Additionally, workers applied more than 10,000 square feet of traffic coating at various mechanical rooms throughout the Public Transit Center and Westin hotel, and Dow Corning® AllGuard Silicone Elastomeric Coating was applied at the interiors of two main fresh-air intake shafts. Because the shafts were three levels tall, workers assembled full-height scaffolding before applying the coating.
All areas with the American Hydrotech Monolithic Membrane 6125 were leak-tested using electronic leak detection.
Challenges
Working in the middle of an open prairie with nothing to block the harsh winds, workers faced brutally cold temperatures. An open gap between the terminal and new hotel created a wind tunnel where the insulation and drain boards were stacked, making material handling tricky.
In addition, building access was competitive among the trades working on the renovation project. Black Roofing was required to use an off-site staging area where workers unloaded material from semi-trucks and reloaded it onto smaller trucks and trailers for transport to the job site.
"The extruded polystyrene foam boards alone filled 55 semi-trucks of insulation," says Tim Black, founder of Black Roofing. "The process was slow and cumbersome. The crane also was not available for the duration of the project, so most materials were moved by our workers using hand carts."
A project requirement called for a 7/8- to 1 3/8-inch thickness of sand below the concrete pavers covering the waterproofing assembly at the level 5 plaza surrounding the Westin hotel, so specified slopes had to be accomplished strictly with the tapered insulation. Because of undulations within the structural slab, this proved to be challenging for the workers installing the insulation.
Black Roofing workers installed Dow STYROFOAM™ boards with a 1/8-inch-per-foot slope over plastic drain boards and 215 mils of American Hydrotech 6125 hot rubber. After the first couple of weeks installing the insulation and drain boards on top of the waterproofing membrane, workers realized the final tapered slope exceeded the slope by 3/8 of an inch per foot. Dan Zahtila, president of Black Roofing, spent six weeks on the job site modifying the taper, trying different slopes and cutting new insulation with custom slopes.
In addition, the sand bed specification was so thin, it wasn't possible to adjust the slope. Even worse, the sand and pavers would not hold down the drain board.
"We spent thousands of dollars and many sleepless nights trying to make an unworkable situation workable," Zahtila says. "The precise requirement of the 1/4 inch per foot deck slope dominated the job for four months until we found a resolution. We finally convinced the general contractor it was impossible because the structural concrete was poured so poorly and inconsistently, there was no hope of achieving the desired criteria. After many days of negotiations, the City and County of Denver inspector accepted our best effort."
Workers hand-shaved much of the deck with a 20-foot hot wire so the pavers laid flat.
"Our estimate for this work was more than $300,000," Zahtila says. "It was so cold, the plastic drain board curled and we could not hold it down flat enough for the pavers to remain flat. Our solution was to screw down the drain boards with 125,000 3-inch screws and plates."
Heat cables were laid out to keep the sand from freezing so the sand could be screed to accept the pavers. In many cases, workers had to tear out the insulation and sand where the 2 percent slope requirement was not met.
Most of the waterproofing membrane assembly on the plaza also had to be repaired numerous times as a result of damage from other trades. Making repairs, continuing installation in other areas and maintaining the schedule posed quite a challenge.
"The bottom line is we totally laid-up and roofed the 97,000-square-foot plaza about 2.3 times," Zahtila says. "We received more than $1 million in change orders, and it wasn't nearly enough."
Additionally, four plaza areas were designated as art areas and required Black Roofing workers to spread nearly 450 tons of 4- to 6-inch diameter cobble ballast. The cobble ballast was hoisted to the plaza areas one bucket at a time by a crane tightly positioned between two light wells 100 feet below. When the wind blows, the metallic art presents an amazing display.
Safety
Providing a safe, clean worksite was an active and ongoing priority for Black Roofing. Each employee was provided with on-site training and had to pass drug screening before being allowed on the project. Because Denver's Regional Transportation District operates and manages the train hall and train platform, workers required separate, additional safety training for working in the public transit area.
At least three safety professionals (the safety manager for the building owners, the general contractor's safety manager and Black Roofing's safety manager) continually monitored all aspects of the scope of work. The safety plan for the entire project was strict. With thousands of tradesmen on-site every day, watching out for others was a daunting task.
"Our specific job-site safety plan was amended daily to coincide with our scope of work and location," Zahtila says. "Because we had two kettles on the deck at all times, we had to be especially careful using hot asphalt with open flames."
Four 20-pound fire extinguishers and five 10-pound fire extinguishers were on-site and placed according to kettle placement.
A DBI-SALA Removable Bolt-in Anchor Point was used for the horizontal lifelines, and workers wore standard personal protective equipment, including leather gloves, face shields, safety glasses, hard hats and high-quality vests.
When applying the deck coating under the pool, workers wore Scott E-Z Airline full-face air respirators and used Scott Safety™ Ska-Pak™ 5-Minute Type C Emergency Escape Breathing Respirators and a MSA ALTAIR 4x Gas Meter.
"We could not even recognize our workers because they all wore full face masks," Zahtila says.
Negative-air machines and intrinsically safe fans also were placed for ventilation depending on the area for deck coating or hot work on the pool deck.
Ready for takeoff
After working nearly 25,000 man-hours on the DIA South Terminal Redevelopment Program project during sub-freezing weather and high-wind conditions, Black Roofing's crew completed its work in April 2016. During Black Roofing's nearly two years on the job site, three minor injuries occurred requiring only basic first aid. Black Roofing completed work in time for the hotel to open April 22, 2016.
"This job put us on the map with the general contractor community as a roofing contracting company that can handle any waterproofing job, regardless of size or difficulty," Black says. "We are proud we handled this job with the utmost professionalism and completed the project in time for the hotel's grand opening."
For excelling in project management and safety, Black Roofing received a 2017 Gold Circle Award in the Outstanding Workmanship: Low-slope category and a Gold Circle Safety Award.
Chrystine Elle Hanus is Professional Roofing's associate editor.
Project name: Denver International Airport South Terminal Redevelopment Program
Project location: Denver
Project duration: May 15, 2014-April 20, 2016
Roof system type: American Hydrotech Monolithic Membrane 6125®
Roofing contractor: Black Roofing Inc., Boulder, Colo.
Roofing manufacturers: American Hydrotech Inc., Chicago; BASF Watson Bowman Acme Corp., Amherst, N.Y.; Capital
Safety, Bloomington, Minn.; The Dow Chemical Co., Midland, Mich.; NEOGARD,® Dallas
COMMENTS
Be the first to comment. Please log in to leave a comment.