Building on that success, Weitz and Turner Construction have formed a joint venture to deliver another project, the $445-million Des Moines International Airport expansion.

Space on the airport site was at a premium as the project moved along. Weitz/Turner’s original project office was in an old airport building that first had to be moved for site soil stabilization and, eventually, demolished after the JV contractor moved its office across the street from the airport site.
Photo by Jeff Yoders for ENR

That project has its own inherent challenges. Ambitious municipal plans to add gates and make the most of terminals that have existed since the Douglas DC-3, one of the first commercial airplanes that operated in the 1930s and 1940s, often run against budgets approved years prior. Those budgets had pre-pandemic pricing baked in and revenue streams dependent on airlines quickly paying gate fees to pay back bonds and other debt instruments.

Des Moines did not even have an airport authority until 2011. By 2016, the 1948-completed airport was handling 900,000-plus passengers passing through it annually. So its 12 gates and its concourse, last updated in the 1970s, needed a major expansion as the airlines it serves (American, Allegiant, Delta, Frontier, Southwest and United) all wanted more modern security and amenities.

The six-county Des Moines region is one the fastest-growing metropolitan regions in the Midwest, with its population growing by 3.1% between 2020 and 2023.

Construction of 18 new gates in Des Moines necessitated routing traffic to the existing terminal around construction of the new one.
Photo by Jeff Yoders for ENR

After the COVID pandemic hit, the still new-ish Des Moines Airport Authority was trying to figure out a long-planned expansion, and that’s when they decided to go out to all of the communities in the six-county region and ask for public investment.

“It’s so rare that a community would actually come in—but the city of Des Moines, whether it’s [for] a Hilton Hotel and how that was put together through a financing model or whether it’s [for] the riverwalk—all of the greater Des Moines partnership leaders get in a room and understand what the goal is they [are] driving toward, because expanding the airport is going to improve the community as a whole,” says Ben Bunge, general manager of aviation at Weitz Co. He was also a project executive on the convention center and Hilton Hotel project that constituted the first use of design-build in Iowa. The Weitz Co. is headquartered in Des Moines.

Polk County and Story County contributed $10 million and $1 million, respectively. Over 20 cities, including Des Moines ($10 million), West Des Moines ($2 million) and Ankeny ($2.02 million) contributed. The Prairie Meadows Racetrack and Casino gave $5 million. The state of Iowa committed $58.7 million in American Rescue Plan funding toward the project, and the federal government contributed a $10.8-million grant from the Federal Aviation Administration via the Infrastructure Investment and Jobs Act.

Polk County voters approved a bond issue to raise $350 million for the airport expansion in November 2023.

The existing 12 gates were last renovated in the 1970s. The new terminal will have 18 gates, expanded check-in and security screening.
Photo by Jeff Yoders for ENR

Six Gates, Modern Amenities

With funding in hand, what was initially a five-gate expansion plan became six gates and a new parking garage that’s already open. Weitz/Turner expect that the new gates will be completed in January 2027.

Revenue from the parking garage, which Weitz also delivered, plays into the airport authority’s financing plan. The airport authority is also putting in a new glycol system and redid both of its runways as part of the overall $775-million project.

A key driver of cost certainty was the construction manager at-risk delivery method becoming available in Iowa on July 1, 2022. The airport authority was able to hire HNTB as the design architect and have the entire design team work with Weitz-Turner during the design process.

“Having CMAR available to us as a public entity in Iowa was huge, because otherwise we would have had to do everything low bid in the design-bid-build process,” says Brian Mulcahy,” executive director of the Des Moines Airport Authority. He was the finance director of the authority before his promotion in 2024 and was instrumental in creating the deal for the expansion.

“We would have had to design the whole thing 100%, and we likely would have had change orders,” Mulcahy says. “From my perspective, CMAR allowed us to select the team, the construction team, and then get our design team involved early.”

Mulcahy adds that he’s been involved with many aviation projects where architects would say, “‘Well, we’re not construction people. We don’t know how much that’s going to cost.’ We had the whole project team [do] the costing along the way so we didn’t wind up with our basis of design, or even 10% design, being so far out of the ballpark that we had to cut it back by half,” he explains.

Construction of the new terminal and drop-off area required ground stabiliization and movement of a building that was serving as Weitz/Turner’s project office. The new office is across the street.
Photo by Jeff Yoders for ENR

While the use of design-build has exploded in aviation, including at the Kansas City airport that Bunge and Weitz were involved in, only CMAR allowed the Des Moines Airport Authority to use a guaranteed maximum price along with revenue from opening the 1,122-stall parking garage that Weitz delivered in July.

One airport project going through a very public value engineering exercise right now is the O’Hare 21 project in Chicago, with anchor airlines American and United pushing back against increasing costs for the new Global Terminal. It was approved at an overall $8.5-billion cost in 2019.

Mulcahy said the Des Moines project was also the recipient of good economic luck in the form of lower inflation as the project went on.

“We were probably intentionally conservative from the get-go in terms of escalation, building that into the budget,” he says. “We may have gotten a little bit lucky on timing, because at the beginning of the project [design completed in 2022 and construction in 2023], there was still high inflation.

“The concerns were that inflation was going to be even higher—but as we got into bidding, there’s been enough interest in the project, enough competition, that we get good bids in the first phase. Now, we’re bidding the last phase, the third phase, this summer, and I think the market is maybe slowing down enough to where there’s even more interest and more competition.”

Support buildings and taxiways have to be rearranged during construction.
Photo by Jeff Yoders for ENR

Staying on Track to Six More Gates

To make the most of that interest, Weitz/Turner used a sophisticated VDC strategy and rerouted traffic to the existing terminal around the airport’s 2,600-acre site to free up laydown and construction space. In October 2023, Weitz/Turner put in a new sanitary line along with a grease interceptor.

Early on, project managers identified soil conditions that required remediation. “One of the things that was unique about this project was the geotechnical report. Some of the borings showed this site sits on an old riverbed,” says Dan Solem, Weitz Co. project executive. “Along with that, there had been development over the years, multiple existing buildings—and from those buildings there were rubble reports within the geotechnical report.”

Weitz aviation group leader Ben Bunge explains how the drop-off for the existing terminal is being moved while roads for the new terminal are built. When the new terminal opens, the old roads will be demolished.
Photo by Jeff Yoders for ENR

Solem adds that the team needed to install deeper structures and heavy fill to stabilize the ground in preparation for future work.

“They actually surcharged the entire site to make sure it was compressed, and then that happened over the winter months [of 2023],” Bunge says. “Then in the spring, these underground utilities went in, and then once the surcharge happened, we were able to peel that off and really take off with construction.”

For the electrical upgrade, a full primary feed and loop was brought in. “We feed the building from multiple directions from Mid-American energy services. So they come in from the east and the west, and then it feeds the substations,” Solem says.

“One of the unique things about airports in general is the redundancy requirements for the electrical services,” Solem explains. “There’s a future service that would be coming from the garage to the main terminal that is still being developed. There was a wait on some switchgear items with a long lead time. We also were able to work with the client on a reserve power or a commissioning power.”

Solem says a separate transformer solution was brought in to bring temporary power for the construction crews. “That allows us to stay on temp power ... from a safety perspective. The way to go is to try and get your temp power and get that set up. That allows you to really build efficiently and put your permanent works in,” he says.

To get a better grasp on the densities of materials for installation, the Weitz/Turner VDC team had to model down to half-inch conduit to have M/E/P detail ready for installation.
Photo by Jeff Yoders for ENR

Work is moving swiftly, with concrete placements simultaneously going on in the terminal and the parking garage. Mulcahy says revenue from the parking garage will help pay for the final stages of construction. The $445-million terminal project is still expected to be completed by January 2027.

Another early obstacle was an airport fence move that couldn’t be completed as originally scheduled. It was pushed back to May 2023.

“It was the spring break holiday,” Solem says. “We had to make sure we got past spring break, so the airport could then rearrange, reshuffle airlines—and then we were able to shut down gates. So [we were] trying to work with the airlines to maximize the gate usage of the existing facility during construction before they lost those gates.”

Throughout construction, Turner/Weitz’s VDC teams were on site and collaborating with HNTB and all of their major subcontractors to nimbly react to such issues on the site. The team was never apart thanks to the CMAR delivery method.

Enterprise Precast in Omaha did most of the precast concrete panels on the project. Another advantage of CMAR was that Weitz’s concrete self-perform group was able to bid on concrete packages on both the airport and the parking garage, with Turner acting as deciding member of the joint venture. Weitz won both of those contracts as the lowest bidder.
Photo by Jeff Yoders for ENR

“All the bidding and the preconstruction that we did in 2023, we were able to do all that because of the new CMAR bill,” says Jenessa Frey, Turner’s project executive for the airport expansion. “The airport was able to bring our group on early and help with all the preconstruction. So imagine the planning and the work that we could get in place, ready for the spring break fence move.”

Solem and Frey both assert that the CMAR delivery method gave the client a lens into what was going on with the project at all stages.

“I think anyone associated with this project would say absolutely that CMAR really allowed us to give the owner more budget certainty,” Frey says. “I would say we were able to help them with a lot more market information so they could proceed with more certainty.”