Precast builds underground support for New Indianapolis Airport.

By Greg Snapper

With more than 8 million passengers served each year, Indianapolis International Airport has grown to become one of the Midwest’s busiest. That growth – as well as increased projections for future air travel – has sparked the construction of a new $1 billion main passenger terminal building and support facilities – structures that will extensively benefit from the use of precast concrete products.

The New Indianapolis Airport will feature a modern glass-enclosed passenger terminal building located between the two existing main runways along with new highway access, new and improved parking and support facilities, and improved utilities and airside operations. Integral pieces of this mega-project include multimillion dollar features specifying precast concrete.

Thirty years in the planning, the new passenger facility will include two concourses featuring 40 gates, new baggage handling facilities and security checkpoints, and 96 passenger ticketing positions. The highlight of the structure will be Civic Plaza, a skylit 200-foot diameter public gathering space. Terminal support facilities will include a 7,100 vehicle parking garage, which will include a Ground Transportation Center to house offices and service counters for car rental companies. The Indianapolis Airport Authority began constructing the new facility in July 2005. It will be completed in late 2008.

A new dedicated interchange from nearby Interstate 70 as well as new surface access roads, aircraft aprons, and a new Air Traffic Control Tower and support building complete the project.

“As the gateway to Indianapolis and Central Indiana, the New Indianapolis Airport will help define the modern character of both the city and the state,” said project director John J. Kish. “It will be a symbol of the long economic and cultural history of Indianapolis and solidify our future as ‘Crossroads of America’ for generations to come.”

Benefits of the new airport include reduced aircraft taxiing times, more gates and more passenger-friendly amenities. The new airport is being financed through a combination of federal grants, passenger facility charges, airline facility rents and aircraft landing fees. No state or local tax money is being used to finance construction or to repay construction bonds.

Airside underside

The cast-in-place concrete industry has a tight grip on highway and road construction, and airport apron construction is no exception. The new aircraft apron at the New Indianapolis Airport is being cast in place, but precast-specific infrastructure beneath it shows the conservation niche held by the precast concrete industry.

Building structures under the aircraft apron to provide for containment and treatment of apron runoff is vitally important in airport construction, said Marc Bloomfield, project executive for construction manager Turner-Trotter Joint Venture of Indianapolis. These structures are particularly critical during the winter, when aircraft require regular deicing.

Since 1995, deicing fluid at Indianapolis International Airport has contained polypropelene glycol, a syrupy liquid with toxic properties. During the winter season, October through April, safe air travel depends on this ice-melting chemical.

In the winter of 2004-05, the airport used 320,487 gallons of polypropylene glycol for aircraft deicing. Liquid runoff from deicing was safely contained within the airport’s current infrastructure, said Todd Cavender, environmental manager for BAA Indianapolis LLC, the company that manages day-to-day airport operations. The current airport uses two main watersheds and control structures for runoff collection, transfer and discharge.

“We don’t have a channel per se for deicing runoff, but as it relates to how we control aircraft deicing, we do have conveyances that transfer to large detention/retention ponds,” Cavender said.

In an effort to contain, treat and eventually recycle the polypropylene glycol used at the new airport, twin box culvert runoff channels were built beneath the new airport’s 100-acre apron. When the new airport terminal opens in 2008, these channels will help protect the environment by transferring stormwater runoff containing deicing fluid from the adjacent apron to an underground storage container. When not collecting deicing runoff, these structures will collect and transfer stormwater under the appropriate environmental regulations.

“Deicing fluid contains chemical compounds,” Bloomfield said. “So it’s very important to us from an environmental standpoint to capture that fluid before it gets to the stormwater system.”

Twin box culverts create two separate channels beneath the aircraft apron: One culvert will trap the high concentrate deicing runoff, while the second will trap the lower concentrate runoff. Both lines will deposit the liquid into an underground storage container. In the near future, the airport will begin to recycle the high concentrate runoff. In the interim, the runoff will collect in a 2-million-gallon cast-in-place concrete container before being discharged into the environment. The functionality of precast concrete led to a “great design” for the culverts, a solution airport officials were happy with.

“Precast was very convenient for us because of the tight tolerances it allowed in terms of the box culverts’ joints,” Bloomfield said. “We didn’t have to worry about infiltration or exfiltration from the culverts into the groundwater.”

With the chance to build from scratch, airport officials showed foresight when they specified precast box culverts to remedy a potential environmental threat. Box culverts underneath the scene at the New Indianapolis Airport serve as environmental safeguards to protect nearby ground and surface water and the surrounding ecosystem.

The dual box culvert channels allow flexibility in both current methods of deicing treatment as well as future recycling plans, Cavender said. The precast dual channels are planned to transfer runoff to the existing main retention units at the airport. The two airport systems, old and new, will work together to protect surrounding streams. “I think we are in a better position to address recycling setups for the future, too, with the new airport’s system,” Cavender said.

As the Environmental Protection Agency (EPA) continues to develop an Effluent Limitation Guideline for deicing discharges at airports, the New Indianapolis Airport is poised with its infrastructure to meet new recycling targets.

“What the EPA will do is set a national technology standard across all U.S. airports and set a numerical limit based on a specific technology,” Cavender said. “With the dual collection system in place, however, we’re not that far off that we couldn’t slide in and do what we needed to meet the effluent guideline.” The EPA plans to draft a final rule by fall 2007. “Indianapolis will be at an advantage with the new precast system. The city had the foresight to prepare for future EPA rules,” Cavender said.

Landside underside

Projected stormwater runoff from the terminal and concourse roofs in part prompted airport builders’ design of the airport’s landside stormwater drainage package.

Rinker Materials of Mt. Comfort, Ind., was contracted to precast 25-foot by 4-foot box culvert sections for the system’s central collector. Part of the collector is an open channel, or runoff conveyance, which features enclosed reinforced concrete box culverts. The easternmost sections run 10 to 15 feet under surface parking and service roads, while the western sections snake through adjacent airport land as an open drainageway.

Part of this bid package included lining the open ditch. The Airport Authority considered three options: channel ventilation, concrete paving or a proprietary product called Armaflex. The latter, a precast energy dissipater, resembles a patchwork quilt made of concrete when connected with reinforcing members.

“We wanted a low-maintenance channel, and the energy dissipater was less expensive and better for our schedule,” Bloomfield said.

Ahead of schedule

The western end of the open drainageway collector once butted up against a construction vehicle access road. Because vehicle access to the terminal construction site was vital for the construction timetable, replacing the roadway demanded a quick turnaround to meet tight deadlines. Engineers decided to replace the road over the drainageway with aprecast concrete bridge.

“Building the western sections of the central collector under an existing road created a problem,” Bloomfield said. “We resolved this from a design standpoint by specifying a precast concrete bridge, because it was critical that we maintain the access across the existing road.”

“It was very important that the length of time the road was out of service be kept to an absolute minimum,” he said. “The contractor only had 25 days from the date the road was out of service until it was back to servicing delivery vehicles.”

Construction finished ahead of schedule, according to airport officials. The 25-day time frame was nearly cut in half, and the road was out of service only 11 days.

“So the decision to use the precast structure worked out perfectly for us,” Bloomfield added.

The $9 million landside storm sewer drainage system included the entire central collector (box culvert sections and open drainageway), pipe sections, lining and bridge. Turner-Trotter Joint Venture officials were pleased and reassured with the outcome.

“In hindsight, it was the right decision,” Bloomfield said.

Staying local

It was also the right decision to hire Indianapolis firms and manufacturers for construction, said assistant project director Greta Hawvermale. With the primary exception of retaining St. Louis-based Hellmuth, Obata + Kassabaum Inc., an internationally known architecture, engineering and construction planning firm, as master designer, much of the work at the new airport is being done by Indiana-based companies.

Much of the “down and in” work – putting all the airport pieces together – was awarded to qualified responsive and responsible local companies, Hawvermale said: “We wanted local talent, local companies and local resources to do as much of this work as possible.”

For example, Indianapolis-based Independent Concrete Pipe Co. landed several pipe and box culvert contracts on several different bid packages, including both landside and airside projects. Independent’s strong presence in the local precast concrete market made it a safe choice for airport work.

The bulk of underground work is wrapping up at the New Indianapolis Airport, but many bid packages are yet to be contracted.