Kansas City Int'l Develops Unique Solution to Chilled Water Distribution Problem

Author: 
Robert Nordstrom
Published in: 
July-August
2012

Kansas City International (MCI) had a decade-long problem with its chilled water system. At more than 40 years old, the underground distribution network providing chilled water to and from each of MCI's three terminals had a long history of line breaks that caused costly disruptions to airport operations.

The three centrally located chillers, which had been replaced in 1996, were still in good shape, reports Ken Potter, facilities supervisor for the Kansas City Aviation Department. But the underground piping couldn't keep the necessary chemicals in the system.

"When things got really bad," Potter recalls, "we were putting 5,000 to 10,000 gallons of water a day into the system. We were treating the system with chemicals at least once a year, which cost $12,000 to $15,000 per treatment."

 

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Project: Chilled Water Distribution System Replacement

Location: Kansas City (MO) Int'l Airport

Owner: Kansas City Aviation Dept.

Cost: $8 million

Funding: Airport General Funds

Prime Design & Engineering Consultant: Burns & McDonnell

General Contractor: Rand Construction

Engineering Consultants: VSM Engineering; Custom Engineering

Roofing: Great Plains Roofing

Insulation: Insco Industries

Underground Piping: Rodriguez Mechanical

Boring: G&G Mechanical

Hoisting: Prestige Crane

Cured-in-Place Piping Supplier: InsituMain

Benefits: Increased reliability; reduced water, chemical & energy expenses

Assisted by design and engineering consultant Burns & McDonnell, airport officials considered their options. Replacing the entire underground distribution system with new piping was deemed both cost-prohibitive and impractical, given likely disruptions to airport operations. Installing a chiller in each terminal proved to be similarly unattractive.

In the end, the team decided to improve the distribution piping and keep the endpoints as they were, explains Burns & McDonnell project manager Mark Schuette.

The two-phase $8 million project began in 2010, with the replacement of the cooling towers. "We felt we could get another 10 to 15 years out of our existing chillers," elaborates Melvin Price, the Aviation Department's project manager for critical infrastructure.

The second phase included replacement of the distribution lines - a measure that helped keep costs down, notes Price.

Combination Approach

MCI's decision about the project scope begat a question about strategy - namely, how to replace the lines without massively disturbing airport operations.

The underground distribution system consisted of 7,000 linear feet of piping - mostly 12-inch lines, but some ranging in size from 8 to 24 inches. There were three main areas of distribution piping: in the central plant, connecting the central plant to each terminal and at the terminals.

With the counsel of engineering subcontractors VSM Engineering and Custom Engineering, airport management explored multiple options. Replacing all the underground lines from the chiller building to the terminals would have required crews to dig up the street in front of the terminal buildings as well as generous portions of the surface parking lot, explains Valerie McCaw, civil engineer for VSM. Instead, the team opted to replacing part of the underground system, then run aboveground piping up the side of the terminal buildings and along the roof.

For the underground portion of the project, part of the existing piping was replaced with new materials; cured-in-place piping (CIPP) was used for the remaining portion.

Underground Aspect

Although the underground portion of the installation ran the shortest distance, it proved to be the most complicated part of the project. The existing line route left the chillers, extended through the central plant building wall as two 24-inch pipes, then split into 12-inch and 16-inch pipes just outside the wall. Two concrete-encased telephone duct banks lay on top of the piping.

Engineers designed the new exit route to leave the building aboveground and run approximately 75 feet before pushing back below the surface to complete the new underground portion of the installation. Plotting a way for the new piping to meet up with the existing piping in the parking lot required close coordination with the onsite contractor, recalls McCaw. "There were telecom lines, fiber cable, jet fuel lines - a lot of adjustments had to be made," she explains.

Cured-in-Place Portion

The decision to use CIPP technology was a calculated risk, because it is traditionally used for sewer lines where access points are available every 300 feet at manholes. It is not commonly used for water lines. Upping the ante, the CIPP portion of MCI's project was the longest run of the distribution system.

After winning the bid for the airport's CIPP installation, InsituMain essentially manufactured new piping onsite by running a tube-like sock through the host piping and impregnating it with an epoxy resin liner. Crews then pumped 140°F - 180°F water through the piping for 12 hours to expand the lining and cure it in place to form a 1/4-inch hard resin wall.

Because the longest run for the process is 500 feet at a time, crews often run bypass lines along the top of the ground, which adds considerable construction costs. To render such bypass lines unnecessary and avoid associated expenses, MCI shut down the chilled water delivery system during the wintery stretch from November to April.

Locating vertical bends of 45 degrees or more in the host piping was a critical step, because CIPP installations require gentler angles. Old schematic drawings were used to plot the general locations of bends in the piping, and ten access locations were excavated - primarily in the surface parking areas. Crews then removed a section of piping and ran cameras through the lines to determine the structural integrity of the host piping and flag problematical bends.

Larry Stevens, project manager for general contractor Rand Construction, says the process worked well. "(Before checking) we weren't sure what the actual condition of the existing piping was or whether we would be able to pull the CIPP liner through," relates Stevens.

Despite such uncertainties, the project needed to be complete by April, so the airport would have air conditioning when spring weather arrived in Kansas City. "Although the old drawings weren't 100 percent accurate, we were able to locate the general location of the bends for excavation, and camera work determined the host piping was structurally sound for CIPP installation," he recalls.

Aboveground Piping

The previous distribution system featured a buried reverse/return loop in front of each of the circular terminals to move chilled water to and from the mechanical rooms. Approximately 15,000 linear feet of aboveground roof-supported piping was installed to replace this system. The layout of the new piping had to follow the form of the roof as well as connect to the lower level mechanical rooms of the respective terminals.

Pipe supports were located on major structural beams so they didn't interfere with structural expansion joints, and access points were identified to drop the piping through the roof into the terminals' mechanical rooms. Crews also installed two-inch thick insulation to protect pipes against freezing temperatures. Aluminum metal jackets that color-matched the existing soffits along the roof were added to prevent the new piping from compromising the aesthetic integrity of the terminal buildings.

The piping ranged from eight to 12 inches in diameter, and 900+ roof supports were fabricated onsite. Welding the mitered joints to follow the curvature of the roof presented added challenges, recalls Stevens.

"The roof work required a lot of coordination between our field staff, fabrication shop and crane operators," he notes. "Driving lanes had to be closed, which affected passenger drop-off points."

Up & Running

MCI's chilled water distribution system went back online in mid-March and quickly began earning enthusiastic praise.

"The new system is working tremendously well," Potter reports. "We've been able to keep chemicals in the lines. We won't have to be putting 10,000 gallons of water at a time into the system. Our water bill, as well as our electric, will be going way down."

With the project complete, team members agree that the decisions to use CIPP and rooftop piping limited inconvenience to the traveling public.

"Instead of blocking the roadway and going from six lanes to three lanes for who knows how long, we were able to minimize disruptions for travelers," explains Price. "The CIPP access points in the parking lots created the biggest disruption for the public. However, by using CIPP, we only had to block off five parking spaces as opposed to 30 spaces. It was an ambitious undertaking given the timeframe we worked with and everything that had to be pulled together."

Aviation Department officials cite open lines of communication as a key to the project's success. "We took a proactive approach," Price says. "We held weekly progress meetings with all the key players, including facilities, parking, the contractor and the design team. We also reported progress at our monthly security consortium meetings."

Subcategory: 
Operations

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