Chicago O'Hare International Airport has been expanding its runway system and installing a new airfield lighting system, a new electric lighting vault and a lighting control sys-tem that provides and regulates power for runway and taxiway lighting throughout the airport. Divane Bros. Electric Co., Franklin Park, Ill., has undertaken the installation as well as construction of one electrical vault and expansion of another.
Divane Bros. has a long history with O’Hare airport. The electrical contractor has had a presence at the airport for decades and worked on the original electric vaults. With O’Hare’s Modernization Program (OMP), a runway would be crossing over the existing south airfield vault, so building a new one was necessary in addition to constructing new duct banks.
In 2008, O’Hare International Airport supported 881,566 flights, but the Federal Aviation Administration (FAA) estimates the number will rise to 1.2 million by 2018. The airport has had flight caps in place since 2004, limiting the number of flights to ensure the runways are not overwhelmed. In the fall of 2008, however, with new runways constructed, those caps were lifted.
The runway work is divided into two sections—the north and south airfields. To accomplish this renovation and expansion of runways in the south airfield, Divane Bros. is building a new lighting vault 3,000 feet from the existing lighting vault. Divane Bros. constructed that existing south airfield lighting vault in 1987. It still is fully functional but sits in the path of the runway expansion. Its 26,000-square-foot replacement, however, (17,856-square-foot grade floor and 8,064-square-foot basement) will not only clear the runway area but will be large enough to accommodate further growth for the OMP’s completion phase, for when the airport requires additional runway and taxiway lighting. About 50 percent of the vault is dedicated for airport expansion, said Joel Saucedo, resident engineer, O’Hare International Airport.
The south airfield’s new vault has substantial room for growth to accommodate lighting associated with future runways and taxi-ways. In it, Divane Bros. assembled four series of regulators that provide control of power to runway and taxiway lighting. Each individual lighting circuit is dedicated to a single regulator. Every circuit has 4,160 volts of power with two feeds from Commonwealth Edison, the local utility, for the vault. The south airfield lighting vault will contain 70 regulators. The vault also has three 2,275-kilowatt Caterpillar generators, which the FAA mandated to guarantee power in the event of an outage. The generators are fueled from a 25,000-gallon underground fuel storage tank that was installed by Divane Bros. The vault itself is a precast structure with a poured-in-place foundation.
The vault project has a green element to it as well. On top of the vault, Divane Bros. has constructed a vegetated roof.
“As we move forward with the remainder of the O’Hare Modernization Program, we continue to support Mayor Richard M. Daley’s green vision for Chicago by incorporating sustainable initiatives at our airports,” said Chicago Department of Aviation Commissioner Rosemarie S. Andolino. “To date, we have built over 32,000 square feet of green roof space resulting in tremendous construction efficiencies in terms of cost savings and reduced use of natural resources.”
The OMP is building five green roofs during the first phase of construction. Three are already in use, including the new FAA tower, the main airfield employee guard post entrance and the new electric vault for the entire airfield. The green roofs counteract the heat island effect, which is when an area has a higher air temperature than surrounding areas, due to large amounts of impervious surfaces, such as concrete, which radiate more heat. An airfield, such as O’Hare, has many concrete areas, and, therefore, a green roof can somewhat alleviate that heat island effect.
In the north airfield, the current vault, which Divane Bros. constructed 30 years ago, will continue to operate, but an additional 3,000 square feet of space will be tacked on to the existing 16,000 square feet. This expansion will house six additional regulators; there are approximately 40 airfield lighting regulators already there.
This project, which does not require new duct banks, was opened and operational in November 2008. The airfield lighting circuits are divided geographically. For now, an equal amount of circuits are powered from each vault. However, that may change, as the airport expands and modernizes. All airfield cable installed is designated to feed existing runway and taxiway circuits while empty ducts were provided for future expansion, Maicke said.
Altogether, Divane Bros. will complete more than 4,700 feet of open trench excavation containing approximately 300,000 feet of concrete-encased PVC conduit. Divane Bros. workers will run 250,000 feet of 5-kilovolt airfield lighting cable to to existing lights as well as new fixtures coming online and 40,000 feet of power cable. They also will install 250,000 feet of fiber optic cable to operate the airfield lighting control system, supervisory monitoring system and the O’Hare Campus Connectivity.
The fiber optic cable Divane Bros. installed throughout the airfield and within the lower levels of concourses will provide connectivity to the existing air traffic control tower, the new north air traffic control tower, the existing north airfield lighting vault and the new south airfield lighting vault. These destinations are what dictated that Divane Bros. install the cable under several runways and taxiways.
The lighting control system also provides the latest touchscreen technology for all runway and taxiway lighting in the airfield. Lighting control is provided from remote locations, including the two air traffic control towers, as well as the north and south lighting vaults. The control system is available on desktops at both towers and connected using fiber optic cable.
To install power and control cabling for the airfield lighting, said Mike Maicke, Divane Bros. vice president, the crew performed a large percentage of the work at night when air traffic was limited.
Divane Bros. began the project with an underground duct bank system to connect into ductwork in the existing vault junction. Workers dug trenches and installed 45 manholes, constructing them as well as pouring the concrete within the area between the main duct bank and other ancillary banks of cable. These giant cables begin at 80 cells and narrowed to 50 and then down to 45 as the trench crosses under the runway.
These large duct banks pass under an existing runway and various taxiways by way of jacked steel casings, which are reinforced with concrete grout. Deep excavations were required to facilitate the jacking and tunneling equipment, which were required for conduit lengths in excess of 500 linear feet. To run the cables under the active runway, Divane Bros. used equipment suited for the task, which “blew” the fiber optic cabling through connected innerducts installed in the existing and new duct banks. This method alleviated some of the challenges working around operational runways.
This part of the project took 10 days and nights, Maicke said, and required complete safety surveys and a safety plan reviewed by the FAA before the work began. John Hamilton, site safety manager for Divane Bros., oversaw the work and won a safety award from the OMP.
“We do a lot of work at O’Hare and it can be a challenging place to work,” Maicke said.
Both Divane’s management and field personnel have enough experience working in an airport of this size to take on a task without needing additional training. Much of the challenge is centered on the multiple agencies and regulations that dictate safety requirements. The city of Chicago, the FAA and Chicago Department of Aviation all have an interest in the work that is being done. On the other hand, Maicke pointed out, they also have other projects they need to focus on, so they need to have confidence that the electrical contractor is doing the work properly without requiring a great deal of input from them.
“One of the biggest challenges was running cable from the new vault location to the runway while working around the existing infrastructure,” Saucedo said.
Safety is always a concern at airports where existing utilities, such as high-pressured fuel lines containing jet fuel or other volatile substances pose significant challenges.
Safer, Cleaner, More Labor Efficient
When Divane Bros. Electric installed the lightning protection system for the runway lighting this summer at O’Hare airport, the company sampled a relatively new technology—a remote exothermic welding process—that allowed the electricians to weld the grounding rods from several feet away. Harger Lightning & Grounding, a lightning protection and grounding equipment-manufacturing company based in the Chicago area, provided the system.
In late June, Divane Bros. tried the Harger UltraShot product to weld several ground rods to the grounding conductor, which was accomplished more safely and with less waste, ultimately creating a better connection than can be managed with the traditional welding method.
The system consists of a drop-in copper weld metal container and an electronic ignition system. Divane Bros. simply dropped in the weld metal cartridge, attached it to the igniter and pushed the button instead of the traditional method of inserting a weld metal disk, pouring in weld metal powder, sprinkling starter material on it and then using a flint igniter to fire the connection. The 6-foot cord connecting the controller allows the user to maintain a safe distance from the connection as well.
Throughout the O’Hare aircraft operations area, Divane Bros. installed counterpoise copper cable above FAA and common electrical duct banks. This copper cable is welded to 3/4-inch diameter by 10-foot-long stainless steel ground rods at intervals of 90 feet and 250 feet. Divane Bros. installed a total of 2,000 ground rods over a 100,000-foot space along runways and other operations areas at O’Hare.
The grounding rods were installed above the duct bank, 18 inches below the finish grade, said Martin L. Holleran, project manager at Divane Bros.
Once the graphite mold clamp was attached onto the top of the grounding rod, a powered metal shot was poured, the lid was flipped and Divane Bros. ignited it with a spark. The technology itself was already familiar to Holleran.
“It’s not unusual to exothermically weld the counterpoise [ground conductor] to the ground rod,” he said.
Divane Bros. has used similar exothermic welding technology in the past on other projects to weld the bare copper conductor to the ground rod. However, this was the company’s first time using the Harger product.
The weld was accomplished more cleanly, Mark Harger, company president, said, because the whole copper container was consumed in the welding process.
“That just makes for a cleaner work place,” Holleran said.
After overseeing the first welds, Harger Lightning & Grounding left enough material for about 50 connections.
“Now the powdered shot receives its electrical impulse with a battery pack that can be held at a safe distance,” Holleran said. “It’s the tool that allows us a more efficient installation. It’s safer and cleaner.”
The welding process itself also is faster and provides a superior connection, Harger said. The UltraShot controller is powered by a rechargeable battery, rather than AA batteries, such as other electronic exothermic systems on the market require, Harger said, meaning it can accomplish between 600 and 800 connections before the battery needs to be charged as opposed to about 50 times for other exothermic welding systems that use AA batteries.
UltraShot was released in April 2009 and has been used in most cases by utility companies, wireless cellular companies and other locations in which there are towers or lighting such as at O’Hare airport.
To build the project, Divane Bros. had an on-site office at the airfield with a senior project manager, two assistant project managers, an administrative assistant, an on-site safety manager, QAQC manager and two field inspectors.
“There is a tremendous amount of paperwork,” Maicke said, adding that the project peaked at about 25 electricians on the site as well as approximately five supervisors.
“The key is having people out there with experience navigating the way.”
He said coordination was one of the greatest challenges, since the project has about 20 subcontractors on-site including underground excavators, building contractors, landscapers, mechanical and concrete contractors, traffic control and painters. Maicke said Divane employees met out at the airport frequently and coordinated directly with the OMP on progress. Two electrical contracting companies also are providing subcontracting work. Quantum Crossings LLC is assisting with the airfield control system, and Bonaparte Corp. is handling the switchgear and regulator work.
Just working around existing cables is another challenge on an airport of this size, age and activity.
“The biggest thing is the logistics of working in an airport. You have to have a coordination plan, and you have to have a couple of backup plans,” Maicke said, adding that this is in case the first plan is not accepted.
Because earthwork specifications are so rigid, there is little flexibility in, for example, location of holes. Poor weather during fall 2007 also caused many more headaches.
“The FAA’s primary concern is keeping the airport functioning,” Maicke said.
The final hurdle was accomplishing the cut-over from the existing lighting automation system to the new one, O’Hare engineer Saucedo said. The cut-over required switching 60 circuits on each the north and south airfields, at the rate of 10 to 15 per day, during consecutive days.
The project came in several weeks ahead of schedule, Saucedo said, who credits Divane Bros. for much of its success.
SWEDBERG is a freelance writer based in western Washington. She can be reached at firstname.lastname@example.org.