Air Force Academy Ditches Grass for Synthetic Turf

Author: 
Robert Nordstrom
Published in: 
September
2012

When the United States Air Force Academy in Colorado Springs, CO, (KAFF) invested $5.4 million in 19 new gliders last year, officials knew that its sailplane landing area would no longer suffice. Dried clumps of native grasses made for an extremely rough landing surface that was overstressing and fatiguing the aircraft.

To prevent the premature degradation of its new fleet, the Academy updated the landing surface with a $3.6 million improvement project. The move was especially critical because its new fiberglass TG-16 gliders would be more expensive to repair than the metal TG-10 gliders they replaced.

factsfigures

Project: Synthetic Turf Application

Location: United States Air Force Academy, Colorado Springs, CO

Surface Covered: Sailplane Landing Area

Size: 1.4 million sq. ft.

Cost: $3.6 million

Installation: 4½ months

Annual Operations: 17,000+

Product Manufacturer & Installer: AvTurf

General Contractor: TolTest

Soil Removal & Grading: Tezak Heavy Equipment

Site Restoration: Blue Mesa

Key Benefits: Eliminates down time for mowing & weed removal; enhances flight safety because it doesn't attract wildlife; increases long-term sustainability of Academy's newest gliders

The project also conformed to findings of a 2005 study by the Academy's Engineering Mechanics Department and Center for Aircraft Structural Life Extension. The study detailed the landing area's poor conditions and concluded that the grass landing surface needed to be improved. The cost to install new sod and attendant irrigation measures, however, proved prohibitive - an estimated $40 million. The Academy opted instead to carpet the landing surface with approximately 1.4 million square feet of synthetic aviation turf - the equivalent of 23 football fields. Officials were comfortable with the change in strategy because a test patch of the material applied to the beach area, where aircraft are staged adjacent to the runway, had performed well since its installation in 2006.

Improving landing conditions at the airfield was a top priority when Lt. Col. Doug Downey took command of the 306th Operational Support Squadron two years ago. But doing so was no simple task. "We had to run it all the way up to the Pentagon to get approval," Downey recalls.

With the project complete, he puts the $3.6 million project into perspective: "We're saving over 90% of what it would have cost to replace and maintain a grass surface."

Big Green Target

At 430 feet wide and 3,000 feet long, the Academy's new landing surface is thought to be the largest single installation of synthetic turf in the world. Even without official Guinness World Records status, the new landing area provides an ample target for Air Force cadets who are just beginning their sailplane training.

"They look out over a big sea of green with clearly identified lane markings," explains Lt. Col. Brad Roller, commander of the 94th Flying Training Squadron. "That's reassuring for someone who has never flown before. The instructor can draw the student's eyes onto the target and say, ‘pick one of those lanes and land it.'"

The landing surface is divided into four lanes, each with a centerline and numbered markers at both ends. While the white numbers are cut and glued into the green surface, the dashed centerlines are sewn directly into the panels at the factory using white yarn. Red lines in the beach area designate the safe zone where cadets remain until cleared to enter the sailplane landing area.

From a safety standpoint, Deputy Airfield Manager Courtney Davis, of the 306th Operations Support Squadron, describes the new surface as "cutting edge."

With synthetic turf replacing natural grasses and weeds, the sailplane landing area is no longer an attractive feeding ground for Colorado wildlife. "We've removed their food source," explains Roller, "which in turn enhances safety. We don't have to worry as much about BASH (bird airstrike hazard) for our aircraft. It's also much easier to identify FOD (foreign object debris) on the huge carpet of green."

Hold On

Before the Academy's new synthetic turf could be installed, crews had to kill existing vegetation in the area, remove the associated topsoil and add new native soil, which was then compacted with water. Installation of the turf ran from mid-October 2011 to early March 2012.

Officials at AvTurf, the company that won the project bid, originally hoped to finish the project before the end of the year, but bad weather and high winds slowed the installation. "Weather is a critical factor when installing artificial turf," explains AvTurf President Daniel McSwain. "With panels 200 feet long by 15 feet wide, if wind gets under them they act like a kite and literally take off. Fortunately, we have trained and experienced project managers who are accustomed to installing artificial turf at airports and know how to maximize safety in that environment."

The turf is installed in pairs of panels. The first is rolled directly on the compacted surface face up, and the second is rolled face down on top of the first. After the panels are sewn together on one end, crews open them like a sandwich, explains McSwain.

Although the 15-foot-wide panels can range up to 300 feet long, pieces used to create the Academy's landing surface ranged from 60 to 220 feet long.

To secure the outside edges of the turf adjacent to asphalt, crews stapled the panels to a recycled plastic header set 1½ inches below the top of the asphalt surface. On the three outside edges of the runway that do not butt up against a hard surface, the turf was set into a one-foot-square trench that was backfilled and compacted.

Crews further secured the new surface by grooming nearly 5,000 tons of sand into the turf - roughly 7 pounds per-square-foot. After the sand was applied, only ½ inch of the 1½-inch synthetic fibers remained exposed. Water drains through the turf and into the subsurface.

By choosing masonry sand instead of a silica variety, the Academy achieved an almost concrete-like surface, because masonry sand retains moisture and provides stiff compaction. On the downside, however, it can also serve as a growth media for vegetation.

Lt. Col. Downey considers the project an absolute success: "We shut down the landing area and moved one-third of our operations to the other side of the airfield in September and were back up and running in March - at a fraction of what it would have cost us to lay sod."

Care & Keeping

Although synthetic turf may seem like an environmental step backward from natural grass, Academy officials are pleased with the material's "green" features. With no grass to mow or weeds to eradicate, associated carbon emissions and the need for chemicals are eliminated. Occasional applications of additional sand are the only maintenance the Academy anticipates needing to perform.

AvTurf warranties the product for eight years, but McSwain expects the Academy's installation to last at least 15 years.

"We feel confident," he says, noting that the product contains ultraviolet stabilizers to prevent sunlight from breaking down the turf's fibers.

The Civilian Side

The same year AvTurf installed a test patch of its synthetic turf at the United States Air Force Academy in Colorado Springs, CO, it also carpeted a 1,240-foot runway at Calhan Airport (5V4), a nearby privately-owned facility.

"It's been nothing but a good experience," reports Airport Manager David Glaser of the 2006 installation. Since then, a variety of aircraft, including P-51s, Yaks and a DC-3, have tested the material.

A few years ago, the Army rented the airport for three days of high-altitude assault training with a Cathay, recalls Glaser. "They had 22 people on board and did 12 to 16 landings a day," he explains. "The pilot locked up the brakes and slid. I had black marks out there that were 20 to 30 feet long, but the turf held up great. I just took my rotary broom out there and dressed it up."

Glaser has also put the turf through other tests: "I've tried to tear it and burn it. I've put weed kill on it. It's held up great."

He's similarly pleased with its care routine. Other than brushing some sand into the surface about three years ago, Glaser says the surface has been nearly maintenance free.

From a user's perspective, a pilot who flies hunters into the airport provided Glaser with glowing feedback about the airport's synthetic turf: "He told me that it's better than grass, that it's the best thing he's ever landed on."

 

Subcategory: 
Runway/Ramp

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