About 90 miles east of State College, in rural Columbia County, mountains of waste tires scatter across an abandoned farm field. Collected over a period of decades in anticipation that the rubber would bring riches, the Starr Tire Pile is the state's largest, with about eight million tires filling 14 acres. Unfortunately, the tires generated more hazards than wealth and have become a major concern of Pennsylvania's Department of Environmental Protection (DEP). Waste tire stockpiles present a serious fire hazard and the warm damp crevices are an ideal breeding ground for mosquitoes, which carry the threat of West Nile virus.
In 2004, the DEP created a grant to encourage innovative techniques to make beneficial use of the millions of tires piled across the state. Penn State's Center for Dirt and Gravel Road Studies came up with the perfect solution: Use them as fill for severely eroded and entrenched rural roads.
Kevin Abbey, director of the Center, first proposed a plan to shred the tires into usable material. However, the method proved too tedious, and so in early 2006, Penn State readjusted its proposal to use tire bales.
A hydraulic compressor (similar to a trash compactor) was employed to bale the tires into one-ton building blocks, bound together with nine-gauge wire. Each block contains 100 tires and measures 30 inches high by four feet by five feet.
Abbey selected Mike Perks of Alternate Aggregate Development (a subsidiary of QuestCo, LLC located in Pittsburgh) to supervise the baling process. Due to the proposal change, the team had little time to meet the state's deadline, so Perks moved onsite to monitor round-the-clock. Stadium lights were mounted in the field and night surveillance cameras were installed.
Under Perks' direction, 350,000 tires were processed in three months. Over 200,000 tires were used in a demonstration project at Diehl Road in nearby Madison Township, and the remainder were collected as inventory.
Dave Shearer, project designer for the Center, explains the plans for Diehl Road to intern Abby Minor. The mission of the Center, which was established in 1999, is to provide technical assistance to township road crews throughout the Commonwealth, whose responsibility it is to maintain the nearly 20,000 miles of unpaved roads in Pennsylvania.
"Local municipalities do not have the equipment or funds to adequately maintain their roads," says Abbey, former executive director of the state senate's transportation committee. "There is a great need for low-cost materials to repair erosion and raise road surfaces, and waste tires are ideal." The porous nature of tires allows water to drain freely, and the bales provide good insulation during freeze and thaw cycles. "They are structurally perfect building blocks."
Diehl Road was chosen for its proximity to the Starr Tire Pile. The easily loadable and stackable bales were hauled by log trucks daily. The crew traveled back and forth between the two sites, placing approximately 300 bales per day.
A crew member with a firm grip and steady hands uses a grappling hook to hoist the bales from the truck and place them into their appropriate spots along the width of the road.
The claw also serves as a hammer to secure the bales in place.
Most dirt roads are immediately adjacent to streams, making them the largest source of sedimentary pollution. When rainwater collects and travels in concentrated volumes, the unstable soil from the banks and ditches accumulates and descends into the nearby streams.
Abbey and his team understand the importance of an environmentally sensitive approach to road construction and maintenance. "Environmentally sensitive maintenance should be applied to every road corridor, not just dirt and gravel roads," Abbey explains. "We need to consider the impact that roads leave on the environment long after the engineering, design, and construction is complete. More money is spent on maintenance if we're not mindful from the beginning."
After 25 years in the construction business, this is Shearer's largest project to date. It's also the first of its kind in Pennsylvania. The team relied heavily upon the case of Chautauqua County, NY. After a catastrophic tire pile fire occurred in 1995, causing substantial evacuation of the rural community, a team of civil engineers took immediate action. They successfully compressed all of the remaining tires into bales to use as fill for several roads in the area.
According to Abbey, bales dramatically decrease environmental and health concerns. Fires are easier to extinguish and the condensed environment is less attractive to mosquitoes.
"The beauty of this project," says Abbey "is that we're using local resources in every phase."
Once the bales are arranged, bottom ash (a granular incombustible coal by-product similar to sand), donated by PPL Montour Plant (100% coal fired power plant) just two miles from Diehl Road, is spread by a bulldozer to fill the voids between the tires. Shale rock, also locally available, is then used to shape the surface into the desired crown.
The final layer of the road is a driving surface aggregate (DSA) developed by Penn State.
"The DSA provides structural strength and includes an abrasion resistance factor to decrease dust," Abbey explains. "The completed road provides a stable surface for the milk trucks and log trucks and school buses that frequently travel rural roads. And it can be easily maintained by local road crews."