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Dirt, gravel and low volume roads (DGLVR) are an essential part of our transportation system and a major source of pollution. Water runs along roads, picks up pollution and delivers it to nearby streams or lakes.

The DGLVR grant program provides education, technical assistance and funding to improve roads and subsequently the landscapes they travel through. Every year, projects are funded that promote cost-effective, environmentally-sound maintenance practices to correct pollution and improve safety.  
 

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Repairing Toms Run Road

Like many roads in Allegheny County, Toms Run Road in Kilbuck Township is wedged between a stream and a slope. Water from the hillside floods the road and causes ruts, cracks and deformities.

Repairing this road ensures safe and continued access to Toms Run Nature Reserve and reduces potential damage to the nearby stream caused by the deteriorated roadway. Together, ACCD and Kilbuck Township developed a plan that built on the success of previous road improvements in earlier phases of the project.

While simply resurfacing a roadway can improve its appearance, ACCD’s projects address the source of the damage. Capturing excess water plays an integral role in ensuring repaired surfaces stand the test of time.

The Dirt and Gravel Roads Grant Project on Toms Run Road included 800 linear feet of roadway excavation to replace the depleted paved surface with 12 inches of compacted stone. In addition to resurfacing, the project also sought to address drainage issues in and on the road itself. Crews designed a rock-lined swale to capture water from the hillside before it enters the roadway, and a newly-installed French Mattress allows water to safely move across the road.

What is a French Mattress? 

This project included the installation of a practice called a “French Mattress.” A French Mattress is best installed in locations where water is saturating a road base. The goal is to allow water to travel across the road while maintaining the integrity of the road itself. 

How does it work? Crews place a large piece of geotextile fabric in the roadway just below the surface and cover it with medium-sized rocks. These rocks create needed pore space for water to move through. The fabric is then wrapped around the rocks to prevent smaller material from filling the pore space once the road is resurfaced. The mattress is exposed on either side of the roadway to allow water to enter and exit with ease.