Erosion control mats enhance scenic and economic appeal

In most cases, commercial and industrial real estate development spurs new highway construction, since new or expanding developments require more efficient roadways.

But the Pennsylvania Department of Transportation (PennDOT) undertook construction of the Lackawana Valley Industrial Highway chiefly for the opposite reason: to encourage future economic development in an area sorely affected by limited access.

When completed in 1997, the construction of the new roadway will help return the Lackawana Valley to a cleaner, more attractive condition, enhancing the scenic and economic appeal of the area.

Scarred by decades of strip mining operations, limited access and relocated textile industries, the area has been in economic decline. The long-range goal of the new project is to encourage future economic development and attract industry. The mid-portion of the new highway presented a particular challenge. Winding continuously through the mountains, the road required a balance between cut and fill sections in order to meet PennDOT’s list of specifications.

The resulting steep slopes and drainage channels created concern about erosion control. The anticipated water runoff velocities could disrupt and displace existing vegetation and make new growth very difficult.

PennDOT had two options: either conventional hard-armor (rip rap) lined drainage channels and swales to contain runoff water or erosion control mats to promote, protect and maintain the vegetation on the face of steep slopes and within natural drainage channels.

PennDOT opted for the mats because they were significantly more cost effective, performance oriented and aesthetically pleasing.

The mats, manufactured by Contech, Middletown, Ohio, help establish new vegetation while preventing any runoff damage to site soil and vegetation. The erosion control mats also help stabilize the soil against the uprooting shear stresses created by runoff forces. This stabilizing effect helps promote fast and dense germination of mature vegetation.

The company’s Erosion Control Revegetation Mats have a dense matrix of polyolefin fibers that initially protect seeds from surface runoff.

Meanwhile, silt fills the voids within the matrix to retain soil moisture, moderate soil temperatures and promote timely germination. As new vegetation matures, the matting reinforces the roots and shoots.

The mats were used at various locations on the project. Following grading, the erosion mats were installed directly on the unprotected soils.

The mats were initially secured in 12-inch-by-six-inch anchor trenches and by placing U-shaped wire staples at one-foot intervals. After the anchor trench backfill was compacted, mats were unrolled down the slope or along the channels with a three-inch overlap and were secured to the ground using two staples per square yard.