Pennsylvania development minimizes environmental impact
Metropolitan Management Group selected a 19-acre tract of land to develop a 160-unit luxury apartment complex in Muhlenberg Township, Pa. The tract was at the base of a steep mountainous terrain and immediately upstream of a watercourse, which has Pennsylvania Department of Environmental Protection protected use for migratory fishes and warm water fish. Extra care had to be taken to minimize accelerated erosion and the resulting sedimentation during the phased construction of the various structures.
The final plan called for 2:1 slopes at the base of the mountain. East Coast Erosion Control ECSC-2 double-net straw/coconut erosion control blankets were installed on the slopes to promote the establishment of vegetation.
Run-on from the steep slope above had to be captured and safely conveyed around the project. Two large swales were designed to capture the run-on as it entered the project site and then safely convey it to a detention facility for passive treatment. The 12-ft-wide swale that received the mountain run-on was lined with East Coast Erosion Control high-performance turf reinforcement mat.
The second steeply sloped swale was lined with East Coast ECC-2 double-net coconut erosion control blankets. ECC-2 has a permissible shear stress of 3.3 lb per sq ft and a permissible velocity of 10.0 ft per second in an unvegetated condition.
Vegetation quickly established and turned the slopes into a lush green carpet within weeks of germination.
Vegetation was observed within two weeks as it grew through the single monofilament mat. Both swales were quickly covered with vegetation that aided in the management of storm water flows through the project. Neither swale nor the steep slopes protected with the East Coast Erosion Control products experienced any erosion problems.