Section 206 Aquatic Restoration
Challenge & Solution
The southernmost portion of a community park outside of Pittsburgh consists of a riparian ravine that flows through a railroad underpass and discharges stormwater into the floodplain bordering Chartiers Creek, a tributary of the Ohio River. Four primary problems were identified: 1) the degradation of ecosystem functions via unmanaged stormwater runoff entering the riparian ravine; 2) disruption of habitat quality within the floodplain due to uncontrolled release of stormwater runoff and sediment/erosion from the ravine; 3) dominance of non-native plant communities; and, 4) low overall wildlife suitability.
Rhea was contracted by the federal government and the local sanitation authority to restore the aquatic ecosystem of the park.
Project Description & Highlights
Rhea was first tasked to improve the existing riparian channel to better transmit stormwater from a previous combined sewer separation project. Under Rhea’s redesign, stormwater flowing through the ravine passes through a series of step pools to slow its velocity, thus reducing overall soil erosion to the ravine and the surrounding area.
As part of the total aquatic restoration, Rhea also designed eighteen vernal pools of various sizes and depths; these were placed throughout the floodplain bordering Chartiers Creek. The vernal pools store stormwater flowing across the floodplain from the ravine and create a temporary wetland. This effort restored the natural hydrologic cycle by allowing water to slowly infiltrate into the subsurface. These pools were specifically designed to provide habitat and breeding grounds for various local amphibians and reptiles.
The last task as part of the restoration project was to develop a program for the eradication of invasive plant species, primarily Japanese knotweed, by using an herbicide designed for use around aquatic environments. The program required replanting and reestablishing native grasses and hedges, as well as shrub and tree species.
Rhea hopes to use this site to demonstrate how an area once consumed by invasive species can be restored to its natural, thriving, native state. Rhea has completed the design of the riparian ravine, vernal pools, and invasive plant removal program, bringing the park several steps closer to that goal.