Stony Clove Creek Bank Stabilization and Channel Restoration
Ethan Ely, PE
SLR Consulting
Waterbury, VT
Miguel Castellanos, EIT
SLR Consulting
New Paltz, NY
Authors: Ely, Ethan, P.E. and Castellanos, Miguel, E.I.T.
Stony Clove Creek, located in the Catskill Mountains of New York, is one of the primary streams that supplies water to the Ashokan Reservoir, which is an integral component of New York City’s drinking water supply. The stream is also a major contributor of suspended sediments (i.e., turbidity) that reduce water quality and impact drinking water disinfection processes. In 2011, Tropical Storm Irene caused major flooding within the region and destabilized Stone Clove Creek, exposing glaciolacustrine clay deposits along the bed and banks of the eroded stream. As a result, the New York City Department of Environmental Protection (NYCDEP) initiated a project to identify and monitor sites that were major contributors of turbidity within the Ashokan Reservoir watershed. Along Stony Clove Creek, numerous Bank Erosion Monitoring Sites (BEMS) were identified, one of which developed when the stream channel avulsed during Irene, initiating a hillslope failure that exposed a large glacial deposit of clay. SLR Consulting was hired to monitor the BEMS using both traditional survey and drone-based photogrammetric survey techniques.
After several years of monitoring, NYCDEP retained SLR to design a bank stabilization and stream restoration project for the site where the channel avulsion and hillslope failure occurred. The restoration project, which covered approximately 1,500 linear feet of stream corridor and included 6.6 acres of stream channel, floodplain, and riparian areas, was completed in September 2022. Overall, the project required extensive evaluation of the stream’s hydrology and geomorphological processes, the use of two-dimensional hydraulic modeling, and implementation of innovative bioengineering techniques for stabilizing the riparian corridor. A critical aspect of the design was selecting the alignment for the channel and reshaping the floodplain to minimize the potential for clay exposure while also giving the creek some freedom to “wander” within the geomorphically dynamic valley setting. This presentation will give an overview of project components including the use of drone-based aerial survey, implementation ground penetrating radar to map clay deposits, evaluation of restoration alternatives, key project design elements, and floodplain restoration techniques. Thus far, the project has been a success and recently won the 2024 ACEC-NY Platinum Engineering Excellence Award.
About Ethan Ely, PE
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About Miguel Castellanos, EIT
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