Stony Clove Project Site Visit

Posted on: August 21st, 2014 by Leslie_Zucker

Here’s a more detailed description with photos of the Stony Clove Creek stream restoration project under construction this summer. The site is located at the confluence of Stony Clove Creek and Warner Creek and extends downstream ending before the Silver Hollow Road bridge. A history of development and stream erosion has led to frequent manipulation of the site. By 2001, about 1,366 feet of stream banks at the site were actively eroding and 1,103 feet of banks were lined with rock revetment. Floods in 2010 further destabilized the stream bed and banks. If left unchecked, bank erosion will threaten both Route 214 and Silver Hollow Road. The Stony Clove Creek Stream Management Plan recommended full restoration of the site. The project under construction now implements plan recommendations, including installation of large step/pool structures to stabilize the stream bed and direct erosive forces away from the banks, and a floodplain bench vegetated with trees and shrubs installed between the active channel and eroding banks.

Stacked Rock Wall

Construction of a stacked rock wall to protect the left bank below Silver Hollow Road.

Glacial Till Streambank

The project should prevent and reduce erosion of glacial tills and fines that degrade water quality and threaten Route 214 (above).

Sheet Piling Grade Control

Because of the intense stream power through this site, the step/pools installed for grade control are constructed from metal sheet piling driven into the ground with a large pneumatic hammer. Here the buried tops of sheet piling can be seen in the stream bed at the feet of Project Manager Adam Doan, Ulster County Soil and Water Conservation District, and Site Supervisor Vernon Bevan, Milone & MacBroom, Inc.  The stream bed will be rebuilt above the sheet piling.

Water Diversion

The flows of Stony Clove Creek are diverted around the construction site to protect water quality and meet permit requirements. The 48″ plastic pipe is covered with a concrete blanket. The blanket and the cool water flowing inside prevent the pipes from expanding due to summer heat and sun. The pipes can pass stream flow of at least 50 cubic feet per second (cfs). In this photo, the Stony Clove is flowing at 12-13 cfs.

Coffer Dam

A metal coffer dam was installed to stabilize and divert flows around the project site. This dam is temporary and will be removed.

Project Site Construction

The site at the peak of construction. Despite how it appears now, this site will be left in a natural looking condition at project end. After the grade control structures are installed, the stream bed will be restored with natural cobble and large rock boulders. Contractors have set aside native rocks that were left by glaciers and rounded by millennia of water flows for placement back into the stream. After that, the Stony Clove will do its part to move and sort material at the site. Work will complete by end of September.

The project should result in modest fish habitat improvements. Installation of step-pool structures may increase fish passage at low flows and increase the amount of shallow margins. Installation of the bankfull bench with overhead vegetation should provide more cover and shading for fish passing through the site. Projects are not constructed during trout spawning seasons to protect the fishery.