Headwater streams play an important role in downstream water quality.
Restoring upper watershed streams to their natural functioning state is a priority in Vermont. Sugarbush Resort in Warren, VT contracted Watershed to design a cost-effective stream-restoration plan. The plan included a culvert retrofit, designed to improve stream flow to allow fish to again swim upstream and sediment to move downstream.
Sugarbush Ski Resort is one of the oldest ski areas in the state. Many of its roads and smaller bridges were built using culverts that were sometimes too small. This has the potential to constrain stream flow – causing upstream flooding and downstream scouring.
Problems associated with upstream flooding include road washouts and road bed destabilization. Downstream scouring can cause the bed of a stream to sink, resulting in a ‘culvert waterfall’. This type of waterfall makes it difficult for vertebrate and invertebrate life to migrate up- and down-stream. Additionally, many of these older culverts are round which minimizes the stream bed surface within the culvert, creating a bottleneck both for stream water and for stream-dwelling organisms.
Watershed was brought in by Sugarbush to help design the proper size and shape culvert for anticipated storm flows. Restoration of the natural stream ecosystem was also a priority for the final design. Using HydroCAD hydrologic and hydraulic analysis, a better solution was found for the stream crossing at Rice Brook. To mimic a natural stream bottom ecosystem, a flattened-bottom metal culvert with metal baffles that hold natural river stones and gravel in place was chosen. This shape disperses flow and provides surface roughness to eliminate scouring, and provides a wider channel to allow higher flows to pass through with less resistance, minimizing upstream flooding.