Design FAQ

Why is the restoration needed?

  1. The stream channel had vertical incisions, was experiencing erosion, and fine sediment was accumulating within the pool features.
  2. Fast moving water from the pipe under North Tollgate Road caused the channel bed to drop in elevation and bank height to increase. 
  3. Erosion caused the banks to become undercut and the potential for tree fall was present.
  4. Fast moving water around the pedestrian bridge was scooping out soil and depositing it downstream. This is called scouring. It was negatively impacting the stability of the bridge and contributing to the mucky conditions of the pond. 
  5. The structures previously installed in the pond have failed and are now contributing to the decline in water quality.

What will the constructed features be?

  • Cascade Structure: limits erosion in areas with high slops by adding large rocks to the stream bed that slow the water. 
  • Outfall Pool Protection: stabilizes the stream bed near the outfall pipe by slowing the water with a pool. 
  • Overflow Stabilization: Protects the bank where flooding is anticipated by lining the banks with large then smaller rocks.
  • Riffle Stabilization: diversifies flow patterns, maintains a concentrated baseflow and provides habitat in areas with low slope by arranging different size rocks and wood in the stream.
  • Step-Pool Structure: reduces erosion where water is moving quickly downhill by constructing a series of small pools.
  • Toe Boulder Protection: protects channel banks from fast-moving water by adding a row of boulders along the stream banks. 
  • Tributary Stabilization: maintains wetlands by filling the vertical incisions of the tributary with riffle mix