CSW|ST2 is happy to announce that right before the holidays, and subsequent rain events, we completed the Redwood Lodge creek wall repair and fish passage project in Mill Valley. Last spring heavy rains had caused significant damage to a portion of the 100-year-old mortared stone walls, which contained the creek, and a concrete apron which were both located directly adjacent to the Lodge. To avoid further damage to the Lodge our client applied for and received a Regional General Permit 5 Repair and Protection Activities in Emergency Situations from the U.S. Army Corps of Engineers to begin the repairs to stabilize the creek walls and the Lodge. The above picture shows the final project where three new weirs were designed and installed to provide an upstream anadromous fish passage and new creek walls to stabilize the corner of the Redwood Lodge for future restoration.
In the pictures above you can see the damage to the former creek walls and the impact it had on the corner foundation of the Lodge. The lodge was originally constructed in the 1890′s as a summer home by shipping magnate George Billings and had eventually been expanded over the years after the family moved from San Francisco to the lodge in 1906. The current owner has plans to restore the Lodge and develop the property in the near future.
CSW|ST2 worked with Redhorse Constructors Inc., A.A. Rich and Associates, and local and state agencies to develop a solution of new concrete walls along approximately 50 feet of the creek, and at the request of the National Marine Fisheries Service new weirs were designed to help promote fish passage upstream. Here you can see workers from Redhorse and R.V. Stitch Construction Inc. smoothing the top and face of the shotcrete walls. The entire wall system was founded on reinforced concrete drilled piers. (View looking upstream.)
In order to shotcrete the walls a bypass pipe was installed to redirect the water. (View looking downstream.)
The existing 4.5 foot high weir created an impediment to the upstream passage of anadromous fish so three weirs were designed to help facilitate the movement. The weirs are spaced approximately 12 feet apart with large boulders and river gravel upstream and a minimum 2.5′ jumping pool downstream to create a pool sequence that facilitates an easier upstream migration. Removable redwood slats are situated in each weir to help low flow passage.
In the two picture above you can see success of the new walls and weirs as the water flows through the creek during a recent storm event. Downstream image on the left, and upstream image on the right.
Project Details:
- Civil & Structural Engineering: CSW|ST2
- General Contractor: Redhorse Constructors Inc.
- Contractor : R.V. Stitch Construction, Inc.
- Fisheries and Ecological Consultant: A.A. Rich & Associates
- Planning Consultants: International Planning Associates, Richardson Architects
- Geotechnical Engineering: Miller Pacific Engineering Group
- Environmental Consultants: LSA Associates, Georgia McDaniel & Associates
