Presidio Coastal Trail (Completed Spring 2012)

Channel Design Progress at Muir Beach

The channel design in the upper alluvial fan is almost complete. Below are before/after photographs of the project site and a list of the constructed design features.

Before photo (left): Existing erosion gully from channelized water flow from previous agricultural uses. After photo (right) : New channel and trail alignment to work with the natural topography and water flow of the site.

Design Features Include:

  1. Coastal Trail Re-alignment: The coastal trail has been re-aligned on the opposite side of the valley in order to improve the hiking experience (average 12% grade vs. the previous 17+% grade) and to reduce erosion that was happening on the trail. The trail has an out sloped surface for sheet flow from the hill side and rocked drain lenses in areas with heavy spring activity.
  2. New Channel Alignment: The new channel has been located in a more central location within the valley. Six rock key ways are constructed in order to dissipate the water flow during storm events and seasonal spring flow.
  3. Re-contouring the Hillside: The hillside where the old coastal trail was located has been re-contoured back to a more natural and stabile state.