Napa River Dry Bypass, CA

The Napa River Dry Bypass was built to eliminate destructive flooding that the Napa Valley Oxbow market had experienced in the past. Conceptualized by the USACE, the project design called for diverting flow prior to flood stage into an approximately half-mile long channel, with and including designated ponding areas. This design posed some challenges: first, being the erosive forces from the water flow; secondly, offering structural support for the slopes, roadways, and walking paths; while thirdly, the project site would need to be utilized for multiple purposes once completed. The finalized project would be utilized not only as a spill way but also as walking paths, community events, and even outdoor concerts.

The high strength and durable woven structure of the PP5-Xtreme was a key factor in overall performance for this project. Along with the use of the Gripple Anchor System, this material was able to be used to support the establishment of vegetation while resisting the loading of foot and vehicle traffic. The anchors were able to provide the needed force to support all of the slopes along the project as well as reinforce the HPTRM in the channel from scour during a flood event.

After completion of the project in 2017, the NAPA valley experienced a historic wet season. The bypass started to flow and carried water for weeks. The system proved that it was able to take the flow, and it kept the city dry and free of costly flooding.

Using the Gripple Anchor System allowed us to secure the erosion control system quickly and with confidence. The anchors saved time during installation and delivered the holding power needed to keep the bypass functional, even as it carried water for weeks during record rainfall.