Arroyo 1 Dam Detention Improvements
The Arroyo 1 Dam Detention Improvements project includes low-impact, green stormwater infrastructure in the arroyo bounded by Franklin Ridge Drive, Franklin Hills Street, Franklin Hawk Avenue. This project aims to slow the velocity of water runoff from the mountain and prevent rock and silt material from clogging the concrete lined Bear Ridge channel while maintaining the natural aesthetic of the arroyo.
Past rain events (most notably in 2006, 2015, and 2021) overwhelmed existing infrastructure due to debris and silt clogging culverts and filling concrete channels. The Arroyo 1 Dam Improvement Project will reduce the amount of rock and silt that accumulates in the Bear Ridge Channel. Proposed improvements will also slow the speed of water as it comes off the mountain while reducing the amount of maintenance necessary.
This project will be completed winter 2025 at a cost of $5.8 million.
Scope of Work:
- Excavating and reshaping one-third mile of the Arroyo 1 channel just east of the Franklin Hills culvert
- Installing mortared rock rip-rap
- Implementing a geogrid gravel-filled soil stabilization system
- Adding gabion mattresses along the channel
- Constructing seven gabion basket structures to slow water speed and catch debris
- Constructing a maintenance road that will run the length of the arroyo Improvements
Green Infrastructure
This project will use steel wire structures filled with rock or stone used to improve stability and prevent erosion all while blending into the natural environment. These permeable structures will allow water to filter through while slowing velocity and over time allowing vegetation to grow through these structures.
Display boards shown at the Arroyo 1 Dam Detention Improvements Open House held Tuesday, Feb. 27, 2024.
Fact sheet (pdf)