In response to repeated and large-scale floods through the 1950s, the Santa Clara Valley Water District (District) constructed many miles of flood protection projects, including concrete-lined channels. Many of these channels are now well over 50 years old and are reaching the end of their life cycle. Most agencies now refrain from using hardscape flood protection solutions because newer methods and alternative solutions exist. Rather than simply replacing these channels, this project took a natural approach to flood protection. These methods included flood retention, stream restoration, and multi-stage earth-lined, vegetated channels. If successful, this pilot project will serve as a model for restoring other South Bay concrete channels facing similar issues.
McGuire and Hester Crews removed approximately 650 feet of existing concrete trapezoidal channel lining on Hale Creek from upstream in the City of Mountain View to downstream in the City of Los Alto. Once removed, it was replaced with a vegetated earth channel, including hardened outside retaining walls.
This work provides the following benefits:
- Widened the flood-prone area available to the stream
- Restored the natural channel bank and inverted lining
- Allowed natural stream recharge
- Reduced the channel slope
- Restored channel meander
- Permitted meander development into the future
- Lowered the one-percent and lower flood event water surface elevations.
Additionally, crews removed a 30x15-footbridge and replaced it with a new 30x12-foot prefabricated steel bridge to span between the east and west banks slightly downstream of the previous bridge.