CWE Project with Caltrans Wins a Storm Water Solutions 2016 Top Project Award

by PRC Agency PR

Storm Water Solutions (SWS) magazine, a national publication, recently celebrated the most noteworthy stormwater and erosion control projects with the eighth annual installment of its Top Stormwater and Erosion Control Projects awards. Each year, the SWS editorial staff recognizes new facilities and projects, as well as innovative upgrades and notable stormwater and erosion control solutions. SWS encouraged project leaders to submit entries showcasing projects in the design or construction phase within the previous 18 months. The judges selected 10 winners based on obstacles faced and overcome, and final goals achieved. Although they vary in size and scope, the winning projects shared several main objectives, including meeting population and regulatory demands, addressing aging infrastructure needs, and implementing cost-efficient technologies and best practices.

The North Fork of Matilija Creek, located northeast of Ojai, California, is critical habitat for the Southern California steelhead trout. Due to development along the coasts and throughout the watersheds, stream habitat for steelhead is scarce in Southern California. All streams with habitat and potential habitat are carefully regulated to provide opportunities for steelhead population growth and expansion. A section of grouted stone highway embankment owned by the California Department of Transportation (Caltrans) posed a danger to traffic as erosion undercut the embankment and created a void under a travel lane on a section of the creek. Caltrans District 7 quickly learned that keeping drivers safe on State Route 33 also meant precautions would need to be taken to protect the steelhead.

CWE conducted the studies for Caltrans District 7 on this unique project that required fish passage characteristics and sediment transport analysis. CWE has been providing civil and environmental engineering services for over 10 years and has offices in Orange County and San Diego, California, and Springville, Utah. Staff from the Fullerton and Springville offices conducted the analyses and designed fish habitat enhancements on this project. The project required approval from the California Department of Fish and Wildlife and National Marine Fisheries Service since the project did not fit within their standard design guidelines due the channel steepness and the step-pool geomorphology. This project improved habitat for juvenile steelhead rearing and fish passage for adult fish returning to spawn. The project will help increase the number of steelhead within the creek system.

The North Fork of Matilija Creek’s step-pool geomorphology is an important aspect of the steelhead trout habitat critical for sheltering juvenile steelhead. Of particular importance was the creek’s sediment transport, which CWE aimed to disturb as little as possible. “Analysis showed that the design would preserve sediment transport conditions for flows up to the two-year flow and allow sediment transport during larger events while providing resting areas for fish migration during extreme events,” said Dr. Ben Willardson, Director of Water Resources for CWE, the firm tasked with designing the streambed stabilization and fish passage features for the $3.23 million project.

“The project included a fish management plan using pumps, a dam, and a discharge system to bypass flows around the project. The system prevents sediment from entering the stream flows and stressing juvenile fish in downstream habitat. The grouted stone revetment will be removed from the top down, removing the waste materials away from the stream rather than working in the stream corridor, which further reduces the potential impacts to the stream area. Additionally, fish had to be relocated, which posed additional challenges to the work,” said Willardson. Sediment control for construction also includes a setback from the stream with standard erosion control practices, such as silt fencing to prevent movement toward the stream.

Widening of the floodplain increased the space for fish to find shelter during high flow events. The channel cross-section capacity had to be large enough to move the sediment while also providing shelter in the overbank. Native riparian plants and special fish habitat structures were implemented to shelter fish from velocities of almost 25 feet per second during large events. CWE and Caltrans worked closely with staff from the National Marine Fisheries Service to develop the project design to get the project approved quickly. "This project is a great demonstration of CWE's commitment to Create a Better Tomorrow, Today! We look forward to working with Caltrans on more project that provide such benefits to the communities we all serve," said Jason Pereira, one of the firm’s Principals.

Learn more about other SWS Top Projects of 2016 here.