Pinole Creek Restoration and Greenway Park Project

Abstract:

The Pinole Creek Restoration Project will modify the lower 1.5 miles of an existing single objective engineered earth flood control channel to increase flood conveyance capacity. It will also restore structure and function, enhance aquatic and riparian habitat. In addition the project will provide recreational trail access and landscaping and integrate the discharge of high quality (tertiary treated) wastewater to improve year round creek flows and provide landscape irrigation.

Purpose: The Pinole Creek Restoration Project has three primary purposes: 1. Increase flood protection, 2. restore the environmental structure and function of the waterway, 3. provide a non-motorized transportation route with recreation and environmental education benefits. If this project is not implemented, significant flood damages are expected to occur in the communities of Pinole and Hercules. The project is expected to provide increased flood conveyance capacity by removing one longitudinal access road and widening the channel to provide flood terrace and a sinuous bank full channel. The enlarged flood way will increase flood conveyance capacity and allow aquatic and riparian planting within the channel. The existing channel was constructed in 1965 as a trapezoidal earthen bank channel and contained the 1 in 50 return interval (RI) storm event. The project traverses the historic downtown district of the City of Pinole. The most recent hydraulic analysis estimates the channel capacity to be adequate only for the 1 in 13 RI storm event. The level of flood protection provided by the Pinole Creek project, as originally constructed by the U.S. Army Corps of Engineers in the 1960's, has diminished due to sediment build up and more intense development in the watershed than expected. The existing creek channel provides poor ecological value since its flood control performance depends on minimal obstruction due to vegetation. However, Pinole Creek supports native anadromous fisheries and has been the focus of local community efforts to restore the channel for over two decades. The restoration project will include the removal of maintenance access roads to allow for the inclusion of a bankfull channel, floodplain and native riparian vegetation. In the lower reaches, the project will include the removal of bridge crossings and a levee and the restoration of adjacent tidal marshes. A pedestrian trail and bikeway will follow the restored creek. One of the existing channel maintenance access roads is currently utilized as a recreational trail. However, the trail is a relatively stark, utilitarian facility - its principal environment feature being low turf grass. The Pinole Creek Greenway Park project will enlarge the channel resulting in an increased level of flood protection while providing more area for robust vegetation growth. It is anticipated that the attraction of a highly landscaped Greenway Park corridor will be the focal amenity that influences the redevelopment of the City's downtown area. Without the project, Pinole Creek will remain essentially a single purpose flood control facility that remains isolated from the community.

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