Ever wonder why Shoreline Dr. regularly floods when it rains?
Surface runoff from the streets and other impervious surfaces enter drainage inlets on Shoreline Dr. and side streets. This runoff is conveyed through storm pipes (“outfalls”) that discharge to the Bay. When the outfalls fill with sand, the stormwater can’t discharge and the first low point for the water to release are the inlets on Shoreline Dr. This flooding is a safety hazard and in past years staff responds by working to clear the pipes.
What is the City doing to fix it?
To address the chronic flooding on Shoreline Dr. the City worked with and obtained permits from the East Bay Regional Park District (EBRPD) and the San Francisco Bay Conservation and Development Commission (BCDC) to construct improvements to the Park St and Kitty Hawk outfalls that traverse Crown Memorial Beach. The City will install a grated junction box and inline check valves on both outfalls. The boxes are placed at specific elevations on Crown Beach to serve as points of overflow if the outfalls are unable to discharge. To prevent sand from entering the system and causing blockages, the inline check valves will also be installed. The outlet valve is designed to “cut” through sand that may be built up in the pipe. Rip rap will be placed around the grated box structures. To minimize sand in the portion of the pipe from Shoreline to the new box structure, the City will rehabilitate the two outfall pipes to ensure sand is not entering the system from cracks and eroded joints.
What’s happening inside the fenced construction area on the beach?
The fenced area is the construction zone to install the box structures and check valves. The outfalls are fairly deep and this requires heavy equipment and shoring for the excavation. The pipe rehabilitation will be with a trenchless method to minimize impact to the beach. The inlets on Shoreline and newly placed box structures will serve as insertion pits for the pipe rehabilitation work.
Are environmental precautions being implemented?
Absolutely. The City provides inspection oversight to ensure all construction operations are performed in strict compliance with issued permits, the contractor’s approved Water Pollution Control Plan and other relevant regulation. In addition, the City consulted with BCDC and EBRPD to schedule this work so as to prevent any significant adverse impact to sensitive Bay resources.
The WPCP address, among other provisions, soil stabilization, sediment control, wind erosion control, and waste management and disposal. It also requires inspections of the construction site before, during and after storm events to ensure implemented practices are effective.
What’s the project schedule and when will the work be complete?
The work will start the week of November 30, 2020 and is expected to be complete in mid-January 2021, weather dependent. You’ll first see construction fencing on the beach at the Kitty Hawk outfall where the contractor installs the grated junction box. The project then moves to the Park St outfall for a similar installation. Once that work is complete the trenchless pipe rehabilitation will commence and lastly, installation of the check valves.
Who can I call for questions or concerns?
Erin Smith is serving as project manager. She can be reached at 510-747-7938. John Tallitsch is the project inspector. He can be reached at 510-846-8012.