Fixing the Storm Drain Flap Gate

BIAC at 1450 Maple St. in Redwood City has on its north-west end a parking lot with a storm drain that connects to an abandoned Redwood City 30" corrugated pipe. This drain pipe empties into an eroded marine cove (within the aerial view, circled below). Dated: January 2009

The flap gate on the end of this pipe is broken and water backs up through the storm drain at high tide. At a 9+ tide the road begins to flood. At a 10+ tide Maple Ave is impassable due to contributions from tidal overflow at the Docktown launch ramp.

Redwood City has requested that this Parking Lot storm drain, installed in April of 2007, be capped off with an appropriate flap gate to prevent tidal backflow and early flooding of Maple Ave. The possible issue of the outflow pipe's flap valve was never discussed during the original Parking Lot permit and design process. A drawing by Redwood City management in the Spring of 2008 suggests a good fix.

Note: Low tide conditions will be needed to see and access this decrepit duct.  You can find tide conditions at www.gobair.org by clicking on the right hand side Tides and Wind link.  You can also get long term tide outlooks from http://www.gobair.org/links/index.html in the Environment section. BIAC itself is a gated but not locked facility, so access to the site is easy for you.