Proposed Santa Venetia Levee Upgrade Project existing elevations and berm condition

A levee and timber-reinforced berm sits behind homes on Vendola Drive. The timber-reinforced berm was installed in 1983 by Flood Control Zone 7 after devastating and widespread floods happened two years in a row in Santa Venetia. The purpose of the timber-reinforced berm is to prevent flooding when the tides in Las Gallinas Creek reach high levels.

existing Timber-Reinforced Berm
The existing Timber-Reinforced Berm is deteriorating in many places

Timber-reinforced berm

The timber-reinforced berm (TRB) consists of two vertical panels of wood filled with soil. It's installed on top of the levee. Typically the wood panels have to be replaced every 20 years due to deterioration. The TRB system has worked so far for high tides, but the the deterioration of the timber, compounded with rising sea levels and sinking land elevations, threatens its ability to protect Santa Venetia from flooding.

Elevations

In 2019, the Zone completed a topographic survey of the project area using an unmanned aerial vehicle (a drone) equipped with a LiDAR 3D laser scanner. The digital elevation model gives a sense of levee location, variability, and the interior ground surface.

existing levee
King tides threaten the timber-reinforced berm and levee

Levees

10 years of prior work has pointed to the levees as the weakest link in the flood protection system for Santa Venetia including interior drainage and watershed-scale studies.

A comprehensive levee analysis was completed by a geotechnical consultant in partnership with the U.S. Army Corps of Engineers. It indicated that high tides would likely damage the TRB and flood the community before they were high enough to reach the top of the TRB. The analysis also revealed that some sections of the earthen levee without the TRB are not high enough to hold back expected high tides over the next few decades.

Read the Levee Evaluation Reports:

CAP 205 Study Termination Letter for Las Gallinas (U.S. Army Corps of Engineers, 2017)

Geotechnical Alternatives Analysis, Las Gallinas Levee System, San Rafael, California (Kleinfelder, Inc., 2014)

Las Gallinas Creek, CA - Preliminary Flood Damage Analysis (U.S. Army Corps of Engineers, 2014)

Geotechnical Data Report - Las Gallinas Levee System - San Rafael, California (Kleinfelder, Inc., 2013)

Las Gallinas Creek - Hydrologic, Hydraulic and Coastal (U.S. Army Corps of Engineers, 2013)

 

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