Southgate Beautification and Re-Greening Project

Before 2014, the City of Palo Alto’s Southgate neighborhood lacked curb and gutter systems, which caused deep street ponding during storms. To address this issue, the City installed bioretention areas, pervious pavement crosswalks, and a pervious walkway linking the neighborhood to a major commercial area. These neighborhood features are all examples of Green Stormwater Infrastructure (GSI) — an alternative way to design streets to drain water quickly, capture pollutants, and enhance neighborhood landscaping. The Southgate GSI measures dramatically decreased the frequent ponding, as shown in the before and after images below.

Southgate street before and after GSI measures were installed.

What kind of GSI was installed in the Southgate Neighborhood?

The Southgate Project consists of several bioretention areas and pervious pavement installations throughout the neighborhood. The bioretention areas filter stormwater runoff from the neighborhood streets during smaller storm events. During larger storms, the runoff overflows into street gutters to the expanded underground storm drain system in the southeast corner of the neighborhood.

Bioretention area located at Sequoia and Escobita Avenues.
Bioretention area located at Sequoia and Escobita Avenues.

 Crossview of a bioretention area.
Bioretention areas reduce street ponding and beautify neighborhood streets.
Rendering created by Wetland Studies and Solutions, Inc.
 

Pervious concrete pavers cover approximately 3,200 sq. ft. of crosswalks and pedestrian walkways in the Southgate neighborhood. These pavers allow water to pass through the void spaces between the solid pavers. During storms, water filters into these crosswalks and then into retention areas underground rather than running over impervious roadways, which can cause street ponding.

Diagram of pervious pavement layers.
Pervious pavement diagram showing typical installation

Pervious pavement crosswalk in Southgate neighborhood
The Southgate Project has converted many crosswalks and pedestrian walkways in the neighborhood to pervious pavers.

Where are the GSI measures located?

Below is a map indicating the locations of the bioretention areas and pervious pavement crosswalks and walkway in the Southgate neighborhood.

This element requires javascript to be enabled.

Please wait while we load your map...

Southgate Project Updates

In late 2020, the City launched a pilot project with the local nonprofit Grassroots Ecology to maintain and update these measures for better performance. Improvements include amending existing soil to assist with drainage and plant health, replacing rocks with mulch, and exchanging current plants with native and drought-tolerant species. The first phase of the pilot focused on two bioretention areas located on Castilleja Avenue near Peers Park (as indicated by the purple pinpoints above on the map). The next phase, to take place early 2021, will include the two bioretention areas located at Mariposa and Sequoia Aves. and two located at Castilleja and Miramonte Aves. The City and Grassroots Ecology hope to involve the residents and community members as pandemic restrictions allow.

The first phase, which took place in fall 2020, is portrayed in the pictures below. These two areas were replanted with native plants and received new mulch (instead of rock). With regular monitoring, plants have taken root and begun to grow in time for the rainy season!

Before (August 2020)

Before_August.jpg

October 2020 Planting Day

GR_00850.JPG

After (December 2020)

DSC_4791.jpg

Learn more about GSI measures