Adapting Combined Sewer-Stormwater Systems to Climate Change

Only one coastal city has a sewer system that must handle stormwater as well as wastewater. San Francisco's efforts to adapt its combined sewer-stormwater system has put it on the vanguard of the city's climate adaptation efforts.

2 minute read

October 31, 2017, 11:00 AM PDT

By Irvin Dawid

"Using combined systems was common practice for urban sewers built before the turn of the 20th century, said [San Francisco Public Utilities Commission] PUC General Manager Harlan Kelly Jr., when wastewater and rainfall both were typically dumped into nearby bodies of water," reports Dominic Fracassa for the San Francisco Chronicle on Oct. 21.

Because the city's sewer system can be easily overwhelmed during heavy downpours, and is vulnerable due to king tides and sea level rise, all of which will become more intense due to climate change, the San Francisco Public Utilities Commission, which provides retail drinking water and wastewater services to the city of San Francisco, is at the forefront of climate adaptation efforts.

The PUC’s improvement program will be rolled out in phases through 2032. The improvements themselves — everything from replacing outdated sewer pipes to raising critical electrical systems in treatment plants in anticipation of the higher sea waters — are designed to respond to how San Francisco’s climate could look in the year 2100. 

Another critical element of the PUC plan is an ambitious program of installing bioretention or rain gardens to divert stormwater from the sewer system and allow it to be absorbed into the ground. "[B]y allowing natural processes to take over the work we've been building infrastructure to handle, operations and maintenance costs also fall," according to a 2012 study on green infrastructure co-authored by the American Society of Landscape Architects.

In August, Fracassa reported on a ribbon-cutting by the PUC for the first of the eight rain gardens planned for the Ingleside district, an investment of $7.3 million.

Saturday, October 21, 2017 in San Francisco Chronicle

View of Mount Hood at golden hour with Happy Valley, Oregon homes in foreground.

Clackamas County Votes to Allow ADUs, Residential RVs

County officials hope the zoning changes will help boost the housing supply in the region.

June 18, 2024 - Mountain Times

Single-family homes in a suburban neighborhood in Florida.

New Florida Law Curbs HOA Power

The legislation seeks to cut down on ‘absurd’ citations for low-level violations.

June 16, 2024 - The Guardian

Aerial view of intersection in New York City with yellow cabs and zebra crosswalks.

Planners’ Complicity in Excessive Traffic Deaths

Professor Wes Marshall’s provocatively-titled new book, "Killed by a Traffic Engineer," has stimulated fierce debates. Are his criticisms justified? Let’s examine the degree that traffic engineers contribute to avoidable traffic deaths.

June 13, 2024 - Todd Litman

View of Palos Verdes Drive along Pacific Ocean in Palos Verdes, California at sunset.

Erosion Threatens SoCal Road, Lloyd Wright Icon

The city of Palos Verdes is closing parts of a roadway to cyclists, citing safety concerns as the land underneath moves between 7 and 12 inches per week.

5 hours ago - Daily Breeze

Faded image of vacant storefront in rural area with American flag stars painteind on windows.

COVID Isn’t to Blame for the Retail Vacancy Crisis

A drop in demand for retail space began well before the seismic shifts of the pandemic.

7 hours ago - Slate

Heavy New York City traffic headed toward Holland Tunnel in Manhattan.

Judge Rules in Favor of MTA in Congestion Pricing Suit

Advocates of the program are calling on Gov. Hochul to reinstate the program in light of the decision.

June 23 - StreetsBlog NYC

City Planner I

Department of Housing and Community Development

City Planner II

Department of Housing and Community Development

City Planner Supervisor

Department of Housing and Community Development

Urban Design for Planners 1: Software Tools

This six-course series explores essential urban design concepts using open source software and equips planners with the tools they need to participate fully in the urban design process.

Planning for Universal Design

Learn the tools for implementing Universal Design in planning regulations.