SF Sewer Safety

  Combined sewers systems (CSS) are a system of pipes which carry both sanitary wastes and rainfall runoff. Most cities in the US have separate sewers where sanitary wastes are managed in a separate system of pipes as storm water runoff.  CSS are an artifact of older sewers systems typically built before sewer treatment plants started to be built circa 1900. In the old days (ie 150,000 years ago to 100 years ago) most humans lived in small towns or rural areas with no organized systems of drainage nor to manage human waste except privies (outhouses). As towns developed from small villages, systems of pipes were developed to replace ad hoc collection of ditches along streets and typically drained these ditches (then gutters as streets are paved) away from developed areas to the nearest point of discharge, typically the closest stream, river, bay. These systems made a lot of sense, a single pipe under the street would carry both household/municipal sewage and rainfall...

Sewers have been used by humans for several thousand years. The original purpose was carry human waste away from our habitations. Over time, the goals and purposes of sewers evolved. Many human settlements and early urbanized areas started to include simple drainage of rainfall. This is a collection of notes and observations about combined sewer safety issues in San Francisco. The target audience is San Francisco residents, regulators, the press and general public interested in drainage, etc. Much of this will be outline formats, short paragraphs and notes with hyperlinks to external or internal documents.  The goal is to share information collected over the years, thoughts and observations on many aspects of combined sewer management, drainage, environmental and community impacts, and start to organize them for a more comprehensive set of documents to discuss various issues related to combined sewers and flooding, primarily focused on San Francisco.  All documents have been d...