What's underneath those brick circles?


Scheswohl has worked for the San Francisco Public Utilities Commission for six years photographing pump stations and reservoirs. She says this cistern was built in 1910, following the 1906 earthquake, as part of a supplemental source of water for the fire department. Scheswohl notes that, like the worker who was engaged in seismic upgrade work in the image, she wore a hazmat suit, a harness and an air quality monitor as part of her equipment to get the shot. The monitor was used to detect the presence of hydrogen sulfide gas.

There are 172 cisterns strategically located throughout the city so as to provide the Fire Department with a total storage capacity of approximately 11 million gallons of water.

Access to underground cisterns is made by removing the manhole cover located in the street. Determination of cistern location is based on two fundamental fire-control considerations. One is where the underground water distribution system is more susceptible to damage by earthquake. The six-lane Van Ness Avenue, running north and south from the San Francisco Bay to Market Street, best describes the other example.

Van Ness Avenue was a stand-and-fight location for firefighters in 1906, the year of the great earthquake. It was here that firefighters fought hard to stop the fire from burning further west. This major thoroughfare is lined with cisterns and high-pressure hydrants that may be called on some day in the future to stop a major conflagration from burning down the city.

The average capacity of a cistern is 75,000 gallons with the smallest being 9,600 gallons, located at Stockton and Vallejo Streets, and the largest being 243,000 gallons, located in front of City Hall at the Civic Center.

Cisterns are designated by manholes with CISTERN SFFD marked on them, and most with a ring of bricks around the manhole cover in the street asphalt. Additionally, the nearest low-pressure hydrant's bonnet is painted green. Engines would utilize normal drafting procedures when using such cisterns. The manhole cover is removed and the engine spotted within 3 feet of the cistern opening, allowing for plenty of space to hook up and drop two lengths of hard-suction for drafting.

Previously, previously, previously.


Printed Machine with Concrete

(Concrete not technically printable.)

This is a printable version of Machine with Concrete. The sculpture is a series of twelve 1:50 worm gears, with each gear reducing 1/50th of the previous gear. With 12 gears, the final gear ratio is a mind boggling 244,140,625,000,000,000,000:1 (244.14 quintillion to 1). With the first gear spinning at 200RPM it would take over 2 TRILLION years for a single revolution at the end of the machine, so the final drive shaft can be embedded in concrete or plaster.

Previously, previously, previously.

Tags: , ,

Soma Nature Walk: Mom Chung's High Pressure Jets

Since they dropped a road over the trench, there's nothing much to see on the Nature Walk, and we're just left with their Flickr feed:

Previously, previously.

Tags: ,

The now.


Tags: ,

  • Previously