engineering

San Francisco Fire Department Auxiliary Water Supply System

San Francisco Fire Department Auxiliary Water Supply System is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand San Francisco Fire Department Auxiliary Water Supply System rather than just read about it. In short: The Auxiliary Water Supply System (AWSS, though often referred to on manhole covers and hydrants as HPFS for High Pressure Fire System) is a high pressure water supply network built for the city of San Francisco in response to the failure of the existing emergency water system during the 1906 earthquake. Most damages to the city from the earthquake were caused not by the seismic event but by the fires that ensued, d…

Key takeaways

San Francisco Fire Department Auxiliary Water Supply System belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect San Francisco Fire Department Auxiliary Water Supply System to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of San Francisco Fire Department Auxiliary Water Supply System from memory before moving on to harder problems.

Reference excerpt

The Auxiliary Water Supply System (AWSS, though often referred to on manhole covers and hydrants as HPFS for High Pressure Fire System) is a high pressure water supply network built for the city of San Francisco in response to the failure of the existing emergency water system during the 1906 earthquake. Most damages to the city from the earthquake were caused not by the seismic event but by the fires that ensued, destroying 80% of the city's property value at the time. The improved water system was originally proposed by San Francisco Fire Department chief engineer Dennis T. Sullivan in 1903, with construction beginning in 1909 and finishing in 1913. The system comprises a collection of water reservoirs, pump stations, cisterns, suction connections and fireboats. While the system can use fresh or salt water, it is preferential not to use salt water, as it commonly causes galvanic corrosion in fire equipment.

The large, white oversized hydrants that are supplied by the AWSS/HPFS, of which there are 1,889, are visible throughout the city. The hydrants have painted tops that are color-coded as to their zone:

Black-topped hydrants are in the West of Twin Peaks zone and are fed by the Twin Peaks Reservoir. Red-topped hydrants are in the upper zone and are fed by the Ashbury Street tank. Blue-topped hydrants are in the lower zone and are fed by the Jones Street tank.

Upper zone

Reservoirs

Twin Peaks Reservoir

The Twin Peaks Reservoir is the backbone of the AWSS system and is located at the top of San Francisco's Twin Peaks hilltop. It is made up of a 10.5-million-U.S.-gallon (40-million-liter) storage reservoir made out of 6-inch-thick (150 mm) reinforced-concrete slabs. Two 750-US-gallon-per-minute (2,800 L/min) centrifugal pumps deliver fresh water from the city's domestic water system. For safety, the reservoir is broken up into two tanks, and each tank can be emptied separately so that only half of the reservoir is lost in case of a pipe breakage. The tank is set at 758 feet (231 m).

Ashbury tank The Ashbury tank is directly connected to the Twin Peaks reservoir and has a total capacity of 500,000 US gallons (1,900,000 L). The tank is set at 494 feet (151 m) and, when combined with the Jones Street tank, can provide hydrants with 214 pounds per square inch (1,480 kPa) of pressure. It is located at 1234 Clayton Street, in the city's Ashbury Heights neighborhood.

Jones Street tank The Jones Street tank is directly connected to the Ashbury tank and has a total capacity of 750,000 US gallons (2,800,000 L). The tank is set at 369 feet (112 m), providing hydrants with 160 pounds per square inch (1,100 kPa) of pressure. It is located at 1239 Jones Street in the city's Nob Hill neighborhood.

Lower zone

Pump stations

There are two emergency pumping stations present within the AWSS:

Pumping Station No. 1: Basement of San Francisco Fire Department Headquarters, 698 Second Street at Townsend St. Pumping Station No. 2: Van Ness Avenue and San Francisco Bicycle Route 2 in Fort Mason. Both stations are capable of pumping 10,000 US gallons per minute (38,000 L/min) of salt water at a pressure of 300 pounds per square inch (2,100 kPa) with on-site generators. Pumping Station No. 2 is listed on the National Register of Historic Places.

Fireboats

To supplement any failure of the pumping stations or reservoirs, the city’s two fireboats can be utilized to deliver salt water into the system. They can also deliver water by hose line to areas near the waterfront.

Phoenix: 9,600 US gallons per minute (36,000 L/min) at 150 pounds per square inch (1,000 kPa) St. Francis: 18,000 US gallons per minute (68,000 L/min) at 150 pounds per square inch (1,000 kPa)

Cisterns

As a final measure to counter a failure of the AWSS piping, the city maintains a network of 177 independent underground water cisterns. Sizes vary from 75,000 to 200,000 US gallons (280,000 to 760,000 L) with a total storage capacity of over 11 million U.S. gallons (42 million liters) of water. These cisterns are easily spotted at street level with manholes labeled CISTERN S.F.F.D surrounded by red brick circles or rectangles.

References

Illustrations

Worked examples

Example 1 — a first encounter with San Francisco Fire Department Auxiliary Water Supply System

Start with the simplest possible case. Write down what San Francisco Fire Department Auxiliary Water Supply System claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to San Francisco Fire Department Auxiliary Water Supply System before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about San Francisco Fire Department Auxiliary Water Supply System ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of San Francisco Fire Department Auxiliary Water Supply System

In research: San Francisco Fire Department Auxiliary Water Supply System appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses San Francisco Fire Department Auxiliary Water Supply System in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: San Francisco Fire Department Auxiliary Water Supply System is common in secondary-school and first-year university syllabi. It links to neighbouring topics Buildings and structures in San Francisco, Fire prevention, Fire protection, so understanding it makes those chapters shorter.
In everyday life: Look for San Francisco Fire Department Auxiliary Water Supply System outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study San Francisco Fire Department Auxiliary Water Supply System in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what San Francisco Fire Department Auxiliary Water Supply System means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain San Francisco Fire Department Auxiliary Water Supply System out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is San Francisco Fire Department Auxiliary Water Supply System in simple terms?

Why does San Francisco Fire Department Auxiliary Water Supply System matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study San Francisco Fire Department Auxiliary Water Supply System?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on San Francisco Fire Department Auxiliary Water Supply System.