Water Distribution Flashcards
First water distribution network
a. Roman aqueduct system – 2000 years old and still standing. It’s what allowed for ~1mil people cities…
First US water system was created in ____ in the city of ____
1801
Philidephia
When did Tucson Water Company first start delivering water?
1881
Describe early water mains.
d. Early 1800 – wooden water mains. “Plugging” a line came from the fact that you literally bored a hole in the wooden pipes and then had to replug it.
What are the two sources of water TFD uses?
Static and pressurized
Static water
i. Any source of water that needs to be mechanically moved into a fire apparatus
1. Lakes/ponds/rivers
2. Portable tanks
3. Cisterns
4. Swimming pools
5. Test pits
What is drafting?
ii. Drafting is the process of raising water from a static source to the pump.
1. TFD only drafts at the test pit during pump tests and Water Tender Shuttle Operations
3 things that affect drafting
a. Lift – the difference between the level of the water and the center of the pump.
b. Vacuum – an enclosed space from which matter, especially air, has been partially removed.
c. Atmospheric pressure – the weight of a column of air at a given location on the surface of the earth
i. On average, at sea level, the atmospheric pressure is 14.7 psi
ii. Tucson is normally 13.9 psi
What is Tucson’s atmospheric pressure?
13.9psi
How does drafting work?
- By decreasing the pressure (mmHg) in the pump and hose below atmospheric pressure, the water is forced into the hose. Atmospheric pressure is still pushing on the static water source. The pressure/force on the water source will push the water up the hose
Pressurized water
Any source that will flow freely into a fire apparatus.
Booster tanks
Water Tenders
Hydrants
Booster tank details
a. Must be able to deliver 250GPM to the pump gravity fed if the tank is less than 750 gallons
b. Must be able to deliver 500GPM to the pump (gravity fed) if the tank is 750 or more.
Water tender details
a. Bring water to places where there are few or no hydrants
b. WT20 (8779) carries 2500 gallons of water (10 tons)
(Yes, I know WT20 has been moved around, but we haven’t gotten any official written documentation of what station its at, so I’m going off of the PP we got.)
Hydrant details
a. Fire hydrants are part of a water distribution system that is designed to meet the needs of the community it serves.
b. Hydrants are placed for the specific purpose of providing an adequate and reliable water supply for fighting fires
Components of a distribution system
Supply source Treatment plants Reservoirs Mains Hydrants
Supply sources
i. There are 206 active or standby wells in the Tucson water system
ii. 91 million gallons per day come from well within Tucson (2014 data)
iii. CAP – 57 million gallons of blended water (2014 data)
iv. CAP aka Clearwater
Treatment plants
i. Treated with chlorine at well sites
ii. Monitored throughout the system at reservoirs and other sites
iii. Additional chlorine can be added throughout the system as needed
Reservoirs
i. Reservoirs are filled from well sites
ii. 57 total reservoirs
iii. 29 are over 1 million gallons
iv. 28 are under 1 million gallons
Mains
i. Booster stations boost water along mains.
ii. Grid system
1. Pressure in a grid system is created by gravity from reservoirs at higher elevation and from pumping stations
Advantages of using grid system of mains
a. Helps reduce dead end mains
b. Loop or grid systems will reduce friction lose by a power of 4
c. Only one or two hydrants shut down if a main is broken
Friction loss in mains
a. Total pressure lost in the system while water is forced through pipes, fittings, valves, etc.
b. 1000GPM through 100ft of pipe will lose:
i. 52psi in a 6in line
ii. 12.8psi in a 8in line
iii. 1.78psi in a 12in line
Main sizes
- From reservoirs: 16-56in
- Primary feeders: 16in-24in
- Secondary feeders: 12in-18in
- Distributors or laterals: 8in if dead end main, 6in being the smallest line to a hydrant
Three things that reduce flow
- Sedimentation
a. Dirt and other products that collect in the system - Incrustation
a. Mineral deposits inside of pipes, valves, fittings etc.
b. Hard water. It’s everywhere. - Tuberculation
a. Actual pipe breakdown
Zone stats
- Due to elevation changes in Tucson (SE to NW), the city must be broken into zones to prevent overpressure in the mains.
- 22nd & Wilmot is the same elevation as A mountain
- A pipe laid from Houghton rd to the Santa Cruz River would create 300psi at the river due to 600-700ft elevation change.
- There are 19 zones within the Tucson Water system
- ~105ft elevation change within zone
- Normal pressure will range from 40-85psi
- Head pressure is .434psi per foot in elevation loss
- All zones are connected and then separated by valves
- Valves are computer monitored and controlled