Water Supply PDF - Greensboro Fire Department

GREENSBORO FIRE DEPARTMENT TRAINING DIVISION WATER SUPPLIES STUDENT OUTLINE  Water Supply I. Water Distribution System – A means by which water is moved from a source to the point at which it i...

GREENSBORO FIRE DEPARTMENT TRAINING DIVISION WATER SUPPLIES STUDENT OUTLINE  Water Supply I. Water Distribution System – A means by which water is moved from a source to the point at which it is used. A. Quality – Free of disease-causing organisms B. Supply – Must be adequate C. Reliable – Must supply normal use as well as support Fire Dept Operations D. Economically Feasible – Cost of treatment II. Four components of a water system A. Source of Supply 1. Ground Water Supply – Wells and water-producing springs 2. Surface Water Supply – Rivers, lakes, aqueducts, and reservoirs B. Means of moving water (mechanical, gravity, or combination) C. Processing or treatment facility D. Distribution system III. Types of supply systems A. Gravity System 1. Used in cities where the source is located above the city. 2. Extremely reliable due to lack of dependence on machinery 3. Primary source must be at least 100’ above the highest point in the system to be effective Greensboro Fire Department 1-2 Training Division  Water Supply B. Direct Pumping System 1. Dependent on pumps and power to run them. 2. Water is pumped from the source to the treatment facility and into the distribution system. C. Combination System 1. Most Common ( Greensboro ) 2. Combination of both gravity and direct systems. 3. The system utilizes elevated tanks and reservoirs as a means of storage. 4. Towers vary in height 5. Steam coils in the tank prevent water from freezing Greensboro Fire Department 1-3 Training Division  Water Supply IV. Make-up of the distribution system A. Water Treatment Facilities 1. Treat water intended for domestic use 2. Add Chlorine to kill bacteria 3. May add fluoride to prevent tooth decay B. Distribution System – that part of a water utility that receives the water from the (source) pumping station and delivers it throughout the area to be served. 1. Water mains are made of cast iron, ductile iron, asbestos cement, and plastic a. Primary Feeders - large pipes with relatively wide spacing that carry large quantities of water to various points of the system for distribution to smaller mains. b. Secondary Feeders – the network of intermediate-size pipes that reinforces the grid by forming loops that interlock the primary feeders. Should not be installed over 3,000 feet apart in built-up areas, according to NFPA standards. c. Distributors are the smaller internal grid arrangements that connect to branch piping that serves consumer blocks and the individual fire hydrants. d. Grid – A network of waterlines that make up a distribution system. NOTE: Arranging pipes in grids allows hydrants to be supplied from at least two directions. Will not have a dead-end water main. Greensboro Fire Department 1-4 Training Division  Water Supply V. Piping size (recommendations) A. Residential 1. 8-inch or 6 inch which will complete a good grid and is cross-connected at intervals not exceeding 600 feet. 2. Six inches is not recommended for fire service supply if not looped in a grid where no leg exceeds 200 feet (no dead ends) 3. According to the new NFPA, in congested areas, distributors should not be less than 8 inches and interlocked at 600 feet or less. B. Industrial 1. 8-inch and 12-inch (or larger depending upon building size, layout, and occupancy) VI. Hydrants (Started with fire plugs – hollow logs below ground level. When needed, a hole was bored and the pit filled with water. Then had to be plugged when the fire was out, location of the plug was noted for future use. Very inefficient. A. Usually made of cast iron with bronze working parts B. Must be opened and closed slowly to prevent water hammers C. Specifications 1. American Water Works Association has adopted a national standard hydrant for ordinary waterworks service. Standards were designed to prevent the following difficulties in hydrants: a. trouble in opening/closing b. working loose of interior parts c. leakage d. excessive friction loss e. failure to drain properly D. Types 1. Wet Barrel (warm climates) a. valve located at hose outlet b. water remains in the barrel at all times 2. Dry Barrel (cold climates) a. Drain valve to permit water escape Greensboro Fire Department 1-5 Training Division  Water Supply b. Required in freezing climates c. Have the main valve located at the base, below the frost line that prevents water from entering the hydrant barrel. d. Must be completely opened or closed to prevent ground erosion. **NOTE: Do not confuse this with a “Dry Hydrant” E. Installation 1. The area of installation should be free from obstructions that would impair use. Examples – trees, mailboxes, posts, signs, etc. 2. With the 4 ½ outlet positioned to face the street 3. Perpendicular to the ground with the lowest discharge 18” above grade. This allows for hydrant wrench operation. 4. Proper drainage should be provided for dry barrel hydrants, coarse gravel or stone may be used for this purpose. F. Hydrant color codes 1. NFPA (Bonnet and discharge port caps) a. Class AA; light blue; 1500 GPM or greater b. Class A; green; 1,000 – 1,499 GPM c. Class B; orange; 500 – 999 GPM d. Class C; red; less than 500 GPM 2. Greensboro Fire Department a. Red Bonnet - less than 500 GPM b. Red Operating Nut - muddy water c. Yellow Bonnet - low pressure on large mains G. Outlets 1. Standard outlets are considered to be one 4 or 4 ½” outlet and two 2 ½” outlets 2. National Standard threads are considered the most desirable type of thread for mutual aid and inter-departmental operations. Greensboro Fire Department 1-6 Training Division  Water Supply H. Spacing 1. Residential – at each intersection and intermediate spacing not to exceed 500 feet. 2. High-value or high-hazard districts (Fire District downtown) one or two hydrants at each intersection with intermediate spacing not to exceed 300 feet. I. Maintenance – Hydrants should be operated once a year and flow tested every 5 years 1. Procedure a. Check for obstructions to hydrant b. Hydrant faces street c. Sufficient clearance – height d. Damage e. Rusting – the condition of paint f. Hydrant Barrel – free from foreign objects (remove all caps) g. Assure ports are not loose from the barrel h. Look for water in the barrel, indicating a bad drain valve i. Stand behind the hydrant. Do not straddle ports j. Open the hydrant carefully and completely k. Flow until water is clear (a minute or longer) l. After flushing, close slowly m. Lubricate threads with graphite n. Inspect gaskets o. Replace caps p. Make notations on hydrant form of repairs needed J. Hydrant Brands in Greensboro 1. Darling 2. Kennedy 3. Metropolitan 4. Mueller 5. Woods 6. Clow Greensboro Fire Department 1-7 Training Division  Water Supply VII. Types of pressure A. Normal Operating Pressure – That pressure which is found on a water distribution system during normal consumption demands. NOTE: Generally considered to be static pressure for fire flow tests. As soon as water flows in the system, static pressure no longer exists. B. Residual Pressure – That part of total pressure that is not used to overcome friction or gravity while forcing water through pipes, fitting, firehose, and adaptors. C. Flow Pressure (Velocity Pressure) – That which is forward velocity pressure at a discharge opening while water is flowing. D. Static Pressure - Stored potential energy that is available to force water through pipe fittings, firehose, and adaptors. The pressure of water at rest. VIII.Water main valves A. Function 1. To provide a means of controlling the flow of water through the distribution piping. 2. Valves should be: a. Operated at least once a year – This keeps the valve in good condition. b. Spaced no more than 500 feet apart in high-value districts and 800 feet in other areas. c. Opened fully. If partially closed, domestic flows might not notice but flows will be decreased due to friction loss. B. Types 1. Indicating – a valve which usually shows the position of the gate or valve seat a. open b. partially closed c. closed d. Valves in private fire protection are of this type. Examples: Outside Stem and Yoke (OS&Y) (Expanded threaded stem indicates valve is OPEN). Greensboro Fire Department 1-8 Training Division  Water Supply Post Indicator Valve (PIV) OPEN/SHUT – kept in the open position with padlock 2. Non-indicating a. Most valves in public water systems are of this type. b. Usually are buried or in a manhole c. Require the use of a valve (water) key to open or close (carried on apparatus) NOTE: Can be butterfly or gate valves. Butterfly valves pivot on a center stem to block the opening, or turn parallel to allow for flow. An indicator matches the valve position symbolically or with words. Open is left. Gate raises or lowers. IX. Causes of increased friction in water mains A. There is some friction loss in all water mains. Cast iron is higher in friction than plastic or asbestos cement. Fittings, elbows, valves, and meters cause friction loss. B. Incrustation (2 types) – a buildup of corrosion inside the pipe caused by rust, chemical content of water, and growth of biological or living organisms. 1. Tuberculation (Rust)– a type of incrustation Inside water pipes, the build-up of deposits looks like small round nodules called tubercles. Greensboro Fire Department 1-9 Training Division  Water Supply 2. Sedimentation – mud, clay, leaves, or vegetable decay X. Determining available fire flow A. Need for conducting test 1. To determine available fire flow for pre-planning. 2. To determine the need for modifications of the existing system. 3. To determine if the water system will support fire suppression systems. 4. Annually to detect changes in available flow B. Conducting the Test 1. Determine the closest hydrant to the test area and designate it as a “Test” hydrant. 2. Determine the next fire hydrant on the water main situated in line with normal water flow, and designate it as a “Flow” hydrant. 3. Open the “test” hydrant fully and flush, then close and attach the cap gauge. 4. Record Static pressure at the “Test” hydrant. 5. Remove one 2 ½” cap from flow hydrant and determine coefficient.7,.8,.9. 6. Open the hydrant fully and allow the stream to clear. This may take 3 to 5 minutes. 7. Insert the pitot gauge into the stream from the “flow” hydrant read pressure, and have an assistant record residual pressure at the “test” hydrant. 8. Hazen Williams Formula NOTE: Sufficient “flow” hydrants should be opened to drop static pressure of the “Test” hydrant by 10 psi, however, if more accurate results are desired, bring the residual pressure as close as possible to 20 psi at the “Test” hydrant. Greensboro Fire Department 1-10 Training Division  Water Supply XI. Pitot tube and gauge A. A small hole in the blade, not over 1/16”, catches the water to measure the flow B. Used to determine forward velocity pressure at a discharge opening XII. Determining GPM flow A. D2 x 29.83 x NP x coefficient B. Coefficients =.7,.8, or.9, depending upon construction of outlet C. Coefficients are determined by feeling the contour of the hydrant orifice. XIII. Alternative water supplies A. May be needed in the event of a failure of the municipal system. B. Industries may have their private water system C. Drafting 1. Lakes 2. Ponds 3. Rivers 4. Farm Stock Tanks 5. Pools D. Make sure the static water source is not contaminated causing health problems E. Pre-planning will identify sources F. Consider if the source will be accessible year-round Greensboro Fire Department 1-11 Training Division  Water Supply XIV. Dry hydrants A. Installed at static water sources to increase the water supply available B. Usually constructed of steel or PVC pipe with strainers at the water source, steamer ports to connect to pumper C. Designed to supply at least 1,000 GPM XV. Rural water supply A. Shuttle Operations 1. Water Shuttle – the hauling of water from a supply source to the portable tanks which water may be drawn to fight a fire 2. Key Elements Attack pumper at fire location Fill apparatus (pumper) at the fill site Tankers to move water from the fill site to the portable tank One tanker for every 100 GPMs B. Fill Site Procedures (Fill Apparatus – Pumper) 1. Once the pumper is at the drafting site 2. Follow procedures for drafting from the negative water source 3. Once a pumper starts tanker filling operation, it should not be shut down – to prevent loss of prime (negative source only) – wastes time having to re-prime. 4. Put a gate valve on the supply line to allow for immediate flow when connecting to the tanker Greensboro Fire Department 1-12 Training Division  Water Supply C. Drafting 1. Atmospheric pressure a. Sea Level – 14.7 b. Greensboro – 14.2 2. Priming devices D. Loading Tankers 1. Fill one tanker at a time 2. Select the best hydrant available 3. Large hose lines – 2 ½” or larger. However, piping is usually 2 ½” inlets, some 3” 4. Multiple hose lines 5. Minimum backing required 6. Primary Means of Filling a. Through the 2 ½” inlet with quick connect coupling at the rear of the apparatus. This inlet bypasses the pump and leads only to the tank. The tank may be filled at pressures up to 100 psi. An average fill time of 75 seconds may be anticipated. 7. Alternative Means of Filling a. Through the tank fill valve, routing water through the pump and piping. The average fill time at 100 psi, is approximately 200 seconds. E. Portable Tank Construction 1. Collapsible with a square metal frame. Synthetic liner 2. Use tarps to protect the tank Greensboro Fire Department 1-13 Training Division  Water Supply F. Unloading Tankers (at fire scene) 1. Spread the tarp on a level surface 2. Position the portable tank for multiple access 3. Deploy portable tank 4. Completely empty the tanker before offloading another. 5. Methods of Off-Loading Tankers a. Gravity dumping b. jet dumping – Speeds the off-loading process c. pumping G. Siphon/Tank Connectors 1. More than one tank can be used. (multiple tanks for large operations) 2. Jet siphons to transfer water between portable tanks 3. Hard suction hose with 1 ¾” nozzle another option H. Drafting from Tank 1. Assemble and connect equipment 2. Attack pumper drafts from portable tank a. from the corner of tank b. side of tank 3. Low-level Intake Strainer a. Make it possible to use water down to 1 to 2 inches from the bottom of the reservoir. Greensboro Fire Department 1-14 Training Division