INS 310 Water Supply and Sewerage

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1 INS 310 Water Supply and Sewerage Water Transmission and Distribution Systems Dr. A. Ozan Celik Monday, April 8,

2 Components of water supply systems: Municipal water systems generally comprise (a) collection works, (b) purification works, (c) transmission works, and (d) distribution works. 2

3 Transmission systems Supply conduits, or aqueducts, transport water from the source of supply to the community and, hence, form the connecting link between collection works and distribution systems. The location of the source determines whether conduits are short or long, and whether transport is by gravity or pumping. 3

4 Transmission systems The hydraulic design of supply conduits is concerned chiefly with (a) resistance to flow in relation to available and needed heads or pressures and (b) required and allowable velocities of flow relative to cost, scour, and sediment transport. In long supply lines, frictional or surface resistance offered by the pipe interior is the dominant element. In short transport systems, on the other hand, form resistance (minor losses) may be of controlling importance. 4

Transmission systems Multiple parallel pipes may be better than a single pipe for transmission lines: (a) when the maximum pipe size of manufacture is exceeded; 36 in.

5 Transmission systems Multiple parallel pipes may be better than a single pipe for transmission lines: (a) when the maximum pipe size of manufacture is exceeded; 36 in. (900 mm) in the case of centrifugal cast-iron pipe, (b) when possible failure would put the line out of commission for a long time, and (c) when pipe location presents special hazards floods, ice, and ships anchors endangering river crossings or submarine pipes and cave-ins rupturing pipe lines in mining areas, for example. 5

6 Transmission systems Structurally, closed conduits must resist a number of different forces singly or in combination: 1. Internal pressure equal to the full head of water to which the conduit can be subjected 2. Unbalanced pressures at bends, contractions, and closures 3. Water hammer or increased internal pressure caused by sudden reduction in the velocity of the water by the rapid closing of a gate or shutdown of a pump, for example 4. External loads in the form of backfill and traffic 5. Their own weight between external supports (piers or hangers) 6. Temperature-induced expansion and contraction. 6

7 Transmission systems Important considerations for the transmission pipe lines are: 1. Depth of cover 2. Strength of material 3. Durability 4. Safety 5. Transportation 6. Leakage 7

8 Water distribution systems Water distribution systems have three major components: pumping stations, distribution storage, and distribution piping. Water Resources Engineering, 2nd Edition ISBN-13: , by Mays, Larry W 8

9 Water distribution systems Two distribution patterns emerge from the street plan: (a) a branching pattern in which ribbon development follows the primary arteries of roads and (b) a gridiron pattern within the built-up portions of the community where streets crisscross and water mains are interconnected Most common pipe system appurtenances: Gate valves Air valves Check valves Blowoffs Pressure reducing valves Flow control valves 9

10 Water distribution systems To determine the operating point of a pump system, the pump headcharacteristic curve (H-Q curve of the pump) and a system-head-capacity curve (H-Q curve of the piping system) are required. The pump operating point is the single point on these two H-Q curves where they intersect. Water Resources Engineering, 2nd Edition ISBN-13: , by Mays, Larry W 10

4A General Information A. Concept... 1 B. Conditions... 1

4A General Information A. Concept... 1 B. Conditions... 1 Design Manual Chapter 4 - Water Mains Table of Contents TOC Table of Contents Chapter 4 - Water Mains 4A General Information 4A-1---------------------------------General Information A. Concept....... 1