5.16 Valves
a. Sizes.
1) Valves shall be the same size as the mains in which they are installed. Reducers for reconnection into existing water mains less than eight (8) inches in diameter (or existing mains smaller than the new mainline) shall be placed between the new valve and the existing line (ie. the new valves shall be the same size as the larger mainline).
2) Unless otherwise approved or required by the City Engineer, valves shall conform to the following table.
Valve Size | Static Pressure | Valve Style |
|---|---|---|
10-inch and smaller | < 120 psi | Gate Valve |
8-inch & 10-inch | 120 psi | Butterfly Valve |
12-inch & larger | All pressures | Butterfly Valve |
3) Valve types and materials shall conform to the requirements of these Design Standards.
b. Location.
1) Distribution system valves shall be located at the tee or cross fitting as nearly as possible.
2) There shall be a sufficient number of valves so located that not more than four (4) and preferable three (3) valves must be operated to effect any one particular shutdown. The spacing of valves shall be such that the length of any one shutdown shall not exceed 500 feet.
3) A tee-intersection shall be valved on two branches and a cross-intersection shall be valved on three branches.
4) Hazardous crossings (ie. creek, railroad, freeway crossings, etc.) shall be valved on each side of the crossing.
5) Transmission water mains shall have valves at spacings as required by the City Engineer.
c. Mainline Tapping Tee & Valve.
1) A tapping tee & valve to make connection to an existing, in-service line is only allowed in cases where the City determines that water service cannot be interrupted to cut in a tee or cross, and where the additional in-line valve required is not needed for system isolation as outlined above.