City of Frisco Engineering Standards

Engineering Standards
3. Isolation valves shall not be over 500’ apart in all other non-residential areas on lines 12” and
smaller. For lines 16” and larger, valves shall not be over 1000’ apart.
4. Two isolation valves shall be placed such that only one fire hydrant/fire fighting apparatus
and one fire sprinkler private service system is shut down at a time. No more than three
isolations valves shall be used to shut down the combined fire hydrant/fire fighting apparatus
and fire sprinkler system private service main.
5. Water mains supplying an automatic fire sprinkler system shall include isolation valves on
the private fire service main.
6. Isolation valves shall not be located in parking spaces.
7. In undeveloped areas, main line isolation valves shall be spaced every 1,200’ and adjacent to
fire hydrants.
B. Air Release Valves
1. The Engineer shall be responsible for locating and sizing air release valves in accordance
with AWWA Manual M51: Air-Release, Air/Vacuum & Combination Air Valve.
2. Air release valves shall be installed on water mains larger than 12”. Vent pipes shall
discharge air above grade and above 100-year floodplain elevation if applicable.
3. Air valves are not required on water distribution mains smaller than 12” where fire hydrants
and service connections provide a means for venting trapped air.
4. Air valve manholes shall not be located in parking spaces.
C. Blowoff Valves
1. Blowoff valves shall be provided on water mains 16” and larger, at low points and at isolation
valves where the water main slopes toward the valve.
2. Blowoff valves shall discharge to a drainage channel, creek, storm sewer or culvert.
5.1.9 Fire Hydrants
Fire hydrants shall be provided as recommended by the “GUIDE FOR DETERMINATION OF
REQUIRED FIRE FLOW” published by the Insurance Service Office. The following minimum
guidelines shall be met:
A. Fire hydrants shall be installed at a minimum of 10’ from the curb return on Thoroughfare Types
A, B, and C.
B. Fire hydrants shall be installed at a minimum of 2’ and a maximum of 6’ from the edge of
pavement on Thoroughfare Types D, E, and F and fire lanes.
C. Fire hydrants shall be located at all main entrances and intersecting streets and fire lanes.
D. Fire hydrants shall be spaced every 1200’ along undeveloped roadways.
E. Fire hydrant leads exceeding 100’ shall be looped with a minimum 8” line.
Section 5 – Water & Wastewater Design Requirements May 2012 Page 5-6