Sometimes the situation will arise where the building or retrofitting of a road right-of-way will require that a fire hydrant be moved to suit the vertical and horizontal demands of its newly constructed surroundings. The first thing a contractor will typically ask himself in this scenario is will the water main itself need to be shut down for me to perform the extension/adjustment of the hydrant?
Extending or Shortening
If the hydrant is being moved back closer to the mainline, the water main will typically need to be shut down. In this case the two nearest mainline valves will need to be closed to isolate the hydrant branch in case the main itself needs retrofitted. Any services on the isolated section of the main that has been closed off must be notified ahead of time, and usually put on a boil advisory prior to the mainline gate valves are opened back up (unless the isolated section was flushed and bacteria tested prior to repressurizing and reopening).
If a hydrant requires extension, this can often be done by closing the hydrant branch watch valve, adding the proper length of pipe or anchor coupling, and resetting the hydrant, without disruption of the main.
Adjustments Up or Down
In terms of hydrant adjustments being required, they will either require being raised or lowered to meet the proposed adjacent grades. Often even with survey grade stakes being in place nearby to reference, it is still difficult to adjust the hydrant with precision until the actual final grade is established around the hydrant. If the hydrant requires being raised, the work can be relatively simple often only requiring a ‘hydrant extension kit’. The hydrant is disassembled at the seat ring and the hydrant extension is attached between the top of the lower standpipe and the bottom of the hydrant.
If the hydrant adjustment requires lowering the elevation of the existing hydrant, the process can be much more difficult requiring excavation and often cutting or replacing the standpipe below or in some cases, a new hydrant must be installed altogether.