Unidirectional flushing
is the most effective means of cleaning water mains.
It involves the closure of valves and opening of
hydrants to create a one way flow in the water mains
for removing the built-up sediment. This type of
flushing (i.e., high speed flushing) increases the
speed of the water in the mains so that the shear
velocity near the pipe wall is maximized. This high
flow velocity produces a scouring action in the
mains, effectively removing sediment deposits and
biofilm.
(Click
to enlarge the picture)
Flushing should start at a clean water source
(e.g., pump station) and proceeds outward in the
system so that flushing water is drawn from previously
flushed reaches. This step-wise approach ensures
that clean water is always used to flush the mains
and, thus, systematically washing out the pipes
without pulling contaminants from other lines
as can happen with conventional flushing.
InfoWater UDF features
include:
•
Develop pipe sequences for optimal flushing
•
Automatically analyze pipe flushing sequences
at the precise hydraulic EPS time step (based
on the exact boundary conditions) corresponding
to the time of the actual field testing
•
Automatically close the necessary valves
to effectively isolate all pipe sequences
•
Directly use existing hydrant and lateral
pipe data if already included in your model
•
Calculate static and residual pressure at
each hydrant
•
Calculate hydrant discharge flow
•
Calculate available hydrant flow at the
specified minimum residual pressure
•
Determine the minimum pipe flushing length
and volume
•
Compute and report pipe velocities for each
flushing sequences
•
Compute and report shear stress for every pipe in the flushing sequences
•
Report all critical pressures and velocities
throughout the system
•
Determine minimum flushing time
•
Determine minimum flushing velocity
•
Maintain required minimum residual pressures
in the distribution system
