Proceedings, September 2007,
YATES, C.D., AND G.M. MacDonald. Water
Loss Control - Sustainability on Both
Sides of the Meter, IWA Conference
Proceedings, April 2009, Capetown,
(See Figure 3). The algorithm incorporates
fail-safes to accommodate possible communication losses and other technical
scenarios, with the fallback to fixed outlet
INITIAL RESULTS HAVE been positive.
Communications are reliable and flow
updates to the controllers occur in less
than four seconds. To accommodate
local hydraulic conditions, controllers at
each PRV can be configured at differing
incremental levels. Since solving the control problem, operating results are more
consistent than when the system ran
initially in 2006.
Since permanently establishing this
system in 2012, Halifax Water has been
working to both refine the technology
and evaluate other DMAs for implementation of advanced pressure management.
This system has also relied on proprietary
devices to hydraulically control the valves.
While effective, the devices are expensive
to replace and do not always provide the
function required. Halifax Water developed its own hydraulic controller, which
uses a programmable logic controller
(PLC) with control software developed
by staff, to operate solenoid valves on
the control valve pilot piping. This was
initially tested at bench scale and is now
installed in the Dartmouth Central DMA.
This control strategy will allow settings
to be downloaded remotely through the
Halifax Water Supervisory Control and
Data Acquisition (SCADA) system.
Halifax Water initially thought this con-
trol methodology would be applicable to
a small percentage of its pressure zones:
those where water main breaks could
be exacerbated by higher pressure and
those with high background leakage.
Since deploying this system in Dartmouth
Central, Halifax Water has conducted addi-
tional research on the occurrence of water
main breaks. This research indicates that
in most DMAs, pressure does increase a
small amount at night. This is either due
to increased hydraulic grade line elevation
because of lower flows and less friction
head losses, or alternatively (and more
likely) from hydraulic grade line eleva-
tion increases because of PRVs that are
unable to maintain a precise downstream
pressure during very low nighttime flows.
This research also revealed that approxi-
mately 80% of water main breaks occur at
night, when pressure creeps up. This sug-
gests that the application of this pressure
control methodology may have a much
broader application, both within Halifax
Water and to the municipal water industry
AWWA (AMERICAN WATER Works
Association). 2016. Manual M36, Water
Audits and Loss Control Programs. 4th ed.
Denver, Colo.: AWWA.
FANNER, P.V., R. Sturm, J. Thornton,
R. Liemberger, S.E. Davis, and
T. Hoogerwerf. 2007. Leakage
Management Technologies. Denver,
YATES, C.D., AND G.M. MacDonald.
Advanced Pressure Management via
Flow Modulation, IWA Conference
Figure 3. Control Features of Flow Modulation - Dartmouth Central DMA
CARL YATES, M.A. Sc., P.Eng., is General Manager
at Halifax Water. Reid Campbell, M.Eng., P.Eng., is
Director of Water Services at Halifax Water.