TM 5-813-9
CHAPTER 2
DESIGN CONSIDERATION
2-1. General Design. The sizing of each
(3) Peak Hour Consumption on Annual Maxi-
component in the distribution system will depend
mum Day (MDC/Peak-Hour)
upon the effective combination of the major system
(4) MDC plus Simulated Fireflow
elements: supply source, storage, pumping, and
Several analyses should be made to investigate
distribution piping. The hydraulic analysis of the
alternative piping arrangements within the distri-
total distribution system is discussed in TM
bution system as well as for connecting proposed
5-813-5. Water storage is discussed in TM
pumping stations to the distribution system. If
5-813-4.
future improvements are contemplated, the analysis
should be performed based on future conditions,
2-2. Demand.
thus assuring the correct selection of the final
a. General. Population and water consumption
alternative to be implemented initially.
c. System Pressures. The pressure distribution in
estimates are the basis for determining the flow
demand of a water supply and distribution system.
the system will assume the following criteria:
Flow and pressure demands at any point of the
(1) Maximum curb pressures (70 psi)
system are determined by hydraulic network analy-
(2) Minimum curb pressures at any point on the
sis of the supply, storage, pumping, and distribution
network (usually 30 psi)
system as a whole. Supply point locations such as
(3) Residual curb pressure to be maintained at
wells and storage reservoirs are normally known
a point of simulated fireflow (20 psi minimum) For
based on a given source of supply or available
large distribution system design a pressure contour
space for a storage facility. Criteria for determining
map will be developed using known topography
water demands are discussed in TM 5-813-1 and
and the hydraulic network analysis and showing
TM 5-813-7.
pressure in pounds per square inch. Pressure
b. Factors for Determining Demands. The hy-
contours must be adjusted for elevations of
draulic network analysis should assume the follow-
surrounding terrain. The pump discharge head will
ing demand rates:
be derived from the system pressures at the pump
(1) Annual Average Daily Consumption (ADC)
station location plus the pump station piping head
(2) Annual Maximum Daily Consumption
loss.
(MDC)
2-1
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