CHAPTER 4
DESIGN AND CONSTRUCTION OF WATER STORAGE FACILITIES
tuated instruments. The direct pressure measure-
4-1. Reservoir Covers
ments of elevated tanks will be suppressed to read-
All treated water reservoirs must be covered to
out only the water depth in the elevated bowl.
prevent contamination by dust, birds, leaves, and
High and low level pressure sensitive switches will
insects. These covers will be, insofar as possible,
be used for alarm status monitoring and for pump
watertight at all locations except vent openings.
cut-off controls. Intermediate level switches, pres-
Special attention should be directed toward
sure or float actuated, will be used for normal
making all doors and manholes watertight. Vent
pump controls. Metering, monitoring, and pump
openings must be protected to prevent the entry of
control requirements at some point remote from
birds and insects; and vent screens should be kept
storage must use level telemetering instruments.
free of ice or debris so that air can enter or leave
Telemetering over local direct wire communica-
the reservoir area as temperature and water levels
tions facilities will use 15 second time duration or
vary. All overflows or other drain lines must be
impulse duration telemetering equipment. Teleme-
designed so as to eliminate the possibility of flood
tering over leased telephone lines often requires
waters or other contamination entering the reser-
the introduction of a tone transmitter and receiver
voir. Reservoir covers also protect the stored water
keyed by the time-impulse telemetering equip-
from sunlight, thus inhibiting the growth of algae.
ment. High storage level will initiate the shut-
Further prevention of algae growth or bacterial
down of supply pumping units and actuation of an
contamination, due to the depletion of the chlorine
overflow alarm in that order. Low storage level
residual, can be obtained by maintaining sufficient
will initiate startup of supply pumping or well
flow through the reservoir so that water in the
pumping units or distribution pumping unit shut-
reservoir does not become stagnant. Minimal flows
down.
through the reservoir also help to prevent ice
buildup during cold periods.
4-4.
Disinfection
4-2. Altitude Valves
Potable water storage facilities, associated piping,
and ancillary equipment must be disinfected
All storage tanks will be provided with altitude
before use. Disinfection will be accomplished fol-
valves to prevent overflows. These altitude valves
lowing procedures and requirements of American
will be installed in concrete pits having provision
Water Works Standard D105. In no event will any
for draining either by gravity or pumping. Drains
of the above equipment or facilities be placed in
will not be connected to sanitary sewers. Every
service prior to verification by the supporting med-
precaution will be taken to prevent the collection
ical authority, by bacteriological tests, that disin-
of water from any source in valve pits.
fection has been accomplished.
4-3. Instrumentation and Control
4-5. Design Analyses
Storage measurements are used for monitoring, in-
ventory, and system controls. Elevated and ground
The design analyses will set forth the basis by
storage measurements will be made by pressure
which storage capacities and locations have been
sensitive instruments directly connected by static
determined. Except where standard specifications
pressure lines at points of no flow. Underground
for tanks or towers are used, the analyses will
storage measurements will be made by air bubbler
show the method by which the structural adequa-
back pressure sensitive instruments or by float ac-
cy of the unit has been determined.
4-1
Previous Page
