5.2
Place isolation valves to provide control over reasonably sized
area. In addition, designate valves in fire hydrant branches and
building service lines, near their connection to feeder mains.
6.
DOMESTIC WATER PUMPING SYSTEM: Use a three pump system. Size one pump
for approximately one-third of the total water demand. Each of the
other pumps shall be sized for approximately two-thirds of the total
demand. The smaller will operate until water demand exceeds the pump's
capacity, at which point it will stop and one of the other larger pumps
shall start. When the demand exceeds the capacity of this larger pump,
the smaller pump will restart and both pumps will operate together. The
other large pump will be a standby and alternate with the first large
pump. Provide a pneumatic tank and "NO-FLOW" shut-down controls. Each
pump shall be on emergency power.
7.
LAWN IRRIGATION SYSTEM:
7.1
The VA Site Design Manual will indicate if irrigation is necessary
and if so, the mm (inches) of water per week that is required.
7.2
Provide an automatic irrigation system to operate between the
hours of 10:00pm to 6:00am.
7.3
Keep the number of irrigation system connections to potable system
to a minimum. Equip such connections with reduced pressure-type
backflow preventers. Limit maximum draft from any connection to
11 L/s (180 gpm).
8.
SANITARY AND STORM SEWERAGE SYSTEMS:
8.1
Design separate underground sanitary and storm sewerage systems,
including building connections, manholes, clean-outs, drainage
inlets (yard and curb), cooling tower waste lines, open drainage
channels, dry wells, etc., and all appurtenances. Storm drainage
system shall serve all areas under construction or affected by
construction.
8.2
If meter readings are not available, average daily sewage flow is
estimated to be 80% of water demand.
8.3
Design all components of storm sewerage system on basis of not
less than 10-year storm frequency for one hour.
8.4
Comply with the requirements of off-site receptor of storm water.
Retention may be required, however, roof storage of storm water is
not allowed.
8.5
Do not connect storm drainage system to sanitary sewerage systems.
8.6
To extent feasible, do not locate sewer pipes and manholes under
pavement. Provide manholes at junctions, changes in direction,
changes in slope, and changes in invert elevations of sewers 200
mm (8 inch) and above [Clean-outs are required for 100 and 150 mm
(4 and 6 inch) sewers]. Limit spacing between manholes to 90 m
(300 feet), except 150 m (500 foot) spacing is permitted in
straight runs of long out-fall sewers.
8.7
Indicate on drawings where extra strength pipe is required to
support anticipated trench and superimposed loads. Include
adequate pipe bedding and, if necessary, provide structural
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