TM 10-4320-303-13
existing roads to ease transportation, assembly, inspection, maintenance, and disassembly of TWDS. Avoid
routes along the banks of streams, marshes, ponds, gullies, ravines, or other areas subject to flooding.
Whenever possible, the hoseline should be laid out on firm, dry level ground that allows easy access and is not
subject to flooding.
2.3.1.3 Minimum Route Selection Requirements . Ensure minimum requirements necessary for route
selection are available when selecting a route for the TWDS. The minimum requirements for selecting the
route are as follows:
A sketch of the proposed hoseline route.
Odometer distances.
Enough topographic information (surveying altimeter elevations) to establish relative altitude at various
points along the hoseline route.
2.3.1.4 TWDS Installation and Operation Guidelines. The following guidelines should be utilized to gain
maximum effectiveness for installation and operation of TWDS:
The route should be direct and present a minimum number of obstacles and obstructions.
A route parallel to a secondary all-weather road is preferable to one along a heavily traveled road.
If roadways do not exist or cannot be utilized, select a route that is accessible to vehicles required for
laying the hoseline.
Plan to locate junction of two hoseline lengths at installation sites for each boost pumping station and
storage assembly.
Keep security precautions in mind. Utilize natural camouflage wherever possible and avoid routing
hoseline through populated areas.
2.3.1.5 Pumping Station Installation Sight Selection . When selecting pumping station installation sites, the
location of the lead or first pumping station will be determined by location of the water source. Boost pumping
stations are intended to be spaced at approximately two mile intervals, assuming that the route is reasonably
direct and the terrain is level. However, a substantial rise or fall in elevation along the hoseline route may
require adjustment of standard spacing intervals between pumping stations. When substantial rise or fall in
elevation occurs between two consecutive pumping stations the following pumping station movements must be
performed:
If the next downline pumping station is substantially higher in elevation than the upline pumping
station, decrease distance between pumping stations.
If the next down line pumping station is substantially lower in elevation than the upline pumping station,
increase distance between pumping stations.
Adjusting distance between pumping stations when elevation changes occur assures that water pressure will be
maintained within optimum operational range. Under normal conditions, TWDS will deliver water to the suction
port of each boost pumping station at a pressure of 20 pounds per square inch gage (psig). Whenever
pressure falls below 20 psig, boost pumping station pumping assemblies are designed to begin reducing speed,
when operated in the electric automatic mode. Therefore, if an upline pumping station is substantially lower
than the next down line station, and the elevation difference has not been offset by spacing adjustment
between pumping stations, suction pressure at the down line pumping station may fall below 20 psig and cause
that pump to slow down. This in turn will cause remaining down line boost pumping stations to slow down,
seriously degrading overall TWDS performance.
2.3.1.6 Ground Profile and Pump Spacing Triangle . A ground profile (drawn on graph paper) and a pump
spacing triangle can be utilized to determine the location of each boost pumping station. Proper construction
and use of the ground profile and pump spacing triangle will ensure that the installed TWDS will perform within
its' optimal range.
2-31
