TM 5-814-9
contaminated by wastewater from the facility.
of the utilities are not available, the best alternative must be
Excavation into bedrock also increases construction
found.
costs. If no other site is available, fill material may
Water. The wash facility should be sited near
be used to increase the soil depth at the site.
(1)
Another alternative would be to excavate material
existing water or supply lines if possible. Water
that is easy to remove down to the bedrock, then use
meters should be installed so that the potable and
the excavated material to build a berm around the
recycled water can be metered.
basins. The gradient of the berm slopes must be low
(a)
Potable water. A potable supply must be
enough to avoid interfering with operations and
maintenance (O&M) and to prevent sheet erosion of
provided as drinking water for personnel. If it
the slope.
is not feasible to tie the facility into the
potable water system, portable equipment can
Water table. The planner must know the depth of
(4)
be used to supply drinking water. Signs must
the water table at the proposed construction site.
be posted informing personnel not to drink
Sites near marshes, swamps, or low areas should be
the wash water and telling them where
studied to determine if the water table will have an
drinking water is available.
adverse effect on construction or O&M of the
(b)
Makeup water. Potable water is not required
facility. The facility must be placed above the
maximum height of the seasonal and permanent
for washing the vehicles; however, the water
water tables. Areas with high water tables may
must be free of particulate matter that would
require complex drainage systems, usually with
interfere with pump operation and cause pre-
high construction costs. Should the basins and
mature wear of the wash equipment. The
filters be constructed when the water level is low
water source must charge and maintain a
and then water rises and surrounds the structures,
working water level in the treatment system.
the hydraulic pressure can damage the liners and
A dedicated well may be used if that proves
cause leaks. Clay lenses or other impervious sub-
more economical than tying into the existing
surface features can create a high, perched water
water lines. If the planner considers using an
table. Excavation to repair the subsurface structures
untreated well, the groundwater must be of an
would be hindered by the high water table; it would
acceptable quality and must provide a
also be expensive because the groundwater would
consistent supply. If the area is water-rich,
have to be removed from the site to allow personnel
rain can be used as a source of makeup water.
to work.
Ponds, lakes, and streams are other potential
raw water supply sources for the facility. The
Drainage. It is important that wastewater generated
(5)
amount of water needed at the facility will
by the facility not contaminate drinking water
depend on several factors: frequency of
supplies. Therefore, wastewater from the washing
washing, number of vehicles, types of
structures must not drain into a surface or subsur-
vehicles, and type and size of treatment
face water recharge area for a public drinking
system provided. The planner must also
supply. Surface and shallow subsurface water
consider the best source and method of
should be directed away from the site unless it will
charging a recycle treatment system initially.
be used as a source of makeup water. The area will
Once a recycle treatment facility is charged,
be wet due to washing, storage, and treatment; in
the only demand for water will be to makeup
certain climates, ponding and uncontrolled collec-
that lost to vehicle carry-off, evaporation, and
tion of stormwater can cause discomfort to the
leakage.
workers (i.e., from being cold and wet) and speed
the rate at which equipment wears. Sites with
(2)
permeable soils allow surface waters to percolate,
existing power lines. If electrical power is not
which prevents ponding and sheet erosion.
available at the site, new lines must be run. Elec-
tricity will be required to run the pumps that circu-
History. It is important to have historical knowledge
(6)
late water throughout the facility and to provide
of the site. Past uses of the site may make it
power for security and night lighting. The amount of
unsuitable; this could be from an archaeological
power that the planner should expect the facility to
standpoint such as old burial grounds, or from a
use will depend on the volume of water treated,
hazardous standpoint such as old landfills or old
recycled, and discharged; the type of washing op-
firing ranges and impact areas.
erations; the frequency and duration of washing at
night; and the number of washing operations per-
d. Utilities. The planner must consider all utilities required
formed each year. It is important that electrical lines
at the facility with respect to those available at the site. If some
not span areas of vehicle movement. Vehicle
antennas, especially on wet vehicles, must not come
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