TM 5-814-9
CHAPTER 2
CVWF DESIGN CONCEPT
2-1. Overview
In a discharge system, secondary treatment is done at the
installation, local municipal, or regional sanitary wastewater
The standard CVWF consists of a vehicle preparation area,
treatment facility. Essentially, all recycle systems are partial
wash stations, and vehicle assembly area (fig 24). However, the
treatment systems, as release of some wastewater may become
layout of a facility will be site-specific, based on the
necessary to maintain water quality and to allow discharge of
installation's mission and needs. Information on siting and
excess storm water collected at the facility.
master planning is found in chapter 3. A design example is
provided in appendix A.
Intermittent sand filter system. This secondary
(1)
treatment system is comprised of an equalization
2-2. Prewash (optional)
basin and an intermittent sand filter. The equal-
At installations with heavy soiling conditions, high demands for
ization basin holds the wastewater after primary
washing, and/or limited washing times, a prewash system is
treatment and before it is applied to the filters to
recommended. Three types of prewash systems have been
equalize flow rates by dampening the high and low-
constructed for use in tactical vehicle washing: bath, spray
flow variations.
stand, and automatic washer. The vehicle bath is the most
effective prewash system for Army tactical vehicles. Figure 2-2
(a)
A dosing tank may be provided after the flow
shows a typical CVWF plan with the CONUS approved bath
equalization basin to provide a water volume
prewash system for tactical vehicles. Commercial type, such as
of one charge or dose to a portion of the sand
those in a Transportation Motor Pool (TMP), would utilize
filter. The dosing tank is a designer's option
commercial automatic washers and not facilities described for
which allows for flexibility in sizing the
the CVWF.
pumping facilities.
2-3. Wastewater treatment
(b)
Water quality testing and metering capabili-
A system for conveying and treating wastewater is included in
ties are recommended to be provided at a
the CVWF design, since water used to wash the vehicles will
point following the intermittent sand filters to
become contaminated with dirt, debris, and products related to
measure the quality and amount of the treated
vehicle operation such as oil and grease. All wastewater must
wastewater to be recycled. At this point,
receive primary treatment to remove settleable and floating
facilities should be provided which allow
materials. Following primary treatment, the wastewater is either
recirculating all or a portion of the filtered
released to a collection system or further treated onsite and
water back though filters via the equalization
stored for reuse during future washing operations. The water
basin. The remaining filtered water flows into
used to wash vehicles should be recycled whenever possible
the water supply basin and is stored for reuse.
and feasible. However, even in a total recycle system, some of
the wastewater may need to be released to a discharge system
(c)
Water overflow facilities to provide hydraulic
before or after receiving secondary treatment. This discharge is
protection for the secondary treatment process
done to ensure that water quality and water balance are
should be located at the water supply basin
maintained. Measured makeup water is added to the recycle
for emergency storm release. This overflow
system to compensate for the volume of water carried off on the
system should also be able to make controlled
wet vehicles, released, and lost to evaporation.
partial wastewater releases to further assist in
maintaining the quality and quantity of the
a. Primary treatment. All wastewater must receive primary
recycled water. Hydraulic protection should
treatment. A sediment basin that provides primary treatment is
also be provided at the equalization basin as
required to allow most of the suspended solids to settle and to
a backup. Chapter 6 presents details of the
allow the free grease and oils to separate from the wastewater.
sand filter treatment system.
b. Secondary treatment. For the purposes of this manual,
Lagoon system. This secondary treatment system
(2)
secondary treatment refers to intermittent sand filters, lagoons,
consists of a basin or a series of basins where the
or discharges to sanitary sewage systems. Two systems of onsite
wastewater is held for an extended period of time to
secondary treatment are used following primary treatment if the
achieve the desired water quality. The treated water
water is to be recycled. These methods include intermittent sand
is allowed to flow to the water supply basin for
filters and lagoons. Lagoons are not the standard system but are
reuse. Water quality testing and metering capabili-
included because they have been used as a wastewater treatment
ties are recommended to be provided, as well as
method for CVWFs. The third system of handling wastewater,
overflow protection. Chapter 6 explains the lagoon
discharge to sanitary sewer, may be available at an installation,
treatment system in greater detail.
but this method is not used in conjunction with a recycle system.
2-1
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