TM 5-814-9
Volume from interior wash points
V7= Q7Tw
Qmax = Q1 +Q2+Q3+Q4+Q5+Q6+Q7+Q8
(eq 6-1)
Volume from yard hydrant
V8= Q8K
or
Volume of stormwater runoff-pavements
V9= Q9Ts
Qmax=Q9+Q10
Note: The designer must determine which
Volume of stormwater falling on basin
V10= Q10Ts
combination of flows are applicable to
surface
any particular conveyance feature; not
b.
Average volume. Vave is an estimate of the total
all flows will be present in all
conveyances, trench drains, or
volume of water used during an average wash
overflows.
period. The average wash period is the period of
time during which the vehicles are being washed in
6-10. Water volume
typical washing operation. Usage factors are ap--
plied to each source of water, since not all water
a.
cannons, hoses, and trench flushers will be
on the following parameters:
operating at all times. Vave (eq 6-2) is used to
estimate the size of the water supply basin and the
Terminology.
(1)
equalization basin or polishing lagoon:
K = cleanup time (generally 1 hour)
Vave
= U1V1+U2V2+U3V3+U4V4+U5V5+U6V6
+U7V7+U8V8+V9+V10
Tw = wash period
(eq 6-2)
Tt = wash period + cleanup
Note 1:
V1, V5 and V6 are included in the equation
only if these volumes are withdrawn from the
Ts = storm duration (generally l hour)
water supply basin. Volumes withdrawn from
the equalization basin are not included in the
B = number of times the bath is filled from
formulation.
the water supply basin per wash
period. (Bath volumes taken from the
Note 2:
V9 and V10 are not apart of Vave in a standard
equalization basin are not counted
design. Including V9 and V10 as a part of Vave
since these volumes do not receive
is the designer's option.
complete treatment through the
secondary treatment system. The
c.
Maximum volume. Vmax is an estimate of the total
number of times that the bath is
volume of water used during the peak use period of
drained and filled will depend on the
the facility. The same equation (6-2) used to
length of the wash period and the
calculate Vave is also used to calculate Vmax; the
visual quality of bath water.)
difference is that the wash period used to calculate
the individual volumes, V2 through V8, is the length
Ui = usage factor (from 20 to 90 per cent)
of the peak washing operations, not the length of the
at source
average washing conditions. Usage factors are still
applied in the equation to compensate for the time
Volume calculations
(2)
during which the nozzles are not operating. The
Vmax value is the primary volume used in sizing the
Formulation
water supply basin and the equalization basin or
settling lagoon. Vmax is also used in the sizing of the
Volume from bath flush
V1=VBB
intermittent sand filters.
Volume from bath water cannons
V2= Q2Tt
d.
Water balance. The designer must perform a water
balance during the preliminary design phase. The
Volume treated at wash station hoses
V3=Q3Tt
purpose of the water balance is to ensure that basins
such as the equalization basin do not overflow and
Volume from additional preparation area
V4=Q4K
that the water supply is not totally drained. Thus,
flushers
the designer must make provisions to handle the
peak use water volume in each basin during the
Volume from bath U-drain flushers
V5=Q5K
washing operations. Based on the results of the
water balance, the designer may be required to
Volume from wash station trench flushers
V6= Q6Tt
increase, or may be able to decrease the size of the
basins.
6-3
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