TM 5-814-9
Filter maintenance considerations. The filter
(7)
prevent water from collecting in the
sand and the filtered matter support the
filter and underdrain to a depth at
growth of weeds and grass. Weed control is
which freezing damage can occur.
not required since low grasses and weeds can
(b)
protect the surface sand from direct sun rays.
Where wind-blown dust and dirt could
This shades the sand and reduces evaporation.
be transported to the filters from
However, trees and other plants with root
unpaved tank trails or erosion-prone
systems that could clog or otherwise interfere
areas, natural or artificial screens may
with the filtering process should be removed.
be considered.
(a)
(c)
Winter operations are mostly similar
When a filter is observed to be
to those during warm weather except
plugged or approaching a plugged
that cleaning the filters during cold
condition, it will be necessary to
weather is more difficult. Cold season
rejuvenate the filter surface. Two
filtering should be started with a clean,
approaches are recommended. The
raked filter surface. If the CVWF (and
first consists of raking the media
therefore the filters) will not be used
surface to remove debris and breaking
during
freezing
months,
the
the surface incrustation that results
distribution piping including header,
from the drying of fines and debris.
distribution main, and laterals must be
The filter is raked manually with a
designed to be fully drained to prevent
garden rake or a small tractor rake or
damage due to freezing. The
disk attachment. When raking no
underdrain network must also be
longer appears to rejuvenate the filter
designed to be fully drained or to
surface due to the buildup of filtered
6-20
Previous Page
