7 (9)
NOAQ BW52 2.1 200325
Left hand and right hand gables
Gables to cope with kerb stones
Drag the boxwall behind gullies
6. Length adjustments
If a boxwall needs to have an exact length, for example between two buildings, there are
different options for adjusting this. As the boxes can be coupled in angles of up to +/-3°
a straight boxwall can be shortened by deploying it in a slight arch between the end points.
An other option is to insert some corner boxes, either in the middle of the boxwall, or towards
the end of it. A third way to span a gap of exact width is to put a straight boxwall a little
obliquely.
7. Pump away leaking water
When using mobile flood barriers you always need one or more pumps
to pump away
the water that will collect on the intended dry side of the barrier. A certain leakage will always
occur, through the barrier, under the barrier and also through the ground itself. Upon this
comes rain water that runs down towards the barrier but cannot reach the river or the lake
as the barrier itself blocks the way. If the ground is level or if it slopes towards the flood, this
water must be pumped clear with a pump. If the ground slopes away from the flood (e.g. on
the crown of permanent embankments), the water will run away without the need for pumps.
Water leaking through or under a mobile flood barrier is no problem as long as the pumping
capacity is sufficient. When needed the leakage rate can be reduced by covering the barrier
with a liner. NOAQ is supplying a suitable liner that is 2 meters wide liner and 75 meters long.
Be aware of any surface water drains or manholes and try to lay the boxwall behind such.
If there is a risk that culverts might lead flood water under the barrier and into the protected
area, these channels must be plugged or blocked.
8. Combine boxwall and tubewall
A NOAQ Boxwall can be combined with a NOAQ Tubewall. The walls are laid so that they
overlap by a metre or so, ideally with the tubewall closest to the flood and the boxwall beneath
and behind the tubewall. One or a pair of the tubewall’s joint covers are used to form a seal
between the two wall sections.
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