Water for Every Farm - Yeomans Keyline Plan
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Yeomans Lockpipe System: Information and Fittings
The above diagram shows the cross section of the wall of an
7 metre deep farm dam fitted with a Lockpipe.
The Lockpipe consists of: a pipeline with an inflow Cone
Strainer, a valve and several Baffle
A Lockpipe System may include a Flota-filter,
which enables water to be drawn from near the surface of the dam and be
piped through the main pipeline to supply stock and yard water.
Features of the wall in the above diagram:
- The green coloured fill represents the undisturbed material under the
- The water is on the left side.
- The inside batter (slope of the wall) is 1 in 3 and the outside batter
is 1 in 2.5. Steeper batters, especially 1 in 2 both inside and
out were the standard for Keyline dams since the mid-1940. They
required less pipe and earthworks are still in use.
- The wall is 8 metres high. This is measured vertically between the
crest down to natural surface by the outside toe of the wall (in this
case by the valve).
- The crest (width on top) is 4 metres.
- The Lockpipe is 48 metres long and 300 mm in diameter.
- The pipeline consists of four lengths of flanged pipe; each is twelve
- Two (2) of the ten baffle plates are used in the core trench and six
(6) are used between the core and the inlet. Two (2) other baffle plates
support the remainder of the pipe.
- The intake for a Flota-filter is suspended by a float about a metre
below the top water level.
- A Keyline pattern irrigation channel (trench) is shown on the right
side. It is positioned far enough away from the main valve to enable
vehicle access past the wall above the channel. Note: One (1) Cone
Strainer and Ten (10) Baffle plates pairs are recommended for each dam.
(ie 20 plate halves)
The dimentions of baffle plates for pipe diameters from 324 mm to 457 mm
OD (12 to 18 inch nominal) are 1200 x 800 x 3 mm. Standard baffle plates
are made of black steel. Galvanising is optional. PVC or Polyethylene
baffles are sometimes used.
The image above shows a steel baffle fitted to 300 mm steel pipe. Baffle
plates prevent water leaking along the outside of the pipe. Silicon
sealant is used around the pipe and between the two baffle plate halves,
which are bolted together. Usually ten baffles plates are used. Back
They provide a coarse filter with a large surface area to minimise pipe blockage
Cone StrainersCone strainers are fitted to the inlet of each Lockpipe System.
through sediment, wall slip and flood debris.
The cone strainer also induces laminar flow into the main pipeline and so maximise
the flow rate through the Lockpipe.
The Flota-filter pipe passes through the large socket visible in the lower part
of the filter.
A flange, usually Table D (or E), is used to bolt the Cone Strainer to the pipeline.
Back to Dam
Yeomans Keyline Designs / firstname.lastname@example.org / revised 2
A Flota-filter enables water to be drawn from near the surface of the
dam and delivered through the main pipeline. The upper layers of water
are more suitable for stock and domestic requirements.
Between irrigations the water trapped in the main pipeline tends
to become stale and soon develops an offensive odour. This stale
water is quickly flushed away when the Lockpipe is turned on for
irrigation. However, for stock or domestic requirements the water is
drawn off relatively slowly. Consequently water in the main Lockpipe
soon becomes unsuitable for stock.
The Flota-filter System delivers water through a second, much
smaller, pipeline running inside the main pipeline. The stale water
in the lockpipe system remains isolated. The smaller pipeline
extends beyond the cone strainer up into the pond area of the dam.
Its inlet is fitted with a filter attached by rope or chain to a
float. The Flota-filter draws cool fresh water from a metre or so
below the surface of the dam. The actual depth is controlled by the
length of the rope or chain.
The discharge end of the Flota-filter pipeline is attached to a
socketed elbow fitting that passes through the wall of the main
lockpipe just before the valve. On the outside end of this socket is
fitted a suitable valve. The pipeline to stock or domestic outlets
may be connected to this valve.
The Flota-filter pipeline is usually about 50 mm in diameter. The
section of the Flota-filter pipeline that passes through the
Lockpipe must be relatively rigid. Flexible pipe like black
poly-pipe (polyethylene) proved unsuitable on one occasion when the
flow of water through the main lockpipe caused the 50 mm (~2")
poly-pipe to prolapse out through the main valve, which then could
not be turned off. The operator coupled a tractor to the
prolapsing poly-pipe and destructively ripped the poly-pipe out
through the main valve, which could be turned off, saving the
irrigation water for later use. Back
1/69 Falconer Street, Southport, Queensland 4215 AUSTRALIA
Mobile: +61 (0) 4 1874 5120
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© 2000 Keyline Designs
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