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Water for Every Farm - Yeomans Keyline Plan

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Yeomans Lockpipe System: Information and Fittings

A Keyline Dam Wall (cross sectional view)

Features of the wall in the above diagram:
• The green coloured fill represents the undisturbed material under the wall.
• 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 metres long.
• 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)
  

  Baffle Plates

  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 to Dam 

Cone Strainers
Cone strainers are fitted to the inlet of each Lockpipe System. 


They provide a coarse filter with a large surface area to minimise pipe blockage 
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 

Flota-filter

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 to Dam



Keyline Designs
1/69 Falconer Street, Southport, Queensland 4215 AUSTRALIA
Mobile: +61 (0) 4 1874 5120

Yeomans Keyline Designs / webmaster@keyline.com.au / revised 2 Feb 2022

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