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How long will it take to drain a bunker or turfed depression using Bunker Dry?

It depends on the size of the bunker, or turfed depression, as well as any external flows entering these features and the duration of the storm. In comparison with a bunker which has a conventional drainage system in the substrata, the duration is up to 10 times faster. An average size bunker or turfed depression fitted with Bunker Dry units will drain after a significant storm in less than 30 minutes.

Does the Bunker Dry work in all types of sand?

Yes, however the flowrate from the Bunker Dry depends on the permeability or hydraulic conductivity of the sand which surrounds the device.

Why install Bunker Dry in a turfed depression?

Bunker Dry was originally designed for sand bunkers, but further testing has revealed excellent performance installing Bunker Dry below turfed depressions. Providing grass is laid on sand which extends to the base of a Bunker Dry unit, the same principle applies to the drainage characteristics in bunkers. The most compelling reason is the eliminate grated pits (drains) at low spots, as they are unsightly as well as an obstacle for Golfers.

What is a typical flowrate?

The Bunker Dry will flow at 120 litres/min (30 gallons/min). An average flow of 20 litres/min (6 gallons/min) has been measured under storm conditions where a bunker has filled with water quite rapidly.

Does the build-up of silt in sand affect the flowrate?

Silt will naturally build up at the surface of the bunker especially at the low point/s. Silt is encouraged to form if water in the bunker cannot drain. Water leaches out silt and particulates from the bunker edges. Bunker Dry does not allow water to pond in the bunker, therefore silt is minimised. As part of bunker maintenance any silt which accumulates at the base of bunkers should be removed periodically.

Will silt flow into the Bunker Dry and block up the system?

No, the design of the Bunker Dry unit will not allow silt and or sand to pass through it into the drainage system. The design relies on gravity to separate the water from the silt and sand grains, effectively filtering the water and allowing only water to flow into the drains. The water exiting the bunker is clear and almost good enough to drink!

Can the Bunker Dry be damaged installed below the surface of the sand or turfed depression?

We don’t believe so. The top of the Bunker Dry (Dome) is installed between 5” and 8” below the surface of the sand (low point). A Golfer making a stroke, or a grooming machine will not penetrate far enough into the sand to connect with the Dome.

How often will the Bunker Dry units need replacing?

The Bunker Dry units are designed to withstand a significate impact, if by any chance the unit is close to the surface of the sand. The unit is constructed of polypropylene with 10% glass for added strength and flexibility. All components which make up Bunker Dry are corrosive resistant and will not degrade. A Bunker Dry will outlast the bunker or turfed depression before it is due to be renovated.

What type of drainage system will adapt to a Bunker Dry?

Any drainage system which has a free outlet. In other words, the outlet must be lower than the lowest surface of the bunker or turfed depression. A free outlet will discharge into a stormwater system, creek, pond, lake, surcharge pit, Absorption or transpiration bed, if it lower than the bunker.

What type of pipe will it adapt to?

A standard Ø100mm (Ø4″) PVC or Polyethylene agricultural pipe. We recommend a solid PVC pipe as the ideal collection system.

Can the Bunker Dry system work with other bunker drainage systems?

Yes, the Bunker Dry system will enhance other methods such as liners and porous membranes because the water flow out of the bunker below the sand is much more efficient.

How long will it take to install?

For a new build, the collection pipe/sub-soil drain is installed in the normal fashion. At the designated low points, a Ø52mm(Ø2″) hole is drilled through the top of pipe and the Bunker Dry device is simply snapped onto the pipe and set level. For existing bunkers, the sub-soil drainage pipe needs to be located at point/s where a Bunker Dry device is required. Exposing the pipe for a length of 12” is all that is needed to install.

For bunkers which do not have a drainage system, the procedure for new builds is applicable.

What do we need to install the Bunker Dry?

Apart from excavation implements, the installer will need the following:

  1. Cordless power drill
  2. A Ø52mm (Ø2″) hole saw
  3. Panel saw to cut pipe
  4. 1x square meter (1x square yard) of Shade cloth
  5. 2x 10 litres (2x 4 gallon) buckets of 10mm (3/8″) aggregate.

Why doesn’t sand go through the Bunker Dry and enter the drainage system?

The Bunker Dry is designed to take advantage of gravity and velocity change. Wet sand will travel as a slurry under pressure at the base of the bunker and conventional drainage systems cannot separate the water from the sand. Where Bunker Dry is different is that water and sand mixed together flow into the outer chamber and rise within the void space to enter the primary weir. The water and sand mix will travel some 75mm (3″) before the sand becomes too heavy and the water separates and flows some 40mm (1 1/2“) to the primary weir. Another feature is the velocity chamber, which was added during testing and development. In extreme cases where excessive volumes of water mix with the sand, a condition known as liquefaction occurs. Liquefaction increases the flow and velocity of the water and sand mix and under pressure will rise higher within the void space threatening to over top the primary weir. To exclude any sand, the void space between the outer chamber and the primary weir is tapered which creates a larger space near the primary weir thus slowing the velocity of the slurry, much like a river flows quicker through a narrow opening and much slower as the banks are wider apart. See illustration below

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