The more water used in yard cleaning, the greater the volume of effluent produced. Water doesn’t have to be high quality to clean the yard, consider this when sourcing water. High volume, low-pressure systems work best.
What sort of yard surface is easiest to clean?
Excessively rough and cracked concrete surfaces increase the time spent hosing and you could consider resurfacing the yard. Large grooves running across the slope can slow water flow and trap sand particles. Grooves running down the slope do not cause as much restriction and enable any sand to be flushed away. Concrete should not be over-finished, as it can become slippery.
Water pumps should be placed close to the storage tank to reduce the distance water has to be ‘dragged’, so is less effort for the pump. Pump suction and discharge have a large effect on the amount of water a pump can output.
The delivery to the pump is best from above, but if suction is necessary, the lift should be as short as possible. The delivery pipe should be at least 51mm internal diameter.
Manual yard cleaning systems
Manual systems involve a higher labour input, but if the right system is used, there is huge potential for saving time. Manual yard cleaning systems can either be hose or hydrant.
- Hose cleaning systems can be used on any slope but are costly in terms of time and water.
- The hose diameter needs to be approximately 40mm and nozzle should be 20–25mm in diameter.
- Locate hoses up the top of slopes to work effluent towards drains. Hoses longer than 10m become too heavy to pull.
- Multiple hoses connected a convenient points are more useful than one big hose.
Hydrant washing systems are becoming very popular – there are no hoses to drag around and they can reduce yard cleaning time. These may be the best option if yard slopes make flood washing ineffective.
Hydrant systems have significant OSH benefits. There is no long hose to drag around and the high volume swivel hose is easy to direct.
Features & requirements:
- Hydrant systems can output up to 2000 litres of water a minute.
- Most yards require no more than 3 hydrants - small yards may be able to get away with only one.
- Several fixed risers with hydrants are attached and mounted along the yard – generally attached to a 100 mm supply line.
- The top may be fitted with a swivel. When turned on the operator only needs to direct the nozzle.
Automated yard cleaning systems
Automated systems reduce labour requirements, but some tasks may still need to be completed to ensure a high-quality clean. Options include:
Backing gate cleaning systems
Cleaning times can be reduced using scrapers and water jets mounted on backing gates. Options include:
- Four or five nozzles mounted with a drag chain between each water outlet – as the gate moves the chain breaks up manure pads and the water flushes the manure away.
- A system with a number of small high pressure jets behind a scraper-like barrier. This washes the yards as the backing gate moves. It still may be necessary to scrape or hose a narrow wedge of the yard but this should take less than a minute.
Flood wash systems
Flood wash systems work best in single slope yards with no cross flow. If the yards are appropriate, a well designed system can mean opening a gate valve or pushing a button and walking away.
There are a number of different ways to flood wash holding yards, two examples are:
- elevated tanks in yard or on the roof
- sub surface risers.
In suitable yards, flood wash systems are the ultimate in high volume, low pressure cleaning systems. A stored volume of water is released from the top of the yard and sweeps the yard clean in one hit.
Features and requirements
- To shift the manure at least a 50 mm high wave of water moving at 1 metre per second needs to wash over the yard.
- A flood washing system usually takes between 15 seconds and 1 minute to clean a yard.
- 5,000 - 25,000 litres are usually used per milking. A minimum of 1,000 litres per metre width of yard is recommended – for example, if the yard is 8 metres wide, a minimum of 8,000 litres will be required per cleaning.
- Two single 250 mm outlets or several 150 mm outlets may be needed to produce the correct wave effect.
- The facilities receiving the waste water must be designed to handle a large amount of water in a short space of time.
- Slopes that are too steep (greater than 4% or 1:25) or too shallow (less than 2% or 1:50) impact on cleaning performance - appropriate slope design is critical for flood wash systems.
- Keeping the yard wet during milking helps a flood washing system to work effectively.
- Cleaning can be difficult if the main manure build up is near the sump area. A build up near the sump can restrict the flow of wash water and effluent from the rest of the yard.
Pipe and riser flood wash
This flood wash system delivers water via pipes laid under the concrete yard and about one metre down-slope from the top of the yard.
Features and requirements:
- Riser pipes are placed at regular intervals to bring water from the main supply pipe up onto the yard.
- Risers are usually placed where the greatest amount of waste is expected to accumulate e.g. in the entry and exit lanes of the yards.
- Where possible, people entry points should be away from the path of flood wash water.
Flood wash drums
Drums used in this system will automatically fill and tip as long as the water supply continues to run. A pivot system is used to tip the drums over – they over-balance when full. Once empty, they return to an upright position. This system is not very effective and can use a lot of water.
Large tank in yard
This flood wash option uses a tank that is filled between milkings. This system can use a lot of water.
Features and requirements:
- Locate a gravity storage tank beside the yard or place a tank on either side of the yard to ensure adequate flow.
- The advantage of a large tank with an outlet in the middle of the yard is that water can be distributed evenly across the yard - this is especially useful for wide yards.
- The efficiency of these systems is improved by increasing the height of the tank and the delivery of water through a large diameter outlet onto the yard surface.
- Pre-wetting the yard improves the effectiveness of this system.