Dairy effluent: Overview of effluent management in north-east Victoria
Published: June, 2000
Note Number: AG0434
ISSN 1329-8062
Andrew Crocos, Wodonga
The dairy industry in north-east Victoria produces approximately $35 million of milk at the farm gate which represents 3% of Victorian milk production. The average number of cows per farm is 135, giving a total number of over 54,000 cows in the area.
The dairy industry in north-east Victoria is predominantly located in river valleys. Typically these valleys are relatively narrow with steeply rising hills either side of the river flats. The annual rainfall rises quickly as you travel from the bottom of the valley to the head of the valley (750 mm to 1250 mm). Historically, dairy sheds were located adjacent to water courses so a permanent water supply was available for stock water and cleaning the dairy and associated equipment.
Modern dairy sheds have large concrete holding yards and refrigerated bulk milk handling equipment all of which has to be washed with large volumes of water.
Large quantities of water are used by the heat exchange equipment to cool milk (plate cooler), and by the high volume wash down pumps used to clean the dairy shed and yards. When all this water is directed into the effluent collection system together with stormwater from the yards and shed roof, large volumes of highly diluted effluent are generated. As the volume of effluent increases it is much more likely to flow greater distances over the soil surface and eventually reach a water course if it is not managed correctly.
The high rainfall characteristics of the north-east combined with the fact that most farms milk during the winter months has led to the situation where most effluent management systems include a storage pond in the design of their system.
The requirements of the EPA are the same for both dryland and irrigation dairy farms in north-east Victoria. These requirements can be simply interpreted as requiring all dairy shed effluent to be held and managed on the farm. No effluent is permitted to leave the farm or contaminate the ground water.
The need for effluent storage facilities is more pronounced on farms in the higher rainfall areas especially if the herd is milked through the winter months.
The easy access to reliable water supplies in north-east Victoria dairying areas has led to the use of unnecessarily large amounts of water for cleaning the dairy facilities in some instances. On some farms storm water from the roofs of buildings and water from the plate cooler is not collected for reuse and finds its way into the effluent system. This will increase the size of the storage facilities unnecessarily by a considerable amount.
Since dairy sheds in north-east Victoria are often close to streams and creeks, effluent will often have to be pumped from the dairy to a storage pond.
When effluent is to be pumped or piped over substantial distances the ease of performing this task can be made much easier and more reliable if the debris and coarse solids including stones, gravel and sand are removed prior to transferring the waste. See the Agriculture Note AG0443: Dairy effluent: Trafficable solids traps.
Generally in north-east Victoria effluent will need to be stored from May to October as during this period conditions are not suitable to apply effluent to pasture.
The transfer of effluent from the dairy to the storage facility is best achieved by utilising gravity. Effluent is easier and more efficiently pumped from a storage pond rather than directly from the dairy yard. If pumped directly from the dairy yard a manure pump is required whereas pumping from a storagefacility will provide the flexibility of using a more efficient and trouble free conventional pump.
Effective effluent management systems require careful planning and must complement other aspects of farm management.
The actual operation of any effluent system will be ultimately determined on how successfully the farmer's needs and the legal requirements are met.
A demonstration effluent management system has been set up on a commercial farm in the Kiewa Valley. For further information see the Agriculture Note AG0430: Dairy effluent: Source of information on dairy shed effluent management.
This publication may be of assistance to you but the State of Victoria and its officers do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
