Save tank space by separating clean and dirty water
Eugene McBride, Countryside Management Branch, Department of Agriculture and Rural Development (DARD)
Many farms generate significant volumes of dirty water, which must be collected, as it has a polluting effect and must not enter waterways. The volume of dirty water is often increased when clean water is allowed to mix with dirty water, which has implications for storage capacity in collection tanks on the farm.
For example, 110 cubic metres of dirty water, generated from a 200 square metre soiled yard over the winter, could increase to 330 cubic metres if clean water from a similar sized yard and adjoining roofs is allowed to mix with it. This volume could be further increased by run-off from adjacent fields.
Take action to reduce the volume of dirty water on your farm.
- Separate clean and dirty water by installing effective guttering and storm water drainage systems. Install channels to divert clean yard water away from dirty yards.
- Minimise the area of dirty yards. This will reduce the volume of dirty water for collection.
- Keep yards clean after use. Collect all dirty water that is produced when yards are soiled and during cleaning. There is no requirement to collect run-off from a clean yard.
In the consultation paper for the Nitrates Directive proposed Action Programme, dirty water means water contaminated by manure, urine, effluent, milk and cleaning materials. It should have a Biochemical Oxygen Demand (BOD) no greater than 2000mg per litre. The BOD measures the polluting strength of dirty water; it indicates the amount of oxygen needed to break down organic wastes in a waterway. Dirty water that is stored with livestock manure is classified as livestock manure.
It is good management practice to provide sufficient dirty water storage capacity for those periods when weather and ground conditions are unsuitable for land application. Storm water diverters can be used to divert run-off from yards to the storage tank when contaminated, and to the storm drain when clean, by altering the position of the drainage pipe. Careful management is required to operate diverters satisfactorily in order to prevent pollution of waterways.
Contact Countryside Management staff at your local DARD Office if you require more information on managing dirty water on your farm.