Landowners urged to curb contamination from silage pits

The Otago Regional Council (ORC) is urging landowners in the Otago region to minimise the risk of leachate discharges from silage pits contaminating waterways.

ORC group manager regional services Jeff Donaldson said his staff had noticed several instances this year of leachate encroaching on waterways – a by-product of heavy rain in February and March.

“Silage effluent can be a valuable nutrient source for pasture, but it can also be one of the most contaminating farm wastes,” Mr Donaldson said.

This was why the Otago Regional Council (ORC) is concerned about what happens to the leachate from silage stacks and the wrap used to enclose them.

Silage stack leakage can cause severe de-oxygenation in waterways, resulting in serious deterioration of water quality, affecting fish, plants and other stream organisms.

It is 40 times stronger than farm dairy effluent, is acidic, and contains high levels of nutrients.

Mr Donaldson said location is crucial when deciding where to put a silage pit.

“If, as is the case with many silage pits, landowners have old pits close to water, they should prevent leachate from getting into waterways by shifting them to a more suitable location,” he said.

Under the Otago Waste Plan, silage pits are a permitted activity only when:

Ø There is no groundwater seepage into the pit; the silage stack or pit is more than 100 metres from any well used for domestic purposes or drinking water for livestock;

Ø Leachate from the silage stack or pit does not enter any water body;

Ø The silage stack or pit is more than 50 metres from any water body;

Ø Silage is made on production land;

Ø The silage stack or pit is more than 50 metres from a property boundary, excluding road boundaries;

Ø The silage stack or pit is not noxious, dangerous, offensive, or objectionable beyond the property boundaries.

Mr Donaldson said landowners who do not meet the permitted activity conditions need a consent under the Resource Management Act.