Northland’s dairy farmers are advised to follow local guidelines for dumping milk in the wake of a major Taranaki gas leak which may effectively force the region’s dairy factories out of action for several days.
The gas line which links the Maui gas field to the upper North Island closed this morning after gas began escaping from the pipeline in north Taranaki.
Northland’s dairy plants – which rely on that gas to process milk – have already stopped collecting milk from the region’s farms as they are now unable to operate their plants.
The Northland Regional Council says as most Northland farmers lack the capacity to hold milk on their farms for longer than a day or two, mass milk dumping may soon be the only option for most.
Dennis Wright, an Environmental Monitoring Officer – Farm Waste, with the regional council says ‘A Guide to Managing Farm Dairy Effluent - Northland’ – a joint council and dairy industry publication – contains a short best practice guideline for disposing of large volumes of milk.
The relevant section of the guide reminds farmers that milk must not be discharged in any way that enables it to reach drains or watercourses. (This section can be found on page 33 of the PDF file at the following link www.nrc.govt.nz/milkdumping )
Mr Wright says where possible, uncollected milk should be fed to stock.
It can also be spray irrigated, but must be diluted at a ratio of one part milk to 10 parts water and applied to pasture.
“Once again though, this can only be done if the spray application is kept well clear of drains and watercourses. Those farms which don’t have a permanent land application system should consider hiring a contract slurry wagon.”
Mr Wright says dumping milk into effluent treatment ponds which discharge to water isn’t an option as it reduces treatment pond effectiveness and the resulting discharges could breach consent conditions and cause long-term damage to waterways.
“If feeding the milk to stock or spray irrigation isn’t possible, digging an emergency trench or pit is another option.”
“These trenches or ponds should only be used in areas where leakage is not likely to contaminate ground or surface water. The trench or pit can also be backfilled later to reduce offensive odour.”
Mr Wright says few people realise that milk which is inappropriately released into the environment is actually many times more polluting than even farm dairy effluent.
“This is because it virtually eliminates oxygen from the water, kills stream life (including fish and eels) and has many other long-lasting adverse environmental effects. It also gives off very offensive odours as it decays.”
Mr Wright says anyone uncertain about which option is the best one for them should contact the regional council on (0800) 002 004.