By Neil Ritchie
THE NEW Zealand government is establishing a new working group to look into the practice of spreading drilling wastes on some designated Taranaki dairy farms.
The Ministry for Primary Industries, Ministry for the Environment, Taranaki Regional Council and others make up the group, formed after the Parliamentary Commissioner for the Environment, Jan Wright, called on central government to take action regarding how the so-called land farming is being monitored.
While an independent investigation into the practice late last year vindicated the science behind the process, environmentalists continue to decry the practice, saying there is presently nothing preventing dairy cows or other stock from grazing on land farms that may be unsafe due to the incomplete breakdown of contaminants in drilling wastes.
That independent investigation, by soil scientist Doug Edmeades of AgKnowledge Ltd in Hamilton, found there was no indication of any problems with stock grazing or either scientific risk or actual risk to the quality of milk or meat after the bio-remediation process was complete.
He investigated soil fertility, heavy metal and barium concentrates and petrochemical residues in the soil at three Taranaki land farming sites and found the concentrations of nutrients, heavy metals and soluble salts in the soils and pasture were similar to normal New Zealand soils.
The process of land farming sandy, coastal farm land, together with appropriate management, increased the agronomic value of the land. Land farming actually made these otherwise very poor soils ten times better for dairying.
Taranaki Regional Council director of environmental quality Gary Bedford said the TRC followed Ministry for the Environment guidelines regarding the safe levels of concentrations of contaminants. But the question of stock grazing on land that did not meet those guidelines remained.
There were some occasions where these guidelines were not met and concentrations of contaminants exceeded, particularly on the most recently completed land farms.
But contaminant levels declined over time as the soil’s naturally-occurring microbial population broke down the hydrocarbon wastes.
Onshore oil and gas explorers have used land farming for several years as an economic way of disposing of the usual drilling wastes, plus sometimes fracking fluid wastes from deep wells – usually from Taranaki but also occasionally from other regions such as the East Coast.