Sewage sludge the Queenstown Lakes District Council proposes to dump on land near Tarras contains pathogen levels 650 times higher than the optimum recommended level.
The QLDC has applied to the Central Otago District Council for consent to store and discharge up to 2000cu m of sludge, derived from effluent from the Wanaka wastewater treatment plant, on a 3500ha Ardgour Rd property each year until at least 2045.
Under the proposal, solid waste derived from raw sewage would be transported from the Wanaka wastewater treatment plant and stored on an uncovered concrete pad at a Tarras property, owned by Wanaka residents Bruce and Linda Jolly.
It would be applied to paddocks on the farm once a year.
Under Resource Management Act requirements, the QLDC last year successfully applied to the Otago Regional Council to discharge "sludge from human sewage to land".
That submission stated the E. coli pathogen levels in the sludge were well above optimum level stipulated by the NZ Guidelines for Land Application of Biosolids (2003).
Martin O'Malley, a strategic project manager for the QLDC, confirmed the sludge pathogen level was about 650 times higher than the national guidelines for "grade A" biosolids. However, the use of the sludge differed greatly from the grade A product, which could be applied directly to domestic gardens.
The less-processed Wanaka sludge would be stored and applied to land only once a year.
"It is a material that is suitable for the process we are proposing but it's certainly not a stabilised product.
"For a person like me, who is used to dealing with these issues, I wouldn't find it alarmist, but the reality is what it is.
"We are not claiming the pathogen count is below the biosolids guideline.
"What we have measured is that much greater than the guideline."
He said the key thing was that the ORC had assessed the effects of the sludge on the area it was looking to use it on.
"The ORC is comfortable with the fact that the risk of the pathogens that are in there can be mitigated, as are we."
In its 2009 decision, the ORC stated: "Pathogenic organisms present in the sludge do not typically survive in the soil environment.
Pathogens are not expected to have an effect on groundwater quality in the area ... the effect of pathogens on soil and plants will be insignificant."
