An Environment Waikato hearing committee has granted Taupo District Council resource consent to discharge up to 350 cubic metres of treated domestic effluent per day into the ground from its Waitahanui wastewater treatment plant.
Environment Waikato received six submissions on the consent application and a held a hearing in Taupo on July 18 and 19.
Issues discussed at the hearing included the potential impacts of nitrogen on Lake Taupo and the risk to private drinking water supply bores in Wairau Avenue.
After carefully considering all the evidence, the hearing committee granted the discharge consent, as the effects of the discharge were not expected to have “any more than minor effects on the local groundwater and Lake Taupo”.
“We are satisfied that with the proposed UV treatment of effluent in place, in conjunction with the monitoring regime for detecting indicators of human health, that downstream drinking water supplies will continue to be protected at least within the confines of a discharge up to 350 cubic metres per day,” the committee said.
However, it imposed a range of consent conditions, including:
- limits on the concentration of nitrogen, phosphorus and E. coli bacteria in the discharge
- routine monitoring of the groundwater for nitrogen and E. coli bacteria
- non-routine monitoring of the groundwater for viruses.
The Taupo District Council proposes to upgrade the plant to meet the new consent limits.
“The Taupo Variation Plan identifies that the high water quality of Lake Taupo is in decline, and is an issue of local, regional and national significance,” the committee said.
“Along with nitrogen, phosphorus is also identified as a nutrient of potential that needs to be managed. In order to avoid increasing the effects from a discharge of increasing flow, the treatment efficiency of the plant will need to be improved.”
In the committee’s view, the current method of effluent disposal was “not ideal in the longer term because it involves elements of cultural unacceptability and does not have the benefit of further land treatment that alternative methods can offer”.
However, until investigations had been undertaken to consider alternatives, the current method of disposal was acceptable “given that the effects are considered minor”.
The consent also provides for the establishment of a liaison group to allow community representatives to discuss operational issues and alternatives methods of effluent discharge with the council.
The resource consent was issued to Taupo District Council for a period of 15 years.