Taupo District Land Treatment Scheme - Revisited

The surface waters of the Taupo district are of high quality and are sensitive to inputs of nitrogen. To reduce the amount of nitrogen discharged to surface water, the Taupo District Council (TDC) has employed a land treatment scheme (LTS), where treated municipal wastewater is irrigated onto ryegrass pasture. To limit the possibility of nitrogen pollution, consent conditions for the scheme govern the amount of effluent that TDC may irrigate. 

An expansion of the LTS in late 2008 (referred to as the View Road LTS) was established to accommodate projected Taupo population increases and the potential for future connection of two additional satellite communities, Acacia Bay and Waitahanui. In addition, the original LTS scheme at Rakaunui Road had reached nutrient loading operating capacity and has since further reduced in operating capacity as a result of the Eastern Taupo Arterial Bypass which bisects the site. 

The combined LTS (View Road and Rakaunui Road) has been in operation for over five years now and has the potential to irrigate up to 15,000 m3 /d of treated wastewater effluent across almost 500 hectares of farmland. The cut and carry haylage crop is bailed and sold to dry stock farmers as part of this sustainable reuse initiative and helps to fund the scheme which now represents the largest municipal wastewater irrigation scheme in New Zealand. 

We explore here a number of the successes and operating challenges that have faced TDC over the past five years. An update on the nitrogen loading rate trials, that were implemented as part of the scheme to quantify the nitrate leaching rates from the proposed scheme, are also presented.