Location: Waitakere Ranges, Auckland
ACH Consulting were engaged to design an on-site wastewater system for a large steep property situated in the Waitakere Ranges. The site, covered by dense native bush, provided adequate fall to use a system that is entirely gravity fed. The system chosen for the property uses a combination of vermiculture (earthworms) and native plant species. Differential treatment of blackwater and greywater allows for the higher level of treatment required to process elevated levels of nitrogen pathogens produced by toilet and kitchen waste and phosphates and nitrates which are the main by-products of household greywater. On this site the system fit in well with the natural landscape and has the added benefit of not requiring any power at all to operate.