Beca was engaged by Tasman District Council (TDC) to review options for upgrading the pond-based Motueka Wastewater Treatment Plant (WWTP) and the treated effluent discharge. An Issues and Options report was prepared by Beca in June 2014, which included a review of earlier reports relating to the Motueka WWTP. Much of the earlier work was focused on land application for wastewater disposal. However, this option had been found to be not viable due to unsuitable land conditions in the local area and predicted sea level rise. TDC and its stakeholders now consider that moving the WWTP to an inland site to allow for future land application could be required, perhaps in a 30 year timeframe.
For the immediate future, continued discharge to coastal water would be required. The Beca 2014 Report considered the treatment required to achieve the treated effluent quality limits that could comply with the required nearshore receiving water criteria, primarily based on the Ministry for Environment/Ministry of Health (2003) shellfish gathering and contact recreation guidelines.
The report recommended a combination of treatment upgrades as follows:
Consents were granted in October 2015 with a 20 year term. The project was delivered through a number of contracts and completed in September 2016 within the $8 million budget. The paper describes the above upgrading methods and presents a summary of effluent quality during the first nine months of operation.