Considerable work and investment has taken place on the wastewater treatment plants over the last six years. The plants were originally built to appropriate standards of their day, but these standards have recently been increased, particularly with respect to the quality of treated effluent discharged into natural waterways. Legislation and resource consent renewal requirements have resulted in higher minimum standards that are forcing further upgrades to the treatment of waste. This reflects a public view that is less tolerant of pollution in waterways.
Council has a number of resource consents with Horizons Regional Council (Horizons) with regards to wastewater activities. These consents mainly relate to controlling of pollutants and discharges affecting the environment and waterways.
The Dannevirke discharge is currently the single largest contributor of phosphorus to the upper Manawatu River at low flows and Council is not currently able to comply with the current consent conditions for this facility. Problems with meeting discharge conditions also exist in Pahiatua, Woodville, Norsewood and Ormondville. An upgrade to the wastewater treatment process to meet higher resource consent requirements is planned for Pahiatua. The results from the Eketahuna pilot plant currently being tested will be used to inform the design solution for Pahiatua.
Council, with Horizons input, is investigating a move to land based discharges during low river flow periods (generally summer). This will significantly reduce the treatment costs required to meet discharge consents during low flow periods, and make a contribution to meeting the River Accord actions. Additionally the land based discharge will improve the productivity of the land involved over summer. In order to move to land disposal, investigations are required into the soil quality of available land. The type of soils near some of the treatment plants are generally not ideal for discharge given the high clay content and high water table.
While Council has a number of timing and design options for these projects there is little choice in the need for further investment. The quality of the treated discharges has to meet existing consent conditions and consent renewals will have to meet the higher standards of the new Horizons One Plan.
In 2011, Council identified that one of its three oxidation ponds in Dannevirke is seeping effluent into the Manawatu River. Council has a duty to stop this leakage to protect the river water quality, and to comply with current consent conditions in regards to discharge of effluent. Council is working closely with Horizons to rectify this issue.
Council will line all three ponds over the first three years of the Long Term Plan. Council has estimated that the total cost to line the three ponds is $3.75 million over a three year period (years 2012 to 2014). Council, in working with Horizons and other council signatories to the River Accord, has secured a $2.1 million subsidy from the Ministry for the Environment fund. Once scope of works is determined, an agreement will be entered into with the Ministry for the Environment. Council is only able to line one pond each year as it needs the other ponds available to treat effluent. Council will line the leaking pond first and has the option of leaving the other two ponds if the subsequent monitoring results show a reduction in pollutants in the surrounding water ways. This would require the support of Horizons Regional Council and iwi, and an acceptance of the risk of the other unlined ponds leaking in the future.
Council aims to carry out the eight projects identified to ensure Council complys with it’s resource consent requirements by improving quality of discharges and reduce treatment cost. The total cost of these projects over the 10 years of the plan is $7.56 million with $2.1 million of subsidy available from central government. Council's share is loan funded.
The following is a summary of Wastewater project upgrades:
Project 1: Dannevirke oxidation ponds - lining 3 settling ponds
2013 - 2014/15
Project 2: Dannevirke land based discharge at aerodrome in low flow
20/13 - 2014
Project 3: Pahiatua treatment upgrade - and land based discharge in low flow
Project 4: Pongaroa Treatment Plant upgrade
Project 5: Woodville Pond relining and treatment upgrade and land based discharge in low flow
Project 6: Eketahuna treatment upgrade
Project 7: Norsewood land based discharge in low flow
2013 - 2015
Project 8: Ormondville land based discharge in low flow