Published: 24 November, 2020
Motueka Wastewater Treatment Plant Discharge of Partially Treated Wastewater to Land
Kia ora koutou,
After the recent rains (183mm since 2 Nov) and the related increase in groundwater level (0.5m by Friday) under Motueka, flows to the wastewater treatment plant have exceeded the treatment rate since 02 November 2020. This has resulted in a rapid rise in the oxidation pond water level. There is a risk that the pond could reach overflow point (approximately 4.2m) in the next rain event, forecast for Tuesday evening (Nov 24) and into Wednesday and another following on Sunday.
TDC has permission to carry out an emergency discharge of partially treated wastewater to the adjacent planted area, which used to be the sand filter and soakage area. The ex-sand filter covers approximately 3.5 hectares and has been planted in 30,000 natives. A discharge of 1000m3 to this area would be less than 3mm of liquid per day, equivalent to a small rain shower. TDC anticipates the sand will provide good removal of bacteria, as it has done in the past, and don’t anticipate any elevated bacteria on the beach. Monitoring of the one remaining groundwater bore downstream of the planted area will be undertaken to confirm this.
Over pumping will only occur while an operator is on-site, so the water levels and any impact on the planted area can be monitored. This will also allow the area to drain away overnight.
Signage is being put up at the planted area advising of the discharge. The usual signage warning of the treated wastewater discharge remain in place by the outfall and on the beach.
Continued tracing of inflow and infiltration and repairs remains a priority.
Please contact TDC on 03 543 8400 if you have any questions.