The Whangarei District Council (WDC) had asked the Northland Regional Council (NRC) to allow it to discharge up to 1,770,000 litres of treated wastewater daily to land from the existing Sime Rd site for up to 24 years.
The WDC had also sought permission to discharge contaminants (odours) to air from the plant and a two-member NRC Hearings Committee heard its application in Whangarei on 31 October and 1 November.
However, in a just-released decision - while it grants both consents - the NRC Hearings Committee has limited the wastewater discharge to a lesser 660,000 litres per day, with the consents set to expire in 10 years.
The Committee notes that while the WDC plant itself appears to be operating well, “there are monitoring matters that need to be addressed by the applicant and the consent authority”.
Committee Chairperson Lorraine Hill says there is a “very poor understanding of the range of wastewater inflows to the plant”.
“For example, mean daily wastewater inflows to the plant are variously estimated at between 385 and 532 cubic metres per day – a 38% variation.”
There is also uncertainty about the length of time it is taking treated wastewater to seep from an infiltration basin to Ruakaka Beach (anywhere from a matter of months to 12 years) and whether the plant is contributing to any erosion.
Those uncertainties are among the reasons the Committee has granted a reduced consent term and limited the quantity of wastewater that can be discharged.
The Committee has imposed a raft of conditions and says that subject to these, the WDC will be able to “service the present and short term future wastewater needs of the Ruakaka/One Tree Point area, thereby allowing time to address the noted information gaps”.
Consent conditions include a requirement to install equipment to accurately measure all wastewater flows to the treatment system. The equipment must be installed within three months of the commencement of the consent.
The District Council also has 12 months to provide a report on the operation of the plant’s wetland, which must include recommendations for any upgrades it may need and a schedule of works for these.
The Committee notes that disposal of treated wastewater to land, rather than any direct discharge to surface or coastal waters, is the preferred method under the NRC’s Regional Water and Soil Plan for Northland.
“The proposal, as consented, will sustain the natural resources within the coastal environment and safeguard the life supporting capacity of air, water and ecosytems in a manner that avoids, remedies and mitigates any adverse effects on the environment. The plant and the infiltration area (both present and potential) occupies a small area of the coastal environment and the public will not be disadvantaged by the granting of consent”.