Ōpōtiki District Council Funded Work on Private Laterals
Annual Conference
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The Ōpōtiki District Council public sewer network is old (1950’s), leaky, and subject to significant inflows of stormwater and infiltration (I&I) associated with storm events. Asset management decisions needed to be made which address the age and sometimes poor condition of the sewer network, and the contribution of I&I flows to the wastewater treatment plant from the public wastewater system and private laterals. Large I&I flows result in significantly increased volumes (> 10x ADWF) requiring wastewater treatment, and disposal.
Ōpōtiki town has a population of 3,8791 (Statistics New Zealand, 2013), with 1,4371 occupied dwellings. The median income for Ōpōtiki is $19,600pa1 (Statistics New Zealand, 2013) (vs national median of $28,5001 2018 census data), and unemployment rate of 13%1 (vs 7.1% nationally1).
Private laterals were found to be significant contributors to the overall I&I. A decision by a Council working group for Council to fully fund inspection and repair of all domestic private laterals was made. Latterly it was agreed that commercial laterals would be inspected and repaired as well. The inspection and repair has been carried out using a combination of open trench and trenchless technologies.
This paper describes the decision-making process, asset planning, and program of works undertaken by the Ōpōtiki District Council for the private and public wastewater network, and the treatment system.