Wastewater services are provided to 29 residences in the coastal settlement north of Dunedin and contractors for the Dunedin City Council (DCC) have been working on a $3 million upgrade since July.
Seacliff resident and geoscientist Alex McAlpine told the Waikouaiti Coast Community Board last week some construction activities should be suspended.
"The plant upgrade aims to increase the discharge capacity of the plant and dispose of wastewater in an area potentially susceptible to more serious landslides," Dr McAlpine said.
"Given the nature and scale of the site-work now going on apace, I feel I must also request this board urgently asks the DCC to immediately suspend all work at the site that will, or has already, altered the volume and distribution of wastewater, stormwater and groundwater runoff at the site."
A council spokesman said there were no plans to suspend work, but staff would be happy to meet Dr McAlpine to discuss concerns.
"Land instability in the area is a known issue and can be appropriately managed as part of the upgrade and plant operation," he said.
Consent was processed by the Otago Regional Council on a limited notification basis and granted in 2021, he said.
The decision noted land instability issues in the area were considered no more than minor.
It is envisaged the system will discharge treated wastewater to two new and expanded irrigation fields, covering about 1.5ha in total and located further from the coast than the existing facility.
The work would include providing new septic tanks, a new dosing tank, refurbished sand filters and new pipework, a new treated wastewater storage or dosing tank and other improvements designed to accommodate future demands, the council spokesman said.
Dr McAlpine has also pushed for a community meeting.
In his speech notes for the community board, he said a suspension of work should remain until consultation had been held with the community and "a satisfactory independent technical assessment completed".
