Queenstown’s mayor has conceded the council shares the blame for a series of sewer system failures.
Vanessa Van Uden says her authority was not delivering an acceptable level of maintenance.
Queenstown sewers have overflowed three times in recent months – spilling waste water onto streets and into Lake Wakatipu.
Last month, engineers concluded the blockages were caused by fat, grease and building materials disposed of down drains.
“What we now understand is that in addition to individuals making poor choices, the council was not delivering an acceptable level of preventative maintenance,” Van Uden says.
“We have moved to remedy this as a priority.”
Council has expanded its preventative maintenance programme to clean and inspect nearly 15km of pipes over the next three months.
The priority work comprises 10km of pipes in Queenstown, including Frankton and Arthurs Point, along with 2.2km in Arrowtown and 2.5km in Wanaka.
Pipes are being waterblasted to clear obstructions, such as congealed fat and small quantities of debris, and then inspected by video cameras.
This allows workers to identify any structural problems such as cracks or tree roots breaking through pipes.
Council has drawn up a Trade Wastes Bylaw to increase its enforcement powers.
It is expected to be up for consideration by councillors before the end of the year.
“We take these matters extremely seriously,” Van Uden says.
“The community can be assured that any future spills will come under intense scrutiny.
“We will want to understand how it has happened and what more we need to do to prevent it.”
And an education programme will inform residents, tradespeople and business staff about what is unsuitable for drainage.
Council chief engineer Ulrich Glasner says most of the people causing the problems are unaware of the repercussions.
“We have about 400km of pipe, used by 29,000 different residents and 2.7 million visitors every year, on top of the commercial users.
“We can’t control what they all do, but we can make them aware of the effect their actions have – things don’t just ‘disappear’ when they drop down the drain or into the toilet.”
Gravel and debris from construction sites and infill housing has been identified as a common source of foreign material in the sewers, and has been the cause of the most recent overflows.
As a result, a council inspector is now on site when new connections are made to the wastewater system, to ensure no construction material or fittings are dropped into the pipes.
Contractors clearing blockages in the sewer pipes and pumps often pull out construction debris, disposable nappies, cleansing wipes or plumbing fittings – usually stuck together with congealed cooking fat.
To counter this, the education programme will target construction companies, building trades and food outlets. It will include workshops, site visits and checklists.
Glasner says poorly maintained grease traps in commercial kitchens were a particular target.
Information is already being provided to householders, through the council’s newsletter, displays and by direct mail, to help residents understand the consequences of flushing nappies and other inappropriate items down the toilet.