Action Underway to Prevent Wastewater Overflows

A three-pronged programme is underway to address the most common causes of wastewater overflows in the Queenstown Lakes District.

Recent overflows have been traced to blockages caused by fat and building material.

QLDC Chief Engineer Ulrich Glasner said most of the people who were causing the problems would not necessarily understand the implications of what they were doing, but the consequences for the environment and the Council’s reputation were serious.

“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.”

The overflows resulted in a request by the Council for a full review, Mayor Vanessa van Uden said. “What we now understand is that in addition to individuals making poor choices, the Council was not delivering an acceptable level of preventative maintenance. We have moved to remedy this as a priority.”

The 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 Arthur’s Point; 2.5km in Wanaka and 2.2km in Arrowtown.

The work is already underway, and is in addition to the routine inspections that were already programmed in this year’s infrastructure maintenance programme.

Mr Glasner said the pipes were being waterblasted and then inspected with CCTV cameras. The waterblasting clears obstructions such as congealed fat and small quantities of debris, allowing the CCTV camera to get a clear view of any structural problems such as cracks or tree roots breaking through the pipes.

Separately, a team drawn from council engineers, building and health inspectors is working together to target the most common causes of blocked pipes and pumps, and enlist the help of those whose actions are most closely linked to those causes.

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, the Council now has an inspector 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, an education programme is being developed which will target construction companies, building trades and food outlets. It will include workshops, site visits and checklists.

Mr Glasner said 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.

The third “prong” of the Council’s action plan is enforcement, with a Trade Wastes Bylaw expected to be up for consideration by Councillors before the end of the year.

“We take these matters extremely seriously,” Mayor van Uden said. “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.”

Fast facts:

Work now underway includes:

Preventative maintenance
• 14.7km of pipes prioritised for waterblasting and CCTV inspection
• subdivisions and infill housing sites inspected when they’re first connected to the sewerage system

Education
• Workshops for builders, plumbers and drainlayers
• Site visits and information for construction companies and developers
• Workshops and site visits for commercial kitchens including hotels, restaurants and takeaway food outlets, particularly targeting grease traps
• Community awareness through Council newsletters, displays, social media and direct contact with residents

Enforcement
• Investigating the causes of all overflows to try and identify those responsible
• Developing a Trade Wastes Bylaw

ENDS

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