Southern Landfill environmental monitoring

We do specific tests at the Southern Landfill as part of the conditions of our consent for operating the Landfill.

Wellington landfill, showing the large space on a bleak, overcast day. Large yellow trucks and machinery can be seen operating on it.

Odour monitoring

As a responsible neighbour, the Southern Landfill aims to limit odour to within its designated area.

It can be difficult to determine the source of an odour. There are two separate facilities on site that could potentially generate odour:

  • The sewage dewatering plant and associated works.
  • The Southern Landfill and associated works.

When we receive an odour complaint, we work with the other facility operators to investigate and track the source.

The description of the odour helps us identify the source. A rotten egg smell is likely to signal a sewage sludge issue, whilst a sweeter smell is likely to signal a landfill gas issue.

Sometimes, we need to do maintenance and improvement works that could produce odour in the short term. These works include:

  • Installation of more landfill gas capture pipes.
  • Placing pipes to collect water generated by the landfill.
  • Leachate to ensure dirty water does not escape into the environment.
  • Works to cap the landfill as part of the closure.

When the works begin, we send out a notice to the neighbouring Residents Associations and other stakeholders. The notice will advise there is a potential for increased odour issues, with controls around the length and times of the works. Mobile odour suppression machines are used while the work is carried out, to eliminate potential odours.

We also proactively monitor odour levels on the site and use odour suppression machines if  odour levels are too high.

Reporting an odour issue

If you need to report an odour, which you think is coming from the Southern Landfill, please call our Contact Centre on 04 499 4444 (24 hours a day, 7 days a week), or log the issue using our FIXiT app.

Monthly water testing

The water tests are taken at four points within the Carey's Gully stream adjacent to the Southern Landfill, including:

  1. Carey's Gully stream upstream of the landfill
  2. Carey's Gully stream downstream of the landfill
  3. Four boreholes that access the ground water in various locations adjacent to the landfill
  4. Leachate collected by our pipes (tested at a manhole)

Tests are collected by a third party and sent to a laboratory for testing to ensure independence. Reports are then sent to the Southern Landfill and a third party peer reviewer monthly.

If we find issues that could be considered to be a breach of our consent, we alert Greater Wellington Regional Council (GWRC) as well as our Community Liaison Group (CLG). The CLG is made up of representatives from the Greater Regional Wellington Council, Wellington Water, the sludge dewatering plant operators, the landfill operators, the Greater Brooklyn Residents Association, Ōwhiro Bay Residents Association and Council’s Waste Operations officers.

We do the following monthly tests on all the sites:

  • pH levels
  • 5-day Biological Oxygen Demand (BOD5)
  • Conductivity
  • Iron
  • Ammonia as Nitrogen (NH4-N)
  • Manganese
  • Faecal Coliforms

Additionally, we do the following tests every six months on all the sites:

  • Aluminium
  • Chromium
  • Copper
  • Lead
  • Dissolved Reactive Phosphorus (DRP)
  • Nitrate-Nitrogen
  • Boron
  • Zinc
  • Cadmium
  • Chlorides
  • Arsenic
  • Nickel
  • Macro Invertebrate Sampling*

* Macro Invertebrate Sampling to get a Macroinvertebrate Community Index (MCI) score.

Yearly review

At the end of each year, the water quality sampling results are compiled and reviewed by a third party reviewer and sent to the Greater Wellington Regional Council (GWRC) as part of our annual Southern Landfill Compliance report.

GWRC then reviews the information using their own third party experts as required, and once satisfied, provide us with a compliance document.