Southern Landfill water quality monitoring

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

Hand dipping a testing cup in water

Monthly water testing

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

Test 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, Owhiro 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.