Appendix G Details of the selected landfills and the sampling of leachate
Hampton Downs has been selected as an example of a recent landfill which has received waste over a short period (2005 – 2009) from municipal and commercial / industrial sources (30%). Cell 1 has been closed in 2009 after 4 years of operation and capped with 2 meters of compacted clay.
Cell 1 Hampton Downs under construction in 2005 (photo ref. EnviroWaste)
Cell 1 leachate is transported in underground pipes to collector wells where it is mixed with the leachate from the newer cells. The combined leachate is pumped from the collector wells to above ground storage tanks. From these the leachate is transported by road tanker to Manukau where it is disposed of in the municipal sewer. On average 60,000 litres of leachate is transported off site each day.
Cell 1 leachate was sampled by the timely placement of the sampling bucket under the appropriate leachate pipe consistent with the pump cycle. (see pictures below).
Sampling leachate at Hampton Downs Landfill.
Taupo District Council Landfill located at Broadlands Rd has operated since about 1985 after the Wharawaka East and Mangakino landfills closed. The landfill mainly receives domestic waste plus some from the rural and small scale commercial sector.
Broadlands Road Landfill Taupo (ref. Google Maps).
Samples were collected directly from the landfill leachate pipeline. This underground pipeline discharges into a holding pond, however is normally closed. When the pond is emptied by suction truck the valve is opened to allow leachate into the pond.
Collection has been undertaken by placing the sampling bucket under the leachate pipe and opening the valve (see T handle in the foreground in the picture on the right).
Greenmount Landfill on Smales Road in East Tamaki, Auckland has operated for 25 years till 2005. It is one of the older landfills in New Zealand which accepted industrial / hazardous waste.
There are quite a number of leachate collection wells. During the site visit it was unclear which leads to what section of the landfill. The collector well which was most likely to contain an average mixture of leachate has been sampled. To open the well to allow sampling was a rather involved process, therefore no other wells could be inspected.
