Old unlined landfills which have been used for waste disposal for many years can give rise to big concerns due to the fact that far less was known of the contaminating effects of these chemicals in the past, and far less care was taken. This seems to be a particularly relevant concern for locals at this New Zealand unlined landfill which has been used as a waste dump since the 1950s.
One contaminant of concern which is described is he presence of acid herbicides. A landfill in which I was involved in remediating near Peterborough had been used for disposal of herbicides from a nearby factory when the production run had failed, or produced substandard product etc. The landfill was not lined, and a plume of contamination was allowing the herbicide and pesticide contaminated groundwater to flow into a major East Anglain river. I was part of a team which constructed an cut-off trench to collect the groundwater and design and supervise construction of a leachate treatment plant which we commissioned and is I belive still operating. This was fully successful in extracting the pollution and the treatment plant has worked successfully for many years, and as far as I am ware is still being operated throughout the year by the landfill owner. This shows that such pollution can be prevented even after the pollution has entered the groundwater. Please read the extract below, and visit the orginal article by clicking on the link at the bottom of the article:
The Awapuni landfill is leaking and the toxic waste oozing from almost 60 years of rubbish buildup is seeping into the Manawatu River. The revelation was confirmed by a top Horizons Regional Council scientist at the strategy and policy committee meeting in Palmerston North yesterday. A report on landfill leachate was expected to be presented to the committee, but a lack of data meant it had to be deferred, and science manager Dr John Roygard instead gave a summary of findings from the months of monitoring."The evidence is showing that leachate is making its way to the [groundwater] bores, however the amount of leachate is reducing."
Dr Roygard said he was concerned about the discovery of leachate coming from the lined landfill.
"We must follow up on that."
Dr Roygard told councillors he expected to receive more information from Palmerston North City Council by the end of the week, enabling the report to be completed.
At a meeting late last year, regional councillors asked for a report on leachate issues concerning the unlined Awapuni landfill.
Claims that Agent Orange, reported to be in the landfill, was escaping were rejected by Dr Roygard who said testing had shown no evidence of the toxin. However, issues around coal tar leachate were not so definitive. "We found one chemical related to it, but not any others that we would expect to find if there was a problem," he said.
An independent groundwater scientist and a landfill specialist were contracted to compile a report containing information about what was in the landfill, when material was dumped there, the landfill design and the leachate collection, treatment and discharge system. The original unlined landfill started operating in 1951 and was operational until 1995 when it was replaced by a lined extension, which was used until 2007.
Leachate from the old landfill has been seeping into the Mangaone Stream and on to the Manawatu River, while leachate from the lined landfill is collected and taken to the city's wastewater treatment plant.
Dr Roygard said landfill leachate breakouts breakouts had slowed since the dump was closed, but were still happening.
"We have got to be careful about how that is happening and where it is going, which is what this monitoring programme will tell us."
The monitoring of groundwater bores and surface water for chemicals and dissolved metals has been made easier by the unseasonably warm weather and low river flows.
Acid herbicides have been found in groundwater and elevated ammonia levels in the Mangaone Stream downstream of the landfill.
"It appears the landfill is affecting the Mangaone but once it [groundwater] gets to the Manawatu River it is diluted quite quickly."
There are no requirements in the city council's consent to monitor leachate, but Dr Roygard said the regional council could review the consent next year.
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