Commentary on Methane Production at Former Sabiston Landfill

Commentary on Methane Production

The following is my summary of the methane readings provided to me by Councillor Howard Shore.

Readings from March 18, 2010 to December 2, 2011

Western header (7 probes)               Average reading 0.4%        All zero since August 28, 2011

Northern Subheader (2 probes)      Average reading 0.03%      All zero since August 17, 2011­­­­­

Northern Main Header (6 probes)  Average reading 0.17%      ≤ 0.1% since August 17, 2011

Remove 1 anomalous reading and average drops to 0.03%


South side of Property (6 probes)   Average reading 11.8%      ≤ 0.7% on December 2, 2011 the                         last available data.


One probe, GP2-10, has shown a number of relatively high readings.

One probe, GP7-10, has shown one reading of 14.7%, and all other readings below 6.0%.

All the other probes have had all their readings below 6%.

Readings from January 24, 2012 to April 23, 2012

Western header (7 probes)               All readings zero

Northern Subheader (2 probes)      All readings zero

Northern Main Header (6 probes)  Average reading 0.28%

South side of Property (6 probes)   Average reading 3.57%

Monitoring has been largely discontinued at three headers

Monitoring has been largely discontinued at the Western Header, Northern Subheader, and the Northern Main Header. At these locations, only two readings have been taken this year. I have not been provided with an explanation for discontinuing more frequent readings, but it seems reasonable to assume that it is because the levels being recorded were trivially low. Why was this not divulged at the Public Meeting?

The only part of the property which is still being regularly monitored is the “South Side of Property.” The average reading for this year, for that site, is only 30% as high as it was for the period from March 18, 2010 to the end of last year. (The average reading is now 3.57%, while the previous average was 11.8%.)

For how long do landfill sites emit methane? The consultants at the public meeting said on numerous occasions that methane would or could be emitted for 100 years or more.

The report, EPA 430-R-12-001, “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990 – 2010” states:

‘Significant CH4 production typically begins one or two years after waste disposal in a landfill and continues for 10 to 60 years or longer.’ 

The consultants seem to have given a high estimate. It is possible the former Sabiston landfill is already well past its period of significant methane production. Indeed, the methane readings suggest to me that is very likely the case.

Total Methane Production

At the Public Meeting, we were told the purpose of the Aerobic Scheme was to prevent methane production, because it is a greenhouse gas. Since there are financial and environmental costs to implement the scheme, it can only be justified if there is a net environmental benefit. The fundamental question is: ‘Are the costs involved justified by the reduction in methane production?’


The most optimistic scenario is that implementation of the scheme would reduce current methane production rates to zero. The current methane production rate could be estimated from knowledge of the gas flow from the headers to the atmosphere multiplied by the average concentration of methane in the gas flow. We know the concentrations of methane in three of the headers are negligible. At the South Side of the Property the concentration is low. However, it is not possible to calculate total methane production from this part of the site because, apparently, the gas flow rates are not known. Why have they not been measured?

And how can anyone justify an expensive and environmentally disruptive aerobic scheme without having any idea of the potential benefit?

Bob James.

May 7, 2012

Historical Probes Data-2010-2011

2012 – Landfill Gas Probes Data Jan2012 to Apr 2012


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