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Gold Bar Wastewater Treatment Plant has been safely treating Edmonton's wastewater since 1956. We're continually investing in ways to improve our treatment processes and operations while respecting our community and our neighbours.

Odours at Gold Bar Wastewater Treatment Plant

The safety of the public and our employees is always our number one priority. We are constantly monitoring air quality levels at Gold Bar to confirm that all of our odour-control systems are working as designed. Odours occasionally occur at Gold Bar and are a normal part of the treatment process due to the raw wastewater that flows through the plant. Most of these odours are related to hydrogen sulphide gas (H2S).

This gas is naturally produced by biological activity in wastewater and has a characteristic rotten-egg smell that can be noticed even at very low levels.  

H2S levels around Gold Bar can vary depending on plant activties like maintenance work or from changes in water flow due to melting snow or rain. EPCOR actively monitors H2S levels at the plant and is a member of the Strathcona Industrial Association (SIA), which conducts environmental monitoring across the region including ambient air quality. While there are occasional times H2S levels at the plant exceed Alberta Ambient Air Quality Objectives (such as during equipment maintenance), our H2S levels are much lower than those associated with health concerns outlined in OH&S legislation.

If the H2S levels ever exceed the OH&S legislation limits, EPCOR will alert the public to the concern and to any precautions they should take. One of the ways we will notify you is our through our water outages and alerts page. Any alarms you hear at the Gold Bar plant are specific to onsite workers and don't apply to nearby communities.

​High odour levels in 2014/2015 from equipment failure

When Gold Bar first opened in 1956, and as the community around the plant grew, there were few reports about odour. Odour reports in the 1980s led to the addition of air collection systems and odour scrubbers which have been relatively effective in controlling and reducing odours from wastewater treatment. However, in late 2014 and into 2015, this changed.

In November 2014 a member of the Nordic Ski Club complained to Alberta Environment about odour from Gold Bar. Alberta Environment conducted air monitoring from February to April 2015 and found that over the 83 days, there were 4 days where H2S levels were higher than targeted levels.

EPCOR determined that the chemical tanks for the odour scrubbers were failing; they were removed from service for repair in early 2015. This meant more un-scrubbed air was being released, causing more odour problems and complaints while repairs were being made. By late 2015, the repairs were made and the scrubbers returned to full service in January 2016.

Investing in improved odour control

Public and employee safety is always our number one priority. Over the past few years, EPCOR has invested $10M to further enhance odour management at the plant and made several operational improvements to reduce odours. Upgrades include:

  • Balancing the existing odour ducting
  • Improving the odour scrubbers
  • Enhancing primary treatment upgrades
  • Planning and designing a continuous monitoring system

Results from investments

These investments are showing results, and there has been a significant reduction in odours from 2017 to 2018. At the intake part of the plant, in particular, H2S readings are 80% lower than in the previous year.

  • 72% of spot samples taken in 2018 show H2S levels of 0 ppb
  • 22 of 1,112 samples in 2018 show results above 10 ppb: the threshold for smelling odour (2% vs 9% in 2017)

Prior to any of the above changes, the air around Gold Bar was deemed safe for recreation (according to health limits set by the Government of Alberta's OH&S Legislation). In 2016, the Minister of Health wrote that "the current evidence does not support any restriction of activities or identify a health risk to users of Gold Bar Park." Operational improvements have made significant reductions in H2S at the fence line since that time, which further reinforces the conclusion that recreation in Gold Bar Park is safe and healthy. Through continuous improvement we're working to limit our impact on neighboring areas.

Air quality monitoring reports

SIA ambient air monitoring network

EPCOR is a member of the Strathcona Industrial Association (SIA) Ambient Air Monitoring Network. The SIA conducts environmental monitoring across the East Edmonton and Strathcona County region. Their monitoring uses a number of parameters to assess ambient air quality. There are two monitoring stations near the Gold Bar Wastewater Treatment Plant.

Fence line monitoring

EPCOR consistently monitors 8 locations around the Gold Bar plant fence line for H2S levels (numbered). The readings at these stations are spot readings. The air conditions captured in these samples may only exist for a moment in time, so these results are not compared to standards that are quantified in 1-hour, 8-hour or 24-hour averages.

2019/2019 monthly reporting

Data from the previous month is posted by the 15th of the following month.

Fence Line H2S Monitoring - June 2019
Fence Line H2S Monitoring - May 2019
Fence Line H2S Monitoring - April 2019
Fence line H2S Monitoring - March 2019
Fence line H2S Monitoring - February 2019
Fence line H2S Monitoring - January 2019
Fence line H2S Monitoring - December 2018
Fence line H2S Monitoring - November 2018
Fence line H2S Monitoring - October 2018

Previous annual reporting

The chart below shows the average H2S levels from spot readings recorded annually at each station.

Fence Line H2S Monitoring

Average Parts Per Billion (ppb)