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​M​easuring air quality at Gold Bar

In alignment with EPCOR's long-term plans and commitment to continued investment in odour mitigation and reduction, we measure air quality near the Gold Bar Wastewater Treatment Plant.

How we collect & measure air quality data 

Air substances are measured in one of two ways at the Gold Bar plant: 
  • Continuous monitoring at the Ambient Air Quality Monitoring Station (AAQMS)
  • Measurements at eight locations along the Gold Bar fenceline​


Ambient Air Quality Monitoring Station

 We have installed an Ambien​t Air Quality Monitoring Station adjacent to Gold Bar Park Road and close to 50 Street.​
Ambient Air Quality
Monitoring Station


Fenceline monitoring

View our monthly air quality fenceline monitoring reports and see how annual odour levels have decreased over time.​
Fenceline monitoring​​​​


Honouring Indigenous ties to the Gold B​ar area

Learn about the Indigenous art installation at the air quality monitoring station.​
Indigenous art installation​​​​​​​


Ambient Air Quality Monitoring Station​

Air quality monitoring stations measure the concentration of certain substances in the air, also referred to as the outdoor ambient air quality.

The A​mbient Air Quality Monitoring Station that EPCOR installed is located adjacent to Gold Bar Park Road and east of 50 Street. ​​​

​Ambient air quality monitoring stations are strategically located to continuously measure the air quality where people live and to track trends over time. EPCOR's Approval to Operate under the Alberta Environmental Protection and Enhancement Act required that the AAQMS be installed between the Gold Bar Wastewater Treatment Plant and surrounding community, i.e. outside the fenceline. As such, proposed locations for the AAQMS near the Gold Bar plant were vetted with the community, and the final location was based on community feedback and the assessments of a third party consultant specializing in odour dispersion modeling. 

The benefits of continuous monitoring at ambient air quality monitoring stations are that it is:

  • Timely. Automated continuous monitoring can identify upset conditions or product leaks in time to minimize negative impacts.
  • Responsive. Continuous monitoring enables more proactive and timely responses to possible issues. 
​​View of AAQMS location on Gold Bar Park Road

​​​Image of the ​​​new AAQMS

​Project Design

The Ambient Air Quality Monitoring Station is composed of two parts. The main structure contains the analyzers, air sampling equipment, and equipment for data handling and calibrations. Next to that, the meteorological tower, an antenna-like structure, contains instruments for measuring wind speed/direction, and ambient temperature.

What is being monitored?

The AAQMS monitors one hour average concentrations of the following substances: Nitrogen Oxides (NOx); Sulfur Dioxide (SO2); Hydrogen Sulfide (H2S). Meteorological factors such as wind speed, wind direction, ambient temperature, relative humid​i​​ty, and barometric pressure are also recorded to help interpret the monitoring results. The data collected from the AAQMS are submitted to the Alberta government. These data become publicly available at the Alberta Air Data Warehouse every month.

​Concentrations of these substances are monitored and compared with the Alberta Ambient Air Quality Objectives (AAAQOs). These objectives are pre-established concentrations of certain substances that pose a potential risk to the environment or human health. If an AAAQO is exceeded, it is reported to the Government of Alberta.​​​

  • ​H2S: Due to the raw wastewater that flows through Gold Bar, it is normal for odours to occasionally results. Most of these odours are related to H2S. This gas is naturally produced by biological activity in wastewater and is characterized by a rotten-egg small that can be detected at very low le​​​vels. The odour of H2S is detectable at a very low level (around 10-20 parts per billion). Health issues are only a concern at much higher concentrations (with exposures greater than 10,000 parts per billion).

  • NO​x: Nitrogen Oxides (NOx) are a by-product of combustion.

  • SO2: Sulphur Dioxide (SO2) is a by-product of equipment such as boilers and flares, which are used during the wastewater treatment process.​

Ambient air quality monitoring and reporting

The data collected from the new Ambient Air Quality Monitoring Station are being submitted to Alberta Environment and Parks (AEP), to comply with the Gold Bar Wastewater Treatment Plant operating approval. These data (which represent the hourly average) become publicly available from the AEP Air Data Warehouse every month. 

​A reading from any of the Air Quality Monitoring Stations (the new station, the Gold Bar station, or the Beverly Station) that exceeds the objectives established by AEP is immediately reported to AEP. At the same time, operations staff at Gold Bar initiate an investigation into the occurrence. The investigation includes:

  • ​Verifying the time, date, location, and substance of the exceedance.
  • Modelling to corroborate the exceedance and to identify the potential sources.
  • Checking the wind direction at the time of the exceedance.
  • Reviewing scrubber performance during the exceedance. (Scrubbers reduce odours by treating the air collected from the primary treatment process.)
  • Checking data from the fenceline monitors during the time of the exceedance.
  • Checking for other maintenance activities or drainage operations that may have contributed to the exceedance.
  • Taking note of any public odour complaints received during this time. 

These investigations help us determine if the exceedance is due to plant operations and what we can do to correct the situation. Sometimes we can address the situation immediately, however, these investigations also allow us to track trends over time and this will guide our long-term odour reduction plans. 

In the unlikely event that safe levels of these substances are ever exceeded, EPCOR will let you know of any concerns and any precautions you should take. One of the ways we will notify you is our through our water outages and alerts page.​​​

Ambient air quality monitoring network

There is a comprehensive network of about 110 ambient air quality monitoring stations throughout Alberta, operated by the provincial and federal governments, airsheds, and industry.

EPCOR is a member of the Strathcona Industrial Association (SIA) Ambient Air Monitoring Network. The SIA is a multi-stakeholder organization that conducts air, water, and land monitoring in the Strathcona Industrial area. EPCOR has been a member of the SIA since 1999. SIA ambient air quality monitoring stations are regularly audited by Alberta Environment and Parks. ​

Locations of Air Monitoring Stations in the SIA Network

​View enlarged image

Fenceline monitoring

EPCOR monitors eight locations around the Gold Bar facility’s property boundary for H2S levels (see the locations number in the map).​

Monthly average concentrations​ of hydrogen sulphide are obtained from these passive monitors. The fenceline monitors take spot readings, which are a snapshot in time. These readings indicate the conditions at the exact time when the sample was taken.

While spot readings can provide a precise numerical reading, they do so without context of whether that reading represents a stable, rising, or falling trend and no indication in rate-of-change. 

These readings are not compared to Alberta Ambient Air Quality Objectives (AAAQOs) that are quantified in 1-hour, 8-hour or 24-hour averages.​​​​

Monthly reporting 

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

Previous annual reporting

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


The readings in 2021 are slightly higher partly due to a dryer than average summer season and construction of the drainage Utilidor project.​

Regulatory requirements for air monitoring 

The Environmental Protection and Enhancement Act (EPEA) is the primary Act in Alberta through which regulatory requirements for air, water, land, and biodiversity are managed. 

The Act supports and promotes the protection, enhancement and wise use of the environment by designating proposed activities for which an approval or registration is required. 

EPCOR Water Services Inc. has an EPEA approval for operating and maintaining the Gold Bar Wastewater Treatment Plant. Air quality monitoring and reporting requirements for EPEA approval holders as set out in the Air Monitoring Directive (AMD). ​​

Indigenous art at the Air Quality Monitoring Station​

Honouring Indigenous ties to the Gold Bar area

​We have adorned the air quality monitoring station with Indigenous art. This art installation provides an opportunity to share part of the culture of the Indigenous Peoples who used these lands and adjacent waters long before Edmonton became a city. 

The history of EPCOR is interwoven with the development of Edmonton, the histories and legacies of interaction between settlers and Indigenous peoples, and the siting of our facilities within Edmonton. The banks of the North Saskatchewan River, where our two water treatment plants and our wastewater treatment plant are located, have been gathering places since time immemorial. We recognize the need to work collaboratively and in the spirit of reconciliation with Indigenous governments and peoples as long as we continue to operate in areas that hold these significant ties. ​


Odour ma​nagement plan

Learn how Gold Bar WWTP will continue to reduce its impact on the environment and neighbours by further investing in odour control.

Odour action plan