The City of London is required to report emissions to Environment Canada under the Canadian Environmental Protection Act 1999, Part 3 Information Gathering and as amended in the Canada Gazette. Further details on reporting can be found on the Environment Canada website.
The City of London is required to report for the:
- Adelaide Pollution Control Plant
- Greenway Pollution Control Centre
- Oxford Pollution Control Plant
- Pottersburg Pollution Control Plant
- Vauxhall Pollution Control Plant, and
- W12A Landfill
- Facilities and Substances 2017 (14 pages)
- Facilities and Substances 2016 (14 pages)
- Facilities and Substances 2015 (172 pages)
NPRI data is used on some web sites to identify the "largest polluters". The listing of a quantity in total tonnes does little to differentiate between contaminants and their effects on the environment and actually masks contaminants with lower reporting thresholds such as dioxins (measured in grams), mercury and arsenic (measured in kilograms).
The NPRI data is broken down into Releases (discharges to the environment) and Disposal (material captured and put into landfills or other final treatment methods). The largest tonnage compound reported from the sewage treatment plants is Nitrate (1,080 tonnes). The City of London wastewater treatment plants utilize bacteria to convert ammonia, which, in significant concentrations, is toxic to fish, to nitrates and this is called nitrification. The city sewage treatment plants convert over 94% of the ammonia to nitrates. Ammonia and nitrates are nutrients and are used to fertilize farms and gardens.
The City of London monitors nitrate levels upstream of the City on two branches of the Thames River and the average for 2017 was 5.9 mg/L. Downstream of the City the average for 2017 was 6.2 mg/L. The implications are that the nitrates are not above drinking water criterion. There is no Ontario surface water criterion for nitrates but a CCME criterion is 2.9 mg/L. The criterion is based on Lake trout which do not spawn in rivers. Levels of nitrate in Lake Huron and Lake Erie range from 0.2 to 0.8 mg NO3-N/L based on City of London water supply data. The Maximum Acceptable Toxicant Concentration (MATC) for Rainbow trout is 8.6 mg NO3-N/L due to delay of sac fry to the swim-up stage. Rainbow trout are found in lakes, and move to rivers and streams in the spring and fall. The average concentration of nitrates in the spring and fall between 2012 and 2017 inclusive is less than 5.3 mg NO3-N/L in the Thames River entering or leaving the City of London. Levels of nitrates are below the MATC for rainbow trout.
While the amount of ammonia released in 2017 is 92 tonnes from the wastewater treatment plants the average concentration over the year was 1.1 mg/l which is well below the City compliance limits of 3 to 5 mg/l. This is the residual amount of ammonia that remains after nitrification and it is low enough that it is not toxic to fish in the concentrations discharged from the City’s sewage treatment plants into the river.
The City’s wastewater treatment plants remove 95% of phosphorous and dispose of it as ash at the City landfill in 2017. The plant has been using geotubes to dewater the ash instead of using the ash basins. The residual ash in the basins was removed and disposed of at the landfill in 2015. The balance of the phosphorous in 2017, released into the river, is 33 tonnes. Phosphorous is not toxic but is a nutrient that can enable excessive algae and plant growth. The sewage treatment phosphorous is approximately 12% of the phosphorous found in the Thames River based on annual averages. Other sources of phosphorous include agriculture and lawn fertilizer. Other parameters reported in kg include lead, arsenic, cadmium and mercury. Concentrations in the sewage plant effluent for these metals are 2 ug/L or less (parts per billion). There is little that can be done at the sewage treatment plant to reduce levels further. Regulating consumer products that have trace metals would be one method of pollution prevention but this would have to be done at the federal level. An example is cadmium in bleach. Dentists have been required to install ISO certified amalgam separators to reduce mercury discharges.
The W12A landfill emitted 117 tonnes of Carbon monoxide in 2017 based on emission factors from the United States Environmental Protection Agency. Ammonia from leachate sent for treatment at the Greenway Wastewater Treatment Centre was 47tonnes and releases after treatment are noted above.
The Canadian Council of Ministers of the Environment (CCME) reported (October 2004) that there were 195 grams of Dioxins and furans discharged from 26 sector groups per year. Of the 26 sectors, incineration was responsible for 2.4% of the dioxin and furan emissions or about 4.6 ITEQ grams. This is a decrease of about 90% from numbers reported in 2001. The Incinerator sector includes municipal solid waste, hazardous waste, hospital waste, and sewage sludge. Sewage sludge incinerators accounted for 0.05 grams of Dioxins and furans or 1% of the Incinerator sector. There are 6 sewage sludge incinerators in the group and the Greenway Incinerator had the lowest dioxin and furan emissions of the group. The CCME has come out with a dioxin and furan standard for sewage sludge incinerators and Greenway emissions are below the standard.
As a comparison, an October 2004 CCME report suggests that burning of domestic waste in barrels represented between 12% and 22% of the Canadian emissions of Dioxins and furans (an emission level greater than the Incineration sector).
Hexachlorobenzene was not detected at the Greenway Incinerator and a value of the detection limit 0.08 ug/m3 was used for the reported emission estimate.