Sour gas is natural gas containing hydrogen sulphide (H2S). Sour gas has H2S levels above 5.7 milligrams per cubic meter of natural gas, or 4ppm (parts per million). However, a distinctive odour is detectable at low levels (less than 1 ppm) and can overwhelm a sense of smell at around 50 ppm. Sour gas differs from the natural gas that may fuel appliances in your home. Natural gas in your home has an additive so that a leak in your home can be detected by smell. Even though the smell of natural gas in your home differs from that of sour gas, both have been described as a “rotten egg” type of smell. Sour gas is not used in its raw form to fuel appliances. The percentage of H2S in natural gas – which makes it “sour” - can vary greatly from well to well, and pipeline to pipeline. A sour gas leak would occur outside from a well or pipeline, although you may smell gas in your home.
The best way to protect yourself is to be prepared. The following are some tips to let you know how to prepare for and what to do during a sour gas leak:
- In case of a sour gas leak, you may be instructed to evacuate or shelter-in-place (stay indoors).
- Having a plan and a stock of emergency supplies readily available will make it easier for you to evacuate or shelter-in-place. To prepare for a sour gas leak, make a family emergency plan and a 72-hour kit.
- Make sure that you have a way to stay informed. It’s important that you be able to listen to the instructions of local authorities.
- If you or a family member experience respiratory distress, call 9-1-1. Those with chronic conditions and breathing difficulties may be more affected and should seek medical attention as soon as possible.
More info on sour gas wells
Sour gas wells are present in all quadrants of Calgary, but they are generally concentrated on the east side of the city. Although the risk of any sort of problem with a sour gas well is low, it is best to be informed. Each facility with a sour gas well must post a sign with the name and contact information of the operator. Contact the operator directly for more information on a particular well and their emergency procedures.
More information about sour gas is available here.