Testing has once again revealed evidence of creosote near some homes in the neighbourhood of West Hillhurst.
Alberta Environment has been monitoring the area since the early 1990s when it was discovered the chemical had leached from the site of an former creosote plant across the Bow River.
One of the 30 test wells in West Hillhurst is now showing the presence of creosote.
Dan Cicero lives across the street from the test well.
"I think any time you find out there's contamination in your neighbourhood, you're a little concerned," said Cicero.
Nikki Booth with Alberta Environment said the discovery means the monitoring will be expanded.
"In order to be completely assured there is no risk to human health we need to go into some residents (homes) to do air monitoring and also do some additional monitoring outside," she said.
Booth said air quality tests will conducted in six nearby homes and the tests will be repeated four times a year.
Alberta Environment has distributed information packages about creosote contamination to about 300 homes in West Hillhurst.
Creosote is used as a wood preservative and can causing breathing problems and skin irritation. Longer term exposure to creosote has been linked to cancer.
The letter sent to homeowners is posted below. On mobile? Click here.