Frequently Asked Questions about Canada Creosote
What is creosote?
Creosote is a compound of about 200 organic chemicals that was used to preserve wood products such as railway ties and power poles.
Where did the creosote come from?
From 1924 to 1962, the Canada Creosote Company (later Domtar Corporation) operated a wood treatment plant in downtown Calgary. Over time, creosote in the soil migrated under the Bow River and beneath the community of West Hillhurst.
How does creosote migrate
Creosote is made up of a variety of chemical compounds that mostly do not dissolve in water. A small portion of the compounds are lighter than water and sit on top of the water table. A larger portion of the compounds are denser than
water and settles and moves along the bedrock by gravity.
Situation History and Current Status
How was the creosote discovered on the site?
Drilling in 1988 found a mixture of contaminants, including wood preservatives. An investigation in the late 1980s and early 1990s found that creosote had migrated into and beneath the Bow River, and into the community of West Hillhurst.
What has been done to manage the situation?
A containment wall was put in place between 1995 and 1996 to prevent further migration of creosote into the Bow River. This wall is maintained by the City of Calgary. The Government of Alberta has also drilled more than 30 monitoring
wells throughout the community, as well as doing surface water monitoring.
What is the current situation?
Thirty monitoring wells were drilled in the West Hillhurst community as part of an ongoing testing program. While recent monitoring results did not indicate a human health risk, the Government of Alberta has contracted Advisian (WorleyParsons
Group) to undertake additional environmental monitoring to further determine the nature and extent of potential contamination. This will include further sampling of the existing wells and drilling additional monitoring wells. This program
is expected to occur over the next five years (2017-2021).
How has the flood affected the creosote in this area?
It is believed that the effects of the 2013 flood will be temporary in nature and that in the long term there will not be significant effects. Severe flooding as experienced in 2013 is considered an infrequent event and The Government
of Alberta continues to monitor and assess groundwater and contaminants in the area.
Where is the creosote in the community?
Evidence of creosote impacts was identified in bedrock and soil above the bedrock at three monitoring well locations along Broadview Road (MW10-6, MW10-7B and MW11-01). Creosote has also been identified at MW11-06, north of Westmount
Blvd near 18th Street and at the CBC property (MW1, MW2, MW3-A and MW6 B). The Government of Alberta will continue to monitor the plume to determine if there is a human health risk.
What are the next steps for monitoring at the site?
As part of the ongoing environmental monitoring (2017-2021) The Government of Alberta will continue to sample the monitoring network within the community and drill additional wells to further understand the nature and extent of potential
contamination. Results will be compared to applicable standards to determine if there is a human health risk and if further investigation is required.
Creosote and Human Health
Can people be exposed to creosote?
Residents are unlikely to be exposed or come into contact with the creosote, however, vapour inhalation in areas without ventilation (i.e. basements) may be possible if homes are close to creosote contamination. The current monitoring
program includes work to confirm the risk is negligible.
What are the health risks associated with creosote exposure in the soil, water and air?
Health risk depends on the amount of exposure, the duration and the frequency. The most common risks are:
- respiratory irritation from breathing in the vapour
- skin damage from long-term skin or air contact
Long-term exposure, especially through continued direct skin contact, can result in some cancers.
Is my water safe to drink?
Yes. Residents of Calgary get their water from Calgary Water Services. The water supply is not from groundwater sources.
The potential of creosote in areas of West Hillhurst does not affect drinking water. In addition, the water mains that provide water to West Hillhurst are part of a pressurized closed system (metal, jointless pipe) that ensures no hydrocarbon
permeation can take place.
Are people working in the area, like construction workers, at risk? What is being done to protect those workers?
Employers are responsible for protecting the health of workers. If a hazard is identified or known, the employer must take measures to prevent exposure and risk to workers. For example, this may include the use of respiratory protective
equipment as well as equipment to prevent skin contact such as gloves and protective clothing, with subsequent decontamination (i.e. washing hands, showering).
Human Health Risk Assessments
Why is government conducting a Human Health Risk Assessment now?
The last assessment was done in 2014 and no unacceptable health concern was identified at that time. As additional environmental monitoring data is collected, understanding of the site is improved and the risk assessment will need to
be updated. The risk assessment can determine if there are human health risks and inform what actions need to be taken, if any.
Will the assessment report be made public, and if so, when?
Both the 2010 Human Health Risk Assessment and the updated 2014 Screening Level Risk Assessment are available online. Please visit:
Is my community safe?
The Government of Alberta has monitored soil, soil vapour and groundwater at the site. Results have been compared to applicable guidelines and contributed to the development of the risk assessment. The 2014 human health risk assessment
did not identify unacceptable health concerns.
Why is soil vapour a human health risk?
Within soil there are small pockets where vapour and dissolved chemicals can accumulate. When structures such as basements intersect these pockets, vapour can migrate from the soil into the structure.
Modern homes are constructed to be energy efficient and well-sealed. This means that vapours that enter the building may accumulate in the basement, presenting a potential risk to humans if inhaled.
At this site it is interpreted that the two critical factors for increased vapour exposure are when the Bow River water level is low and in the winter when air exchange in houses can be lower. Sampling is done at these times to ensure
that a conservative, worst case scenario is always represented.
What is a carcinogenic compound?
A carcinogenic compound is a compound that can lead to cancer. An example of a carcinogenic compound is benzene which people can be exposed to from tobacco smoke and vehicle fuel.
What is the Incremental Lifetime Cancer Risk (ILCR)?
The Incremental Lifetime Cancer Risk (ILCR) is the incremental increase in lifetime cancer risk above what would be normally experienced by the general population from background environmental exposures. The cancer risk is considered acceptable
if the calculated ILCR is less than or equal to 1-in-100,000 (≤ 1 x 10-5).
What is a Hazard Quotient (HQ)?
A hazard quotient (HQ) is a way to estimate if there is a risk of a human health effect occurring other than cancer when a person is exposed to a chemical over their lifetime. A HQ can be calculated for each pathway of exposure (e.g. ingestion
or inhalation) or a target organ.
Where does the chloroform come from if it is not associated with creosote?
Chloroform is often detected in soil and groundwater in urban setting with chlorinated drinking water systems. Chloroform is generated when chlorine reacts with organic matter.
Updated: Jan 16, 2018