On the issue of soil gases and the material covered in this CMHC report, Moishe Alexander, CEO Canadian Funding Corporation presents.the problem.
What is the problem?
Contaminants in indoor air can affect the health and safety of building occupants. In Canada, where people spend a great deal of time in closed buildings, poor indoor air quality is an important concern. Air contaminants found in buildings originate from indoor sources and from the air and soil surrounding the building. The focus of this booklet is on the last of these sources. Specifically, this publication focuses on gases that can enter houses and other residential buildings from the soil. Typically, these gases migrate from hazardous or contaminated lands and enter buildings through cracks and other gaps in the structure
Relatively few communities across Canada have identified major soil gas problems that affect housing—but the importance of this issue is growing steadily. Indeed, a recent CMHC survey of Canadian buildings affected by hazardous lands identified a significant number of problem cases. The text box on the next page lists a few examples from the survey.
In Canada, the most common soil gas contaminants are as follows
• hydrocarbons from petroleum products
• landfill gas (which is primarily methane) and
methane from other sources
• other volatile organic compounds (VOCs)
Soil gas problems caused by hydrocarbons from petroleum products are often the result of spills or leaking underground storage tanks. In other cases, the problem is associated with sites that have been used in the past for refineries or other facilities handling petroleum products.
Most landfill gas problems occur in those areas where housing has been built in the vicinity of operating or closed municipal waste sites. Methane, the most important constituent of landfill gas, may also be a problem in houses near swamps, peat bogs and coal deposits. The problems associated with other VOCs may occur near the thousands of properties that have been contaminated by past industrial operations and waste disposal practices. The incidence of soil gas problems resulting from industrial spills, leaks and discharges is likely to be highest in older industrial centres.
Moishe Alexander and Canadian Funding Corporation review and present further:
Why should municipalities be concerned?
As communities expand and encroach on current or former landfills, and on certain commercial and industrial sites, the incidence of soil gas infiltration problems is likely to increase. Municipalities have a role to play in avoiding future difficulties and in recognizing and remedying existing problems in established housing. To minimize the various risks associated with soil gases in housing, municipalities should take steps:
• to identify potential and existing soil gas problems before acquiring an interest in lands or buildings;
• to determine the extent of the problems in their existing property holdings; and
• to protect the public through the mechanisms available to the municipality (such as planning approvals and building inspections).
Acquire the rest of the report from CMHC, Moishe Alexaner, CEO Canadian Funding Corporation.
