This report provides the results of a two-phased study conducted for the Canada Mortgage and Housing Corporation (CMHC) to examine the practices and variability amongst practitioners of contaminated sites risk assessment in Canada. Phase I consisted of a survey of practitioners in the private and regulatory sectors. The intent of the private sector survey was to characterize the capabilities and experience of private firms engaged in human health risk assessment across Canada.
Incidents involving landfill gas in buildings have increased in recent years and these are of concern to developers and builders who are faced with the problem of developing sites where this gas is present. The principal components of landfill gas are methane (which is flammable) and carbon dioxide (which is toxic), but these two gases are also associated with coal strata, river silt, sewage and peat.
Air infiltration rates are important in determining greenhouse heating requirements. Design recommendations usually suggest one to two complete air exchanges per hour under calm conditions. Tests made in 10 commercial ranges showed no greenhouse in excess of one exchange per hour, with one as low as 0.34 per hour, and an average of 0.56. However, additional tests at CSU showed marked variation, depending upon greenhouse size and heating methods, as well as type of structure and outside wind velocity.
Compares the air change rates measured using the decay method with several different tracer gases. The tracer gas measurements were conducted in atightly sealed room where constant air leakage rates, ranging from 0.05 to 1 air change per hour could be maintained using an exhaust fan. The tracer gases investigated were CH4, CO, CO2, N2O and SF6. The agreement between tracer gas measurements and measured flow rates of the exhaust fan was very good for CH4, CO and N2O.
Compares the air change rates measured using the decay method with several different tracer gases. Tracer gas measurements were conducted in a tightly sealed room where constant air leakage rates were maintained using an exhaust fan. Tracer gases investigated were CH4, CO, CO2, N2O and SF6. Agreement between tracer gas measurements and measured flow rates of the exhaust fan was very good for CH4, CO and N2O. The agreement was also satisfactory for CO2 and SF6, but the scatter in tracer gas data was much greater then it was for the other three gases.
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