TABLE OF CONTENTS The primary factor in determining the nature of the hazard is the characteristics of the product being transported in the pipeline. It is the product that to a large degree determines the nature of the hazard.
In studying the impact of a leak, it is often useful to make a distinction between acute and chronic hazards. Acute can mean sudden onset, or demanding urgent attention, or of short duration. Hazards such as fire, explosion, or contact toxicity are considered to be acute hazards. They are immediate threats caused by a leak.
Chronic means marked by a long duration. A time variable is therefore implied. Hazards such as groundwater contamination, carcinogenicity, and other long-term health effects are considered to be chronic hazards. Many releases that can cause damage to the environment are chronic hazards because they can cause long-term effects and have the potential to worsen with the passage of time.
The primary difference between acute and chronic hazards is the amount of time involved. An immediate hazard, created instantly upon initiation of an event, growing to its worst case level within a few minutes and then improving, is an acute hazard. The hazard that potentially grows worse with the passage of time is a chronic hazard.
For example, a natural gas release poses mostly an acute hazard. The largest possible gas cloud normally forms immediately, creating a fire/explosion hazard, and then begins to shrink as pipeline pressure decreases. If the cloud does not find an...
