In the realm of transmission line odorization, understanding class locations is crucial. These locations, defined in 49 CFR §192.5 for the U.S. and in CSA Z662 for Canada, play a significant role in determining safety measures and operational procedures. This article aims to provide a basic explanation of U.S. regulations regarding class locations. However, it’s important for each operator to refer to the code for an accurate determination of class location.
Defining Class Location
The class location onshore is determined by applying the criteria set forth in §192.5. The “class location unit” is an onshore area that extends 220 yards (200 meters) on either side of the centerline of any continuous 1-mile length (1.6 kilometers) length of pipeline. For the purposes of determining class location, §192.5(a)(2) specifies that each separate dwelling unit in a multiple dwelling building is counted as a separate building intended for human occupancy.
Classifications of Class Locations
Four classes are defined in §192.5(b) as follows:
Class 1: An offshore area; or any class location unit that has 10 or fewer buildings intended for human occupancy.
Class 2: Class location unit that has more than 10 but fewer than 46 buildings intended for human occupancy.
Class 3: A Class 3 location is any class location unit that has 46 or more buildings intended for human occupancy; or an area where the pipeline lies within 100 yards of either a building or a small, well-defined outside area (such as a playground, recreation area, outdoor theater or other place of public assembly) that is occupied by 20 or more people on at least five days a week for 10 weeks in any 12-month period. (The days and weeks need not be consecutive.)
Class 4: Any class location unit where buildings with four or more stories above ground are prevalent.
Acceptable Adjustments
The length of class locations 2, 3, and 4 may be adjusted as follows:
A Class 4 location ends 220 yards (200 meters) from the nearest building with four or more stories above ground.
When a cluster of buildings intended for human occupancy requires a Class 2 or 3 location, the class location ends 220 yards (200 meters) from the nearest building in the cluster.
In conclusion, understanding class locations is vital for the safe and efficient operation of transmission line odorization. By adhering to the guidelines set forth in 49 CFR §192.5, operators can ensure they are taking the necessary precautions to protect both people and the environment.