The California Air Resources Board (CARB) has asked the US Department of Transportation (DOT) to refrain from adopting an air-purging system to remove product from petroleum tank trailer wetlines.
CARB said in a letter to the DOT document management system that pressurized air used to purge wetlines by forcing the product back into the cargo tank will increase air pollution.
"The large number of gasoline deliveries in our urban areas suggests this purging process could result in the release of a potentially significant amount of additional ozone forming emissions in the atmosphere," the March 24 letter stated.
CARB referred to a proposal by the Research and Special Programs Administration (now titled the Pipeline and Hazardous Material Safety Administration) to prevent flammable liquid from remaining in tank trailer wetlines.
The RSPA proposal does not name a specific method for achieving the standard. For example, a carrier may elect to install accident damage protection devices, or it may decide to equip each tank trailer with a system that will remove any lading remaining in unprotected wetlines after loading.