The following graphs are presented to better illustrate each of the Bay Area refinery's performance in minimizing the frequency and magnitude of flaring. The data used prior to the 2004 Flare Monitoring Rule effective date for vent gas compositional monitoring was based on engineering judgment, less frequent compositional analysis and less accurate flow measuring devices.
A trend line has been added to illustrate the five year rolling average for each parameter. The time period was based on the historical frequency of major maintenance activities, which is a significant cause of flaring. The trend line pattern is segmented to indicate the first five year period (2004-2008) and solid to indicate the trend change for the second five year period ending 2009.