Do I need to perform individual gas or liquid sampling to estimate flash emissions for each stock tank or pigging operation?
A. The AQB realizes the high cost of taking individual samples from each stock tank or pigging operation. To ensure the accuracy of tank-flashing emission estimates, the chemical analysis of gas and liquid used in the models must be representative of that specific geologic formation or region serviced by the process equipment. In a geologic formation or region where the gas has been sampled throughout and analyses show very similar results, additional gas samples may not be needed. When sampling is limited, and the composition of the gas or liquid from different samples results in significant variation in the emissions analysis, a specific gas and/or liquid sample and analysis may be needed. It is your obligation to evaluate existing samples from a formation or region and decide whether you can rely on them for estimating tank-flashing emissions for your site. You will also want to consider the accuracy of the method and relative permit thresholds.
