Establishing data-derived emissions limitations

The emissions limitations found in regulations and permits have traditionally been set using engineering judgement, commercial considerations and public perception of potential harm and achievability. Given the restricted list of pollutants in Section 129 of the Clean Air Act (CAA) and EPA`s decision to base municipal waste combustor (MWC) Maximum Achievable Control Technology (MACT) Floor determinations on limitations in enforceable permits, the need for determining these values from test data seems to be past. However, this does not stop local jurisdictions from imposing additional requirements. Local regulatory bodies and concerned citizens frequently want to regulate pollutants that are not addressable using EPA`s permit limit procedure; too few permits include limitations on specific emissions. The need to correctly calculate achievable emissions remains. At the very least, it is imperative that correctly calculated limitations be placed in the administrative record supporting a permit so that if a problem occurs, a facility retains the ability to defend itself. Fortunately, emissions limitations can be calculated using statistical techniques that consider both regulatory constraints and source variability. These procedures provide a deterministic, objective link between test results and a lower limit that bounds achievable, data-derived regulatory and permit restrictions.