             TSD on Mercury Emissions from State Rules and Voluntary ACI
      For purposes of the necessary finding, EPA does not include mercury reductions attributable to state mercury-specific regulations that result in the construction or operation of Activated Carbon Injection (ACI) mercury controls or voluntary mercury reduction programs, because such rules and programs are not required pursuant to the CAA.   EPA does include mercury reductions from ACI at units that commenced operation after 2007, because states are required under section 112(g) to require HAP limitations (including Hg) for new units.  While EPA has not verified that those units installed ACI pursuant to section 112(g) limitations, we determined it was likely the controls were required pursuant to the CAA so we included them in our emissions estimates.  
      Calculation of the mercury emission reductions excluded from the necessary finding required identification of the affected ACI controls and estimation of the incremental mercury removal in the base case modeling due to the operation of that ACI.  This adjustment required calculation of revised mercury emissions based on each affected model plant's technological configuration once the ACI was removed.   Projected fuel use was assumed to remain unchanged.  These adjustments are summarized at the state level in Table 1.
 Table 1.  Mercury Reductions Attributable to Mercury-Specific State Rules and Voluntary Mercury Controls in 2015 Base Case Projections (tons)
                                     State
                                  State Rule
                                 Voluntary ACI
                                      AZ
                                     0.058
                                       
                                      CO
                                     0.175
                                       
                                      CT
                                     0.003
                                       
                                      DE
                                     0.029
                                       
                                      GA
                                       0
                                       
                                      IA
                                     0.113
                                       
                                      IL
                                     1.628
                                       
                                      IN
                                       
                                     0.123
                                      MA
                                     0.083
                                       
                                      MD
                                     0.074
                                       
                                      ME
                                     0.01
                                       
                                      MI
                                     0.002
                                       
                                      MN
                                     0.39
                                       
                                      MO
                                       
                                     0.027
                                      MT
                                     0.244
                                       
                                      NH
                                     0.005
                                       
                                      NM
                                     0.027
                                       
                                      NY
                                     0.061
                                       
                                      OR
                                     0.064
                                       
                                      TX
                                       
                                     1.443
                                      WI
                                     0.143
                                       
                                     Total
                                     3.109
                                     1.593

