The /MACT/ packet is designed to support the primary MACT controls needed for toxics processing. It is applied first, and uses the following logic. When a source is found that matches a /MACT/ packet entry (source matching is addressed in Section 4.2.1.2, “Source Matching Hierarchy”), Cntlmat first calculates a inventory efficiency value (Eff_inv) for that source based on the control efficiency (C_eff), rule effectiveness (R_eff), and rule penetration (R_pen) provided in the inventory:

Eff_inv = C_eff [inventory] x R_eff [inventory] x R_pen [inventory]

Next, a control factor is calculated for existing sources (Fac_exist) using the control efficiency of existing sources (Eff_exist) and fraction of new sources (Frac_new) provided in the /MACT/ packet entry. If Eff_exist > Eff_inv, then Fac_exist is calculated as:

Fac_exist = (1 - Frac_new) x ((1 - Eff_exist) / (1 - Eff_inv))

Otherwise,

Fac_exist = (1 - Frac_new)

Cntlmat then calculates a control factor for new sources (Fac_new) using the control efficiency of new sources (Eff_new) provided in the /MACT/ packet. If Eff_new > Eff_inv, then

Fac_new = Frac_new x ((1 - Eff_new) / (1 - Eff_inv))

Otherwise,

Fac_new = Frac_new

Finally, the new and existing source factors are summed to compute the final /MACT/ packet control factor (Fac_MACT).

Fac_MACT = Fac_exist + Fac_new

The /MACT/ packet is designed to be used only for sources with MACT codes, currently nonpoint and point toxic sources.

After processing the /MACT/ packet, the /CONTROL/ packet is applied using the following logic. Each entry in the /CONTROL/ packet can be identified as “replacement” or “additive”. If set to “replace”, the /CONTROL/ entry will be used to replace the controls from the /MACT/ packet or the base-year inventory controls; otherwise, the control will be applied in addition to the controls from the /MACT/ packet or the base-year inventory controls. When the controls are replaced, the default behaviour of Cntlmat is to back out the existing controls and apply the replacement controls. Usually, users want to do this only when the replacement controls are more stringent (i.e., a greater reduction) than the /MACT/ packet or base-year controls - so this is the default behaviour of Cntlmat. This default behaviour can be changed by setting the value of COMPARE_REPLACE_CONTROL to "N" in your run script. In this case, the replacement controls will be applied regardless of the existing controls from the base invetory or the /MACT/ packet, which could result in increased emissions.

When an “additive” entry is matched to a source, the /CONTROL/ packet factor (Fac_CONTROL) the control packet information is applied in addition to the exitsing controls, which further reduce the remaining emissions.

For “additive” control packet entries, the control factors are calculated from the control efficiency, rule effectiveness, and rule penetration values provided in the /CONTROL/ packet entry as follows:

Fac_CONTROL = (1 - C_eff [packet] x R_eff [packet] x R_pen [packet])

A cumulative control factor Fac_result is then calculated by multiplying Fac_Existing x Fac_CONTROL.

In the case of “additive” controls only, The overall reduction factor is then used to calculate an overall new control efficiency to be put in any resulting inventory files as: C_eff [result] = 1 - Fac_result . The final Rule Penetration and Rule Effectiveness values are then set to 100%.

For “replacement” entries, Cntlmat first “backs out” the existing controls provided in the inventory from the control values provided in the /CONTROL/ packet entry as follows:

D = (1 - C_eff [inventory] x R_eff [inventory] x R_pen [inventory])

If D = 0.0, then the backout value, B, is equal to 0; otherwise, B = 1/D. Using this backout value, the /CONTROL/ factor is calculated as

Fac_CONTROL = B x (1 - C_eff [packet] x R_eff [packet] x R_pen [packet])

Unlike “additive” entries, the Fac_CONTROL value for “replacement” entries replaces the factor calculated from the /MACT/ packet or base year inventory (if any). The /CONTROL/ packet can be applied to stationary area/nonpoint, nonroad, on-road mobile, and point sources. On-road mobile source inventories do not include control efficiency, rule effectiveness, or rule penetration fields. However, the /CONTROL/ packet can still be used to apply adjustment factors to mobile sources. In this case, B in the above formula will be 1 when computing factor Fac_CONTROL that is applied to the emissions.

The /CTG/ packet is processed next, as follows. The emission value (after application of /MACT/, /CONTROL/, and/or /EMS CONTROL/) is compared to the cutoff value specified as part of the /CTG/ packet record. If the emission value exceeds the cutoff value, then the control technology factor is applied to the emissions. If the resulting emissions value still exceeds the cutoff value, then either the MACT or the RACT factor is used. The MACT factor is used if it is defined (i.e., greater than zero); if it is not defined (less than or equal to zero), then the RACT factor is used. If neither the MACT nor RACT are defined, but the emissions are still greater than the cutoff, then the emissions are set to the cutoff value.

Finally, the /ALLOWABLE/ packet is processed. The entries in this packet override the /MACT/, /CONTROL/, /EMS CONTROL/, and /CTG/ packets. The way this packet is applied depends on whether or not the Cap and Replace values in the packet are defined (greater than zero).