MEMORANDUM

SUBJECT: Bounding Analysis for Portland Cement MACT Floors

TO: Docket No. EPA-HQ-OAR-2011-0817

DATE: May 14, 2012

EPA re-evaluated the floor calculations used in the final NESHAP for the Portland cement 

source category. 75 FR 54970 (Sept. 9, 2010). This analysis is a bounding analysis which 

removes from the Portland cement database any cement kiln which combusts a non-hazardous 

secondary material. This analysis is not intended to determine which kilns are CISWI and which 

remain cement kilns. Rather, it determines what floors would be on the extreme hypothetical 

assumption that any cement kiln which combusts a non-hazardous secondary material is not a 

cement kiln. The analysis then determines what the floors would be under this extreme 

assumption, bounding the possible floors which could result from the data set. 

The results of this analysis are presented below:

Pollutant

Kilns that do not combust 

non-hazardous secondary 

materials

Promulgated – All Kilns

Existing New Existing New

Hg

No. of Kilns 26 26 89 89

No. in Floor 4 1 11 1

UPL (lb/MM tons

clinker) 66.60 46.48 54.10 20.30

Average (lb/MM tons

clinker) 44.75 35.20 31.70 13.90

HCl

No. of Kilns 11 11 21 21

No. in Floor 2 1 3 1

UPL (ppm) 0.56 0.34 0.52 0.34

Average (ppm) 0.40 0.34 0.41 0.34

PM

No. of Kilns 18 18 45 45

No. in Floor 3 1 6 1

UPL (lb/ton clinker) 0.05 0.01 0.04 0.01

Average (lb/ton

clinker) 0.03 0.01 0.00 0.01

THC
No. of Kilns 10 10 15 15

No. in Floor 2 1 2 1

99th percentile (ppm) 14.98 10.84 24.00 24.00

Average (ppm) 5.69 5.68 5.20 4.70

The attachment to this memo (Attachment A) contains the calculations supporting these results. 

Attachment A-9 details the kilns identified as CISWI at reconsideration. These kilns were 

removed from all MACT floor calculations as part of the bounding analysis. Additionally, any 

kilns identified as combusting non-hazardous secondary material from the 2007 portland cement 

ICR were removed from the MACT floor calculations. Attachment A-10 details the kilns that 

were identified as combusting non-hazardous secondary materials. 

We note further that although the HCl floor ostensibly changes (slightly) in this analysis, 

in fact there is no reason that the HCl floor would change. This is because the floor is effectively 

determined by the analytic detection limit, and there are a large group of cement kilns which 

performed identically to the best performers. See 76 FR at 28322 n. 11. The reason for the 

(slightly) different value in this bounding analysis is due to the different number of sources in the 

database, not to any difference in measured performance. Since there is no actual difference in 

kiln performance for HCl, there is no reason that the floor should be altered.

We also note that no cement kilns are reclassified as incinerators in this bounding 

analysis due to processing non-hazardous secondary materials as ingredients. This is because 

none of the non-hazardous materials identified by cement kilns as being used as ingredients are 

combusted, as explained at 76 FR 28322. 

Even under the extreme assumptions of this analysis, EPA does not believe that the 

technology basis for the PM, HCl, THC or mercury standards would change were these bounding 

analysis floors to be adopted as standards.