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OAR Box 1875 

Prepped by Ollie Stewart 

Document Number: 

31) ll-E-49 

Docket Number: 

A-90-19 

Printed 12/1/200811:12:45 AM Sheet 31 of 86 
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A-90-19 

ll-E-49 

MEETING SUMMARY 

Date: July 28, 1992 

Subject: Teleconference with CMA to Discuss the Process 

Vents TRE Equation 

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Attendees: Linda Herring, EPA/SDB ':"^\T'\0 ?• \\ ',r 

Jan Meyer, EPA/SDB \\^\ li •P 1* 

Sheila Milliken, EPA/SDB •\''\r 

Debbie Stackhouse, EPA/SDB \y •. Q£Q \ 8 I99t 

Leslie Evans, EPA/CPB V 

Bob Rosensteel, EPA/CPB v 

Ruth Mead, Radian \ £;./\/7./*-• 'J.^.^--' 

Thomas Olsen, Radian L—-^.I———"-*"'' 

Amy Meyers, CMA (telephone link) 

David Gustafson, Dow Chemical (telephone link) 

Joe Woolbert, Eastman Chemical (telephone link) 

The purpose of the teleconference between the EPA. and CMA 

was to discuss two issues concerning the TRE equation in the 

process vents portion of the HON regulation. The first issue was 

to discuss CMA's request to use engineering assessment/process 

knowledge to determine the TRE index value in an effort to reduce 

the testing burden for measuring the TRE input parameters. The 

second issue was to discuss a TRE index value at which monitoring 

of recovery device or other specified parameters would not be 

necessary (currently a TRE > 8.0). 

I. ENGINEERING ASSESSMENT FOR TRE CALCULATIONS 

The EPA requested that CMA give examples of what type of 

data would be used for the engineering assessment of the TRE 

index value. The CMA suggested that emissions inventories or 

other permitting efforts would contain the data to describe what 

the emissions are at each process vent. Specific examples given 

by CMA were: 

• Design maximum of equipment, such as pump size or 

maximum loading rates; 

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• For existing processes, actual maximum values; 

• Composition knowledge of products and intermediates, 

mass balances; 

• Process measurements, such as product accumulator 

liquid level changes; 

• Worst case analysis of vent concentrations based on 

physical properties (saturation conditions or 

100 percent HAP/VOC composition); and 

• Observable process parameters. 

The CMA added that in the engineering assessment, a facility 

would want to overestimate the emissions to some degree with a 

safety factor to be confident in the designation of the vent as 

Group 1 or Group 2. It was noted that there are inaccuracies in 

estimates, and a TRE level would need to be set at some point 

above 1.0 and below that value, testing would be required to 

support the TRE calculation for Group determination. 

The EPA agreed with the concept in principal, but maintained 

some reservations concerning, in some cases, the accuracy of the 

information to be used in the TRE calculation. For example, it 

might not be appropriate to use old design specifications with no 

reference or supporting information. The EPA expressed concern 

on how the allowable types of data or information would be 

specified or clarified in the regulation. 

The CMA said there was a significant risk in a facility 

using inaccurate information or engineering assessments to 

calculate the TRE since it could mean a facility was out of 

compliance. The types of information that might be used are 

typically in permits. 

The CMA agreed to put together a generic list of allowable 

types of information to calculate the TRE index value as well as 

some specific examples and to supply the list before the 

August 5, 1992, EPA/CMA meeting. 

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II. TRE INDEX VALUE MONITORING EXEMPTION 

The process vents portion of the current draft HON 

regulation exempts process vents with a TRE greater than 8.0 from 

monitoring requirements. 

The CMA conducted an analysis on the sensitivity of the TRE 

equation based on the vent streams presented in the draft BID 

(Volume C, Tables 2-2, 2-3, 2-4, and 2-5) and the propagation of 

variation of the inputs through the TRE equation. The analysis 

included (1) specification of the expected accuracy of the 

engineering assessment for the four inputs to the TRE equation, 

(2) propagation of variation of inputs through the TRE equation, 

and (3) calculation of confidence intervals. For the first step, 

expected accuracy of estimates, it was assumed that for vents 

with high concentrations and flow rates, engineering assessment 

would be relatively accurate (e.g., +/- 10 to 20 percent); for 

streams with medium flows and concentrations, there would be a 

greater inaccuracy; and for low flows and concentrations, 

estimates might be + or -1 order of magnitude. The results of 

the analysis indicated that for all non-halogenated Group 1 

process vents the TRE index value variation was less than 3.0. 

If a vent TRE was estimated to be above 3.0, inaccuracies in 

engineering assessment would not make the TRE fall below 1.0. 

For halogenated Group 1 process vents the variation in the TRE 

index value was less than 1.5, however there were very few 

halogenated vents in the BID, so CMA was less confident of this 

value. 

The EPA pointed out that the analysis failed to account for 

the variability of the vent stream parameters, i.e., the 

fluctuation of vent stream flow rate and actual HAP/VOC 

concentration. 

The CMA asked if the TRE equation inputs (e.g., flow, heat 

content VOC emission rate, HAP emission rate) were based on 

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annual averages or short term values. The CMA added that test 

measurements are only a short term value and could be misleading. 

The EPA responded that the tests were to be conducted at the 

representative process operating conditions. The source should 

conduct tests under conditions that are within their normal range 

of operation and are expected to yield the lowest representative 

TRE value. The rule is not explicit in defining representative 

conditions, but it is the same language as in the SOCMI NSPS for 

distillation and reactors. 

The CMA said if the rule specified the use of the worst 

values of the year (e.g., worst case evaluation) to input into 

the TRE equation, the safety level would be incorporated and the 

level of comfort would be sufficient to allow TRE of 3.0 as the 

testing and monitoring exemption level. 

The EPA proposed that a single TRE index value greater than 

1.0 be set as the level where vents with a TRE greater than the 

value are not subject to monitoring requirements, and engineering 

assessment of the TRE value is acceptable. The current level in 

the rule is 8.0. Using 8.0 as an example, if a source used 

engineering assessment and calculated a TRE greater than 8.0, 

testing and monitoring would not be required. If the engineering 

assessment resulted in a TRE level less than 8.0, testing would 

be required to support the group determination (if the estimated 

value is below 1.0, the facility may test to determine TRE or may 

choose to control without further TRE testing/group 

determination). An alternative is to set one TRE index value 

level for monitoring exemptions and a TRE index value level above 

that for allowing the,use of engineering assessment. For 

example, the rule could specify a TRE index of 4.0 as a 

monitoring level and a TRE index of 8.0 as the engineering 

assessment level. Testing must be performed to establish 

monitoring parameter ranges, so the TRE value selected for the 

use of engineering' assessment must be at least as high as the 

value selected for monitoring. The EPA agreed to consider use of 

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a single TRE level for the monitoring exemption and the use of 

engineering assessment and to determine a TRE between 3.0 and 8.0 

for that level. The EPA requested that CMA provide the 

calculations for CMA's TRE analysis. 

III. ACTION ITEMS: 

(1) The CMA agreed to provide a list of engineering assessment 

procedures for the August 5, 1992, CMA/EPA meeting. 

(2) The CMA agreed to provide their procedures and calculations 

on the TRE analysis and variability study. 

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