DATE: August 8, 2013

SUBJECT: Rockwool Formaldehyde Emission Testing, Flywool Stack, 9/2010 and 3/2012.

FROM: Steffan Johnson

Measurement Policy Group, OAQPS SPPD

TO: Susan Fairchild – OAQPS SPPD

Mineral Wool / Wool Fiberglass Docket [EPA-HQ-OAR-2010-1041]

1. Background

The EPA requested data from the Mineral Wool industry sector to aid in understanding formaldehyde emissions from 

this sector and to determine MACT floor standards for facilities affected by the new rule.

The Rockwool facility in Leeds, Alabama has a unique process variation that places this facility in a subcategory 

consisting solely of itself. As such, the test data from this facility will be used to determine the MACT floor for this 

facility, and only this facility. 

Formaldehyde emission tests at Rockwool took place in September of 2010, and EPA proposed a rule based on these 

data in 2011. Rockwool felt they could not meet the proposed emission limits and re-tested formaldehyde emissions 

from their facility in March of 2012, submitted that data to EPA, and asked EPA to consider the additional data in 

developing a MACT standard for the final rule.

In comparing the two sets of test data, some substantial differences in the data sets were evident which caused a 

deeper investigation into the test reports. During this investigation it was discovered that the data reported for the 

Flywool stack in the 2010 testing contained several potentially serious flaws and have determined that this data set 

should not be used in any emission calculations for the facility, and especially not used in establishing the MACT floor 

limit. We also discovered minor errors in the data reported in the 2012 testing and asked the test contractor to provide 

corrected results.

2. Discussion

2010 Test Data and the 2011 Proposed Limit:

The 2010 test for Rockwool’s Flywool Stack yielded three test run results of varying orders of magnitude. Test Run 1 was 

eleven times higher than test runs 2 and 3, and was deemed to be an outlier. As such, this test result was not included 

in the emission average used to establish the MACT floor. When the lower two test runs were used to develop the 

proposed MACT floor it prompted Rockwool to conduct a second test in 2012 and provide additional data to EPA for 

consideration before the MACT floor was finalized. The 2012 test results showed emissions several times higher than 

the average of the lower two test runs from the 2010 testing, which prompted EPA to take a closer examination of the 

data with the goal of determining why the difference between the two test series was so substantial. This note 

describes the findings of that examination and provides recommendation for the understanding and use of the data.

2010 Testing:

On September 21, 2010 Rockwool conducted testing on the Flywool stack (scrubber outlet) at their Leeds, Alabama 

facility using EPA Method 316; a validated formaldehyde test method for this industry sector. The test results were 

inconsistent from test run to test run, but the test contractor made no note of any issues in the test report and the data 
was submitted to EPA as true, accurate, and correct. The formaldehyde results of the three test runs were reported as 

follows:

Run 1 Run 2 Run 3 Average

Micrograms 

formaldehyde

5600 500 230 2110

Formaldehyde 

lb/hr

3.5 0.32 0.15 1.3

Note that Run 1 results are a factor of ten higher than Run 2, and a factor of 20 higher than Run 3, while Run 2 is only a 

factor of 2 higher than Run 3. A visual chart is below:

When looking at this result set it is clear why EPA considered Run 1 an outlier and did not include those data in 

developing the 2011 proposed emission limit for Formaldehyde from the Flywool process.

2012 Testing:

On March 29, 2012 Rockwool conducted additional formaldehyde testing on the Flywool stack (scrubber outlet) at their 

Leeds, Alabama facility, again using EPA Method 316. The results from this testing show far less run-to-run variation 

than the 2010 testing, however they do show emissions that are much higher than test runs 2 or 3 in the 2010 test.

Run 1 Run 2 Run 3 Average

Micrograms 

formaldehyde

2400 1500 2700 2200

Formaldehyde 

lb/hr

1.47 0.94 1.63 1.35

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0.5

1

1.5

2

2.5

3

3.5

4

Run 1 Run 2 Run 3

Formaldehyde lb/hr - 2010
What is clear from a review of these results is that the emissions levels are much more comparable from run-to-run and, 

as such, may be more representative of actual emissions fluctuation than the 2010 testing.

2010 vs. 2012 Data, Side by Side Comparison.

Combining the data sets from the 2010 and 2012 formaldehyde tests gives us the following chart:

This comparative graph aptly displays the consistency lacking in the 2010 data and present in the 2012 data. This raises 

the question: “Is there a cause for the distinct difference between these two data sets?”

Sample Collection and Analysis

EPA Method 316 is an isokinetic test method that collects formaldehyde proportional to the stack flow rate and retains 

that formaldehyde in water using a set of condensing impingers. The condensate collected in these impingers, along 

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0.8

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1.6

1.8

Run 1 Run 2 Run 3

Formaldehyde lb/hr - 2012

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0.5

1

1.5

2

2.5

3

3.5

4

Run 1 Run 2 Run 3

2010 lb/hr

2012 lb/hr
with a water rinse of the sampling nozzle, probe, filter housing, and emptied impingers are sent to the lab for analysis. 

Note that the sample submitted to the lab should represent the entire volume of condensate and rinse of the sample 

train. 

When the 2010 data was reviewed three significant findings were brought to light concerning the amount of condensate 

collected during the testing, and the amount submitted to the lab for analysis; possibly affecting the reported result of 

each test run. These findings are:

A. There is a substantial difference in the amount of condensate collected during the first test when 

compared to the second test and a much larger difference when compared to the third test. The first 

test run sample captured 2.38 liters of water while the second test captured 1.13 liters of water, and 

the third test captured 0.05 liters of water (52 ml). 

B. The lab report states that the sample volumes analyzed did not match the amounts listed as being 

captured during the test run. Of the 2.38 liters collected during the first test the lab stated 1.16 liters 

were submitted for analysis; in other words only 48.7% of the formaldehyde sample mass was 

measured by the lab. Of the 1.13 liters collected during Run 2 only 0.42 liters reached the lab, 

representing 37.2% of the formaldehyde sample mass. Perhaps most concerning is Run 3 where 52 

milliliters were listed as being collected in the field while the lab reported 460 milliliters were 

submitted for analysis; representing a potential 884% of the sample mass.

C. If an aliquot (partial sample) of the collected formaldehyde-in-water was submitted to the lab for 

analysis the test contractor would need to calculate adjusted emissions mass and rates depending on 

the fraction represented by the analyzed portion. So if 5600 micrograms from the 2010 Test Run 1 

represented only 48.7% of the sample mass, the value should have been adjusted to account for the 

entire 2.38 liters, making the reported value 11499 micrograms, or some 7.18 lb/hr. In a similar 

fashion, the 0.32 lb/hr reported for Run 2 would be correctly adjusted to 0.86 lb/hr. A similar 

correction for Run 3 cannot be performed as there appears to be substantial dilution of the sample 

and this may be accounted for by the rinse of the nozzle, probe, filter housing, and impingers however 

this was not made clear by the data reported. It is possible that Run 3 data are accurate as reported, 

but there is sufficient uncertainty to ask for clarification. Furthermore, if the 460 ml reported for Run 

3 is correct, this calls into question the 420 ml reported by the lab for test run 2 as such an amount 

may constitute ONLY the rinse of the sample nozzle, probe, filter housing and impingers and may not 

represent any of the collected condensate. Both scenarios are cause for concern, and each must be 

ruled out through further investigation.

When the 2012 data were reviewed a minor issue was noted with the amount of moisture collected during testing and 

the amount of moisture that the test results were based upon. Both the 2010 and 2012 tests showed that in-stack 

moisture conditions are super-saturated, meaning that droplets of water exist in the stack and, as such, isokinetic 

collection of stack gas would result in collection of condensed water yielding a moisture catch higher than the stack gas 

could carry at its’ vapor saturation point. The 2010 flow data were correctly adjusted for this phenomenon, where the 

moisture value of 3.6% was used in dry flow rate calculations; representing saturation at 81 degrees F., the measured 

stack temperature. The 2012 data were also collected under super-saturated conditions but were not adjusted in this 

manner as they should have been.

It was decided that we should contact the source, who provided the data, and discuss these issues with the intent that 

they would, in turn, ask their test contractor to clarify the reported data. 

 
3. Request for Data Clarification and Updated Results

As a result of finding the discrepancies noted above, the EPA initiated a call with Tim Scott and Gerald Miller from 

Rockwool, along with Angus Crane, a representative from NAIMA on Wednesday, August 7th, 2013.

The discussion during this phone call confirmed that the stack at Rockwool is capable of emitting high volumes of water 

and that, at times, saturated water droplets literally “rain” from the stack exhaust. This is consistent with the very high 

levels of water collected during the 2010 testing, specifically Runs 1 and 2. 

Neither Mr. Scott nor Mr. Miller were able to address any of the specific questions regarding the test results themselves, 

and so a follow up call with their test contractor, BTEC (B-Tech) was scheduled for Wednesday, August 14, 2013

On Wednesday, August 14, 2013, a follow up discussion was held and, again, Angus Crane, Scott and Miller were in 

attendance, along with Mr. Randy Tysar of BTEC. Mr. Tysar explained that BTEC was the project manager during the 

2010 testing, but that a different air test contractor (Metco Environmental) had been the test contractor on site. Mr. 

Tysar also explained that BTEC had performed the 2012 testing.

Mr. Tysar stated that he had reviewed the 2010 test data and noted the discrepancies in the amount of condensate 

collected during each test. He also noted the discrepancies in the amount of sample analyzed by the lab during each 

test run. He informed EPA that as BTEC was not the test contractor in 2010 he did not have access to the files or 

personnel at Metco, but that he would call Metco and make a return phone call to EPA on Friday, August 16 to resolve 

the questions. 

Mr. Tysar also stated that BTEC would be able to provide revised emissions calculations for formaldehyde from the 

Flywool stack for their 2012 tests, this time correctly adjusted for the amount of moisture that the stack gas could 

contain if saturated at stack temperatures. Such an adjustment is likely to raise the dry emissions rate by 3 or 4 percent, 

he noted.

During this phone call, Mr. Scott from Rockwool also confirmed the scrubber water spray flow rate is normally 360 

gallons per minute, which would provide sufficient water to yield the amount of moisture collected during the 2010 

data. 

4. Findings and Corrected Results

On Friday, August 16, 2013 Mr. Randal Tysar of BTEC sent an electronic mail message to Steffan Johnson at EPA with an 

attached letter stating:

“Although a review of the detailed emissions test data was inconclusive with respect to a reason for the 

discrepancies from one 2010 test run to another, the testing conducted in 2010 is of questionable validity. This is 

because:

(1) The test results were vastly dissimilar from one test run to another even though the process was likely 

continuous and consistent throughout the test program;

(2) The amount of liquid reportedly collected in the impingers (2,585 ml for Run 1, 1,129 ml for Run 2, and 52 ml 

for Run 3) were vastly dissimilar and, in the case of Runs 1 and 2, unrealistic values for the corresponding 

sample volumes; and,

(3) The sample liquid volumes reported by the laboratory are markedly inconsistent with the test run liquid gains 

during the test runs.

Consequently, the testing conducted during 2010 should be considered invalid.”
Mr. Tysar went on to further say:

“In addition, a review of the test results from 2012 indicates that the moisture content calculated for each test 

run is slightly above the moisture saturation point for the given stack gas temperatures. Consequently, BTEC has 

modified the test results table (see attached Table 3) to substitute satutration moisture values for the calculated values.” 

A comparison of the uncorrected 2012 results and BTEC’s corrected 2012 results is shown below:

As a result of the correction to the 2012 data, the average lb/hr value for the three run formaldehyde test increased 

from 1.35 lb.hr to 1.38 lb/hr, or about 2.2%.

5. Summary and Recommendation:

Discrepancies between the 2010 and 2012 formaldehyde test results on the Rockwool, Leeds, Alabama, Flywool stack 

outlet were sufficient to warrant an in-depth investigation of the source test data. Findings during the investigation and 

conversation with the source test contractor have led to substantial and incontrovertible doubt about the validity of the 

2010 stack test results. The 2010 formaldehyde emissions values reported for the Rockwool Flywool exhaust are 

unusable for emissions calculations or MACT floor calculations.

Additional corrections to the 2012 formaldehyde emissions data resulted in a minor increase in the final emissions 

concentrations, and these corrections are in line with required emissions reporting practice outlined in EPA Method 5, 

Section 12.5 which states:

“In saturated or water droplet-laden gas streams, two calculations of the moisture content of the stack gas shall 

be made, one from the impinger analysis (Equation 5-3), and a second from the assumption of saturated conditions. The 

lower of the two values of Bws shall be considered correct.”

The corrected data submitted by BTEC in their letter on August 16, 2013 should be considered accurate and acceptable 

for emissions calculations and MACT floor determination for this source.

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Run 1 Run 2 Run 3

Original 2010 Result (lb/hr)

Corrected 2012 Result (lb/hr)