FROM: Jeff Coburn, RTI International 

TO: Brenda Shine, EPA/OAQPS 

FOR: Docket ID No. EPA-HQ-OAR-2003-0146 

DATE: August 29, 2012 

SUBJECT: Evaluation of the Refinery ICR Cooling Water Analysis Results 

1. Purpose

This memorandum summarizes the results of the cooling water sampling and analysis conducted 

in response to the detailed information collection request (ICR) for petroleum refineries. 

2. Background

On April 1, 2011, the EPA sent an ICR to facilities in the U.S. petroleum refining industry. The 

ICR was comprehensive and designed to collect information on processing characteristics, crude 

slate characteristics, emissions inventories and source testing to bolster our current data and fill 

known data gaps. The ICR had four components: (1) a questionnaire on processes and controls 

to be completed by all petroleum refineries (Component 1); (2) an emissions inventory to be 

developed by all petroleum refineries using the emissions estimation protocol developed for this 

effort (Component 2); (3) distillation feed sampling and analysis to be conducted by all 

petroleum refineries (Component 3); and (4) emissions source testing to be completed in 

accordance with an EPA-approved protocol for specific sources at specific petroleum refineries 

(Component 4). 

Component 4 of the ICR required source testing for twelve different types of emission sources or 

units; one of the types of sources for which testing was required is cooling water systems (also 

known as heat exchange systems). Owners or operators of cooling water systems at 11 selected 

facilities were required to test for total strippable volatile organic compounds (VOC) using 

Modified El Paso Method (TCEQ, 2003). Following Modified El Paso testing, additional testing 

was performed on the cooling water system with the highest total strippable hydrocarbon 

concentration, except for the following situations: (1) if more than one cooling water system 

return line had total strippable hydrocarbon concentration greater than 62 parts per million by 

volume (ppmv), then the facility conducted additional testing for all cooling water systems that 

had a return line concentration greater than 62 ppmv; and (2) if none of the cooling water system 

return lines had a total strippable hydrocarbon concentration greater than or equal to 3 ppmv, 

then the facility conducted additional testing only for hydrogen chloride (HCl) and chlorine (Cl2) 

for any one cooling water system return line. 
Technical Memorandum – Evaluation of the Refinery ICR Cooling Water Analysis Results 

August 29, 2012 

2 

The additional testing included: 

 Speciated volatile organic hazardous air pollutants (HAP) (in stripping air and water) 

 Speciated semi-volatile organic HAP (in stripping air and water) 

 Formaldehyde (in stripping air) 

 Total hydrocarbons (in stripping air) 

 Methane (in stripping air) 

 Hydrogen chloride and chlorine (in stripping air). 

3. Summary of Results

Four of the 11 facilities that were required to test their cooling water systems did not have any 

strippable hydrocarbons in the cooling water at concentrations of 3 ppmv or greater (as 

methane), so these four facilities did not do additional organic sampling and analysis. Three 

small refineries did not conduct on-site flame ionization detector (FID) analysis using the direct 

Modified El Paso Method, but conducted detailed sampling on a select cooling water system or 

each cooling water system at the facility. In total, seven refineries conducted detailed sampling 

of eight cooling water systems. The potential emissions in pounds per day (lb/day) associated 

with the hydrocarbons measured in the cooling water were calculated based on the water-phase 

concentrations and the water flow rate of the cooling water system. Concentrations determined 

in the stripping air were back-calculated to water-phase concentrations using Equation 7-1 of the 

Modified El Paso Method (TCEQ, 2003). The projected emissions from the speciated analyses 

were calculated by summing the emissions projected for each compound detected in at least one 

sample analysis for a given cooling water system. Concentrations of compounds detected below 

the lowest calibration standard (commonly marked in the analytical reports with a “J”) were used 

as reported; concentrations for compounds that were not detected in any samples were assumed 

to be zero. The calculated potential emissions from the ICR testing data are summarized in 

Table 1. A detailed summary of the specific analytical results is available on the petroleum 

refinery sector ICR web page (http://www.epa.gov/ttn/atw/petref/petrefpg.html) under the “ICR 

Component 4 – Emission Source Testing” section. 

4. Discussion of Results

The results of the direct El Paso on-site FID measurements compare well with the results of 

stripping gas collected for total hydrocarbon analysis or methane plus non-methane organic 

carbon (NMOC) analysis. For one cooling water system (Facility ID LA3C0700; Cooling Water 

System 8006), the results of the laboratory analysis of the collected gas is about a factor of 3 

greater than the direct El Paso FID reading. This may be due to an error in labeling the results. 

The NMOC were labeled “as propane” so the calculated water concentrations (and potential 

emissions) are approximately 3 times greater than if these results were actually measured “as 

methane.” The El Paso FID readings were not specifically marked, so they were assumed to be 

“as methane.” If these measurements were made on the same basis (either both “as methane” or 

both “as propane”) then the calculated emissions would have been more similar for the two sets 

of results. 
Technical Memorandum – Evaluation of the Refinery ICR Cooling Water Analysis Results 

August 29, 2012 

3 

The results of the speciated stripping air sample analyses were always much less than the total 

hydrocarbon analyses. The results of the speciated water sample analyses were also much less 

than the total hydrocarbon analyses, as a general rule. There were several water samples whose 

analyses appeared to be contaminated with acetone and/or methylene chloride (see footnotes to 

Table 1 for details). Excluding these analytes, the speciated water sample analytical results were 

generally comparable to or less than the speciated air sample analytical results. The largest 

discrepancy for the air versus water speciation results (not considering the probable acetone 

contamination) were for Facility ID LA3C0700; Cooling Water System 8006. This cooling 

water system had significant total hydrocarbon and speciated HAP emissions based on the 

analysis of the stripping air, but all analytes were below detection limit for the water samples. 

Table 1. Summary of Cooling Water System ICR Analytical Results 

Facility ID/Cooling 

Water System ID 

Estimated Hydrocarbon Emissions (lb/day) based on: 

El Paso 

On-site FID 

Methane+NMOC 

Method 18/TO-12 

Sum Analytes in 

Gas; TO-11/15 

Sum Analytes 

in Water 

M8260B/8270C 

CO4A0340/P2CT-1 16.3 17.9 5.85 BDLa

LA3C0700/8006 867 3,880b 111 BDLa

NM3E0880/CT-1&2 354 83 107 

OK2C0960/Hydrocrkr 82.8 12 112c

PA1B150/West 6.5 4.3 0.35 0.38 

UT4A1380/11 1,100 1,160 0.87 2.43d

WI2B1460/CT1 1.47 0.02 23.8d

WI2B1460/CT2 2.4 0.22 BDLa

a

 All analytes were below the analytical detection limit (BDL). 

b

 NMOC concentration value was reported “as propane.” If this was actually “as methane” the calculated emissions 

would be similar to those determined using the El Paso method (they did not specify if the El Paso concentrations 

were FID “as methane” or “as propane,” but were assumed to be “as methane”). 

c

 One water sample had high acetone concentration; the next two were detected but below quantitation limit (roughly 

a factor of 10 lower concentration). Excluding this one high acetone sample (but using the average of the other two 

acetone concentrations), the emissions would be estimated as 35 lb/day. The next highest detected quantity was for 

methylene chloride, which was also detected in the blank. The refinery notes that both acetone and methylene 

chloride are not expected to be in any of the streams serviced by the cooling tower and are expected to be laboratory 

contaminants. Little to no acetone or methylene chloride were present in air samples. Emissions based on the water 

method’s analytes excluding acetone and methylene chloride are 1.9 lb/day. d

 The primary (or, for WI2B1460/CT1, the only) analyte detected in the water sample was acetone. Little to no 

acetone was present in air samples. Again, acetone appears to be a laboratory contaminant. 

There are several reasons why the speciated analyses yield lower results than the total 

hydrocarbon analysis. The primary reason for this is that the target list of analytes for the 

speciated analyses did not include all of the hydrocarbon compounds present in the cooling 

water. The speciated target analyte list included primarily HAP constituents and only a few nonHAP compounds. Many petroleum refinery hydrocarbons are not HAP, so the target analyte list, 

which focused on HAP, did not include all of the compounds that could have been present in the 

cooling water. Another reason why the speciated analyses may have yielded lower results is that 
Technical Memorandum – Evaluation of the Refinery ICR Cooling Water Analysis Results 

August 29, 2012 

4 

many of the individual constituents were present below the analytical detection limit. Many 

refinery process streams may have hundreds of different organic species. When the compounds 

are separated in a GC and individual peaks are analyzed, the individual peaks may be small and 

some may be so small that the peak is not detected. However, when all these trace compounds 

are analyzed together (no GC separation), these compounds will add to the total hydrocarbon 

concentration measured by the detector. 

Most analytical test methods provide a specific list of analytes for the method. The list of 

analytes may not include all compounds potentially determined by the method, but the method 

will generally list the most common compounds for which the method has been used and for 

which detection limits and other analytical parameters have been assessed. Therefore, if a 

certain test method is specified and the target analyte list is limited to only those compounds 

specifically listed in the referenced test method, then the speciated analyses will invariably have 

a similar low bias compared to the total hydrocarbon analysis as seen in Table 1 for most 

petroleum refinery streams. Another way to say this is that unless the composition of the process 

stream consists of only one to a few compounds that are all included on the target analyte list, the 

speciated analyses will result in lower overall concentration as compared to a total hydrocarbon 

measurement. As such, speciated analyses are less likely to identify a leak into the cooling 

water. For petroleum refineries, where the MACT floor is based on total hydrocarbon analysis 

using the Modified El Paso Method, speciated analysis to identify leaks at the same 

concentration action level used for the total hydrocarbon analyses is expected to be less stringent 

than the MACT floor. 

The low bias of speciated analysis exists for both the stripping air analysis and the direct water 

analysis. The direct water analysis appears to be more limited by detection limits (that is, 

stripping air analysis appears to be more sensitive and capable of detecting trace quantities of 

volatiles in the cooling water). The direct water analysis also appears to be more prone to 

laboratory contamination. It appears that several of the water samples had trace quantities of 

acetone and/or methylene chloride that are more likely to have come from laboratory 

contamination than a leaking petroleum refinery heat exchanger. Volatile loss during water 

sampling has also been identified as a potential bias for the water analysis methods (TCEQ, 

2003). Use of the Modified El Paso Method with on-site FID detection for total hydrocarbons 

(or off-site analysis of the stripping air for total hydrocarbons) eliminates the potential biases of 

the speciated methods and the other potential issues identified above concerning water sampling 

and analysis. 

5. References

TCEQ (Texas Commission on Environmental Quality). 2003. “Air Stripping Method (Modified 

El Paso Method) for Determination of Volatile Organic Compound Emissions from Water 

Sources,” Revision Number One, Sampling Procedures Manual, Appendix P: Cooling Tower 

Monitoring. January.