Date: March 5, 2014 

To: Brenda Shine, EPA/OAQPS/SPPD 

From: Kristin Sroka 

Subject: Meeting Minutes for February 5, 2014, Meeting Between the U.S. EPA and a 

Representative of Marathon Petroleum Company 

On February 5, 2014, representatives of the U.S. Environmental Protection Agency 

(EPA) and their contractor (RTI International) participated in a meeting with a representative of 

the Marathon Petroleum Company LP (MPC). The names and affiliations of the participants are 

included in Attachment 1. The purpose of the meeting was to discuss MPC’s experiences with 

conducting diffusion tube passive sampling concurrently with the EPA. The MPC representative 

provided a presentation summarizing the passive sampling; the presentation is included as 

Attachment 2 to this memorandum. Additional information provided by the MPC representative 

following the meeting is included as Attachment 3 to this memorandum. 

The passive sampling was performed at the MPC Texas City Refinery and a nearby tank 

farm. The MPC representative noted that the company recently purchased a refinery from BP 

that was referred to as the Texas City Refinery as well; MPC now refers to it as their Galveston 

Bay Refinery. The Texas City Refinery is bordered on the west by the Galveston Bay Refinery, 

on the south by a refinery owned by Valero Energy Corporation, and on the east by the 

Galveston Bay. The tank farm is to the southeast of the refinery. The wind is almost always from 

the south, but during the 4 days of sampling, it was blowing from the north part of the time. 

The MPC representative noted that there have been ambient benzene monitors located 

outside of the Texas City Refinery for a number of years. For example, the Texas Commission 

on Environmental Quality’s 11th Street monitor, located to the north of the Texas City Refinery, 

did have exceedances of the benzene effects screening level (ESL) of 1.4 ppb (annual average) in 

the 2008/2009 calendar years. The MPC representative’s understanding was that the refinery 

implemented corrective actions to identify the source of the benzene, which was a benzene 

storage tank, and they took steps to upgrade seals to mechanical shoe-type seals. They also 

changed the way the tanks were operated to reduce working losses. Since 2010, the monitored 

levels have been below the ESL and continue to decrease. 

The MPC representative indicated that there was some variability between MPC’s results 

and the EPA’s concurrent results. These differences may be attributed to the fact that the EPA 

recommended that MPC use a different type of sampling tube (with a different mesh size) than 

the EPA testers themselves were using. Based on an initial review of the concentration results 

presented at this meeting, the EPA representatives noted that, given the differences in the type of 
2

sampling tube and the fact that the samples were analyzed by different laboratories, the MPC 

results seemed to agree well with the EPA results. 

The highest benzene concentration found during the passive sampling was in the tank 

farm, at a level 4 times higher than the other nearby samplers. This sampler was near a benzene 

tank, so slightly higher concentrations of benzene would be expected. However, all the tank seals 

were checked and were operating properly, and the tank was not involved in degassing or a 

turnaround during the sampling. The facility across the street from the tank farm produced 

benzene at one time but does not do so currently. Therefore, the MPC representative was not sure 

of the exact source of the benzene. The second highest benzene concentration was measured at 

the dock. The MPC representative stated that MPC sends only gasoline to the dock for shipping, 

so he suggested that the sources of the high benzene concentrations from this sampler are likely 

from other facilities and operations. For example, there are other manufacturing facilities using 

the docks to ship their products. The MPC representative also suggested the wind could be 

carrying benzene emissions from barges out on the bay. 

Based on their experience, the MPC representative had a few suggestions for 

implementing a fenceline monitoring program in a rulemaking. First, he noted that the EPA used 

two samplers in each location during their study, and they removed the results from one location 

because the results from the two samplers did not agree. He asked the EPA representatives to 

consider providing a mechanism in the rule that would allow for removal of suspect or 

suspicious results in a program that does not require two co-located monitors. Second, he 

suggested reducing the amount of monitors required by not requiring monitors to be placed near 

units that would not be expected to have high concentrations of benzene (such as gasoline 

product streams). Third, he noted that when a sampling tube shows high concentrations of 

benzene, it may take a little bit of work to determine the source, even with tools such as infrared 

cameras. If the source is not inside the refinery fenceline (i.e., the high benzene concentrations 

are from something off-site), it becomes even more difficult to determine the exact source. He 

recommended that the rule include some sort of provision for refinery owners or operators to 

show that the high benzene concentrations are not coming from their facility. 

 
Attachment 1 

Participants in February 5, 2014 EPA/MPC Meeting 

MPC Representatives 

Charlie Bennett 

U.S. EPA Representatives 

Andrew Bouchard 

Jason DeWees 

Eric Goehl 

Penny Lassiter 

Nick Parsons 

Brenda Shine 

Eben Thoma 

RTI International (EPA contractor) 

Kristin Sroka 

 
Attachment 2 

Presentation Slides 

Refinery Passive Sampling Data 

Marathon Petroleum Company LP 
Refinery Passive Sampling Data

1
Refinery Diffusion Tube Passive Sampling

 Diffusion tube readings taken at the Continuous Monitoring System (CMS) GC location were higher 

than the CMS GC readings. These readings were lower than applicable standards. 

 Sampling results around the refiner and tank farm varied significantly on average and individually.

 Contributing to variability is the:

 Average uptake rate for diffusion tubes is +/- 9.0%

 Lab error at an estimated +/- 2% to +/- 4%

 1 out of 25 EPA sample locations was discounted because of apparent error.

 Sampling results in locations between industrial areas were significantly lower that OSHA levels of 

concerns.

 Follow-up with IR camera within the MPC Refinery showed no leaks from MPC operations.

 There was no feasible way to determine if there were unusual operations from adjoining, nonMPC operations.

2
Benzene Passive Diffusion Tube Sampling 

 MPC took duplicate samples at same 

locations as EPA

 MPC used Carbograph X 40/60 

sampling tubes

 EPA used CarboPack X sampling 

tubes

 The 2-week benzene diffusive uptake rate for Carbopack X has 

been determined to be (1.99 ± 0.18) ng ppm−1 min−1 for 

environmental applications, and was found to be constant over a 

wide range of VOC concentrations. 

3
MPC / EPA Preliminary non-QA/QC Benzene Monitoring (ppb)

All neighborhood public receptors within TCEQ annual limits

11th St. CEM: 0.56 ppb

0.21/0.46 0.31/NA

0.65/0.60

0.53/0.41

0.40/0.28

0.49/0.36

0.35/0.42

0.43/0.35

0.79/0.75

0.91/0.55

1.00/1.40

0.55/0.43

4.00/3.35

0.70/0.88

1.00/1.14 0.71/0.69

0.71/0.66

0.74/0.65

0.78/0.71

0.65/0.56 0.59/0.60 0.64/0.77

0.49/0.64

0.58/0.60

Dock 18 3.5/3.1 4
Areas of Note

 Passive sampling results appear to bias toward a higher reading than CMS GC ranging from 7.1% to 16.1% 

 4% of EPA results needed to be discounted for no identifiable reason

 EPA average same location results varied by 13.3%

 EPA individual same location results varied from 0.0% to 40.0%

 MPC to EPA average same location results varied by 21.8%

 MPC to EPA individual location results varied from 1.7% to 73.7%

 Identifiable areas of variability include:

 Average uptake rate for diffusion tubes is +/- 9.0%

 Lab error is at an estimated +/- 2% to +/- 4%

 No feasible method was determined how to identify possible sources of emissions from non-MPC facilities. 

5
0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Emissions Cancer Tox 

Weighted Emissions

Noncancer Tox 

Weighted Emissions

Residential Combustion

Pulp and Paper

Power Plants

Petroleum Refining

Other

Oil and Gas Production & 

Distribution

Minerals (inc Cement)

Metals (Iron, Steel & NonFerrous)

Crop Production

Consumer/Commercial Prod 

Mfct & Services

Chemical Manufacturing

Boiler and IC Engines

EPA Data Shows Refinery Toxics Emissions are Low

6
Attachment 3 

Follow-up Information on Texas City Fenceline Monitoring 

Email from Charlie Bennett to Brenda Shine 

February 6, 2014 
From: Bennett, Charles D. (MPC) <cdbennett@marathonpetroleum.com> 

Sent: Thursday, February 06, 2014 11:18 AM 

To: Shine, Brenda 

Cc: Scott Jr, Harold R. (MPC) 

Subject: Texas City Fenceline Monitoring 

Brenda, 

I wanted to provide the following follow-up information on Dock 18 and also on the 11th street 

monitor. I received some questions on the 11th street monitor and wanted to provide the specifics 

after I discussed with our Texas City Refinery. Please forward. Thanks. 

Charlie 

Dock 18 is permitted to load benzene, but was not loading benzene during the sampling period 

(gasoline was loaded). 

11th street monitoring information: 

1. TCEQ ESL is 1.4 ppb annual average 

2. The monitoring station was established in ~2004 as part of agreement with TQEQ based 

on TCEQ mobile monitoring 

3. In 2008 and 2009, the ESL was exceeded and corrective actions were taken 

a. Investigations including use of IR camera plant-wide 

b. Voluntarily, both of the benzene tanks were taken out of service and Texas city 

upgraded the seals to mechanical shoe seals (existing seals were compliant) 

c. Texas City changed the way the tanks are used in a manner to reduce working losses 

of the tanks 

4. Since 2010, the monitored levels have been below the ESL and continue to decrease