Date: April 22, 2015 

To: Docket, EPA-HQ-OAR-2014-0738 

From: Andrew Bouchard 

Subject: Meeting Record for April 22, 2015 Meeting Between the U.S. EPA and The Dow 

Chemical Company 

On April 22, 2015, representatives of the U.S. Environmental Protection Agency (EPA) 

participated in a meeting with The Dow Chemical Company. The purpose of the meeting was to 

further discuss Dow’s comments that were submitted to the docket on the initial MPGF AMEL 

notice as well as to discuss other comments that were submitted to the docket. See Attachment 1

for the names and affiliations of the meeting participants. See Attachment 2 for the subsequent 

follow-up letter Dow provided as a result of the meeting discussion. 
2

Attachment 1 

Participants in April 22, 2015 EPA/Dow Meeting 

The Dow Chemical Company Representatives 

Russell Wozniak 

Jarod Davis 

U.S. EPA Representatives 

Andrew Bouchard 

Brenda Shine 

Penny Lassiter 

Attachment 2 
3

Copy of Follow-up Letter from Dow 
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May 5, 2015

Ms. Brenda Shine 

Sector Policies and Programs Division (E143-01) 

Office of Air Quality Planning and Standards 

United States Environmental Protection Agency 

Research Triangle Park, North Carolina 27711 

Additional Information - Approval Requests for the Operation of 

Pressure-Assisted Multi-Point Ground Flare Technology 

The Dow Chemical Company, Texas Operations – Freeport, TX 

Dear Ms. Shine: 

The purpose of this letter and attachment is to provide additional information that EPA requested 

in order to continue with the evaluation of the subject approval requests. The requested 

information is contained as an attachment to this letter. 

If you have questions or concerns regarding any of the attached information, please contact me at 

(361) 553-2920. 

Sincerely, 

Russell A. Wozniak

Russell A. Wozniak 

EH&S Operations Regulatory Services 

The Dow Chemical Company 

Attachments 

cc: 

Andrew Bouchard, Sector Policies and Programs Division, OAQPS, USEPA, Raleigh, North 

Carolina 27711 

Penny Lassiter, Group Leader, Sector Policies and Programs Division, OAQPS, USEPA, 

Raleigh, North Carolina 27711 
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Page 1 

Area Maps and Information on Distances to Off-Site Receptors of Interest

The following maps and area pictures are included at the end of this section: 

1. Area map showing the location of the PDH-1 plant, which contains a circle with a radius 

of 3,000 feet and one mile from the center of the PDH-1 plant. 

2. An aerial picture of the Dow Oyster Creek complex at Freeport, TX 

3. An aerial picture of the Dow Oyster Creek complex that shows the approximate location 

of the pressure-assisted flare systems and the property lines. 

The distances from the center of the process units to the property line and off-site receptors are 

provided in the tables below. The distances from the center of the pressure-assisted flare systems 

are not the same, but are very close to these distances. 

PDH-1 Plant

Receptor Distance in Feet

 

Nearest School - Lanier Middle School – 

Freeport 

7,321 

Perstorp Coating, Inc. 3,591 

Nearest Residence (Freeport – Velasco) 3,613 

Nearest Property Line – South 1,167 

 

LHC-9 Plant

Receptor Distance in Feet

 

Nearest School - Velasco Elementary School 6,748 

Nearest Park - Austin Park 6,065 

Nearest Off-Property Receptor (Convenience

Store at the Corner of FM 523 and SH332) 

4,113 

Nearest Residence Freeport, TX 4,748 

Nearest Property Line – FM 523 to East 1,898 

 
Page 2 

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Dispersion Information for Pressure-Assisted Flares

The following is information that is important to consider when evaluating the dispersion of 

any post-combustion air emissions from the pressure-assisted flares. 

1. The height of the heat/radiation fence for the PDH-1 project flare is 51 feet. The 

height of the heat/radiation fence for the LHC-9 project flare is 58 feet. 

2. When the pressure-assisted flare tips are in service, air flows into the area and over 

the top of the fences. Any emissions from the flare systems will be dispersed over the 

top of the fenced area, thus they will have a minimum height of either 51 or 58 feet. 

3. The pressure-assisted flare tips are not in service for most of the time since they are 

only used during times of planned maintenance, start-up, or shutdown, and are also 

designed to combust vents associated with upset venting. 

4. The predominant wind direction at the site is from the south or south east, thus 

dispersing emissions away from the Freeport community for the majority of the time. 

Dispersion modeling of the emissions, after combustion, from the PDH-1 pressureassisted flare system was conducted by an external consultant using EPA’s AERMOD 

dispersion model. The results of the modeling show that the predicted off-site 

concentration for each compound modeled is less than 1% of the published TCEQ Effects 

Screening Level (ESL) for both 1-hour average and annual average concentrations. 

If EPA concludes that periodic ambient air monitoring using a portable system is required 

to confirm that the post combustion emissions from the pressure-assisted flare system(s) 

are not impacting the surrounding area, we suggest that the following text be added as a 

requirement to the AMEL for the Dow flares: 

Suggested Requirement to Add to the AMEL

The Dow Chemical Company shall submit an ambient air monitoring plan within 90 

days after the AMEL is published in the Federal Register. The ambient air 

monitoring plan will be effective 90 days after the EPA approves the ambient air 

monitoring plan. The ambient air monitoring plan must address at least the following 

items listed below: 

1. The sample collection and analytical method(s) to be used to measure the 

concentration of selected organic hazardous air pollutants that may be included in the 

vent gas streams vented to each pressure-assisted flare system. The plan will list the 

compounds covered by the monitoring program. 

2. The location(s) of the ambient air sample collection points. 

3. The frequency of sample collection and analysis. 

4. The duration of the ambient air monitoring program; and 

5.   The method by which the analytical results will be made available to EPA and TCEQ. 
Page 3 

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Responses to Additional Questions Regarding Design Features and Power Outages

The purpose of this section is to respond to EPA questions regarding how the pressure-assisted 

flare systems would operate during a power failure and also whether or not a potential outage of 

the pressure-assisted flare systems was covered in our Process Hazard Analysis assessments. The 

scenario of loss of pilots, which could cause unburned hydrocarbons to be released, was 

evaluated and the main design features to minimize the possibility of this occurring are listed 

below for both flare systems: 

 There are two pilots for each stage of burners; 

 There are two redundant and independent pilot gas headers to each stage of the flare 

system. Each stage has one pilot fueled from one system and one pilot fueled by the 

other system. Therefore, a single failure, such as regulator problem, will not shut off the 

gas to all of the pilots; 

 If both pilots are indicated to be extinguished, that row of flare tips is disabled within the 

control system by an interlock; 

In addition to the design features, an Operating Discipline for the PDH-1 plant will be in place in 

the event that both pilot gas systems fail where the plant would attempt to fuel the pilots by 

supplying process gas from the plant to the pilot gas header. 

In the event of plant-wide power failure (using the PDH-1 plant as example), the flare would 

function to destroy hydrocarbons as long as either pilot gas or process vents were burning. The 

pressure-assisted tips use the upstream pressure of the vent gas to combust the emissions and do 

not require utilities such as steam or air-assist to properly operate. In a total loss of power 

scenario the plant has some reserve capacity on the instrument air header to keep pressure for a 

short period of time, but the plant would eventually lose instrument air. If instrument air is lost, 

the flare staging valves would close and the system would rely on the buckling pin bypass valves 

for a flow path to the pressure-assisted flare tips, thus the pressure-assisted flare system would 

remain in service. Loss of power is the worst case flaring scenario that the flare system is 

designed for in terms of instantaneous quantity and we expect that the vast majority of flaring 

would happen early in the event and that the pressure-assisted flare tips will function normally. 
Page 4 

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Page 5 

Aerial Picture of Dow Chemical Oyster Creek Complex – Freeport, TX

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Copyrighted Map Removed 
Page 6 

Aerial Picture of Dow Chemical Oyster Creek Complex – Freeport, TX

Notes: 

The pressure-assisted flare system for the PDH-1 process is located approximately in the 

green box to the left of the PDH-1 process area, and the pressure-assisted flare system for the 

LHC-9 plant is located approximately in the green box to the left of the LHC-9 process area. 

The property lines for the Oyster Creek complex are noted by the orange, dark blue, light 

blue and yellow lines. State highway 332 runs parallel to the dark blue line and FM Road 

523 runs parallel to the light blue line. Dow also owns some land on the south side of Dow 

Barge Canal, which is not depicted in the above picture.