Date: April 22, 2015

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

From: Andrew Bouchard

Subject: Meeting Record for April 22, 2015 M eeting 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 Chemi cal Company. The purpose of the meeting was to

further discuss Dow’s comments that were subm itted 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 re sult 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 23 Copy of Follow-up Letter from Dow4 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-Po int Ground Flare Technology The Dow Chemical Company, Texas Operations – Freeport, TX

Dear Ms. Shine:

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

in order to continue with th e evaluation of the subject appr oval requests. The requested

information is contained as an attachment to this letter.

If you have questions or concerns regarding any of the attached informatio n, 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 Pr ograms Division, OAQPS, US EPA, Raleigh, North

Carolina 27711

Penny Lassiter, Group Leader, Sector Polici es and Programs Division, OAQPS, USEPA, Raleigh, North Carolina 277115 Page 1

Area Maps and Informatio n on Distances to Off-Si te 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 th e center of the PDH-1 plant. 2. An aerial picture of the Dow Oy ster Creek complex at Freeport, TX 3. An aerial picture of the Dow Oyster Cree k complex that shows th e approximate location of the pressure-assisted flare sy stems 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. Th e distances from the center of the pressure-assisted flare systems are not the same, but are very close to these distances.

PDH-1 Plant

R eceptor Distance in Feet

Nearest School - Lani er Middle School – Freeport 7,321

Perstorp Co a ting, Inc. 3,591

Ne a rest R esidence (F r eeport – Velasco) 3,613

Ne a rest Prope r ty Line – South 1,167

LHC-9 Plant

Receptor Distance in Feet

Ne a rest School - Vel a sco Ele m entary School 6,748

Ne a rest P a rk - Austin P a r k 6,065

Ne a rest Off-Prope r ty R eceptor (Convenience

Store at the Corner of FM 523 and SH332) 4,113

Ne a rest R esidence Freepo r t, TX 4,748 Nearest Property Line – FM 523 to East 1,898P a ge 2

2 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 fo r the PDH-1 project flare is 51 feet. The height of the heat/radia tion fence for the LHC-9 pr oject 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 mainte nance, start-up, or shutdown, and are also designed to combust vents a ssociated with upset venting. 4. The predominant wind direction at the s ite 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 mo deling show that the predicted off-site concentration for each compound modeled is le ss than 1% of the published TCEQ Effects Screening Level (ESL) for both 1-hour av erage and annual aver age 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 fo llowing 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 us ed to measure the concentration of selected orga nic hazardous air pollutants th at may be included in the vent gas streams vented to each pressure-assi sted flare system. Th e plan will list the compounds covered by the monitoring program. 2. The location(s) of the ambi ent air sample collection points. 3. The frequency of sample collection and analysis.

4. The duration of the ambien t air monitoring program; and

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

3 Responses to Additional Qu estions Regarding Design Fe atures and Power Outages

The purpose of this section is to respond to EPA questions rega rding how the pressure-assisted flare systems would operate during a power failure and also whethe r or not a potential outage of the pressure-assisted flare systems was covered in our Process Hazard Anal ysis assessments. The scenario of loss of pilots, which could cause unb urned hydrocarbons to be released, was evaluated and the main design features to minimi ze the possibility of this occurring are listed below for both flare systems:

 There are two pilots fo r each stage of burners;

 There are two redundant and independent pilo t gas headers to each stage of the flare system. Each stage has one pilot fueled fr om one system and one pilot fueled by the other system. Therefore, a single failure, su ch 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 Di scipline for the PDH-1 plan t will be in place in the event that both pilot gas systems fail where th e 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 (usi ng the PDH-1 plant as example), the flare would function to destroy hydrocarbons as long as either pilot gas or process ve nts 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 stea m or air-assist to pr operly operate. In a total loss of power scenario the plant has some reserve capacity on th e instrument air header to keep pressure for a short period of time, but th e plant would eventually lose instrument air. If instrument air is lost, the flare staging valves would close and the syst em would rely on the buckling pin bypass valves for a flow path to the pressure-a ssisted flare tips, thus the pre ssure-assisted flare system would remain in service. Loss of power is the worst case flaring scenario th at the flare system is designed for in terms of instantaneous quantity an d we expect that the va st majority of flaring would happen early in the event and that the pressu re-assisted flare tips will function normally.P a ge 4

4P a ge 5

Aerial Picture of Dow Chemical O y ster Cree k Complex – Freeport, TX

5 Copyrighted Map RemovedP a ge 6

Aerial Picture of Dow Chemical O y ster Cree k Complex – Freeport, TX

Notes:

The pressure-assisted flare system for the PD H-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 gree n box to the left of the LHC-9 process area. The property lines for the Oyster Creek comple x are noted by the orange, dark blue, light blue and yellow lines. State highway 332 runs pa rallel to the dark bl ue 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 depi cted in the above picture.