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**MEMORANDUM** Date: July 23 , 2014 Subject: Report of June 24 , 2014 Site Visit to Dow Chemical, in Freeport Texas From: Alden West, EC/R Incorporated

Lesley Stobert, EC/R In corporated To: Paula Hirtz, EPA/OAQPS This memo randum summarizes the visit to the Dow Chemical facility in Freeport , Texas that was conducted on June 24, 2014 . The purpose of this visit was to better understand the processes used in the Offsite W aste and Recovery Operations (OSWRO) industry , the controls in place to reduce hazardous air pollutants (HAP) emissions, and the characteristics of the emission points at this facility . This information will assist the EPA in the promulgation of amendments to the emission standards for the OSWRO industry . A background discussion of this project is provided, followed by an overview of the plant, a description of the off

- site waste operations at the facility , and a summary of emission sources at the facility . T he final section includes a summary of action items resulting from the meeting with Dow. The participants in the site visit included the following:

Russell Wozniak, Dow Kyle Graham , Dow Maria Valdez , Dow Paul Li ndon , Dow Mark Kuettel , Dow Jeana Schanzer , Dow Elaine Schroe der , Dow Paula Hirtz , U.S. EPA/OAQPS Lesley Stobert , EC/R Incorporated Alden West , EC/R Incorporated **BACKGROUND** Section 112(d) of the Clean Air Act requires the EPA to develop standards for each major source category list ed under section 112(c). These technology- based standards are often referred to as maximum achievable control t echnology , or MACT, standards. The National Emissions Standards for Hazardous Air Pollutants (NESHAP) for Off - site Waste and Recovery Operations (OSWRO) were promulgated on July 1, 199 6 ( 61 FR 34139 ) and codified at 40 CFR part 63, subpart DD . Th e Dow Chemical facility in Freeport, TX is subject to subpart DD because itNON - CBIVERSION

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receives certain wastes from off - site locations for storage and treatment, recovery or disposal. Section 112 of the Clean Air Act contains provisions requiring the EPA to periodicall y revisit the technology- based standards. Specificall y, section 112(d)(6) states that the EPA shall review these standards and revise them “as neces sary (taking into account developments in practices, processes, and control technologies)” no less fre quently than every

eight years. The second stage in the review process focuses on reducing any remaining (i.e., “residual”) risk according to CAA section 112(f). Section 112(f)(2) directs the EPA to assess the risk remaining (residual risk) after the application of MACT standards and promulgate additional standards as necessary to provide an ample margin of safety to protect public health, or to prevent, ta king into consideration costs, energy , safety, and other relevant factors, an adverse environmental impact. On May 30, 2014, the EPA proposed amendments to the OSWRO MACT standards to address the results of the residual risk and technology review (RTR) con ducte d under the Clean Air Act. A site visit of the Dow Chemical facility was conducted to better understand the current processes and control technologies in the OSWRO industry before promulgation of final amendments to the OSWRO MACT standards. As part of the RTR process, the EPA is seeking additional information to improve the Agency ’s understanding of the OSWRO processes and emission points, to improve the data used in site - specific emission profiles and to better characterize the maximum risks to surrounding populations as a result of activities at OSWRO facilities . Further , the May 30, 2014 proposal includes new provisions that may change the way certain OSWRO sources are required to operate . This site visit was conducted to better understand the technical and operational implications of these changes based on current processes observed at the facility and discussions with facility personnel . **PLANT SITE OVERVIEW** The Dow Chemical facility covers 20 square miles south of Houston in Freeport, Texas. The facility consists of 4 plants

– Plant A, Plant B, Stratton Ridge, and Oy ster Creek

– each with a variety of operations related to the production of chemical products and precursors. Plant B is the largest of the four plants in both size and number of production units, and is also the only plant that receives and processes offsite waste . Dow Freeport is currently undergoing an expansion and plans to add or has recently added multiple units, including a prop yl ene production facility , an ethylene cracker, an agrosciences plant, a chlor- alkali unit, and two plastics/polyethyl ene plants. This facility is a major source of HAP. In addition to the OSWRO MACT standards , OSWRO related operations located at Plant B are also subject to numerous other MACT regulations, including:  Benzene Waste NESHAP  Organic Liquids Distribution NESHAP  Hazardous Organic NESHAP (HON)  Misc ellaneous Organic Chemical Production and Processes (MON)  Hydrochloric Acid Production NESHAP  Hazardous Waste Combustion NESHAP  Pesticide Active Ingredient Production NESHAPNON - CBIVERSION

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 Site Remediation NESHAP **PROCESS DESCRIPTION** [process description information claimed as confidential business information by Dow] **EMISSION SOURCES** Emission sources subject to the OSWRO MACT standards at the B - 3300 kiln and the B - 800 thermal oxidizer units include tanks, containers, fugitives, transfer s y stems and control devices. Storage tank emissions can occur from the evaporation of li quid wastes placed in the tank. The storage tanks at Dow are equipped with fixed roofs t o reduce evaporation of tank contents to the atmosphere. Tanks are also equipped with vents that provide relief from fluctuations in pressure resulting from normal operating conditions such as filling/emptying and changes in atmospheric temperature. Vapors released b y the pressure vents on the tanks at B - 3300 are vented to the kiln afterburner and v apors from the tanks at B - 800 are vented to the thermal oxidizer . The kiln and the thermal oxidizer are considered control devices under the OSWRO MACT standards , and there are no flares or other control devices on the OSWRO processes at the facility . All s torage tanks are equipped with PRDs that will emit to the atmosphere if the tank internal pressure exceeds the device threshold setting for safe handling of liquid waste. Containers that store offsite waste materials are another emission source at the facility . S maller containers are stored in a package facility that is open to the atmosphere and roll - off boxes are stored outside. All containers at the facility are controlled by

a cover and closure device (e.g., a lid on a drum or secured tarp on a roll - off box ). Additional emissions from containers can occur if a cover is removed for sampling or other purposes. Dow operates numerous valves, pump seals, flanges , open - ended lines, and other equipment components that could leak haz ardous vapors to the atmosphere. Dow has opted to comply with the HON leak detection and repair (LDAR) requirements as provided for in the OSWRO MACT standards (40 CFR §63.691 (b)(2)). All components included in an LDAR monitoring program are phy sically tag ged . Transfer s ys tems are a potential source of emissions at Dow and are subject to the OSWRO MACT standards . Transfer s ys tems operated at the facility include pumps, such as those used to transport liquid waste from trucks at direct burn areas to the kiln , and conveyors, which are used to transport solid waste to the kiln. **ACTION ITEMS** Dow agreed to look into the level of mercury emissions from OSWRO operations at their facility . No specific action or time period was discussed .