On 3 January 2007 at 72 FR 26, EPA promulgated revisions to 40 CFR Part 63 Subpart HH to include Area Sources within the rule. This rule applies to emissions of benzene from triethylene glycol (TEG) dehydrators located at upstream oil and gas producing facilities and gas plants, which are not Major Sources. Area Source TEG dehydrators are placed into one of four groupings. 1) Black oil facilities, exempted from the rule. 2) Exempted facilities, not controlled because of low volume throughput. 3) Facilities Within UA plus offset and UC, e.g., TEG dehydrators located in Urbanized Areas (UA), plus a two-mile buffer zone (Offset) around each Urbanized Area, plus Urban Clusters (UC) containing ≤ 10,000 people, and 4) TEG dehydrators located outside of UA plus offset and UC.

For purposes of compliance, the term, Urban-1 County, appears in the rule and defined as a county containing a large Metropolitan Statistical Area. Most existing TEG dehydrators must implement the rule by January 2007. New TEG dehydrators must implement the rule before startup.

U.S. Census Bureau defines Urban Cluster as an urban area containing 2500 persons. Accordingly, the U.S. Census Bureau does not provide maps for Urban Cluster data in the "EPA 10,000 person" format. Therefore, API developed a computer program for locating dehydrators relative to the UA plus offset and UC. The computer method has not been implemented, because; no operator was willing sponsor the website. Accordingly, this paper provides a manual method of determining if a dehydrator is within or outside an UA plus offset and UC.

Area Source dehydrator emissions controls depend on facility location and throughput or emissions. Emissions controls range from doing nothing, to optimizing TEG flow rates, to add-on control equipment. Affected TEG dehydrators within UA plus offset and UC areas are required to install benzene emission control equipment and provide automatic surveillance recording. TEG dehydrators outside of the UA plus offset and UC areas must operate dehydrators at or less than the optimum glycol flow rates developed by EPA or decrease emissions to below 1-ton per year. It is doubtful if small operators are in compliance. The paper demonstrates the EPA "optimum glycol flow rate" proposal is so impractical as to be impossible to implement in the field.

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