Letter from EPA Office of Air Quality Planning and Standards to Henry V. Nickel and William L Wehrum of Hunton & Williams setting forth EPA's interpretations of regulatory requirements applicable to potlines at primary aluminum reduction plants during startup under 40 CFR part 63, subpart LL. 

• Clarification of 40 CFR Part 63, Subpart LL Requirements Applicable to Potlines During Startup Periods (PDF)(3 pp, 2 MB, June 17, 2010)