Comment submitted by John Hornback, Metro 4, Inc.

Metro 4 represents local air pollution agencies in the Southeast, which have begun their review of the guidance. On behalf of eight local air agencies in Region 4, I request that the comment period for the proposed guidance be extended an additional thirty (30) days to December 1, 2011. The primary reasons for the request for extension of the comment period are: (1) The guidance document is lengthy. (2) A complete review of the guidance document will be resource demanding. (3) The issues addressed by the guidance are of major substance to the requesting agencies and to other interested parties. (4) The requesting agencies wish to have adequate time to present comprehensive, well thought out comments to EPA. Thank you for your consideration.