Approval and Promulgation of Implementation Plans; State of Missouri

EPA is taking direct final action to approve Missouri's request to revise the State Implementation Plan (SIP). This approval will revise the SIP to include changes to the sulfur dioxide (SO2) emissions rates and averaging times for Kansas City Power & Light's Hawthorn Plant and Montrose Station in the rule, Restriction of Emission of Sulfur Compounds. Previous changes to this rule were disapproved in 2006 because EPA was concerned that the averaging times for the rates at these units had been dramatically increased from a 3-hour average to an annual average, and that the revised averaging times were not demonstrated by the state to be protective of the short-term (3- and 24-hour) SO2 National Ambient Air Quality Standard (NAAQS). EPA believes that the recent changes, which EPA is now approving, have been shown by Missouri to be protective of the short-term SO2 NAAQS. This revision will ensure consistency between the state and the Federally-approved rules.