Approval and Promulgation of Air Quality Implementation Plans; Indiana

EPA is approving revisions to the Indiana particulate matter (PM10) State Implementation Plan (SIP). These revisions are for sources at the ASF Keystone, Inc. (Keystone) coil spring manufacturing facility in Lake County, Indiana. On December 15, 2005, Indiana requested revisions that will increase the PM10 emission limit for one unit and reduce the limits for two units. The changes result in a net decrease of 1.77 pounds PM10 per hour (lb/hr) in the allowable emissions. The emission limits for a fourth unit that has shut down were also removed. Indiana also requested removing the process weight rate limits and using lb/hr as the short-term emission limit. The maximum permissible PM10 emissions will not increase after removing the process weight rate limits because of the net decrease in short-term emission limits.