6.3. ERMUSR 10-09-2007 - Laserfiche WebLink

Home Browse Search

Mr. Bryan Adams September 16, 2007 Page 2 AERA (MPCA policy) The most likely threshold for the MPCA requiring the preparation of an Air Emissions Risk Analysis (AERA) is 100 tons/year of any single air pollutant, after installation of air pollution control equipment. Based on our recent experience permitting identical engines at WMI landfills located in Elk River, Glencoe and Lake Mills, the pollutants with the highest emissions will be CO (with potential emissions of between 31 and 35 tons/year per engine) and NOx (with an emission rate of between 15 and 22.5 tons/year per engine). For eight additional engines, we would therefore expect the total CO emissions to be between 248 and 280 tons/year and the NOx emissions to be between 120 and 180 tons/year. The NOx emissions from the proposed project are below the PSD and EAW thresholds but above the AERA threshold. The lower bound CO emissions from the proposed project are just barely below the PSD and EAW thresholds but above the AERA threshold. We suspect that WMI could be comfortable arguing for and accepting a CO emission rate that will keep the project emissions below the PSD threshold of 250 tons/yr. Because the proposed project is occurring only one year after the construction of the fourth engine, it is possible that the MPCA will consider the two projects to be a "phased action" as defined in Minn. R. 4410.0200, subpart 60 and as explained further on page 3 of the EQB's Guide to Minnesota Environmental Review Rules. You may remember that, when permitting the fourth engine, we considered that project and the installation of the first three engines to have been a "phased action". However, since the purpose of the second LFG-to-Energy Plant is to process landfill gas expected to be generated by a landfill expansion that was not foreseen at the time that the fourth engine was permitted, we think there is a strong argument that the proposed project is unrelated to the first LFG-to-Energy Plant and would propose to proceed on that basis. You may recall that considerable effort was made in 2005 to prepare an AERA and its associated Risk Assessment Spreadsheet (RASS) for the ERL facility as part of the air permitting of the fourth engine. The RASS produced risks that narrowly exceeded the risk guidelines but were considered acceptable by the MPCA risk managers. Since then, we have been working with the MPCA to permit aLFG-to-Energy Plant at Glencoe that will house four engines. For that project, the MPCA is proposing to require stack testing of certain air toxics and we anticipate that the MPCA will very likely require similar testing of any future LFG-to-Energy plants. The implications resulting from such testing are unknown at this time and cannot be known until the LFG-to-Energy Plant at Glencoe is constructed and tested. Based on the limited emission factor data available, we do not believe that the project will be a major source of hazardous air pollutants (HAPs). However, it is possible that MPCA-required stack testing or alternative emission calculation approaches imposed by the MPCA could alter this conclusion. For example, the Iowa DNR recently rejected the standard calculations that have been used at all of WMI's Minnesota and Iowa landfills and somewhat arbitrarily assumed that the Lake Mills landfill is a major source of the HAP formaldehyde. Finally, it should be noted that, with the installation of the second LFG-to-Energy Plant, the post-project facility will qualify as a "major source" under NSR. This is important because any future projects will be subject to a PSD threshold of 40 tons/year, rather than 250 tons/year. Scope of Work Barr will perform the following tasks: