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Southwest Lake Michigan Pilot Study
Developing an Inventory of Toxic Air Emissions from Area Sources in the Chicago, Milwaukee and Gary Urban Areas, 1993
U.S. Environmental Protection Agency
Pilot Program for Emissions Inventory
Under the Clean Air Act
Sections 112(c), 112(k) and 112(m)
The purpose of the Southwest Lake Michigan (SWLM) Pilot Study was to a) inventory small point and area sources of toxic air emissions from the combined urban areas of Chicago, Gary and Milwaukee (see Figure); b) test the Air Toxics Emissions Inventory Protocol for the Great Lakes States; and c) design and test an automated emissions estimation and data management system that could be used in later years in developing larger, multistate, Great Lakes regionwide inventories.
Importantly, emissions from "major sources," as defined by the Clean Air Act, were not inventoried and estimated and are therefore not documented in the regional summary. Consequently, the ratio of area to major source emissions in the study area is not available and the tables and charts provided herein should not be construed to represent an estimate of total emissions of the subject hazardous air pollutants released in the study area. Under the terms of the Clean Air Act (CAA), which defines major sources in terms of quantity, the sources inventoried in the SWLM study are accurately described as "area sources."
The SWLM study began in October 1993 with primary funding provided by the U.S. Environmental Protection Agency (U.S. EPA). The study built upon four previous years of effort by the Great Lakes states, funded by the states themselves through the Great Lakes Protection Fund.
This report is but one of six products of the SWLM study. The complete product package includes:
The three states that conducted the SWLM study (Illinois, Indiana and Wisconsin) believe that the air toxic emission estimates contained in this report (and in the Southwest Lake Michigan Urban Area Source Inventory housed by the U.S. EPA Great Lakes National Program Office) for the Chicago, Gary and Milwaukee urban areas represent the best single compilation of such estimates. The scope of the project did not allow the states to undertake a massive discovery effort; instead, the states used available 1993 calendar year process data, emission factors and reported information. The SWLM study objective was to enhance current inventory capabilities, resolve procedures and protocol issues across several states, and develop and test an automated emission estimation and inventory system. In the process, the urban area source inventory for the SWLM study area was compiled.
In brief, the pilot study should be viewed as an initial effort to bridge the gap between the science of inventorying toxic air emissions and the public policy debate concerning how these emissions affect human health and the environment and how they should be addressed. Follow-up by U.S. EPA and the states is necessary to make further progress toward meeting the goals of Section 112 of the CAA. The SWLM pilot study states recommend that regulatory decisions not be based on this data unless more compelling research is completed or accessed to warrant such action.
The following are the specific sections of the CAA, as amended in 1990, addressed by the SWLM study:
Section 112(c)(6) Specific Pollutants: Each of the 112(c)(6) pollutants was targeted in the SWLM small point and area source emissions inventory. The objective of this study, in terms of Section 112(c)(6) of the CAA, was to locate small point and area sources of these toxic compounds in the 12-county area. The summary regional tables and charts (beginning on page 28) highlight these emissions and respective area sources. Section 5, Results, provides suggested refinements to the procedures listed in the Air Toxics Emissions Inventory Protocol for the Great Lakes States in order to more accurately estimate total emissions of Polycyclic Organic Matter (POM) and related pollutants.
Section 112(k) Area Source Program: The objective of the SWLM pilot study was to provide the mechanism, procedure and the first compilation of data on emissions from area sources of a targeted list of hazardous air pollutants, including those identified in Section 112(c)(6) of the CAA. The study sought to provide the best compilation of such data for calendar year 1993 emissions from small point and area sources. Section 5 of this report presents the best currently available estimates of area sources for the inventoried toxic air pollutants for calendar year 1993 for the Chicago, Milwaukee and Gary urban areas. This project begins a long-term state and federal effort to categorize emissions from various area sources (and major sources) in the Great Lakes region. The states believe this work will provide the strongest foundation upon which the U.S. EPA can build the national strategy to reduce urban area toxic air emissions as outlined in Section 112(k)(3) of the CAA.
The study focused on the identification of small point and area source categories that contribute the most to the total emissions of hazardous air pollutants listed in Table 2-1. The SWLM study concentrated on locating significant sources not currently regulated under the CAA. These sources include many traditionally unregulated sites with relatively small gas-fired, coal-fired, or oil-fired boilers; asphalt and concrete plants; industries dealing with primary metals (including zinc, aluminum and iron), or secondary metals (primarily used in the processing of refined metals); cultured marble companies; woodburning stoves and fireplaces; non-road engines; and generally, any facility with an incinerator. The focus was on finding many small sources within one county or urban area that collectively release large amounts of one or more toxic air pollutants of concern.
Section 112(m) Great Waters and the Great Lakes Toxic Substances Control Agreement: The Great Lakes states made significant progress toward meeting the goals of the governors' agreement and CAA Section 112(m) by developing the Regional Air Pollutant Inventory Development System (RAPIDS) and testing the Air Toxics Emissions Inventory Protocol for the Great Lakes States. The RAPIDS software, and the accompanying protocol will be used by all eight Great Lakes states in future years to jointly conduct point and area source inventories of the 49 target compounds identified in Table 2-1.
The Air Toxics Emissions Inventory Protocol for the Great Lakes States, finalized in June 1994, provides instructions for the states to follow to ensure the completeness, accuracy, consistency and quality of the regional toxic emissions inventory. Each state prepared its portion of the SWLM pilot inventory in the manner outlined in the protocol, and provided a quality assurance check on their state-specific emissions data and estimates to ensure the highest possible quality database.
Rather than comparing one state's emissions against another state's results, the focus of the pilot study was to prepare a reliable and technically accurate inventory for the southwest Lake Michigan region as a whole, and to outline areas where improvements are needed in overall methodology and implementation.
Development of RAPIDS has been the key to the effort to develop a comprehensive, accurate, and consistent urban area air toxic emissions inventory across three states.
As a multistate, regional effort, a high level of coordination and communication was necessary to ensure consistency among the three states in terms of data management, methodology, calculation methods, and other issues. To facilitate the necessary communication on these issues, a Southwest Lake Michigan Pilot Study Subcommittee was established by the Great Lakes Commission's Regional Emission Inventory of Toxic Air Contaminants Steering Committee. During the course of the SWLM study, the subcommittee communicated via daily e-mail exchanges, conference calls on a weekly or biweekly basis, and monthly or bimonthly in-person meetings to oversee contractor development of the inventory software, and to resolve outstanding issues and inconsistencies among the three states contributing to the pilot study.
During the course of this study, the Southwest Lake Michigan Subcommittee worked closely with the project software development contractor, Radian Corporation, to develop and test RAPIDS. The effort represents the first attempt to prepare software for estimating toxic pollutant emissions on a multistate basis. RAPIDS is a client/server system consisting of an ORACLE7 back-end database designed using ORACLE CASE tools, and a "suite" of front-end applications developed using various software tools (primarily PowerBuilder7 and SAS7). The software takes full advantage of new Internet/Great Lakes Information Network (GLIN) connections between the states, Great Lakes Commission, and the U.S. EPA GLNPO office in Chicago.
Finally, a Quality Assurance/Quality Control (QA/QC) Committee was formed to review the pilot study report, establish QA/QC criteria for use by the three states, and ensure the report provides an accurate and useful summary of toxic air emissions at the regional level.
The tables and charts presented in Section 4, Results, provide the results of the regional inventory for the southwest Lake Michigan pilot study area. It is important to note that, as a pilot study, the subcommittee has refrained from interpreting the results or from drawing major conclusions that might have policy implications. In addition, the subcommittee finds that, beyond the actual results, the process of compiling the regional inventory has, itself, proven extremely valuable as a means of resolving the many technical, methodological, and policy-related issues that impact a multistate, regional toxic air emissions inventory. The U.S. EPA GLNPO office serves as the repository for the Southwest Lake Michigan Urban Area Source Inventory. Small point and area source toxic air emissions data collected by Illinois, Indiana and Wisconsin reside in the repository. Internet access to the inventory, using the RAPIDS client software, is available to select researchers.
One important outcome is that the SWLM pilot study illustrated the serious shortcomings that still exist in regional emissions estimates (see regional results page 28), and suggested necessary steps that must be made to ensure data quality for estimating various pollutant groupings (see Section 5, Conclusions). A significant contribution to the goals of CAA section 112(c)(6) relates to the identified need for better methodology for use in next year's full eight-state regional inventory.
The SWLM pilot study emissions inventory for small point and area sources in the Chicago, Milwaukee and Gary urban areas are summarized in the following tables and figures beginning on page 28:
Table 4-1: Regional Summary of Pollutant Emissions, by State and Region, for all Inventoried Sources in the Southwest Lake Michigan Pilot Project Study Area, 1993.
Table 4-2: Regional Toxic Air Emissions by Inventoried Source for the Southwest Lake Michigan Pilot Project Study Area, 1993.
Figures 4-6 through 4-35: Estimated Emissions from Small Point and Area Sources in the Southwest Lake Michigan Study Area, 1993.
Working together on this pilot project, the Great Lakes states, and particularly the lead states of Illinois, Indiana, Wisconsin and Michigan, have set a national example of cooperative emissions inventory development across states. The efforts the state air agencies are undertaking together in this project, supported by U.S. EPA, are unprecedented.
An important result from the SWLM pilot inventory is that the states have learned how to conduct a multistate inventory and are now poised to prepare a successful regionwide, eight-state effort.
On behalf of: