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Prairie Parkway Study Fine Particulate Matter (PM2.5) Project Level Hot-Spot Analysis

5.0 PM2.5 Hot-spot Analysis

The Prairie Parkway project meets the criteria set forth in 40 CFR 93. 123(b)(1) for projects of air quality concern primarily because it is a new highway facility with a significant level of diesel vehicles; thereby requiring a hot-spot analysis. The Prairie Parkway maximum 2030 ADT and total daily diesel vehicle traffic are forecasted to be approximately 50,000 and 10,000 (20 percent), respectively. Comparing these values to those cited in the preamble to the conformity rule by EPA as examples of projects of air quality concern - AADT greater than 125,000 AADT and 10,000 trucks per day - indicate this project should be so categorized.

According to 40 CFR §93.123(b)(2) and (4), a quantitative analysis for applicable projects is not required until EPA releases modeling guidance in the Federal Register. However, a qualitative hot-spot analysis is still required. Therefore, a qualitative projectlevel hot-spot assessment was conducted for the Prairie Parkway Preferred Alternative in order to assess whether the project will cause or contribute to any new localized PM2.5 violations, or increase the frequency or severity of any existing violations, or delay timely attainment of the PM2.5 NAAQS.

5.1 Construction Emissions and Re-Entrained Road Dust

40 CFR 93.123(c)(5) states "CO, PM10, and PM2.5 hot-spot analyses are not required to consider construction-related activities which cause temporary increases in emissions. Each site which is affected by construction-related activities shall be considered separately, using established "Guideline" methods. Temporary increases are defined as those which occur only during the construction phase and last five years or less at any individual site."

At this point in time, no project construction schedule for the Prairie Parkway Freeway and associated IL-47 widening exists. It is, however, probable that the freeway facility will be constructed in at least two phases and that IL-47 south of Caton Farm Road will be built at a later date. As such, localized construction emissions can be considered separately and temporary as construction-related emissions at each individual construction site is anticipated to be less than 5 years. Per 40 CFR 93.123(c)(5), temporary construction-related emissions are not required to be included in the hot-spot analysis.

The Conformity Rule requires PM2.5 hot-spot analyses to include road dust emissions only if such emissions have been found significant by EPA or the state air agency prior to the PM2.5 SIP or as part of an adequate PM2.5 SIP motor vehicle emissions budget (40 CFR §93.102(b)(3)). EPA has not approved a PM2.5 SIP for the Metropolitan Chicago Interstate Air Quality Control Region PM2.5 nonattainment area, nor has EPA or the state air agency made any significance findings related to reentrained road dust for the PM2.5 nonattainment area. Therefore reentrained road dust is not considered in the analysis, per the Conformity Rule. In addition, as there is not an applicable PM2.5 SIP for this area, there are no PM2.5 control measures and the project is in compliance with 40 CFR 93.117.

5.2 Existing Conditions

The affected area for the purposes of this analysis is a new freeway corridor (37 miles) between I-88 in southern Kane County traversing Kendall County to I-80 in northern Grundy County and approximately 12 miles along existing IL-47 between Caton Farm Road in southern Kendall County and I-80 in northern Grundy County. Additional details are in the "Draft Environmental Impact Statement Prairie Parkway Study Grundy, Kendall and Kane Counties, Illinois" and associated documentation. This section includes a discussion of currently available information on existing conditions related to air quality and traffic conditions within and near the Prairie Parkway project study area.

5.2.1 Air Quality Monitors

There are no PM2.5 monitors in Kendall County. Figure 2 shows the four PM2.5 monitors closest to the proposed improvement. Available monitoring data for 2002 through 2005 at the Aurora, Elgin, Joliet and Braidwood sites have been published in the "Illinois Annual Air Quality Report 2005"6; and while not yet published, 2006 PM2.5 monitor data have been prepared and provided by the Illinois Environmental Protection Agency for these same sites. These sites are located in Kane and Will counties: the Aurora monitor is generally south of I-88 and west of IL-31; the Elgin monitor is south of I-90 and east of IL-31; the Joliet monitor is north of I-80 and east of IL-7; the Braidwood monitor is south of the I-55/IL-129 interchange. Tables 2 and 3 show 2002 through 2006 monitor data for the PM2.5 24-hour and annual standards at the four monitoring sites listed.

Figure 2 - PM2.5 Monitors Near Proposed Improvement
General road map showing the four closest PM2.5 monitors to the proposed improvements.  From north to south, the monitors are located in Elgin, Aurora, Joliet, and Braidwood.

It is recognized that in 2005, Illinois, as well as other Midwestern and Northeastern states experienced a most unusual air quality episode. This was the first time Illinois had any Air Pollution Action Days outside the ozone season (May through September). February 2 through 4 were so classified due to elevated levels of fine particulate matter(PM2.5). The "Illinois Annual Air Quality Report 2005" directly addresses the unusual 2005 air quality episode stating "Scientists determined that a combination of a stagnating regional air mass and region wide winter fuel combustion was the main cause of this incident".

The Illinois and NAAQS consist of a primary and secondary standard for each pollutant. The primary standard represents the level of air quality which is necessary to protect the public health. The secondary standard defines the level of air quality which is necessary to protect the public welfare. This includes, among other things, effects on crops, vegetation, wildlife, visibility and climate, as well as effects on materials, economic values and on personal comfort and wellbeing. For PM2.5 the primary and secondary standards have the same value. Two averaging times are used for the PM2.5 standard: 24-hour and the annual arithmetic mean. The specific standards for these two averaging times are 65 μg/m3 and 15 μg/m3 for 24hour and annual arithmetic mean respectively.

Data from 2002 through 2006 for the PM2.5 24-hour standard at the four monitoring sites in Table 2 make apparent the uniqueness of the 2005 data. The 2005 anomaly clearly affected the three year averages, but all values still were well below the 65 μg/m3 standard. It should be noted that EPA lowered the applicable standard from 65 μg/m3 to 35 μg/m3 on December 17, 2006; but the 2006 standards are not subject to conformity until one year after the nonattainment designations based on the 2006 standards become effective. Such a designation has not yet been made so the 1997 standard of 65 μg/m3 is applicable for this hot-spot analysis (although at some future time the lower 2006 standard will be applicable).

Table 2 - PM2.5 24-hour Standard Assessment
Violation is a 3-Year Average > 65.0 μg/m3
Site           Average Average Average
  2002 2003 2004 2005 2006 2002 -
2003 -
2004 -
Aurora       43.6 25.4     34.5
Elgin 35.3 34.5 25.8 41.2 29.8 31.9 33.8 32.3
Joliet 33.7 34.5 29.1 45.3 25.9 31.2 35.1 33.4
Braidwood 32.0 27.9 23.6 43.8 21.6 27.8 31.8 29.7

Monitor data for 2002 through 2005 can be found in Appendix B of "Illinois Annual Air Quality Report" for those same years. Monitor
data for 2006 provided by IEPA. Note - Aurora average based only on two years data.

Table 3 shows the annual arithmetic average standard values at the four selected monitor sites for the years 2002 through 2006. Again the unusual results for 2005 stand out, but it is also clear that 2006 values have returned to those for 2004; and that even when the 2005 values are included in the three year averages the results are well below the 15 μg/m3 standard.

Table 3 - PM2.5 Annual Standard Assessment
Violation is a 3-Year Average > 15.0 μg/m3
Site           Average Average Average
  2002 2003 2004 2005 2006 2002 -
2003 -
2004 -
Aurora    15.9 12.7   14.3
Elgin14.3 13.3 11.5 15.7 11.8 13.0 13.5 13.0
Joliet 14.4 13.8 11.9 15.4 12.2 13.3 13.7 13.2
Braidwood 13.5 11.9 10.3 13.2 9.8 11.9 11.8 11.1

Monitor data for 2002 through 2005 can be found in Appendix B of "Illinois Annual Air Quality Report" for those same years. Monitor
data for 2006 provided by IEPA. Note - Aurora average based only on two years data.

5.2.2 Transportation and Traffic Conditions

As noted previously, there are no PM2.5 monitors located in Kendall County, which is where the majority of the project is proposed to be constructed. Furthermore, there is no facility like the proposed improvement in the area. The principal north-south roadway in the area is IL-47, which is primarily a two-lane rural/exurban road. Current traffic levels on IL-47 are for the most part in the 8,000 to 16,000 ADT range with volumes reaching 20,000 in Yorkville and near I-88. The four most proximate PM2.5 monitor locations were the logical starting point to search for traffic conditions similar to that forecast for the Prairie Parkway.

Traffic data at points nearest the four monitor sites were taken from IDOT published Average Daily Total Traffic and Average Daily Heavy Commercial Vehicle (HCV) Traffic maps for 2005. Monitor locations relative to freeway sections and major road interchanges, 2005 ADT and HCV for these road sections, and the combined ADT and HCV at the monitor locations are shown in Table 4. HCV traffic is taken as the best indicator of how much of total traffic is diesel powered vehicles, with the percent share shown below the combined HCV volume. At the four monitor sites combined ADT ranges from slightly more that 40,000 to just over 140,000 and the HCV share between 9% and 20%. Traffic levels for the Prairie Parkway Preferred Alternative are estimated to be between 13,400 and 28,600 near-term, and 23,400 and 50,000 in 2030 the design year. The share of diesel powered vehicles is estimated to be 20%.

Total traffic at three of the four monitor locations is higher than the maximum forecast for the Prairie Parkway, with the Braidwood location traffic level approximating that of the Prairie Parkway Preferred Alternative at its terminal point near I-88 and I-80. Two of the traffic locations have lower HCV shares than the estimated Prairie Parkway diesel share; while HCV shares at the other two traffic locations are slightly higher than the 20% diesel share estimated for the Prairie Parkway.

Table 4 - 2005 Traffic at Selected PM2.5 Monitor Sites
PM2.5 monitor location Roadway2005 ADT 2005 HCV Combined
2005 ADT
2005 HCV
Aurora (0890007)
~0.5 mile south of I-88
and west of IL-31
I-88 57,300 7,300 80,200 9,000
IL-31 22,900 1,700
Elgin (0890003)
~1.2 miles south of I90
and east of IL-31
I-90108,900 10,700 141,700 12,850
IL-31 32,800 2,150
Joliet (1971002)
~1.1 miles north of I-80
and west of IL-7
I-80 76,000 17,400 109,400 19,550
IL-7 33,400 2,150
Joliet (1971002)
~3.6 miles east of I-55
and south of US-52
I-55 62,800 14,80090,400 16,500
US-52 27,600 1,700
Braidwood (1971011)
~1.8 miles south of I-55
at IL-129
I-55 31,2007,200 39,7007,800
IL-129 8,500 600

5.2.3 Built and Natural Environment

The study area is southwest of the Chicago metropolitan area. Development is radiating out from Chicago. Existing land use in the vicinity of the proposed facility is shown in Figure 3. The greatest concentrations of development currently within the study area are in eastern Kane County, in northern Kendall County along US-34, and in the Morris and Minooka areas along I-80 in Grundy County. Much of this area is agricultural. This is expected to change significantly by 2030 when the area will become primarily suburban in character with residential, commercial and industrial uses dominating. The extent of this change is reflected in the land use plans of municipalities near the proposed improvement as shown in Figure 4. In comparison to agriculture as the dominant existing land use, residential, industrial and commercial uses will predominate in the future. The figures depict this land use transformation in the greatly expanded yellow areas representing residential land and reduced green areas representing agricultural uses. In Kendall County, for example, residential land use was 17% of the total county land area in 2000 and is expected to grow to 67% of total county land area by 2030. Conversely, agricultural land is expected to fall from 80% of total county land area in 2000 to 26% by 2030. It should be noted that while the character of this part of the region will change markedly, the affected counties either have already established or are actively working toward programs to protect significant tracts of agricultural lands using agricultural conservation and protection areas, the conservation reserve program and designating centennial farms.

Figure 3 - Study Area Existing Land Use
General map showing current land usage of the area around the proposed improvements. The majority of the land use is agricultural.

Figure 4 - Study Area Planned Land Use
General map showing planned land usage of the area around the proposed improvements. Much of the area is planned for higher residential, commercial, and industrial use.

6 Information extracted from the "Illinois Annual Air Quality Report 2005", Illinois Environmental Protection Agency, Bureau of Air 1021 North Grand Avenue, East, P.O. Box 19276, Springfield, Illinois, 62794-9276; December 2006
Updated: 7/6/2011
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