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Eagan, Minnesota Technical Support Document

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Definition of important terms used in this document: 

1) Designated “unclassifiable” – an area where EPA could not determine if there was a 

violation of the 2008 lead NAAQS or a contribution to a violation in a nearby area, because there 

was insufficient air quality data for both 2006-2008 and 2007-2009 and where additional 

monitoring data for 2010 could not result in a different designation. 

2) Designated “attainment” – an area which EPA has determined, based on the most recent 3 

years of certified air quality data from 2006-2008 or 2007-2009, has no violations of the 2008 

lead NAAQS during 36 consecutive valid 3-month site means; and which EPA has further 

determined does not contribute to a violation of the 2008 lead NAAQS in a nearby area and that 

additional monitoring data from 2010 could not result in a different designation. 

3) Designated “nonattainment” area – an area which EPA has determined, based on a State 

recommendation and/or on the technical analysis included in this document, has a violation of 

the 2008 lead NAAQS during the most recent 3 consecutive years of quality-assured, certified air 

quality data. 

4) Prior nonattainment area – an area that is currently designated as nonattainment or 

maintenance for the 1978 lead NAAQS (including both current nonattainment areas and 

maintenance areas). 

5) Recommended nonattainment area – an area a State or Tribe has recommended to EPA be 

designated as nonattainment.

6) Violating monitor – an ambient air monitor whose design value exceeds 0.15 micrograms per 

cubic meter (ug/m3). As described in Appendix R of part 50, a violation can be based on either 

Pb-TSP or Pb-PM10 data and only 3 months of data are necessary to produce a valid violating 

design value. 

7) 1978 lead NAAQS – 1.5 μg/m3

, National Ambient Air Quality Standard for lead promulgated 

in 1978. Based on Pb-TSP indicator and averaged over a calendar quarter. 

8) 2008 lead NAAQS – 0.15 μg/m3

, National Ambient Air Quality Standard for lead 

promulgated in 2008. Based on Pb-TSP indicator and a 3-month rolling average. Pb-PM10 data 

may be used in limited instances, including to show nonattainment. 
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MINNESOTA 

Area Designations For the 

2008 Lead National Ambient Air Quality Standards 

EPA has revised the level of the primary (health-based) standard from 1.5 micrograms per cubic 

meter (μg/m3) to 0.15 μg/m3 measured as total suspended particles (TSP). EPA has revised the 

secondary (welfare-based) standard to be identical in all respects to the primary standard.

Pursuant to section 107(d) of the Clean Air Act, EPA must designate as “nonattainment” 

those areas that violate the NAAQS and those nearby areas that contribute to violations. 

The table below identifies the partial county in Minnesota that EPA is designating as 

“nonattainment” for the 2008 lead National Ambient Air Quality Standard (2008 lead NAAQS). 

Area (listed 

alphabetically) 

Minnesota 

Recommended 

Nonattainment 

Counties 

EPA’s Designated 

Nonattainment 

Counties 

Nonattainment 

Area for 1978 

Lead NAAQS 

Eagan Dakota (partial) Dakota (partial) Eagan (partial) 

Table 1: Minnesota Nonattainment Area for the 2008 Lead NAAQS 

Technical Analysis for Eagan

Introduction 

This technical analysis for Eagan identifies the partial county with a monitor that violates the 

2008 lead NAAQS and evaluates nearby counties for contributions to lead concentrations in the 

area. EPA has evaluated these counties based on the weight of evidence of the following factors 

recommended in previous EPA guidance: 

• Air quality in potentially included versus excluded areas; 

• Emissions and emissions-related data in areas potentially included versus excluded from 

the nonattainment area, including population data, growth rates, and patterns and 

emissions controls; 

• Meteorology (weather/transport patterns); 

• Geography/topography (mountain ranges or other air basin boundaries); 

• Jurisdictional boundaries (e.g., counties, air districts, reservations, etc.); and 

• Any other relevant information submitted to or collected by EPA (e.g., modeling where 

done appropriately). 
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Figure 1: Eagan, Minnesota State Recommended Nonattainment Area 

(Office of Air Quality and Planning Standards - OAQPS) 

Figure 1 is a map of the area analyzed showing the locations and design values of air quality 

monitors in the area, and the counties surrounding any violating air quality monitors. Source 

data is also labeled in Figure 1 with the following guidelines: if the source emitted 0.5 or more 

tons, the symbol, name of the facility, and emissions are labeled; if the source emitted 0.1 – 0.5 

tons, only the symbol and emissions are labeled; and if the source emitted less than 0.05 tons, 

only the symbol is shown.1 Emissions in Eagan and the surrounding areas will be discussed in 

the section addressing emissions in Dakota. The location of the detailed area in relation to the 

remainder of the State is shown in the bottom right corner of the figure.

 

1

 Emissions greater than 0.05 tpy round up to 0.1 tpy, and they are marked with the symbol and the emissions value. 

* Sources that are not labeled emitted less 

than 0.05 tpy. 
Copyrighted page(s) have been removed from 

this document. 

Please contact the EPA Docket Center, Public 

Reading Room to view this document. 

Address: 

1301 Constitution Ave, NW 

Room 3334 

Washington, DC 20004 

Telephone: 

202-566-1744 

Fax: 

202-566- 9744 

Email: 

docket-customerservice@epa.gov
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Federal Equivalent Method (FEM) monitors located in the State. Paul Eger, Commissioner of 

the Minnesota Pollution Control Agency (MPCA), submitted the State’s recommendation to 

EPA in a letter dated October 15, 2009. 

Based on EPA’s technical analysis described below, EPA is designating the same partial county 

as previously designated for the 1978 lead NAAQS as nonattainment for the 2008 lead NAAQS 

as part of the Eagan nonattainment area, based upon currently available information. This 

county is listed above in Table 1. 

Detailed Assessment

Air Quality Data 

This factor considers the lead design values (in μg/m3) for air quality monitors in Dakota County 

in Eagan and the surrounding area based on data for the 2006-2008 and 2007-2009 period. A 

monitor’s design value indicates whether that monitor attains a specified air quality standard. 

The 2008 lead NAAQS are met at a monitoring site when the identified design value is valid and 

less than or equal to 0.15 μg/m3. A design value is only valid if minimum data completeness 

criteria are met. A lead design value that meets the NAAQS is generally considered valid if it 

encompasses 36 consecutive valid 3-month site means (specifically for a 3-year calendar period 

and the 2 previous months). For this purpose, a 3-month site mean is valid if valid data were 

obtained for at least 75 percent of the scheduled monitoring days in the 3-month period. A lead 

design value that does not meet the NAAQS is considered valid if at least one 3-month mean that 

meets the same 75 percent requirement is above the NAAQS. That is, a site does not have to 

monitor for 3 full calendar years in order to have a valid violating design value; a site could 

monitor just 3 months and still produce a valid (violating) design value. 

County State 

Recommended 

Nonattainment? 

Monitor Name Monitor Air 

Quality 

System ID 

Monitor Location Lead Design 

Value, 

2006-2008 

(μg/m3) 

Lead Design 

Value, 

2007-2009 

(μg/m3) 

Dakota, 

Minnesota 

Yes Eagan, MN 

Gopher 

Resource 

Corporation 

270370465 149th and 

Yankee Doodle 

Rd. 

0.70 0.70 

Monitor in bold has the highest 2006-2008 and 2007-2009 design value in the respective county. 

Table 2: Eagan, Minnesota and Surrounding Areas Air Quality Data

Dakota County shows a violation of the 2008 lead NAAQS. Therefore some area in this county 

and possibly additional areas in surrounding counties must be designated nonattainment. 

However, the absence of a violating monitor alone is not a sufficient reason to eliminate nearby 

counties as candidates for nonattainment status. Each area has been evaluated based on the 

weight of evidence of these factors and other relevant information. 
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According to EPA’s monitor locator,2 the monitor located at 149th and Yankee Doodle Rd. (AQS 

ID 270370465) has an objective for determining the highest concentration of lead. This monitor 

is in close proximity to Gopher Resource Corporation (GRC). GRC is a secondary lead smelter, 

and the emissions from this facility will be discussed in the section addressing emissions in 

Dakota County. There are 5 other lead monitors in Dakota County, the closest of which is 4.83 

miles away from GRC. The AQS ID for this monitor is 270370423, and the design value for this 

monitor for 2006 – 2008 is 0.005 μg/m3, or 1/30th of the NAAQS. 

Emissions and Emissions-Related Data 

Evidence of lead emissions sources surrounding a violating monitor are an important factor for 

determining whether a nearby area is contributing to a monitored violation. For this factor, EPA 

evaluated county level emission data for lead and population data. 

Emissions 

Emissions data were derived from the 2005 National Emissions Inventory (NEI), version 2, 

which is the most up-to-date version of the national inventory available when these data were 

compiled for the designations process in 2009. See

http://www.epa.gov/ttnchie1/net/2005inventory.html. EPA recognizes that for certain counties, 

emissions may have changed since 2005. For example, certain large sources of emissions in or 

near this area may have installed emission controls or otherwise significantly reduced emissions 

since 2005. Some States provided updated information on emissions and emission controls in 

their comments to EPA. Minnesota did not provide updated emissions information, therefore 

EPA relied on the 2005 NEI emissions data, which are provided in Table 3. 

Table 3 shows total emissions of lead given in tons per year (tpy) for violating and potentially 

contributing counties in and around Eagan and sources emitting (or anticipate to contribute) 0.1 

ton per year of lead or more according to the 2005 NEI. The county that is part of the Eagan 

nonattainment area for the 2008 lead NAAQS is shown in boldface. 

There are approximately 20,000 airport facilities in the U.S. at which leaded aviation gasoline is 

consumed. To evaluate the potential impact of emissions at and near these facilities, EPA 

recommends that States use the draft 2008 NEI. These data are provided in Table 4, and contain 

the facilities emitting (or anticipate to contribute) 0.1 ton per year or more of lead according to 

the draft 2008 NEI. 

 

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 http://www.epa.gov/air/data/geosel.html. 
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County 

Facility in State 

Recommended 

Nonattainment Area? Facility Name 

2005 NEI 

(tpy) Location City 

Dakota, 

Minnesota Yes 

Gopher Resource 

Corporation 3.2 

3385 S. 

Highway 

149 Eagan 

Dakota, 

Minnesota No 

Rosemount 

Aerospace Inc - 

Burnsville 0.6 

14300 

Judicial Rd. Burnsville 

Dakota, 

Minnesota No 

Endres Processing 

LLC 0.3 

13420 

Courthouse 

Blvd. Rosemount 

Dakota, 

Minnesota No 

Seneca 

Wastewater 

Treatment Plant 0.1 

3750 Plant 

Rd. Eagan 

Dakota, 

Minnesota No 

Flint Hills 

Resources LP 0.1 

12555 Clark 

Rd. Rosemount 

 

Dakota County 

Total Lead 

Emissions 4.8* 

 

Table 3: Eagan, Minnesota and Surround Areas Lead Emissions for Stationary Sources 

* Total lead emissions for Dakota County were calculated by adding the 2005 NEI data for facilities not using 

leaded aviation gas to the 2008 Draft NEI data for facilities using aviation gas. Sources with emissions below 0.1 

tpy were included in this final calculation. 

City Facility Name Type 

2008 Draft 

NEI (tpy) 

Distance to NA 

area (km) 

Minneapolis Airlake Airport 0.2 22.13 

South St Paul 

South St Paul Muni-Richard E 

Fleming Field Airport 0.1 5.06 

Table 4: Eagan, Minnesota and Surrounding Areas Lead Emissions for Leaded Aviation Gas Facilities 

According to the 2005 NEI data, there are 5 sources that emit 0.1 ton per year or greater of lead. 

The greatest of these is GRC, which EPA observes accounts for 3.2 tons out of 4.8 tons, or 66.7 

percent of all lead emissions in Dakota County (refer to Table 3). In addition to continued 

monitoring at GRC, 2 new monitors commenced operation in January 2010 at, or in close 

proximity to, stationary sources. These sites include: Federal Cartridge Company - Anoka 

(Anoka County) and Grede-St Cloud Inc (Stearns County). EPA has taken comment on a 

proposal to lower the emissions threshold for monitoring requirements from 1.0 ton per year to 

0.5 ton per year (74 FR 69050). If the final rulemaking requires monitors at sites that emit 0.5 

ton per year or greater of lead, a monitor at Rosemount Aerospace, Inc may be required in the 

future.3

 Lastly, recent stack testing at Dotson Company Inc (Blue Earth County) shows much 

lower emissions that previously thought, and MPCA intends to apply for a waiver under final 

promulgation of revisions to monitoring requirements (74 FR 69050). 

 

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 Communication with MPCA staff in April 2010 indicates that the most recent emissions inventory data for 

Rosemount Aerospace is in actuality, only 0.01 tpy. 
Copyrighted page(s) have been removed from 

this document. 

Please contact the EPA Docket Center, Public 

Reading Room to view this document. 

Address: 

1301 Constitution Ave, NW 

Room 3334 

Washington, DC 20004 

Telephone: 

202-566-1744 

Fax: 

202-566- 9744 

Email: 

docket-customerservice@epa.gov
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County State 

Recommended 

Nonattainment? 

2008 

Population 

2008 

Population 

Density 

(pop/sq mi) 

Population 

Change 

2000-2008 

Population % 

Change 

2000-2008 

Dakota, 

Minnesota 

Yes 

392,755 672 34,905 10 

Table 5: Population Data for Dakota County, Minnesota 

[Source of data: U.S. Census Bureau estimates for 2008 

(http://www.census.gov/popest/datasets.html) and estimation of the area of U.S. counties] 

EPA has considered the population growth rate for this area and does not believe that it affects 

the boundary recommendation.

Emissions Controls

Under this factor, the existing level of control of emission sources is taken into consideration. 

The emissions data used by EPA in this technical analysis and provided in Table 3 represent 

emissions levels taking into account any control strategies implemented in Eagan before 2005 on 

stationary sources. EPA has received additional information on emissions reductions resulting 

from controls put into place since 2005. 

MPCA included a comprehensive description of action items that were taken at GRC in 2009. 

These action items included emissions and procedure control measures for the blast furnace 

penthouse, the material transfer room, and the afterburner tower. The cost of the reductions 

project (as of October 2009) was $2,250,000, and included the addition of 2 new negative 

pressure units, hoods, and enclosures. EPA is currently reviewing the permit associated with this 

project. It is MPCA’s intention to submit the details of this project as a SIP pending final permit 

issuance. GRC is also in the process of addressing several other smaller priority action items 

pertaining to kettle combustion vents, roadways, the warehouse and plastics building, the 

maintenance shop, and other various housekeeping issues. A description of remediation work 

performed at GRC from 1994 to 2008 was also included in MPCA’s submittal. 

Meteorology (weather/transport patterns) 

For this factor, EPA considered data from National Weather Service instruments and other 

meteorological monitoring sites in the area. Historical wind direction frequencies collected 

between 1960 and 1992 are included in Figure 5 and Table 6. These data may provide evidence 

of the potential for lead emissions sources located upwind of a violating monitor to contribute to 

ambient lead levels at the violation location. 
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Figure 4: Historical Wind Direction Frequencies for Dakota County, Minnesota 

Figure 4 is a 3-dimensional bar chart that shows the wind frequencies in 8 directions for the 4 

seasons. These data are taken from 1960-1992 Solar and Meteorological Surface Observation 

Network information issued jointly by the U.S. Department of Commerce: National Climatic 

Data Center and the U.S. Department of Energy: National Renewable Energy Laboratory. The 

chart frequencies reflect the directions from which the winds come. 
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Dakota County 

Wind Frequencies 

Frequency as a % 

Seasonal Wind 

Directions 

8.43 WINWINDFNNE 

5.45 WINWINDFENE 

10.33 WINWINDFESE 

10.47 WINWINDFSSE 

14.40 WINWINDFSSW 

13.85 WINWINDFWSW 

22.16 WINWINDFWNW 

14.91 WINWINDFNNW 

13.30 SPRWINDFNNE 

9.59 SPRWINDFENE 

15.17 SPRWINDFESE 

13.28 SPRWINDFSSE 

13.07 SPRWINDFSSW 

8.07 SPRWINDFWSW 

13.64 SPRWINDFWNW 

13.88 SPRWINDFNNW 

9.89 SUMWINDFNNE 

6.64 SUMWINDFENE 

12.70 SUMWINDFESE 

16.36 SUMWINDFSSE 

20.61 SUMWINDFSSW 

11.04 SUMWINDFWSW 

13.03 SUMWINDFWNW 

9.71 SUMWINDFNNW 

10.08 AUTWINDFNNE 

5.12 AUTWINDFENE 

11.19 AUTWINDFESE 

15.10 AUTWINDFSSE 

18.31 AUTWINDFSSW 

10.67 AUTWINDFWSW 

16.57 AUTWINDFWNW 

12.96 AUTWINDFNNW 

Table 6: Historical Wind Frequency Data as Percents for Dakota County, Minnesota 

As shown in Figure 5 and Table 6, the period with the highest wind frequency occurs in the 

winter months, with winds blowing from the west northwest. With the consistently strong 

representation of winds from the west northwest, and a variation of the west in all seasons, 

special care must be made when determining the nonattainment boundary to the east of the 

violating monitor. 
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Geography/topography (mountain ranges or other air basin boundaries) 

The geography/topography analysis evaluates the physical features of the land that might have an 

effect on the air shed and, therefore, on the distribution of lead over Eagan and the surrounding 

area. 

The Eagan area does not have any geographical or topographical barriers significantly limiting 

air pollution transport within its air shed. Therefore, this factor did not play a significant role in 

determining the nonattainment boundary. 

Jurisdictional boundaries 

Existing jurisdictional boundaries may be helpful in articulating a boundary for purposes of 

nonattainment designations, and for purposes of carrying out the governmental responsibilities of 

planning for attainment of the lead NAAQS and implementing control measures. These existing 

boundaries may include an existing nonattainment or maintenance area boundary, a county or 

township boundary, a metropolitan area boundary, an air management district, or an urban 

planning boundary established for coordinating business development or transportation activities. 

In EPA’s August 21, 2009 guidance memorandum, “Area Designations for the 2008 revised 

Lead National Ambient Air Quality Standard,” EPA reiterated that the presumptive boundary for 

each nonattainment area should be the county containing the violating monitor. This concept 

was first introduced in the guidance for the 1978 lead NAAQS designations, and is described in 

the 1992 General Preamble (57 FR 13549). This same presumptive boundary guidance was 

addressed most recently in the final rulemaking for the 2008 lead NAAQS (73 FR 66964). EPA 

observed, however, that States have the flexibility in their recommendations to deviate from the 

presumptive county boundary to portions of the county containing the violating monitor, stating 

that any “nonattainment area boundaries that deviate from presumptive county boundaries should 

be supported by an assessment of several factors...,” all of which have been discussed already in 

this document, except for jurisdictional boundaries. 

MPCA has recommended that the same portions of Eagan in Dakota County that were previously 

designated as nonattainment for the 1978 lead NAAQS (and current maintenance area) be 

designated as nonattainment for the 2008 lead NAAQS. As EPA performed comprehensive 

analyses of the nonattainment boundary for the designations under the 1978 lead NAAQS, the 

current maintenance area is an acceptable reference point. However, the existing maintenance 

area by itself isn’t a true “jurisdictional boundary,” as it can be perceived to be artificial. For the 

Eagan area, there are several jurisdictional areas that can be considered for this factor. Eagan is 

located in Dakota County, which is part of the Minneapolis-St Paul (Twin Cities) 7-county 

metropolitan area. Specifically, the portion of Eagan that has been recommended as 

nonattainment for the 2008 lead NAAQS lies in District 15 of the Metropolitan Council. As a 

result, air quality planning efforts to address the impending lead nonattainment area in Eagan 

should not be problematic; it should be noted that the final rulemaking for the 2008 lead NAAQS 

(73 FR 66964) specifically addressed transportation conformity by stating, “In light of the 

elimination of lead additives from gasoline, transportation conformity does not apply to the Lead 

NAAQS.” Lastly, MPCA has recommended the nonattainment area be enclosed by well-known 
Copyrighted page(s) have been removed from 

this document. 

Please contact the EPA Docket Center, Public 

Reading Room to view this document. 

Address: 

1301 Constitution Ave, NW 

Room 3334 

Washington, DC 20004 

Telephone: 

202-566-1744 

Fax: 

202-566- 9744 

Email: 

docket-customerservice@epa.gov
16

Conclusion

After considering the factors described above, EPA has determined that it is appropriate to 

include a portion of Dakota County as nonattainment for the 2008 lead NAAQS. 

The air quality monitor in Dakota County shows a violation of the 2008 lead NAAQS, based on 

2006-2008 and 2007-2009 air quality data. GRC is located in the city of Eagan, and this facility 

accounts for 66.7 percent of all lead emissions in Dakota County; there are no other major lead 

emitters in close proximity to the violating monitor. The final and consistent outcomes of the 

emissions control project have not been realized yet, though there is indication that the rolling 

3-month averages have decreased after August 2009. The cumulative process of this factors 

analysis in conjunction with the other relevant information that MPCA provided ultimately leads 

to the final nonattainment area. EPA finds it appropriate to designate the portions of Dakota 

County that are encompassed by: Lone Oak Rd. (County Rd. 26) to the north, County Rd. 63 to 

the east, Wescott Rd. to the south, and Lexington Ave. (County Rd. 43) to the west as 

nonattainment for the 2008 lead NAAQS. Based on the consideration of all the relevant and 

available information, as described above, EPA believes that the boundaries described herein 

encompass the entire area that does not meet (or that contributes to ambient air quality in a 

nearby area that does not meet) the 2008 lead NAAQS. 

On June 15, 2010, EPA communicated to Minnesota that we were proposing to adopt the State’s 

recommended nonattainment designation and boundaries for the Eagan area. A subsequent 

Federal Register notice was published on July 8, 2010 (75 FR 39255), notifying the public that 

EPA was proposing to take action on State recommendations for lead nonattainment areas. In 

the same notice, EPA started a public comment period with an end date of August 16, 2010. 

EPA did not receive any public comments germane to the nonattainment designation and 

boundaries for the Eagan area, nor did we receive any additional information from the State. 

Accordingly, EPA has determined that the portions of Dakota County that are encompassed by: 

Lone Oak Rd. (County Rd. 26) to the north, County Rd. 63 to the east, Wescott Rd. to the south, 

and Lexington Ave. (County Rd. 43) to the west should be designated as nonattainment for the 

2008 lead NAAQS, as seen in Figure 8. 
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Figure 8: Eagan, Minnesota Final Nonattainment Area (OAQPS)