SUBJECT: Technical Support Document Regarding Ozone Monitoring Data —Delaware,

Maryland, New Jersey, and Pennsylvania; Detenninations of Attainment ofthe

1997 8-Hour Ozone National Ambient Air Quality Standard for the PhiladelphiaWilmington-Atlantic City 8-Hour Ozone Moderate Nonattainment Area

FROM: rkAiiorAir Quality Planning Specialist

Office of Air Program Planning

TO: File

THRU: riti

Office of Air Program Planning

This document provides a technical review ofthe air quality monitoring data used to support the

Environmental Protection Agency’s (EPA’s) proposed determination that the PhiladelphiaWilmington-Atlantic City, PA-NJ-MD-DE 8-hour ozone moderate nonattainment area (the

Philadelphia Area) has attained the 1997 ozone national ambient air quality standard (NAAQS)

by its statutory attainment date and EPA’s proposed clean data detennination for the

Philadelphia Area.

I. BACKGROUNDThis Philadelphia Area includes the entire State of Delaware; Cecil County in Maryland;

Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester, Mercer, Ocean, and Salem

Counties in New Jersey; and Bucks, Chester, Delaware, Montgomery, and Philadelphia Counties

in Pennsylvania. The Philadelphia Area was classified as a moderate nonattainment area. See

40 CFR 81.808, 81.321, 81.33 1, and 8 1.339. Moderate areas are required to attain the 1997 8-

hour ozone NAAQS by no later than June 15, 2010. See 40 CFR 5 1.903. However, the EPA

approved a 1-year attainment date extension for the Philadelphia Area on January 21, 2011. (See

76 FR 3838 and 76 FR 3840.) The Philadelphia Area’s attainment date is now June 15, 2011.

II. EVALUATION OF AIR QUALITY MONITORING DATA

A. Data Requirements

The criteria for determining if an area is attaining the 1997 8-hour ozone NAAQS are set out in
each monitoring site within the area, the area meets the NAAQS.

The data must be collected and quality-assured in accordance with 40 CFR part 58, and must be

recorded in EPA’s Air Quality System (AQS). The data supporting attainment ofthe standard

must be complete in accordance with 40 CFR part 50, appendix I. The data completeness

requirement is met when the percent of days with valid ambient monitoring data, averaged overthree years, is greater than 90%, and no single year has less than 75% data completeness. For thePhiladelphia Area, the ozone season extends from the beginning of April through the end of

October. A complete ozone season consists of 214 monitoring days.

B. Certified Air Quality Monitoring Data, 2008-2010

The States of Delaware, Maryland, and New Jersey, and the Commonwealth of Pennsylvania

(“the States”) submitted complete, quality assured air quality monitoring data into AQS. The

States then certified that data. Attached are two AQS reports containing 8-hour ozone data for

the Philadelphia Area for 2008 to 2010. Table 1, below, summarizes those reports.

Table 1: 2008-2010 Philadelphia Area 8-Hour Ozone Design Values & Data Completeness

.

Percent Completeness 4th Highest Value

( 2008-2010 (valid monitored days I

State County Site ID ppm, Design Value required_days)

2008 2009 2010 (ppm) 2008 2009 2010 2008-2010

average

DE Kent 10-001-0002 0.081 0.066 0.077 0.074 100 99 100 100

‘Jew Castle 10-003-1007 0.078 0.068 0.080 0.075 99 90 86 92

10-003-1010 0.082 0.068 0.079 0.076 95 79 85 8610-003-1013 0.077 0.069 0.080 0.075 100 97 97 98

Sussex 10-005-1002 0.081 0.067 0.084 0.077 99 98 99 99

10-005-1003 0.079 0.069 0.083 0.077 100 97 93 97

MD Cecil 24-015-0003 0.088 0.072 0.082 0.080 96 94 93 94

Atlantic 34-001-0006 0.072 0.071 0.080 0.074 95 94 98 96

Camden 34-007-0003 0.083 81

34-007-1001 0.082 0.071 0.088 0.080 98 96 98 97

NJ Cumberland 34-011-0007 0.079 0.072 0.077 0.076 98 99 97 98 Gloucester 34-015-0002 0.089 0.071 0.083 0.081 96 99 99 98

Mercer 34-021-0005 0.079 0.071 0.086 0.078 99 97 99 98

Ocean 34-029-0006 0.085 0.071 0.087 0.081 100 98 96 98

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Montgomery 42-091-0013 0.084 0.070 0.081 0.078 97 100 98 98Philadelphia 42-101-0004 0.062 0.059 0.077 0.066 98 99 95 97

42-101-0024 0.087 0.072 0.088 0.082 100 85 100 95

As shown in Table 1, above, all 2008-2010 design values are below 0.084 ppm. All but twomonitors: 10-003-10 10 and 34-007-0003, meet the data completeness requirements.

Information on the data completeness issues for monitors 10-003-1010 and 34-007-0003 follows.

Monitor 10-003-10 10, New Castle County, Delaware: Data Completeness IssuesAccording to appendix I, at least 75% data capture is required each year, and the percentage ofdays with valid monitoring data averaged over three years must be greater than 90%. However,for monitors that don’t meet these requirements, certain data substitution is allowed.

“When computing whether the minimum data completeness requirements have been met,

meteorological or ambient data may be sufficient to demonstrate that meteorologicalconditions on missing days were not conducive to concentrations above the level of the

standard. Missing days assumed less than the level of the standard are counted for the

purpose of meeting the data completeness requirement, subject to the approval oftheappropriate Regional Administrator.”

Missing Ozone Data Analysis #1: In 2009, monitor 10-003-10 10 in New Castle County, DE,

recorded data on 113 days, which is 53% ofthe 214-day ozone monitoring season. In July 2010,

the Delaware Department ofNatural Resources and Environmental Control (DE DNREC)

submitted to EPA a missing data analysis for this monitor for the 2009 ozone season. Thatanalysis, dated July 19, 2010, uses the data substitution provisions of appendix Ito 40 CFR part

50 to determine that 55 ofthe days when monitor 10-003-1010 was down in 2009 had

metrological conditions that were not conducive to ozone formation above the level ofthe 2008

ozone NAAQS, 0.075 ppm. Based on this analysis, DE DNREC requested that 55 days with

missing monitoring data be counted in determining data completeness for 2009. EPA RegionalAdministrator Shawn M. Garvin approved that request in a letter dated September 24, 2010. DEDNREC’s data substitution analysis and EPA’s approval letter are attached.

Table 2. 2009 Data Completeness for Monitor 10-003-1010, New Castle County, DE AfterEPA Approval of DE DNREC’s July 2010 Missing Data Analysis

Year - Days with Valid Ozone Additional Total Days Percent

Measurements Approved Days Counted for Data Completeness

Completeness

2009 113 55 168 79%

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monitor 10-003-10 10 in New Castle County, DE is 86%, which is below the required 90%. OnJuly 11, 2011, the DE DNREC submitted a second missing ozone data analysis for monitor 10-

003-1010 for the 2009 and 2010 ozone seasons using the data substitution provisions of appendix

Ito 40 CFR part 50. The DE DNREC missing ozone data analysis listed certain days in 2009

and 2010 when no ozone data was collected. However, even though no data was collected,

documentation and analysis provided by DE DNREC justified these days should be counted fordata completeness requirements. DE DNREC provided strong statistical correlations between

monitor 10-003-10 10 and nearby ozone monitoring stations, as well as, observed meteorological

conditions that were not conducive to ozone formation to justifi missing ozone data days would

not have exceeded the 1997 8-hour ozone standard of 0.08 ppm.

In a letter dated September 1, 2011, EPA Regional Administrator Shawn M. Garvin, approved

DE DNREC’s request to allow an additional 15 days in 2009 and 19 days in 2010 to be counted

towards data completeness. The additional valid monitoring days increases the percentage data

capture for 2009 and 2010, and brings the three year average data completeness for 2008 —2010

above the required 90%, as shown in Table 3. DE DNREC’s’s data substitution analysis andEPA’s approval letter are attached.Table 3. 2008-2010 Data Completeness, Monitor 10-003-1010, New Castle County, DE,

After EPA Approval of DE DNREC’s July 2011 Missing Data Analysis

Year Days with Valid Ozone Additional Total Days Percent

Measurements Approved Days Counted for Data Completeness

Completeness

2008 203 --- 203 95%2009 168 15 183 86%2010 181 19 200 93%

2008— 2010 Average 91%

Monitor 34-007-0003. Camden County, New Jersey: Emergency Shut DownThe New Jersey Department of Environmental Protect (NJ DEP) shut down monitor 34-007-

0003 in Camden County in 2008. The Camden Lab station, monitor 34-007-0003, which had

been in operation since 1968, was unexpectedly discontinued on September 29, 2008 due to lack

ofsecurity at the station. NJDEP, in coordination with EPA, is actively pursuing theestablishment of a new monitoring station in Camden. Therefore, it is not appropriate toconsider this monitor in the determination of attainment for the Philadelphia Area.

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considering the data substitution analysis for monitor 10-003-1010, all monitors meet thecompleteness criteria. Therefore, the Philadelphia Area meets the 1997 8-hour ozone NAAQS,considering 2008-20 10 data.

Attachments:

- EPA AQS Quick Look Report (AMP45O), dated May 27, 2011, containing 2008-2010 ozone

air quality data for Delaware, Maryland, and Pennsylvania portions ofthe Philadelphia Area.

- EPA AQS Quick Look Report (AMP45O), dated August 19, 2011, containing 2008-2010

ozone air quality data for New Jersey portion ofthe Philadelphia Area.

- September 24, 2010 EPA letter to DE DNREC approving DE DNREC’s July 15, 2010

“Data Substitution Analysis; 2009 Ozone; Brandywine (AQS Site ID 10-003-10 10).”DE DNREC’s July 15, 2010, “Data Substitution Analysis; 2009 Ozone; Brandywine (AQS

Site ID 10-003-1010),” submitted via cover letter dated July 19, 2010.

September 1, 2011 EPA letter to DE DNREC approving DE DNREC’s July 11, 2011

“Missing Ozone Data Analysis; 2010 and Supplemental 2009 for Brandywine (AQS Site ID

10-003-1010).”

DE DNREC’s July 11, 2011 “Missing Ozone Data Analysis; 2010 and Supplemental 2009for Brandywine (AQS Site ID 10-003-1010),” submitted via cover letter dated July 11,

2011.

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