Technical Support Document (TSD) for the Response to the September 

2010 Section 126 Petition from New Jersey Regarding SO2 Emissions 

from the Portland Generating Station

Docket ID No. EPA-HQ-OAR-2011-0081

Summary of 1-Hour SO2 Monitoring Data from 

the Columbia Monitor in Warren County, New 

Jersey 

U.S Environmental Protection Agency

March 2011
TSD for Columbia Monitor in Warren County, New Jersey

Air monitoring data collected at a newly established air monitoring site are consistent 

with our finding that emissions from the Portland Plant significantly contribute to 

nonattainment and interfere with maintenance of the 1-hour SO2 NAAQS in New Jersey.

New Jersey established the Columbia Site SO2 monitor in Warren County in the 

Allentown-Bethlehem-Easton, PA-NJ Core Based Statistical Area (CBSA). The site is 

located approximately one mile from the Portland Plant, near the area predicted to 

exceed the 1-hour SO2 NAAQS based on the air modeling discussed in the preamble to 

this proposed rule and the modeling TSD.

The majority of the collected data are still considered preliminary. The data appear in 

EPA’s AQS database and AIRNow database (i.e., AirNowTech). 

Quality assured data have been uploaded to EPA’s Air Quality System (AQS) database 

from the monitor’s official starting date of September 23, 2010 through the end of the 

third quarter on September 30, 2010. The fourth quarter data for 2010 (October 1, 2010 

through December 31, 2010) should be uploaded to the AQS by March 31, 2011. Data 

in the AQS database have been fully quality controlled.

The data collected since January 1, 2011 have not been fully quality controlled or 

validated by the state, and are considered preliminary. This data appear only in 

AirNowTech, and will be uploaded into the AQS database after being fully quality 

controlled and assured by New Jersey.

Additionally, the SO2 data from the Columbia monitor have yet to be certified by the 

State. States typically certify their data in blocks of a calendar year at a time. EPA 

rules require 2010 air sampling data to be certified by the State by May 1, 2011 and 

2011 data to be certified by New Jersey by May 1, 2012.

The Columbia monitor is a Federal Reference Method monitor and uses the pulsed 

fluorescent method of analysis. The monitor meets the proper siting criteria as directed 

in Part 58 of the Code of Federal Regulations (Appendix E to Part 58 – Probe and 

Monitoring Path Siting Criteria for Ambient Air Quality Monitoring).

The primary SO2 1-hour standard is at a level of 75 parts per billion (ppb). The design 

value is calculated by taking the 99th percentile of the maximum daily 1-hour averages 

for each of 3 consecutive years. These three 99th percentile values are averaged 

together to get a design value for that monitor. If the design value is greater than 75 

ppb, it is violating the SO2 NAAQS.

Since we do not have a complete 3 year data set, 75 ppb is used as a benchmark to 

determine whether there is a possibility of an SO2 NAAQS violation. The monitor data 
exceeded the 75 ppb benchmark on ten days during the September 2010 – February 

2011 time period. The top 10 maximum daily values and the date they were measured 

from the period September 23, 2010 through February 28, 2011 are:

Max 

(PPB) Date

183 10/30/2010

163 1/24/2011

136 9/24/2010

133 1/22/2011

111 2/13/2011

105 2/16/2011

92 9/29/2010

85 2/23/2011

83 12/30/2010

78 2/14/2011

Data for the entire period can be seen in the chart below. The red line represents the 

level of the 1-hour SO2 standard (75 ppb).

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Maximum 1-Hour SO2 at Columbia Monitor

Columbia
The chart below compares data from the Columbia monitor with all of the other SO2

monitors in New Jersey. The Columbia monitor was set up to measure concentrations 

from a local source whereas the other SO2 monitors in New Jersey were set up to 

measure concentrations from population centers. Again, the red line represents the 75 

ppb standard.

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60

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PPB

Date

Maximum 1-Hour SO2in New Jersey Ancora State Hosptial

Bayonne

Brigantine

Chester

Clarksboro

Columbia

Elizabeth

Elizabeth Trailer

Jersey City

Millville

Newark Firehouse

Perth Amboy