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 99[th] percentile of the maximum daily 1-hour averages for each of 3 consecutive years.  These three 99[th] 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).






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.



