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## Technical Support Document (TSD) for the Response to the September 2010 Section 126 Petition from New Jersey Regarding Sulfur Dioxide ( SO 2 

## ) Emissions from the Portland Generating Station

Docket ID No. EPA

- HQ
- OAR
- 2011
- 0081



# Trajectory Analysis of High SO 2 

# Episodes at the Chester, N ew J ersey Monitor

U.S Environmental Protection Agency

March 2011Page 2 of 6 ADDITIONAL SUPPORTING INFORMATION Trajectory

Anal ys is of High SO 2 Episodes at the Chester, NJ Monitor A. Summary of trajectory analysis submitted by NJDEP The New Jersey

Department of Environmental Protection (NJDEP ) submitted an analysis using air parcel trajectories on days with high concentrations to support its assertion that the Portland Plant causes violations of the 1

- hour SO 2 national ambient air quality standard (NAAQS ) in New Jersey 1

. NJDEP ex amined air trajectories from two episodes with high SO 2 concentrations recorded at the nearb y Chester ambient air monitor in 2008 and 2009. The Chester monitor (34

- 027
- 3001) is located in Morris County, New Jersey , approximately thirtyfour kilometers from the Portland Plant. The Chester monitor is part of N ew Jersey ’s regular State and Local Air Monitoring Station network and was situated to monitor the exposure of the general population of the area to SO 2 and was not designed to monitor th e specific impact of the Portland Plant or any

other impact of any

particular emissions source.
B. HYSPLIT Model selection
NJDEP used the Air Resources Laboratory ’s HYbrid Single

- Particle Lagrangian Integrated Trajectory

(HYSPLIT) model 2 as a tool to help determine if high concentrations of SO 2 are coming from the Por tland Plant. HYSPLIT is a complete s ys tem for computing both simple air parcel trajectories and complex dispersion and deposition simulations. The model calculation method is a hy brid between the Lagrangian approach, which uses a moving frame of referenc e as the air parcels move from their initial location, and the Eulerian approach, which uses a fixed three

- dimensional grid as a frame of reference. In the model, advection and diffusion calculations are made in a Lagrangian framework following the transp ort of the air parcel, while pollutant concentrations are calculated on a fixed grid. In this case, NJDEP used the Lagrangian features of the model to determine the direction and speed of the air. When NJDEP applied the HYSPLIT model, it used a meteorological data set with a grid size of 12 kilometers, which is the finest resolution data set available for use with the model. The HYSPLIT model’s grid size is less than the distance between the Portland Plant and the Chester monitor, so the model is using a data set that is more likel y to be an appropriate tool for this analysis. EPA agrees that using the HYSPLIT model as NJDE P applied it provides useful information on the direction and speed of air parcels in the atmosphere.
C. NJDEP’s Review of Monitoring Data and Nearby Emission SourcesPage 3 of 6

NJDEP reviewed air monitoring data for days when high concentrations occurred at its C hester, NJ monitor located 34 kilometers east

- southeast of the Portland Power Plant. The monitoring data from the Chester, NJ monitor have been full y quality controlled , validated and certified b y NJDEP, a s required by EPA . The data are available in EPA’ s Air Quality S ys tem (AQS) database. During the years 2008 and 2009, the highest 1
- hour SO 2 concentrations occurred in two episodes, July

17
- 18, 2008 and December 7, 2009. During the July 2008 and the December 2009 episodes, the Portland reported that the Plant w as operating at 85 and 55 percent of capacity , respectivel y. NJDEP’s review of emission inventories from its emissions database and Pennsylvania ’s PADEP eFACTS database show that ye arl y emissions from Portland are 1000 times greater than any other sources between the Chester monitor and the Portland Plant
. Inthe area around surrounding the Portland Plant, the Portland Plant’s ye arl y emissions are 1000 times greater than any other source in the area, except for the Martins Creek Power Plant
. Hourl y continuous emissions monitoring s ys tems (CEMS) data from EPA’s Clean Air Markets database (see http://www.epa.gov/airmarkets/) show that the Martins Creek Power Plant was operating at very low levels during these two episodes, with actual emissions recorded well under the level of emissions measured at the Portland Plant
. D. Episode I: July 17 - 18, 2008
The 1

- hour SO 2 concentrations measured during Episode Iwere the highest three hourl y concentrations recorded at the Chester monitor during 2008

- 2009. Data in EPA’s Air Quality System show that d

uring three consecutive hours beginning at 10 pm local time on the 17 th , hourly SO 2 concentrations ranged from 85 parts per billion (ppb) to 53 ppb. The first two hours of the episode exceeded the 75 ppb 1

- hour SO 2 NAAQS. NJDEP included plots of these data showing a rapid rise at the beginning of the episode and drop off at the end of the episode of SO 2 values; values were at or near zero ppb except during the air quality episode. NJDEP used the HYSPLIT model to calculate forward trajectories from the Portland Plant at a height representative of the plume emitted from its stacks (i.e. , 100 meter plume rise added to the 121 meter stack height), and back ward trajectories at a height representative of the Chester monitor (i.e. , 10 meters above ground) during the time periods associated with high SO 2 concentrations at the Chester monitor on July 17, 2008. New Jersey

submitted forward and back trajectories for a 6 hour period (to allow for the transport of the plume from the stack to the Chester monitor) based on wind speed s of 4.5 meters per second (m/s ) at 221 m above ground level (near plume height) to 2.7 m/s at 10 m above ground level (near the monitor’s height) during the episode.
E. Episode II: December 7, 2009Page 4 of 6

The 1

- hour SO 2 concentrations measured during Episode II included four of the twelve highest hourl y concentrations in the Air Quality System for the Chester monitor during 2008

- 2009. During four consecutive hours beginning at 1am local time on the 7 th , hourly SO 2 concentrations ranged from 28 to 33 ppb. Hourly SO 2 during this episode rose and fell more gradual ly ; concentrations were less than 10 ppb on either side of the seven

- hour episode. NJDEP used the HYSPLIT model to calculate forward trajectories from the Portland Plant at a height representative of the plume emitted from its stacks (i.e. 100 meter plume rise added to the 121 meter stack hei ght), and backward trajectories at a height representative of the Chester monitor (i.e. 10 meters above ground) during the time periods associated with high SO 2 concentrations at the Chester monitor on December 7, 2009. NJDEP submitted forward and back trajectories for a 3 hour period (to allow for the transport of the plume from the stack to the Chester monitor) based on wind speed s of 11.2 m/s at 221 m above ground level (near plume height) to 3 m/s at 10 m above ground level (near the monitor’s height) during the episode.
F. Possible Sources Affecting the Readings Observed at Chester At the time of these two episodes, emissions from the Portland Plant were vastly greater than other sources between Chester and the Portland Plant or around the Portland Plant
. The only other facility in the vicinity showing potentially significant amounts of SO 2 is the Martins Creek Power Plant, however, it was operating at levels well less than the Portland Plant, during the two episodes 3

. The following tables show the hourl y emissions from Portland Units 1 and 2, and from Martins Creek Units 3 and 4 during the two air quality episodes
. Table 1 Hourl y Sulfur Dioxide Emissions on July 17, 2008 Hour (EDT) Portland Unit 1

(lbs/hr) Portland Unit 2

(lbs/hr) Martins Creek Units 3 & 4 (lbs/hr) 15 5,024 7,574 35 16 5,041 7,536 42 17 5,051 7,436 33 18 5,013 7,569 21Page 5 of 6

19 5,003 7,556 16 20 4,969 7,580 16 21 4,913 7,532 9 22 4,986 7,548 0 23 4,475 6,792 0

Table 2 Hourl y Sulfur Dioxide Emissions on December 6 and 7, 2009 Hour (EDT) Portland Unit 1

(lbs/hr) Portland Unit 2

(lbs/hr) Martins Creek Units 3 & 4 (lbs/hr) Dec 6
- 18 3,503 5,326 0 1 9 3,554 5,818 0 20 3 , 493 5 , 819 0 21 3 , 352 5 , 611 0 22 2 , 830 4,612 0 23 2 , 856 4 ,5 35 0 Dec 7
- 00 3 , 192 4 , 617 0 01 3 , 305 4 , 653 0 02 3 ,4 23 4 , 532 0

The forward trajectories provided b y NJDEP show that the SO 2 emissions from the Portland Plant arriv e in the vicinity of the Chester monitor during high concentrations at the monitor. For example, winds from the Portland Plant at hour 15 (4 pm EDT) on July 17, 2008, end during the three

- hour episode of high SO2 concentrations at the Chester monitor. In addition, trajectories starting at hour 17 (5 pm EDT) on July 17, 2008 at Chester and going backward end up near the Portland Plant. Th e trajectories submitted by NJDEP visibly show , that high concentrations at Chester were associated with a source in the vicinity of the Portland P lant. Since the PortlandPage 6 of 6

Plant is the only

large emiss ion sources in its vicinity, it is likely that emissions from the Portland Plant caused the high concentrations during these episodes.
G. EPA analysis NJDEP’s method of using HYSPLIT trajectory analyses during the two episodes of high concentrations o f SO 2 at the Chester NJ air monitoring station uses acceptable methods that support the conclusion that SO 2 that was recorded at the Chester monitor was mainly due to emissions from the Portland Plant. The trajectories, run forward and backwards, show air coming from the vicinity

of the Portland Plant to the area near the Chester monitor. The Martins Creek Power Plant is the only facility in the area that has potential SO 2 emissions on the order of the potential emissions of the Portland Plant . However, during these episodes, emissions from the Martins Creek Power Plant are less than one percent of the emissions of the Portland Plant. Thus, it is unlikely

that any facility other than the Portland Plant caused these high concentrations. NJDEP’s analysis of monitoring data and wind trajectories provides supporting evidence that the Portland Plant has a noticeable influence over a wide area around the facility. For reasons explained in the preamble to the proposed rule, EPA continues to re ly primarily on modeling to determine whether downwind areas constitute nonattainment or maintenance receptors for purpose of anal yz ing a section 126 petition with respect to the 1

- hour SO 2 NAAQS. Nonetheless, elevated concentrations , of SO 2 appear to com e from the Portland Plant , observed at a monitor distant from the area of Portland Plant’s peak impact. This finding underscores the need for EPA to approve the petition and to establish limits and a compliance schedule to address these elevated concentrations of SO 2 and is consistent with EPA’s finding that the Portland Plant contributes significantly

to and interferes with maintenance of the 1

- hour SO 2 NAAQS in New Jersey
.

1 Trajectory Analysis of High Sulfur Dioxide Episodes at the Chester, NJ Monitor. Bureau of Technical Services, Division of Air Quality, New Jersey Dept. of Environmental Protection. July 30, 2010. Submitted to USEPA as Exhibit 4 of the September 13, 2 010 Supplement to New Jersey’s May 12, 2010 Petition Pursuant to Section 126 of the Clean Air Act , 42 U.S.C. § 7426 2 Draxler, R.R. and Rolph, G.D., 2011. HYSPLIT (HYbrid Single

- Particle Lagrangian Integrated Trajectory) Model access via NOAA ARL READY Website (http://ready.arl.noaa.gov/HYSPLIT.php). NOAA Air Resources Laboratory, Silver Spring, MD. 3 SO 2 emissions from the Portland Plant were around 5,000 and 7,500 lb/hr for units 1 and 2 respectively on July 17 th . The emissions for Martins Creek unit s 3and 4 were less than 42 pounds per hour during this time. During the episode of December 6
- 7, the Portland Plant units 1 and 2 emitted about 3,200 and 5,000 pounds per hour respectively. The Martin’s Creek units 3 and 4 emitted zero pounds per hour. NJDEP’s data from EPA’s Clean Air Markets data base. The Portland Plant’s potential to emit is 5,820 and 8,900 lb/hr for units 1 and 2 respectively as reported in NJDEP’s analysis. Martins Creek’s potential to emit is 5, 692 lb/hr for both units 3 and 4 as reported in its Title V operating permit.