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TSRIA Document 4: 

Removing Data with QA Failures and Limiting PPL Emissions to Regional Haze 

Levels Results in Almost No Coburn Road Exceedances 

(Supplements Chart 5 from February 27, 2014, TSRIA Presentation)

As a result of the February 27, 2014, meeting with the EPA, TSRIA has conducted 

additional analysis of Coburn Road SO2 concentration and PPL emissions data from 

2009 – 2013. The additional analysis shows that when (1) the data with quality 

assurance (QA) failures from Chart 5 (revised 2/24/14) in the February 27 TSRIA 

presentation are removed and (2) emissions from PPL are limited to the new Regional 

Haze level, almost no high readings occur at Coburn Road. This additional analysis is 

summarized in the following charts, 5b through 5i, which are meant to supplement Chart 

5. 

The first chart (5b) shows the relationship that exists if all Coburn Road data are taken 

at face value, and shows a total of 20 hourly SO2 concentrations exceeding 75 ppb. 

However, TSRIA has demonstrated that most of the high SO2 points must be excluded 

due to quality assurance (QA) failures (see TSRIA, New Standards Application 

document). Therefore, Charts 5c through 5i were developed to show the effects of 

progressively removing invalid data based on objective criteria. As demonstrated by 

Charts 5g and 5i, only one Coburn Road value above 75 ppb remains valid when 1) all 

values from Chart 5 with QA failures are eliminated and 2) PPL emissions are restricted 

to the levels now allowable under the Federally enforceable Regional Haze Limit 

(approximately 840 lb/hr). 

 

 
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Chart 5b: 

Chart 5b shows Coburn Road SO2 levels (ppb) as a function of hourly PPL emissions, 

for all hours from 2009 – 2013. This display includes all Coburn Road data when PPL is 

operating and emitting greater than 100 lbs SO2/hr – including points from Chart 5 with 

QA failures – resulting in a total of 20 values greater than 75 ppb. 2010 data points 

from Chart 5 with QA failures are depicted by a triangle, while those from other years 

are shown by a square. The following observations can be made: 

Every one of the 2010 values above 75 ppb was associated with a QA failure and 

occurred when PPL emissions were below 840 lb/hr. None occurred when PPL 

emissions were greater than 840 lb/hr. This is very inconsistent behavior. 

 
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Chart 5c: 

Chart 5c shows the relationship between Coburn Road SO2 levels and PPL emissions 

from 2009 through 2013 after all data points with QA failures from Chart 5 are excluded. 

This analysis results in only two SO2 data points exceeding 75 ppb. In other words, if 

all high SO2 values with QA failures are excluded, 18 of the 20 high values disappear. 
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Chart 5d: 

Chart 5d is identical to Chart 5b, with the addition of a shaded area depicting periods 

with PPL emissions below the approximate 840 lb/hr Regional Haze limit and SO2

concentrations below 75 ppb. 

 
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Chart 5e: 

Chart 5e is identical to Chart 5c, with the addition of a shaded area depicting periods 

with PPL emissions below 840 lb/hr and SO2 levels below 75 ppb. In both 5e and 5c, 

QA failures from Chart 5 for 2009 through 2013 were removed. The shading 

demonstrates that only one valid SO2 value above 75 ppb occurred when PPL 

emissions were below the approximate 840 lb/hr Regional Haze limit that has been in 

effect since the spring of 2013.

 
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Chart 5f: 

Chart 5f shows SO2 levels at Coburn versus PPL emissions for 2009, 2011, 2012 and 

2013 (i.e. excluding 2010), with all Coburn data included. In the four years, there are a 

total of ten SO2 values above 75 ppb, of which eight have QA failures identified in Chart 

5.

 
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Chart 5g: 

Chart 5g is identical to Chart 5f, except that the eight high SO2 values with QA failures 

have been removed. This results in only two SO2 values above 75 ppb, and only one 

such value during periods when PPL emissions were below the approximate 840 lb/hr 

Regional Haze limit that is currently in effect at PPL. 

 
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Chart 5h: 

Chart 5h depicts the 2011 through 2013 period and includes periods of known QA 

failures. Even with these invalid data included, it is important to note that the design 

value still meets the standard. 

 
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Chart 5i: 

Chart 5i is identical to Chart 5h, except that the eight high SO2 values with QA failures 

have been removed. This results in only two SO2 values above 75 ppb, and only one 

such value during periods when PPL emissions were below the approximate 840 lb/hr 

Regional Haze limit that is currently in effect at PPL.