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TSRIA Document 2.2: 

ATTACHMENT A 

CALCULATION OF DESIGN VALUES EXCLUDING DATA WITH 

DOCUMENTED DATA QUALITY ISSUES 

TSRIA Chart 5 (revised on 2/24/2014) from the February 27, 2014 presentation summarized the 

highest SO2 readings for the Coburn Road monitor and identified data quality issues associated 

with each value. It was noted that 1) each reading shown for years 2009-2011 had at least one 

quality assurance (QA) failure, and 2) QA failures decreased markedly after 2011. Nevertheless, 

the data shown in Chart 5 provided the basis for EPA’s design value calculation of 79 ppb for the 

years 2009-2011. TSRIA has documented numerous QA failures for these values and thus 

continues to assert that many of these values may not be used for design value calculations. 

The contribution of those questionable readings to EPA’s calculated design value is 

unquestioned. TSRIA has performed an additional set of design value calculations using all data 

within each calendar year, with the exception of those specific hours with data quality issues 

identified in Chart 5. Because an exhaustive, hour-by-hour evaluation of the validity of each 

data point in each calendar year is beyond the scope of this appeal, TSRIA has conservatively 

assumed that all data not specifically identified as problematic in Chart 5 is valid. This is likely 

an optimistic assumption. However, this approach guarantees that the resulting design value 

calculation will represent the upper limit of its true value based on the greatest possible number 

of valid data points. 

Table 1 lists the four highest daily one-hour maximum SO2 concentrations for each calendar year 

from 2009-2012, including the date of occurrence, after the invalid values identified in Chart 5 

are excluded. 

Table 1: Summary of four highest daily maximum SO2 values with invalid data points 

excluded. 

2009 2010 2011 2012 

Date SO2 (ppb) Date SO2 (ppb) Date SO2 (ppb) Date SO2 (ppb)

12/28 69 03/16 73 10/19 65 09/13 129 

05/18 68 09/04 73 02/22 64 11/03 70 

01/21 67 12/26 70 08/07 63 09/28 54 

08/26 66 01/09 69 05/05 62 07/25 53 

Previous 

4th-high 

72 Previous 

4th-high 

91 Previous 

4th-high 

74 Previous 

4th-high 

70 

Note: complete results for 2013 have been excluded from this table for readability, and because EPA did not use 2013 in its 

design value calculations. However, removal of the single 2013 data point with data quality problems from Chart 5 decreases the 

fourth-highest value for 2013 from 48 ppb to 46 ppb. 
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It is evident that excluding the invalid data points (23 over the 2009-2012 period) significantly 

decreases the fourth-highest daily maximum SO2 concentration in each year. The “Previous 4thhigh” values represent the results obtained by EPA, based on the assumption that all data points 

were valid. This is especially noticeable in 2010, when the fourth-highest value decreased from 

91 ppb to 69 ppb. 

There is a corresponding decrease in calculated design values: 

 For the 2009-2011 period, the calculated design value decreases from 79.00 ppb to 65.67 

ppb. 

 For the 2010-2012 period, the calculated design value decreases from 78.33 ppb to 61.33 

ppb.