Illinois Administrative Code › Title 35 - ENVIRONMENTAL PROTECTION › Part 355 - DETERMINATION OF AMMONIA NITROGEN WATER QUALITY BASED EFFLUENT LIMITS FOR DISCHARGES TO GENERAL USE WATERS › Subpart B - AMMONIA NITROGEN (as N) WATER QUALITY STANDARDS AND WQBELs › Section 355.205 - Estimation of Projected Effluent Quality

Current through Register Vol. 48, No. 28, July 12, 2024
The Projected Effluent Quality (PEQ) is the estimation of the
				  maximum expected effluent concentration. Individual PEQs shall be estimated for
				  all summer and winter acute, chronic and subchronic exposure periods.
a) The PEQ shall be derived from
				representative facility specific data to reflect a 95 percent confidence level
				for the 95th percentile value. These data will be
				presumed to adhere to a lognormal distribution pattern with a coefficient of
				variation of 0.6 unless the facility's effluent data demonstrates a different
				distribution pattern. If facility specific data in excess of 10 data values is
				available, a facility specific coefficient of variation that is the ratio of
				the standard deviation to the arithmetic average may be calculated. The PEQ is
				derived as the upper bound of a 95 percent confidence bracket around the
				95th percentile value through a multiplier from the
				following table applied to the maximum value in the data set that has its
				quality assured consistent with subsection (f).
PEQ = (maximum data point)(statistical multiplier)
Coefficient of Variation
No. of Samples
0.1
0.2
0.3
0.4
0.5
0.6
0.7
1
1.4
1.9
2.6
3.6
4.7
6.2
8.0
2
1.3
1.6
2.0
2.5
3.1
3.8
4.6
3
1.2
1.5
1.8
2.1
2.5
3.0
3.5
4
1.2
1.4
1.7
1.9
2.2
2.6
2.9
5
1.2
1.4
1.6
1.8
2.1
2.3
2.6
6
1.1
1.3
1.5
1.7
1.9
2.1
2.4
7
1.1
1.3
1.4
1.6
1.8
2.0
2.2
8
1.1
1.3
1.4
1.6
1.7
1.9
2.1
9
1.1
1.2
1.4
1.5
1.7
1.8
2.0
10
1.1
1.2
1.3
1.5
1.6
1.7
1.9
11
1.1
1.2
1.3
1.4
1.6
1.7
1.8
12
1.1
1.2
1.3
1.4
1.5
1.6
1.7
13
1.1
1.2
1.3
1.4
1.5
1.6
1.7
14
1.1
1.2
1.3
1.4
1.4
1.5
1.6
15
1.1
1.2
1.2
1.3
1.4
1.5
1.6
16
1.1
1.1
1.2
1.3
1.4
1.5
1.6
17
1.1
1.1
1.2
1.3
1.4
1.4
1.5
18
1.1
1.1
1.2
1.3
1.3
1.4
1.5
19
1.1
1.1
1.2
1.3
1.3
1.4
1.5
20
1.1
1.1
1.2
1.2
1.3
1.4
1.4
30
1.0
1.1
1.1
1.1
1.2
1.2
1.2
40
1.0
1.0
1.1
1.1
1.1
1.1
1.1
50
1.0
1.0
1.0
1.0
1.0
1.0
1.0
60 or greater
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Coefficient of Variation
No. of Samples
0.8
0.9
1.0
1.1
1.2
1.3
1
10.1
12.6
15.5
18.7
22.3
26.4
2
5.4
6.4
7.4
8.5
9.7
10.9
3
4.0
4.6
5.2
5.8
6.5
7.2
4
3.3
3.7
4.2
4.6
5.0
5.5
5
2.9
3.2
3.6
3.9
4.2
4.5
6
2.6
2.9
3.1
3.4
3.7
3.9
7
2.4
2.6
2.8
3.1
3.3
3.5
8
2.3
2.4
2.6
2.8
3.0
3.2
9
2.1
2.3
2.4
2.6
2.8
2.9
10
2.0
2.2
2.3
2.4
2.6
2.7
11
1.9
2.1
2.2
2.3
2.4
2.5
12
1.9
2.0
2.1
2.2
2.3
2.4
13
1.8
1.9
2.0
2.1
2.2
2.3
14
1.7
1.8
1.9
2.0
2.1
2.2
15
1.7
1.8
1.8
1.9
2.0
2.1
16
1.6
1.7
1.8
1.9
1.9
2.0
17
1.6
1.7
1.7
1.8
1.9
1.9
18
1.6
1.6
1.7
1.7
1.8
1.9
19
1.5
1.6
1.6
1.7
1.8
1.8
20
1.5
1.5
1.6
1.6
1.7
1.7
30
1.3
1.3
1.3
1.3
1.4
1.4
40
1.1
1.2
1.2
1.2
1.2
1.2
50
1.1
1.1
1.1
1.1
1.1
1.1
60 or greater
1.0
1.0
1.0
1.0
1.0
1.0
1) If the PEQ
				determined in this Section is less than or equal to the applicable acute water
				quality standard, there is no reasonable potential and no WQBEL will be
				established in the permit unless otherwise warranted under Section
				355.201(c).
2) If the PEQ as determined in this Section
				exceeds the applicable acute water quality standard but does not exceed the PEL
				determined through Section
				355.209,
				there is no reasonable potential and no WQBEL will be established unless
				otherwise warranted under Section
				355.201(c).