Environmental Engineering Reference
In-Depth Information
TABLE 4.16. Synoptic Measurements of
E. coli
Concentration and Flow Rate
Conc
(CFU/dL)
Flow
(m
3
/s)
Exceed
(%)
Conc
(CFU/dL)
Flow
(m
3
/s)
Exceed
(%)
Conc
(CFU/dL)
Flow
(m
3
/s)
Exceed
(%)
150
37.09
0.5
174
5.44
31.5
106
0.99
72.1
145
30.22
1.3
156
4.78
34.2
74
0.87
75.8
139
24.56
2.8
139
4.12
37.4
97
0.77
78.3
132
22.66
3.6
98
3.49
40.6
87
0.67
81.4
190
21.15
4.4
79
3.13
42.8
122
0.56
84.7
180
19.92
5.2
114
2.88
44.3
117
0.44
87.9
160
17.91
6.7
123
2.53
46.7
120
0.35
90.8
175
16.98
7.5
35
2.33
48.2
101
0.34
91.3
155
15.91
8.6
108
2.08
50.5
88
0.30
92.7
149
15.44
9.2
93
1.87
52.7
113
0.30
93.1
182
14.48
10.4
81
1.74
54.3
105
0.26
94.5
174
12.36
13.6
94
1.59
56.6
78
0.24
95.3
150
10.66
16.8
118
1.49
58.4
90
0.20
96.7
215
9.42
19.7
54
1.40
60.4
121
0.16
97.8
161
8.32
22.4
62
1.26
63.8
44
0.15
98.2
186
7.28
25.3
103
1.16
66.7
108
0.11
99.1
239
6.15
28.9
110
1.09
69.2
-
-
-
mal distribution. The mean and standard deviation
of the logarithm (to base 10) of the
E. coli
data
are 2.328 and 0.481, respectively, where the
E. coli
concentrations are expressed in CFU/dL. Regula-
tory standards require a geometric mean concen-
tration less than or equal to 126 CFU/dL, and a
90-percentile concentration less than or equal to
252 CFU/dL. Determine the required
E. coli
load
reduction to achieve compliance with the water-
quality standards.
4.47.
Measurements of
E. coli
concentration and low
rate are taken in the stream that is described in
Problem 4.36, and these measurements are tabu-
lated as shown in Table 4.16. If the
E. coli
water-
quality standard for the stream is 126 CFU/dL,
determine whether point sources or nonpoint
sources are the likely causes of the water-quality
violations.
4.48.
Instream measurements of
E. coli
concentrations
under a particular flow condition follow a lognor-
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