Table 2.
Measurement findings per category of plant and system
| Number of measurements (shifts) | Number of measurements with peaks (percentage of measurements) [average number of peaks in measurements with peaks] |
Median time in minutes for the peaks above level (min-max) |
Highest measured peak level in ppm | ||||||
|---|---|---|---|---|---|---|---|---|---|
| > 10 ppm | 5 ppm–10 ppm | 1 ppm–5 ppm | 0.1 ppm–1 ppm | Zero peaks | 0.1 ppm | 5 ppm | |||
| Big plants | 31 | 0 | 1 (3%) [2.0] |
4 (13%) [2.5] |
20 (65%) [5.2] |
11 (35%) |
5.5 (1–40) |
2 (2) |
10 |
| Pump stations and small plants | 25 | 3 (12%) [4.0] |
5 (20%) [5.6] |
16 (64%) [7.6] |
20 (80%) [8.9] |
5 (20%) |
11 (3–90) |
3 (1–25) |
30 |
| Sewer network | 12 | 1 (8%) [1.0] |
0 | 1 (8%) [1.0] |
4 (33%) [3.0] |
8 (67%) |
15 (1–40) |
5 (5) |
20 |
| Collecting sewage from cesspools | 25 | 4 (16%) [3.8] |
8 (32%) [2.3] |
12 (48%) [4.0] |
18 (72%) [6.8] |
7 (28%) |
7 (1–80) |
5 (1–11) |
260 |