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 |