TM 10-4610-232-12
NOTE
If the turbidity recorded is more than 0.5 NTU higher than the lowest recorded
turbidity since the last backwash, the filter is no longer efficiently removing sus-
pended solids and must be backwashes as described in para. 2-21.
NOTE
When increased turbidity is noted, recalibrate turbidity meter and check turbidity
again to be sure noted turbidity is correct. If in doubt, check turbidity with the portable
meter.
(b) If the lowest turbidity recorded for a filter run between backwashes is more than 0.2 NTU higher than that
recorded for other filter runs during the mission, the pump setting needs to be changed. If the raw water turbidity is
higher than when the lowest turbidity was recorded, increase the pump stroke at increments of 5 after the next
backwash until two successive increases show no decrease in turbidity. The correct setting is then 5 less than the final
setting.
Media Filter Log (Sample)
Date / Time
5/8
0800
0900
1000
1100
1200
1300
1310
1330
1400
5/10
1000
1100
1200
1300
1400
1500
Turbidities
Raw
32
35
33
33
33
34
34
34
45
65
65
65
63
61
Filter
1.6
1.2
1.0
0.9
0.9
0.9
2.0
1.4
1.5
1.8
1.8
1.4
1.2
1.0
Backwash
Note
Start-Up
Backwash
Polyelectrolyte Optimization Log
Time
1200
1215
1225
1235
1245
Stroke
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
Turbidity
1.8
1.6
1.5
1.5
1.5
Select 80 for new setting
Pump Settings
Stroke
65
65
65
65
65
65
65
65
65
65
65
65
80
80
80
Speed
65
65
65
65
65
65
65
65
65
65
65
65
65
65
65
Date 5/10
Location:
Raw Water Turbidity: 65
Speed Setting 65
Figure 2-55. Sample Logs
2-106
