Filter Backwash Procedure

Filters must be washed when they reach terminal headloss, turbidity breakthrough, or a run time of 72 hours.

Pre-Wash Checklist

• [ ] Ensure Backwash Tank is full (> 20 ft).
• [ ] Verify Air Scour Blower is available.
• [ ] Check Waste Gullet gate is clear.

Automatic Wash Sequence

Initiate "Auto-Wash" on the SCADA panel. The system will cycle through:

1. Drain Down: Level drops to 6 inches above media.
2. Air Scour: Air is injected for 3 minutes to break up the mud ball layer.
3. Low Wash: Water enters at 2,000 gpm to fluidize the bed.
4. High Wash: Flow increases to 8,000 gpm to flush solids to the trough.
5. Settle: 2-minute pause to let media stratify (sand on bottom, coal on top).

Post-Wash Validation

After the filter returns to service: * Monitor: Watch the turbidity meter for the first 15 minutes. * Filter-to-Waste: Ensure the valve closes only after turbidity drops below 0.20 NTU.