Weir overflow rate is flow per foot of weir length.
Weir Overflow Rate
Formula
Weir length = 3.1416 x Weir diameter x Number of clarifiers Weir overflow rate, gpd/ft = Flow, gpd / Weir length, ft
Inputs used
- Flow (MGD)
- Weir diameter (ft)
- Clarifiers in service (units)
- Or total weir length (overrides) (ft)
Worked example (White River WRRF, fictional)
- Weir length = 3.1416 x 86 x 4 = 1,081 ft
- WOR = 8,000,000 / 1,081 = 7,403 gpd/ft
Tips
- For a circular weir, length = pi x weir diameter (per side if double sided).
Results are estimates for operator use. Check units and inputs, and confirm decisions with plant data and procedures.
This calculator also appears on ActivatedSludge.com, our consulting site. Results are for training and operator use; always follow your plant’s procedures.