The area required to keep the maximum head of water within the forebay to 0.15 m is calculated as:
The area required to keep the maximum head of water within the forebay to 0.15 m is calculated as:
:<math>A_{f}=\frac{0.816}{0.1}=8.16\ m^{2}</math>
:<math>A_{f}=\frac{0.816}{0.1}=8.16\ m^{2}</math>
and the area required to settle the 1 mm particles is calculated as:
The area required to settle the 1 mm particles is calculated as:
:<math>A_{f}=120\times 0.1 = 12\ m</math>
:<math>A_{f}=120\times 0.1 = 12\ m^{2}</math>
So to meet the target particle removal, the forebay will be 12 m² in area. This gives the storage volume of 1.2 m³, which can be returned to the initial equation to determine the cleaning frequency as: