2. a) The area of a forebay with (''A<sub>f</sub>'') 80 % capture efficiency of particles ≥ 1 mm may be estimated<ref name="HW"/> as: | 2. a) The area of a forebay with (''A<sub>f</sub>'') 80 % capture efficiency of particles ≥ 1 mm may be estimated<ref name="HW"/> as: |