A mechanically cleaned wastewater bar screen is constructed using 10 mm wide bars spaced 10.0 cm apart center to center. The wastewater flow velocity in the channel immediately upstream of the screen will vary from 0.8 to 1.2 m/s. If the actual area of flow is 60% clogged, calculate the design head loss for the screens at the two extremes of flow. Assume that the coefficient of friction is 0.84.