2. Design rapid sand filters for a water treatment plant to treat a flow rate of 25 mgd. Use 1.5 for a peak factor and consider 6 filters of equal

size in parallel. Consider the location of overflow troughs, free board, and pressure head of water. Assume that the length of the filters is 2 times the width and that the filtration rate is 3 gpm/ft^2. Assume anthracite over sand with 1 ft gravel under media, top of water level during filtration is below troughs, and a 3 ft head drop between bottom of rapid sand filters (bottom of gravel) and top of water in chlorine contact basin. o Design the dimensions (width, length, depth) for each rapid sand filter using a length:width ratio of 2:1. Sketch a simple diagram of the rapid sand filter and label important features (e.g.,media, gravel, under drain, overflow troughs, free board, pressure head, and the water level in chlorine contact basin). o Using a backwash rate of 12 gpm/ft? for 15 minutes, what is the volume of water used in eachbackwash?