Calculate the initial head loss through a dual-media filter consisting of a 12-in layer of uniform anthracite with a grain diameter of 2.0 mm and a 24-in layer of uniform sand with a grain diameter of 1.0 mm at a filtration rate of 4.0 gpm/ft^2. The porosity of both media is 0.40, the shape factor for the anthracite is 7.5, and the shape factor for the sand is 6.0. Assume a water temperature of 60 F.