18. Finally, a 90cm deep dual-media filter bed of total area of 50 m² is being proposed to Fictiontown to processes the water at the design flow rate calculated in question 14 a) with temperature of 10°C. The filter is composed of a layer of sand (d = 1.20mm, G,=2.55, porosity=0.45) that occupies the top 30%, and garnet filter (d = 0.40mm, G.-3.50, porosity = 0.55) that takes up the remaining 70%. Both filter materials have a sphericity factor of 0.75. Using the Blake-Kozeny equation and showing the calculations in the provided table, determine if the overall head loss of the clean filter is acceptable. (15 marks)