A mud-flat (surface elevation 615 ft) next to a bay is to be developed for industrial purposes. The soils at the site are fairly uniform and consist of 40 feet of very soft, normally consolidated clay. To create a dry surface for development, hydraulic fill" will be placed over the mud-flat. Hydraulic fill is constructed by removing sand from the bottom of a bay, pumping it as a slurry through a pipe, and discharging the soil suspension at the site to provide a layer of fill. The design requires that enough fill be placed so that the new ground surface will be at an elevation of 623 ft. Because of settlement in the soft clay, more than 8 ft of fill will be required. Assume that the water level in the bay, and the ground water table, will remain at the interface between the fill and clay throughout the analysis. Calculate the total thickness of fill that must be pumped to the site. Treat the soft clay as two layers, and find your answer by trial and error. Continue iterating until your answer is correct to within 0.1 feet. A spreadsheet or computer code may be very useful in solving this problem: if you program a spreadsheet or code, carry out the first and the last iteration by hand showing ALL your calculations, and attach a print- out of the your spreadsheet (with cell formulas spelled out) or code (with input and output files). Use the following soil properties for your calculations: Fill: Gs = 2.65, dry unit weight = 95 pcf, degree of saturation is 50% above the water table and 100% below the water table. Soft clay: normally consolidated, water content = 75%, GS = 2.72, recompression index (C) = 0.08, compression index (CC) = 0.79. A mud-flat (surface elevation 615 ft) next to a bay is to be developed for industrial purposes. The soils at the site are fairly uniform and consist of 40 feet of very soft, normally consolidated clay. To create a dry surface for development, hydraulic fill" will be placed over the mud-flat. Hydraulic fill is constructed by removing sand from the bottom of a bay, pumping it as a slurry through a pipe, and discharging the soil suspension at the site to provide a layer of fill. The design requires that enough fill be placed so that the new ground surface will be at an elevation of 623 ft. Because of settlement in the soft clay, more than 8 ft of fill will be required. Assume that the water level in the bay, and the ground water table, will remain at the interface between the fill and clay throughout the analysis. Calculate the total thickness of fill that must be pumped to the site. Treat the soft clay as two layers, and find your answer by trial and error. Continue iterating until your answer is correct to within 0.1 feet. A spreadsheet or computer code may be very useful in solving this problem: if you program a spreadsheet or code, carry out the first and the last iteration by hand showing ALL your calculations, and attach a print- out of the your spreadsheet (with cell formulas spelled out) or code (with input and output files). Use the following soil properties for your calculations: Fill: Gs = 2.65, dry unit weight = 95 pcf, degree of saturation is 50% above the water table and 100% below the water table. Soft clay: normally consolidated, water content = 75%, GS = 2.72, recompression index (C) = 0.08, compression index (CC) = 0.79