Question

2. (10 points) Elevated lead in Flint drinking water was not the only violation of federal drinking water standards during the Flint Water Crisis. A summary of the average water quality parameters for treated Flint drinking water from August 2014 are presented in Table 1. Using Table 6-1 from the textbook (note that this table spans 4 pages - in edition 5, refer to Table 6-2), identify all parameters that exceed the maximum contaminant level (MCL) outlined in the Safe Drinking Water Act. For each parameter that exceeds the Safe Drinking Water Act primary standards, indicate possible sources of the contaminant in drinking water (these do not need to be specific to Flint) and listing any adverse health effects associated with the contaminant in drinking water. (Note: if a parameter is not listed in Table 6-1, a primary standard does not exist.) Table 1: Water quality data from Flint's drinking water treatment plant (August 2014) Parameter Value (monthly average unless otherwise noted) Temperature Chlorine (as Cl₂) Total coliform Total trihalomethanes (TTHMs) Calcium, Ca (mg/L) Magnesium, Mg (mg/L) pH Conductivity (mS) 23.3°C 1.6 mg/L (3.3 mg/L max) 8% of samples positive 0.14 mg/L 53.3 5.3 7.78 0.42 3. (15 points) A rapid-mix basin is designed for a flowrate of 20 MGD. The basin is 2.0 m wide, 2.0 m long, and 1.5 m deep. If the mixer is powered with 60 HP and the water is 15°C, calculate the mixing intensity, G (in s¹). 4. (15 points) A sedimentation basin is needed for a new drinking water treatment plant with a flow of 9,000 m³/d. Given that the diameter of the particles to be removed is 0.010 mm, the particle density is 1,397 kg/m³, and the water temperature is 15 °C, determine: a) The terminal settling velocity. b) Would particles of this size and density be completely removed in a rectangular settling basin with a width of 10 m, a depth of 3 m, and a length of 20 m?

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