Problem 4. A 20-ft section of horizontal 6-inch-diameter pipe is being investigated in the lab. A head loss of 0.435 ft was measured when the flow was 475 gpm of water. If the kinematic viscosity is 1.2 × 10-5 ft2/s, estimate the equivalent sand grain roughness, ks. 0.1 0.09 Wholly turbulent flow 0.08 0.07 0.06 0.05 0.05 0.04 0.03 0.02

A cast-iron pipe was installed 50 years ago with a measured friction factor, f, of 0.02and surface roughness height, e, of 0.2mm. The horizontal pipe is 1500m long and has a diameter of35cm. Since installation, significant tuberculation has developed on the inside walls of the pipe. A recentpipe test was conducted. The pressure drop across the entire length of pipe was measured to be 200kPa.The design discharge through the pipe has not changed over the years (Q=0.1m 3 /s, T=20°C). Determinethe current effective friction factor, f, and surface roughness, e, after years of tuberculation buildup.

3.3 Three grit chambers are currently used to treat grits in a WWTP. Each channel is 2.5 ft wide and has a water depth of 2 ft. What is the velocity when the influent flow rate is 12 ft³/sec? a) 1.75 ft/sec b) 0.74 ft/sec c) 1.05 ft/sec d) 0.80 ft/sec 3.4 You performed settling test and found 600 mL settled after 30 min. If the MLSS in the aeration basin was 3000 mg/L, do you have problem? a) yes b) no c) no enough info. d) need to redo test

Q1 Data obtained from a laboratory consolidation test are tabulated as follows: Test points I 2 3 4 5 o' (kPa) Total AH (mm) 20 50 100 0.23 0.87 L.90 3.62 5.55 7.25 200 400 800 G,=2.70, Ho= (initial thickness at zero pressure) = 22.5 mm, w = (moisture content at the beginning of the test) = 0.78. Plot the e-logo' curve and calculate Ce Ae I+eo Ho log a - logo, log(o /06) ΔΗ Hint: and