Chapter 21, Problem 7RQ

can you show me step for step?  Autocad has me irritated.

mummins) Is there any risk from a contaminant if 150 out of 3800 people exposed to the groundwater contaminant develop cancer and 125 out of 5000 people not exposed to the contamination also develop cancer? Why or why not? Use at least two methods to support your answer.

A spare buoy is a buoyant rod weighted to float and protrude vertically, as shown in thefigure below. Suppose that the buoy is made of maple wood ( specific gravity s = 0.6), has arectangular cross section ( 2.54cm by 2.54cm ), a length of 3.7 m , and is floating in seawater( specific gravity s =1.025 ). What weight of steel should be added to the bottom end of thebuoy so that h=0.45 cm? ( The specific gravity of steel s = 7.85 )

8-42. Determine the displacement at point D. Use the principle of virtual work. El is constant. 60 kN 2m- 2 m B 30 kN/m 3 m

Two monitoring wells are spaced 500 m apart along the direction of groundwater flow in a confined aquifer 30.0 m thick. The difference in water level in the wells is 2.5 m. The hydraulic conductivity is 40 m/d. a) Sketch the aquifer and wells and label distances and direction of groundwater flow. b) If the real velocity of the groundwater is 0.6 m/d, what is the porosity? c) If it takes 10 years for a petroleum hydrocarbon plume to appear in the second well, what was the retardation factor?

9. 0000) Water in a lake contains 10.5 ppb of vinyl chloride, which has a potency factor of 2.3 (mg/kg-d) 1 a. What is the incremental cancer risk for children (average weight of 15 kg) who may ingest 0.05 L of water per day while playing in the water every summer (for approximately 60 days) for 10 years? b. Is this risk acceptable? Why or why not?

8-37. Determine the displacement of point C. Use the method of virtual work. El is constant. -12 ft- 3 k/ft -12 ft- B

6. If the initial DO concentration of a diluted (1/50) wastewater sample is 9.0 mg/L and the UO concentration decreases to 2.4 mg/L after 5 days of incubation, a. calculate the 5-day BOD concentration in mg/L: b. If the wastewater degrades at a rate of 0.22/day, what is the ultimate BOD concentration? c. Based on the k value in part (b), what would the BOD concentration be after 10 days? d. What other factor may influence the BOD that is not accounted for in part (c)?

2nYour consulting firm is doing an expansion project for a drinking water treatment plant in a growing urban area that has a current population of 55,000 people and treats 20 MGD. If there is 2.8% population growth, continuously compounded, and you want the expansion to be able to serve the urban area for the 35 year design life of the upgraded facility, what should the new design capacity (in MGD) of the treatment plant be?