3. A small city discharges 3.5 m/s of sewage having a BOD of 30.0 mg/L and a dissolved oxygen concentration of 6.0 mg/L into a river that has a flow rate of 7.5 m/s a negligible BOD concentration, and a dissolved oxygen concentration of 8.0 mg/L Downstream of the discharge. the river has an average depth and width of 2.0 m and 25 m, respectively. The saturation value for dissolved oxygen in the stream for summertime low flow conditions is 8.5 mg/L. The decomposition rate coefficient is 0.35 /day. a Calculate the reaeration rate coefficient using the O'Connor-Dobbins formula. Reaeration rate coefficient day b. Find the critical travel time and the minimum dissolved oxygen concentration. Critical travel time: day Minimum D.O. concentration: mg/ e Will the river meet a dissolved oxxygen water quality standard of 5.0 mg/L? O The standard would be met O The standard would not be met

3. A small city discharges 3.5 m/s of sewage having a BOD of 30.0 mg/L and a dissolved oxygen concentration of 6.0 mg/L into a river that has a flow rate of 7.5 m/s a negligible BOD concentration, and a dissolved oxygen concentration of 8.0 mg/L Downstream of the discharge. the river has an average depth and width of 2.0 m and 25 m, respectively. The saturation value for dissolved oxygen in the stream for summertime low flow conditions is 8.5 mg/L. The decomposition rate coefficient is 0.35 /day. a Calculate the reaeration rate coefficient using the O'Connor-Dobbins formula. Reaeration rate coefficient day b. Find the critical travel time and the minimum dissolved oxygen concentration. Critical travel time: day Minimum D.O. concentration: mg/ e Will the river meet a dissolved oxxygen water quality standard of 5.0 mg/L? O The standard would be met O The standard would not be met

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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In a given year, a watershed with an area of 2500 km'J received 130 cm of precipitation. The average rate of flow measured in a gage at the outlet of the watershed was 30 m3/sec. Estimate the water losses due to the combined effects of evaporation, transpiration, and infiltration due to ground water. How much runoff reached the river for the year (i n cm)?
Two communities, A and B, are found on two opposite sides of flowing river with a 9.10 m3 /s rate of volumetric flow, an uniform average speed of 0.25 m/s, an average depth of 4.0 m, an average temperature of 13°C, a chloride concentration of 8.0 mg/L, a 5.0 mg/L concentration of ultimate BOD, and an 8.0 mg/L concentration of dissolved oxygen. Both communities continuously discharge wastewater at the same point in the river where instantaneous mixing is assumed. The discharge of community A, which has an ultimate BOD of 48.2 mg/L and a dissolved oxygen concentration of 2.50 mg/L, is 2.10 m3 /s. On the other hand, community B discharges 1.80 m3 /s of wastewater, which has an ultimate BOD of 62.9 mg/L and a dissolved oxygen concentration of 1.50 mg/L. Just downstream of the downfall of both point sources, the deoxygenation rate constant is observed to be 0.22 day-1 . (a) What are the ultimate BOD and the initial oxygen deficit of the river and wastewater mixture just downstream of the…
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