Assignment task:
A new dog park in Denver is potentially causing algal blooms in the Cherry Creek forcing the DO below the state level of concern (6.5 mg/L). Upstream of the dog park, Cherry Creek has a flow of 20 cfs and a DO of 7.9 mg/L. The BOD has been measured in Cherry Creek to be historically 1.2 mg/L. The deoxygenation coefficient of 0.52/day and a reaeration coefficient of 0.43/day. Due to over-irrigation, grass fertilizer, and people not picking up after their pets, the runoff from the dog park has a flow of 2.1 cfs, a BOD of 212 mg/L, and a DO of 1.1 mg/L. The velocity downstream of the confluence is 0.06 ft/s. The saturation DO is 8.55 mg/L.
a. What is the initial oxygen deficit just downstream of the mixing point?
b. What is the minimum oxygen level in Cherry Creek due to the dog park?
c. Where does the maximum deficit occur in Cherry Creek given this information?