Question

04-9 (ML 6.12) A pristine stream flowing at 100 cubic feet per second (cfs) in the Rocky Mountains contains 5 mg/L of suspended solids (SS). During the spring, ice melt conveys an additional 250 mg/L of TSS at a rate of 20 cfs into the stream. Determine the concentration of TSS in the stream during the spring. (Hint: Treat the ice melt as a secondary stream added to the first.) Answer: 46 mg/L

Answer 1

`C_(mix) = 45.833 mg/l`

Step-by-step explanation:

Give data:

flow rate of stream is
`Q_1 100 cfs`

concentration of suspended solids
`SS_1 5 mg/L`

During spring time,

concentration of TSS =
`SS_2 = 250 mg/l`

flow rate of stream
`Q_2= 20 cfs`

we know that, concentration of mix is given as

`C_(mix) = (Q_1 SS_1 +  Q_2 SS_2)/(Q_1 +Q_2)`

`C_(mix) = (100* 5 + 20* 250)/(100+20)`

`C_(mix) = 45.833 mg/l`