1. A small stream of 20,000 cfm has a BOD of 5 mg/L. An industrial outfall joins the stream; the outfall has a BOD of 250 mg/L. Downstream of the outfall, the BOD must be 10 mg/L to meet regulations. What is the allowable flow rate of the outfall in cfm? Sketch and label a BLOCK DIAGRAM of the system (the BLOCK is the mixing zone of the 2 flows), showing the appropriate streams (where flow rates are Q1, Q2 etc and BOD concentrations are c1, c2 etc).