Question

A city has a projected population of 60,000 spread over area of 50 hectare. Find the design discharge for the separate sewer line by assuming rate of water supply of 250 LPCD and out of this total supply only 75 % reaches in sewer as wastewater. Make necessary assumption whenever necessary.

(a) 0.26 m^3/s

(b) 0.6 m^3/s

(c) 0.76 m^3/s

(d) 3.26 m^3/s

I got this question during an online interview.

The above asked question is from Schedule of Rates for Water Supply works in section Schedule of Rates Metric and F.B of Civil Engineering Drawing

Answer 1

The correct choice is (a) 0.26 m^3/s

Explanation: Given data, Q = 250 lit/capita/day

Sewage flow = 75% of water supply = 0.75* 250 = 187.5 LPCD

Total sewage generated = 187.5*60000/(24*3600) = 130.21 lit/sec = 0.13 m^3/s

Assume peak factor = 2

Total design discharge = 0.26 m^3/s.