Test: Sewage Collection - 1 - Civil Engineering (CE) MCQ

The sum total of domestic and industrial sewage is termed as sanitary sewage or simply sewage.

When the rain runoff drainage is carried along with sewage it is called a combined system. When the drainage and sewage are taken independently of each other through two different sets it is called a separate system.

The sewer pipes have to be designed and checked for both maximum and minimum flows. This is because:

1. Maximum Flow: The pipes must be capable of handling the peak flow rates to prevent overflow and flooding during periods of high usage, such as during heavy rainfall or when there is a significant discharge into the sewer system.

2. Minimum Flow: The pipes must also be designed to ensure there is sufficient flow even during low usage periods to prevent sedimentation, blockages, and the buildup of foul gases.

So, the correct answer is: both maximum and minimum flows

Maximum daily flow = 2 times the average daily flow
Maximum hourly flow = 1.5 times the maximum daily flow
= 3 times the average daily flow

Minimum daily flow = 2/3 x Average daily
Minimum hourly flow  = 1/2 x Minimum daily flow 
= 1/3 Average daily

Coefficient of runoff is a factor which tells the proportion of water flowing off and not going into the earth. Since, for perfectly impervious area all of the water will flow off and none will get into the ground, therefore, the coefficient of runoff will be equal to 1.

Proportionate perimeter: