Pick up the correct statement from the following: A. Maximum daily flow = 2 times the average daily flow B. Maximum daily flow = $$\frac{2}{3}$$ × average daily flow C. Sewers are designed for minimum permissible velocity at minimum flow D. All the above

The correct answer is D. All the above.

The maximum daily flow is the largest flow that is expected to occur in a sewer system in a given day. It is typically calculated by multiplying the average daily flow by a factor of 2 or 3. The average daily flow is the average flow that is expected to occur in a sewer system in a given day. It is calculated by dividing the total flow that occurs in

a year by the number of days in a year. The minimum permissible velocity is the minimum velocity that is required to prevent solids from settling in a sewer. It is typically 0.75 m/s. Sewers are designed for the minimum permissible velocity at minimum flow. This means that the sewers are designed to be able to carry the minimum flow at a velocity of at least 0.75 m/s.

Here are some additional details about each option:

• Option A: Maximum daily flow = 2 times the average daily flow. This is a common rule of thumb for estimating the maximum daily flow. However, the actual maximum daily flow can vary depending on the size of the sewer system, the type of sewer system, and the climate.
• Option B: Maximum daily flow = $\frac{2}{3}$ × average daily flow. This is another common rule of thumb for estimating the maximum daily flow. It is typically used for smaller sewer systems.
• Option C: Sewers are designed for minimum permissible velocity at minimum flow. This is a requirement of the American Society of Civil Engineers (ASCE) Standard 2000. The ASCE Standard 2000 is a set of guidelines for the design and construction of sanitary sewer systems.

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