If a storage tank is 40 feet high with a diameter of 85 feet, what is the detention time in hours if the flow is 8 MGD?

To find the detention time in hours for a storage tank, you first need to calculate the total volume of the tank and then use the flow rate to determine how long it takes to fill that volume.

1. Calculate the Volume of the Tank:

The formula for the volume ( V ) of a cylinder is given by:

[

V = \pi r^2 h

]

where ( r ) is the radius and ( h ) is the height.

Here, the diameter of the tank is 85 feet, so the radius ( r ) is half of that:

[

r = \frac{85}{2} = 42.5 \text{ feet}

]

The height ( h ) of the tank is 40 feet. Plugging these values into the volume formula:

[

V = \pi (42.5)^2 (40)

]

Calculating ( (42.5)^2 ) gives approximately 1806.25, so:

[

V \approx \pi \times 1806.25 \times 40 \approx 226,980 \text{ cubic