What is the detention time of a 3 million gallon settling basin, with 8,000 gallons per hour wastewater flow?

To determine the detention time of a settling basin, you need to calculate how long a volume of water will remain in the basin before it exits. Detention time can be found using the formula:

[ \text{Detention Time (days)} = \frac{\text{Volume of the basin (gallons)}}{\text{Flow rate (gallons/hour)}} \times \frac{1 \text{ hour}}{24 \text{ hours}} ]

Given a settling basin volume of 3 million gallons and a flow rate of 8,000 gallons per hour, the calculation can be performed as follows:

1. Calculate the time in hours:

[ \text{Detention Time (hours)} = \frac{3,000,000 \text{ gallons}}{8,000 \text{ gallons/hour}} = 375 \text{ hours} ]

2. Convert hours into days:

[ \text{Detention Time (days)} = \frac{375 \text{ hours}}{24 \text{ hours/day}} \approx 15.625 \text{ days} ]

Rounding this to one decimal place gives approximately 15.6 days. This is the correct detention