Which of the following is the correct formula to calculate the area of a drainfield?

The process of calculating the area of a drainfield involves understanding the relationship between the design flow rate and the application rate. The formula consists of dividing the total flow (denoted as Q) by the rate at which the soil can absorb water (denoted as Ra). This division effectively determines how much area is needed to effectively manage the sewage effluent.

When calculating the drainfield area, Q represents the daily flow of wastewater, while Ra represents the soil absorption rate, which is measured in gallons per square foot per day, for instance. By using the formula Q / Ra, you're essentially finding out how many square feet are required to accommodate the flow of wastewater without overwhelming the soil's ability to absorb it. This ensures that the drainfield operates efficiently without causing surface runoff or backup, thus maintaining proper sanitation and environmental standards.

Consequently, this ratio provides a clear portrayal of how much area is necessary to treat the volume of wastewater generated, making the calculation essential for the proper installation and functioning of on-site sewage facilities.