What is the drainfield trench loading rate in gpd/ft2 for a system with twenty laterals each 50-feet long and an average flow of 1.5 gpm?

To determine the drainfield trench loading rate in gallons per day per square foot (gpd/ft2), it is essential first to calculate the total daily flow from the system and then distribute that flow over the total area of the drainfield created by the laterals.

In this scenario, the given flow rate is 1.5 gallons per minute (gpm). To find the daily flow:

1. Convert the flow from gallons per minute to gallons per day:

[

\text{Daily Flow} = \text{Flow Rate} (gpm) \times \text{Minutes in a Day}

= 1.5 , gpm \times 1,440 , \text{minutes/day}

= 2,160 , gpd

]

2. Next, calculate the total length of the laterals. There are twenty laterals, each 50 feet long:

[

\text{Total Length} = 20 , \text{laterals} \times 50 , \text{feet} = 1,000 , \text{feet}

]

3. The drainfield trench loading rate is then determined by dividing