.Example: Size a trench for two (2) UW60 and one (1) UW100

Fill levels UW60 = 24 gallons
UW100 = 50 gallons at high level

Total to drain, gallons = 98 gallons = 2 x 24 gallons + 50 gallons

Drain trench volume in cubic feet = 14.0 cu. ft. (98 gallons ÷ 7.18 gallons/cu. ft.)

Foundation width will be 13 feet 6 inches
(12 inches + 36=5/8 inches + 12 inches + 36-5/8 inches
+ 12 inches + 41-1/2 inches + 12 inches = 13 feet 6-3/4 inches
= 13 feet 6 inches)

Required trench cross section, square feet = 1.04 sq. ft. = (14.0 cu. feet) (14 feet 6 inches)