A facultative pond system is treating a wastewater flow of 2,350 m3/d with a BOD5 of 275
mg/L. Please reference Table 93.36 from DEQ Circular 2 (also found in the NTS notes).
a) Calculate the minimum surface area required if the BOD loading rate should not exceed 25
lb/(acre*d) for the primary ponds.
b) Assuming the ponds are 6 ft deep determine hydraulic retention time of the lagoon if the
bottom 2 ft is excluded in the volume calculation?
c) Assuming the bottom 2 ft will be taken up with deposited solids (which counts toward total
depth), what total water depth range is required to maintain an acceptable residence time?
