Late comment as I just got into this thread:
You mentioned a max allowable flow rate which suggests you have a permit for these ponds and their discharge. If you have a permit you want to find out if any of the ponds are allowed by permit to retain water beyond 48-72 hours after rainfall. If...
Can anyone tell me if thickness testing is required of AST's for atmospheric storage of oil/petroleum storage tanks that are shop fabricated. These tanks are 1,000 gallons or less.