Transfers into the tank shall be reconciled with any receipts of the transfer by measuring the tank inventory before AND after the transfer.
You must also measure any water that may be in the tank.
Do at least once each month
The measurement must be accurate to within 1/8 of an inch
Measure for water in the tank before AND after any transfer of product to the tank
You should also check tanks for the presence of water after a heavy rain or snowfall
Whenever you complete taking measurements of product and/or water in a tank be sure to reinstall the cap making sure it is sealed tightly to the riser.