Abstract: A method of storing fluid from an oil well includes the steps: providing storage tanks; providing a diversion tank; coupling a fill manifold to the storage tanks and to the diversion tank, the fill manifold having a first control valve controlling flow of the fluid to the storage tanks, the fill manifold having a second control valve controlling flow of the fluid to the diversion tank; associating a sensor with at least one of the storage tanks without accessing a top of any of the storage tanks, the sensor being configured to determine a volume of the fluid within at least one of the storage tanks; associating a control system with the fill manifold and the sensor; and actuating the first and second control valves using the control system in response to at least one detection by the sensor to ensure that the storage tanks are not overfilled.