What should be taken care of when draining underground or in-ground water storage tanks?

When draining underground or in-ground water storage tanks, it's essential to be aware that the tank may shift or "float." This phenomenon occurs when the groundwater level rises or when the tank is drained too quickly, causing a reduction in the weight of water that holds the tank in place. If the hydraulic pressure from the surrounding water is greater than the weight of the tank, it can lead to the tank being displaced or lifted from its original position. This shifting can cause damage to the tank itself as well as to surrounding infrastructure, and it can also create safety hazards.

In contrast, while water temperature changes, increased pressure, and potential contamination are relevant factors in water storage management, they do not have the same immediate and physical consequences as the potential for tank shifting when drained. For example, a drop in temperature or a pressure increase is manageable through proper monitoring and control measures, and contamination issues can often be mitigated through preventative protocols. However, the shifting of a tank requires immediate attention and caution during the draining process to ensure safe and effective management of the tank.