Underground concrete tanks are a brilliant method for storing large quantities of water when connected to rainwater harvesting systems. These tanks offer exceptional durability and space-saving benefits, making them an excellent choice for domestic, commercial, and industrial applications. One recurring concern with underground concrete tanks is their potential to float or move, which can create serious structural problems and damage the tanks and their surrounding infrastructure. Fortunately, there are some solid solutions to prevent underground concrete tanks from floating to ensure a reliable and long-lasting water storage solution and continuous non-potent supply.
To prevent underground concrete tanks from floating, the key is to understand the basic principles of physics, including buoyancy. While the tanks are renowned for their robustness and longevity, and the concrete itself is quite heavy, the weight of the underground concrete tanks alone is often not enough to withstand the buoyancy effect especially when they are empty or only partially filled with water. The groundwater pressure around the tanks will push up on the empty space within the tanks, creating an upward force. If this uplift force exceeds the downward force of the underground concrete tanks’ weight, the tanks will start to lift upwards, potentially becoming damaged and disrupting their functionality.
Adding weight to counteract buoyancy is a straightforward yet solid solution. By incorporating concrete blocks or gravel around and on top of the underground concrete tanks, they increase their overall mass. The additional weight counterbalances the buoyant force, keeping the tanks steady even in situations of high groundwater levels. This method is practical and economical, as it uses readily available materials to ensure the underground concrete tanks’ stability.
Another simple but effective method is to place geotextile fabric between the outer surface of underground concrete tanks and the surrounding soil to create frictional resistance. Geotextile fabric is a strong and absorbent material that can act as a protective layer and shield the underground concrete tanks from potential abrasions and external pressures. Furthermore, the resistance the fabric lining causes opposes the buoyant force and can effectively hold the tanks in place.
To ensure underground concrete tanks remain firmly in place even better, they can be anchored to counteract the buoyancy force. These anchors are embedded deep into the ground below the tanks, and thick chains, cables, or straps are then attached to connect the tanks to the anchors. The anchors provide a solid downward counterforce when the tanks are empty and want to float upwards. For excellent security, several anchors should be installed, spaced evenly around the underground concrete tanks and attached at multiple points.
These proactive measures can ensure that your underground concrete tanks remain steadfast and dependable, ready to serve your water storage requirements for years to come. However, preventing underground concrete tanks from floating isn’t a one-time endeavour. Regular maintenance plays a vital role in sustaining the tanks’ stability over the long term. Thus, inspecting their condition, foundation, and anchoring mechanisms annually ensures that everything remains in optimal working order.
No matter the solution, the key is to proactively address buoyancy challenges long before the installation of concrete underground tanks and enlist the expertise of a water tank expert in the process. These professionals can assess the specific conditions of the site, taking into account factors such as soil type, groundwater levels, and your tank dimensions. They can help craft solutions using weighted bases, slabs, backfill, and anchors as needed to minimise the risk of your underground concrete tanks floating. Thus, we advise you to work closely with qualified engineers experienced in water pressure factors in your region.
