The F-line tank is extremely popular due to it's shallow design and pump sump which maximises the use of water within the tank.
However, upon installing the tank it is absolutely vital to ensure that the sump does not prop up the main floor of the tank. My advice for installing these tanks is always to dig the sump hole larger than necessary then back fill firmly through the support struts, ensuring material is packed down firmly into these structural supports, which when properly compacted will create solid supports.
The below pictures are of an installation where the floor of the tank was "propped up" by the sump, which consequent will allow the floor to drop when the tank is full of water. you can see by the picture that the floor has dropped but the sump hasn't, causing the tank to crack.
Thankfully these cracks can be repaired.
Repairing a leaking tank can be done in situ, however, the split must not have water ingress coming in from the outside. To repair a leaking tank one must use a professional welder like an extrusion welder. It is also important to use the same plastic that the tank is made from.
Maybe, if the ground around the tank is moving and causing the walls to bulge in, then a repair may not last due to the ground moving further, in this situation the tank should be removed, repaired then reinstalled.
Nothing sticks to Polyetherline (PE). You cannot Glue, solvent weld, mastic or sikaflex PE. the only way to properly repair PE is to weld it and the best repairs are done using the original material the tank is made from.
If you require a tank welding please email photos and your location to: info@thesewageguy.co.uk