Once the excavation of the ground has been done, it is important to constantly dewater the area and make sure that the area where the underground tank is to be constructed is kept dry. Once the excavation has been completed, stone soling is done after which lean concrete is laid. Once the lean concrete has been properly laid, cured, and dried, it is recommended to apply 2 coats of Waterproofing Membrane over the lean concrete surface. The application of Waterproofing Membrane is to be done in opposite right-angled directions (if the first coat is applied left to right, the second coat is applied top to bottom). Once the coating of Waterproofing Membrane has been dried out, it is recommended to sandwich the coating by applying another layer of lean concrete over the coating of Waterproofing Membrane . The steel reinforcement is to be done over the second layer of lean concrete.
Note: Prior to concreting it is essential to make sure that the water inlet and outlet pipe sleeve provisions are already done within the formwork of the concrete underground tank so that there is no need for hacking or breaking the concrete after it has been casted.