The concrete well is the underground part of the Collector. The container is placed in this and the safety floor is attached to it. It is a prefabricated product made of reinforced concrete that has been specially developed for Bammens. The drainage system consists of a thermally galvanised edge on the concrete and bridges the opening between the container and the concrete well. A specially constructed non-visible drain removes excess rainwater to the outside of the concrete well.

Optional: connection to a chamber or a vertical drainage system.

Volume and construction: the concrete well (3 m³) consists of a single element, the 4 m³ and 5 m³ wells consist of two elements which are positioned on each other with a water-tight connection using special sealant.

Construction materials: reinforced concrete, strength category B45, environment class 3, with Komo authorised product certificate and Kiwa-declaration (Building Materials Decree).

Weight: 3 m³- 4370 kg,
4 m³ - 5280 kg and 5 m³ - 6200 kg.