Basement Dewatering

Dewatering to control and lower groundwater levels to enable construction of a residential basement 

Objective

Stuart Wells was contracted to temporarily reduce the groundwater level to enable underpinning works to be undertaken in the construction of a residential basement. Groundwater was located at 2.89m below ground level, with an excavation depth of 5.15m required.

The new basement was being constructed under a terraced house in a busy street so access needed to be taken into consideration.

Scope of works

To ensure the construction of the basement could be undertaken in dry and stable conditions we installed a 5no deep well temporary dewatering system. Three wells were located externally and two within the basement area. Once the wells were installed and developed using airlift techniques, a 240v submersible borehole pump was installed at the base of each well.

The wells were linked together with a discharge collection main to transfer abstracted groundwater to the discharge location.

Solution

Stuart Wells conducted an assessment of the ground conditions and designed a suitable deep well dewatering system. We submitted licence and permit applications to the Environment Agency on behalf of the client.

To overcome the access issues. the wells were drilled using a cut-down cable percussion drilling rig which can pass through a domestic doorway and operate in restricted headroom of 2.4m.