Client: Private Client
Location: West London
Duration: April 2020 –January 2021
A two-storey basement extension including swimming pool were proposed for an existing terraced property in Central London. Beneath the property, groundwater levels within the River Terrace Deposits were found 2.2m above maximum excavation level. As a result, construction of the proposed basement was not possible without a dewatering system to lower, control and maintain groundwater levels below maximum formation levels.
10no x 7.5m deep wells were installed, penetrating the River Terrace Deposits, and terminating within the London Clay. The wells were evenly distributed across the basement area with positions agreed to prevent clashing with the proposed structural works. The engineered wells were designed and installed to prevent migration of fines, minimising the risk of settlement opposed to conventional sump pumping methods.
Submersible 240v borehole pumps were installed at the base of each well and controlled by our distribution panel with RCD and MCB protection and powered by the existing domestic power supply. Pumped groundwater was collected in a flexible perimeter ring main before discharging into on site manhole.