New London Embassy,
Nine Elms, London

The United States’ new embassy in the Nine Elms area of London, distinguished by its striking glass cube design, stands on a site with a complex industrial legacy. Previously home to a major Post Office sorting office—and before that, a gas works—the location presented significant environmental challenges, including contaminated soil and a high water table.

Prior to construction of the main structure, WJ was commissioned to manage and treat approximately 40,000 m³ of contaminated groundwater. This water was confined within the diaphragm wall forming the perimeter of the basement car park, which also served as a hydraulic cut-off into the London Clay.

To address this, WJ engineered a robust dewatering solution comprising six internal pumping wells and two internal piezometers.

Although the extracted groundwater was discharged to the sewer system, strict regulations on hydrocarbon levels required advanced treatment. The water was processed through a 10 m³ air stripper tower and four 5 m³ carbon filtration vessels, ensuring compliance with environmental standards before disposal.

A comprehensive monitoring system was implemented to track water levels in real time. Trigger thresholds were established to prevent excessive external drawdown, with immediate alerts sent to site staff in the event of any breach. Notably, the project was completed without any trigger level violations, and all discharged water remained within the permitted limits throughout.

This project represents another successful contract contributing to the regeneration of a previously neglected area of London.