Dewatering

During the excavation of the basement in late 2015, we had to address the issue of groundwater.

Various different options were considered in relation to logistics, cost and most importantly the environment.

The solution that best suited was to pump the groundwater into Millwall dock. After much consultation with the Canal & River Trust (C&RT) a process was agreed and the system set up.

We employed an Environmental Consultant and Groundwater Engineer SLR to monitor the process throughout.

Environmental protection for dewatering required the following:

• The ground water being pumped was tested by our consultant every 3 days to ensure bathing water quality standards were achieved.
• Watching brief – our consultant carried out daily visual checks to ensure the pump hoses were working effectively and not causing any distress to marine/bird life using the dock.
• A special filter was fitted to the two-outgoing pump hose ends to ensure water was discharged without causing harm to the local marine and bird life and users of the canal carrying out water sports.
• The discharge waters aided the C&RT operations by allowing the dock to be topped up throughout the 10 week pumping period. Something that the C&RT do manually every 3 days.
• Weekly dialogue with the C&RT to ensure standards were being maintained.

In total we pumped 26,950M3 which equates to 27 million litres of water to the dock whilst maintaining protection to the environment throughout.