GEA was commissioned to carry out a detailed desk study and ground investigation at the Museum of Childhood in order to assist with the redevelopment of this Grade II listed building, including the design of a new steel spiral staircase within the main hall. The investigation had to be carried out without disrupting the daily opening and activities of the Museum so the work inside the Museum was carried out overnight, with no disruption to visitors or neighbours.

In order to determine the ground conditions at depth, a single borehole was advanced to a depth of 15 m in the rear car park whilst ensuring full access to the lift at the rear of the building. Within two days, the working area was set up, the borehole was advanced and geotechnical samples collected, a groundwater monitoring standpipe installed, and the area was returned to normal.

Work inside the Museum began after it had closed one evening. Specialist rubber track mats were laid out along the granite sett paving at the front entrance to track the rig over and were continued through the Museum entrance and into the main hall, protecting the listed fish scale mosaic marble flooring. The borehole was advanced through the base of a service trench. Track mats created a protective base in the working area, whilst acoustic barriers and sheeting surrounded the area to create a safe and contained drilling environment. The borehole was completed upon encountering the London Clay at a depth of around 6 m, and the main hall returned to normal overnight.

The expected ground conditions were encountered in that beneath a thickness of made ground associated with the history of site, Hackney Gravel was present over the London Clay Formation. Groundwater was present towards the base of the gravel, above the relatively impermeable London Clay.

The resultant report included the findings of our investigations, contamination and geotechnical testing, and provided the required parameters for a pile design for the new staircase. The project has since obtained planning approval and listed building consent.

Investigations are ongoing to provide additional information for the proposed new landscaped area and retaining walls for the main entrance to ensure full access to the lower level of the Museum, and we look forward to paying a visit once completed.