27 Jun 2013
June 27, 2013

Tales of the Unexpected

Crossfield Consulting was commissioned by a design and build contractor to undertake a ground investigation at a site in Old Wolverton, Milton Keynes as it is proposed to redevelop the site with a Refuse Waste Treatment Facility.  The site was formerly a cold-store warehouse/distribution centre but, at the time of the ground investigation, the site was operational and being used as offices, a depot and workshops by an Environmental Services Contractor to Milton Keynes Council.

The proposed development includes a large building that is to occupy the same footprint as the existing building.  Therefore, the Client proposed to reuse the footings beneath the existing structure to support the new building.

The ground investigation comprised windowless sampling around the yard areas of the site and hand dug trial pits to expose the foundations of the existing building.  However, the findings of the investigation demonstrated that the existing structure was not supported on pad footings as expected.  Instead, it was found that an insulated floor slab, suspended approximately 1 m above ground level, was supported on thickened concrete cross walls which were sat on top of piles.  The gable columns appeared to be supported on transfer beams at the suspended ground floor level.

A piled foundation solution was not anticipated as competent geology underlay
the site and it was considered that the soils were of sufficient strength to support the loads associated with the existing structure on shallow footings.  However, following some additional research and discussion with others, it was understood that, as the structure was originally a cold-store warehouse/distribution center, the suspended ground floor slab and piled foundation solution was most likely to be a precaution against frost heave due to the temperatures associated with the cold-store.

As part of our assessment, we developed an economical shallow foundation solution that was compatible with the foundations and substructures revealed by the investigation works.

The findings of our ground investigation meant that our Client had to re-assess their costs associated with the redevelopment project.  However, the Client praised our efforts for not only doing the work that we had proposed but for “going the extra mile” to understand the construction of the exiting building.  Although the Client had to come up with a “Plan B” for the redevelopment, it was far better to realise this at an early stage of the project than to find out following demolition and clearance of the site.