Projects

Hangar 202, London Luton Airport

Key details

Project name

Client

Harrods Aviation

Location

London Luton Airport

Services provided:

- Architecture

- Civil Engineering

- Structural Engineering

- Airfield Planning and Design

- Geotechnical

- CDM

- Project and Cost Management

- Construction Supervision

Challenge

The main challenge was the complex ground conditions. Prior to airport ownership, the area was a household refuse tip with records showing this was operating between 1937 and 1979. The depth of the landfill varied between 5m to 8m and overlaid weathered chalk. An aquifer was also present near to the site. A capping layer of made ground up to 3m thick overlaid the landfill material.

Significant design work was required to provide an environmentally sustainable and cost-effective solution for the foundations. A critical factor was the requirement to reduce the amount of geotechnical remediation work for the building, plus the taxiway link and apron areas connecting the hangar to the airport taxiway network. In addition to the foundation design, consideration was required to prevent the ingress of methane into the hangar from the landfill material.

Solution

Our engineering and geotechnical design teams worked collaboratively with the site investigation team to establish a comprehensive suite of foundation designs. These included the following:

Hangar – the floor and superstructure supported on precast concrete piles driven into the chalk material. Prior to this, the area was remediated by excavating to a depth of 5m, a liner installed and area infilled. The piling was carried out with extreme caution to prevent contaminants from the lower layer of landfill entering the aquifer. The design risk assessment identified that the use of driven piles reduced the amount of excavated material brought to the surface which would present a risk to operatives of the piling installation.

To prevent methane ingress into the building a membrane barrier was installed with passive venting.

Apron & Taxiway – ground improvement techniques were used to improve the in-situ materials bearing capacity. This reduced the volume of material that required removal to a licensed tip.

The environmental and CDM risk assessment concluded that foundation design reduced environmental impacts in terms of potential contamination of the aquifer within the chalk formation and to the construction personnel.