Harris Invictus Academy, Croydon – Projects

This project involved the construction of a new £23million secondary school, whilst ensuring the existing school remained operational prior to seamless transition.

The existing school site was historically used for landfill, with clear evidence of ground movement shown as large voids around the perimeter of the existing school building.

Replacing the existing school has provided a greatly improved environment for pupils to learn, which is vitally important for their formative years.

Our civils team undertook the below ground drainage design and external works design. Two key challenges to overcome were the ongoing risk of ground settlement and the proximity of and maintaining of a live secondary school.

To mitigate against the impact of ground movement, the below ground drainage was designed with steeper than usual gradients and incorporated a stabilised base to the manholes and pipes.

The new development had to reduce surface water run off rates to improve the risk of flooding off site. This was done using a below ground attenuation tank. It was essential that consideration was given to the impact of ground movement on the attenuation tank, which we dealt with via use of a stabilised base.

We also developed the below ground drainage scheme to minimise the need for temporary/sacrificial drainage, which provided cost, time and material savings.

The approach to the external build-ups was similar to the drainage in that the external areas were stabilised to reduce the impact of differential movement.