Lots M1 and M2 in North West Cambridge form part of the Eddington scheme, a sustainable community development, and provide 240 new homes including 125 townhouses, 115 apartments and nine villas across the 2.75Ha site.
The south section of the site includes three five-storey apartment blocks built using reinforced concrete (RC) flat slabs and in-situ columns with a large basement car park constructed beneath, shared between the apartment blocks and two rows of townhouses. The basement was formed using a secant piled wall due to the presence of ground water within the layer of sand, which extended approximately 2m below ground level. An RC liner wall with waterproof additive was cast in front of the piles to resist the hydrostatic pressures and provide a barrier to achieve a Grade 2 waterproof basement.
The townhouses are formed in traditional loadbearing masonry with precast concrete hollowcore floors. Developer requirements and planning restrictions regarding the height of the building led to the specification of precast concrete which allowed us to maximise the size of the spanning members while minimising the structural depth. The roofs are a mix of timber and precast concrete in response to the spans, structural zone and loading.
The roof geometry for some of the townhouses was complicated and led to the use of Structural Insulated Panels (SIPs) for some blocks to form the top storey.
We were appointed at planning stage to complete a Flood Risk Assessment and Sustainable Drainage Strategy (SuDS) for the development. To adhere to the strict outfall restrictions, significant surface water attenuation was provided at the site using permeable paving and underground modular tanks. The surface and foul water network has been designed to outfall to the strategic sewers located in the adjacent highways with approval from the local Water Authority.
The drainage was offered for Adoption via a Section 104 Agreement with Anglian Water, with Technical Approval obtained for this at an early stage of the project. The civil engineering design required extensive coordination with the site's utility services and corridors. The basement and associated podium are integral parts of the scheme and so our civil engineering design was adapted to avoid interference with the proposed structure and services, ensuring an appropriate surface water drainage strategy was implemented.
We undertook a cut and fill volumetric exercise, aiming to meet a net neutral cut/fill design mitigating any unnecessary spoil and construction movements to and from the site.
The road networks were designed to adoptable standards, in accordance with local Cambridgeshire County Council's requirements.