The extant scheme had achieved outline planning consent for 650 new homes but Home England wanted to also bring forward an addition 215 new homes on adjacent land and review/revise the existing masterplan to deliver enhanced placemaking (including a re-located local centre), improved accessibility links and land value resulting in a section 73 (S73) application.
Multi-disciplinary coordination between our highways and drainage engineers allowed us to develop a site wide levels strategy that minimised the impact earthworks and maximised the use of gravity sewers across an extremely flat site. Early input into the highway layout resulted in the incorporation of a SuDS corridor for the capture and treatment of highway runoff. This along with the use of conveyance swales and multi-use basins throughout the landscaping areas of the site resulted in a scheme where SuDS not only offered water quality, biodiversity and flood risk benefits, but played an important role in contributing to the overall characteristics of the development. This information allowed Homes England to de-risk the site and provide enhanced information to potential future developers.
Engaging closely with the Lead Local Flood Authority throughout the Phase 1 RMA and Phase 2 OPA, CampbellReith developed a drainage design that was sympathetic to the site’s constraints and formed an integral part to the proposed landscaping.
As part of the Phase 2 application, CampbellReith’s Transportation team reviewed and updated the previous analysis undertaken on the local network to clearly demonstrate the likely impact in traffic terms. A Transport Assessment was submitted in support of the application, which included appropriate mitigation measures in the form of junction upgrades, along with a dedicated Residential Travel Plan to introduce measures which would reduce the reliance on the private car and encourage sustainable forms of travel.
Our Geotechnical and Land Quality Teams undertook desk-based reporting, followed by the design, procurement and management of ground investigation works to inform the detailed design of the spine road, and also providing preliminary design information to inform the future development of adjacent, predominately residential, land parcels.
The investigations were tailored to investigate identified geohazards and contamination sources, including the significant subsidence risk from chalk dissolution, landfill and aviation fuel tanks, whilst also considering planning conditions associated with the re-use of sand and gravel minerals and decommissioning of exploratory holes to avoid contamination of underlying aquifers.
The works culminated in a Phase II Geo-environmental Report and Mineral Assessment and Strategy for the entire DeHavilland Park development area, with the latter informing the sustainable re-use of site won soils during future development. The Interpretative Geotechnical Report for the spine road concluded ground improvement through rapid dynamic compaction paired with grouting of identified features was required to mitigate the risk of subsidence from chalk dissolution. Additional phase specific ground summary reports were produced to support the technical information packages and their disposal to plot developers.