24 May 2023
Project: Launton, Bicester
Size: 65 new homes including 8 live working properties
Disciplines working on the project:
About the project:
Richborough Estates commissioned M-EC to provide support on various pre-planning technical matters. Our services included Flood Risk and Drainage assessments, Acoustic and Air Quality assessments, Utility Investigation, as well as Ground Investigations and a topographical survey.
Our Geo-Environmental team conducted Phase I and Phase II investigations to determine ground conditions and identify potential contamination in the shallow soils. The team also assessed the geotechnical properties of the strata to aid civil engineering design and performed soakaway testing to evaluate the viability of soakaway drainage. The results indicated a low to moderate risk of contamination, and a relevant remediation strategy was implemented to ensure proper disposal of any moderate contamination. Additionally, it was found that traditional soakaways were unsuitable for the site, requiring an alternative drainage solution.
Our flood risk and drainage team conducted a comprehensive flood risk assessment, evaluating both existing flooding and the potential impact of the proposed development on the surrounding areas. The assessment revealed that the development site falls within flood zone 1. However, detailed hydraulic modelling showed that whilst the northern and southwest areas of the site posed a low risk of surface water flooding, the risk increased to high towards the centre and southeast, closer to the existing ditch network.
To mitigate potential flood risks, our team devised an effective drainage strategy. This involved efficiently collecting surface water from roofs and hardstanding areas using gutters and surface water sewers and storing it within three proposed attenuation basins on the site. Furthermore, we emphasised the importance of clearing and maintaining the existing culvert and ensuring it was restored to its original condition, along with installing a new culvert matching the downstream culvert located under Station Road to accommodate flows during extreme storm events.
As an additional precautionary measure, it was strongly recommended that the finishing floor levels be set 300 meters above the flood depths anticipated for a 1 in a 100-year scenario, whilst accounting for a 70% increase due to climate change and blockage possibilities. This measure would significantly reduce the potential risks associated with flooding and ensures the development is future-proofed.
Acoustic and air quality assessments were conducted to evaluate the environmental impact of the development. The air quality objectives were successfully achieved at the designated receptor locations, indicating that the site is suitable for development and that no additional mitigation measures were required. However, to counteract any potential incremental increase in pollutant emissions, our team proposed implementing several sustainable travel measures to encourage the use of environmentally friendly transportation methods.
To comply with the ProPG guidelines, an initial site noise risk assessment was performed. The assessment revealed that the measured noise exposure levels categorised the majority of the site as having a negligible risk during daytime and a negligible to low risk during nightime. Additionally, the team had to consider the future impact of the new mainline railway, which is currently being constructed north of the development. The team modelled the site and environs to accurately determine the existing and future noise levels. Consequently, based on their findings, the team recommended implementing an embedded façade mitigation strategy to achieve acceptable internal noise levels.
An in-house utilities assessment was conducted to identify existing utility services across the development and determine any necessary diversions. Preliminary indications suggest that the site can be adequately supplied with electricity and fibre capacity from the surrounding networks without additional reinforcement. However, overhead and underground cables, an existing SSE pole-mounted transformer, and Openreach underground cables were found within the site boundary, requiring diversion.
Additionally, it was confirmed that there is no existing gas network in Launton, and the nearest suitable connection is a medium-pressure gas main approximately 1.5km from the proposed site boundary. Due to the significant distance required to facilitate a connection, an alternate means of heating was recommended.
To encapsulate the technical elements for this development, our geomatics team conducted a topographical survey to determine the site’s overall topography, accurately map site levels, identify boundaries, and record natural and man-made features.
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