Stage 1 Engineering and Environmental Constraints
A review and validation of existing surveys, data, and reports to inform the other stages and overall outcomes of the feasibility study was initially undertaken during Stage 1 for the project. This included compiling baseline information on the following:
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General site characteristics of Shepley Mill, such as the weirs and culverts as presented in Figure 2.1, including a desk-based site condition assessment of the structures. This provided vital information in confirming the likely suitability of any in-stream structures to accept the potential implementation of a fish pass (or fish pass design), and potential habitat restoration enhancements.
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Site access constraints associated with Shepley Mill, including utilities services search.
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Hydrological, geomorphological, and ecological characteristics of the River Wandle, in particular the Carshalton and Croydon branches of the River Wandle.
To complement the above desk-based information complied for the project, a river morphology and engineering site walkover along the River Wandle immediately upstream and downstream of Shepley Mill was undertaken in order to gain an appreciation of the constraints and opportunities associated with the project. A validation of the existing surveys, data and reports was also carried out, along with a structural inspection of the Shepley Mill weirs; and a topographic (bathymetric) survey of the Carshalton and Croydon branches of the River Wandle, both upstream and downstream of the weirs. The survey included detailed measurements of the weirs and culverts. An aquatic and terrestrial ecological survey of the Carshalton and Croydon branches of the River Wandle was also undertaken along with sediment sampling of the branches, which was followed by an analysis of the chemical elements of the recovered sediments. The site walkover and all surveys were carried out in October 2021, followed by detailed reporting on geomorphology, ecology, sediment quality, engineering, and potential fish passage (habitat) restoration solutions for the project.