Engineering feasibility studies for a large reservoir in the Fens

Feltwell reservoir is a potential strategic water resource for the whole of East Anglia. This paper describes the work undertaken by Binnie Black & Ve atch on the technical aspects of the site identification, pre-feasibility a nd feasibility studies for the construction of a reservoir at Feltwell. The process by which the site was identified is described. The incremental app roach to the assessment of the feasibility of developing a reservoir at the site involving a desk study, preliminary ground investigation, pre-feasibi lity study and feasibility study is outlined. The bulk of the paper discuss es the feasibility study undertaken in 1997/98. A feasibility ground invest igation was carried out and a digital geological model was developed. This geological model was used to assess the optimum reservoir depth and capacit y and to determine the embankment alignment. The problems associated with t he site geology are discussed, particularly in relation to the peat coverin g the site and the sourcing of material for filters and drains. The selecti on of cut-off options and the dewatering requirements are described. The co mplex hydraulics of the inlet/ outlet system are also described together wi th the proposed solution.