Flood Risk Assessment
Priory Mills, Wells Flood Risk Assessment.
Keywords: Flood Risk Assessment, Urban Watercourses.
Client, Architect & Other Organisations
McCarthy & Stone
Graham Garner & Partners
Description
St. Andrew's / The Mill Stream has been channelled and managed for centuries in order to exploit the benefits of an almost in constant supply of clean water to the City of Wells for human consumption and industrial use. Priory/Sheldon Mill is one of a number of similar mills in Wells which once used the water to grind cereal.
Unusually there is no direct fluvial contribution to St. Andrew's Stream. Flow in St. Andrew's Stream is derived from St. Andrew's well, sluices is in the Bishop's Palace moat; surface water run-off from the city and unofficial gray water connections from property on the line of the culvert. The extent of the urban catchment contributing to St Andrew's Stream forms a narrow band through the centre of Wells.
Scope of Work
Edenvale Young (then JYA Ltd) was invited by Graham and Gardner and Partners and appointed by McCarthy and Stone to undertake a Flood Risk Assessment for the Priory Mills development in Wells. The development will comprise of the construction of 34 sheltered apartments on the former site of the factory (Sheldon Engineering Works). A rainfall run-off model was used to evaluate the flow in St Andrew's stream at Priory Mill. Rainfall was based upon the Flood Estimation Handbook (FEH) CD Rom using different storm durations and a range of return periods.
For the purposes of the study, the urban catchment was divided into twelve sub catchments reflecting the surface water features, permeable and impermeable surfaces and conveyance systems. The flood hydrographs for the individual sub-catchments were then combined to produce the full catchment hydrograph for St Andrew's Stream at Priory\Sheldon Mill.