Environmental dredging operations in the Netherlands: a functional approach Chemiehaven Rotterdam and the Haringvliet Estuary
Type:
Presented during:
WODCON XVII: "Dredging in a Sensitive Environment" - 2004, Hamburg, Germany
Authors:
ing. Niek J. Berg
Abstract: What can be done when there is a national environmental dredging programme but insufficient capacity for the disposal of all the contaminated dredged material or when the available finances are insufficient to pay for a total clean-up operation? This paper will show how a functional approach can counter some of the environmental risks.
The Chemiehaven (Chemical Harbour) in Rotterdam is a 22-hectare harbour basin situated in the Botlek area. In the sixties, owing to industrial activities surrounding the harbour, the sediments in the harbour basin became contaminated. In 2003, in cooperation with the major users of the Chemiehaven, Rijkswaterstaat, tackled the environmental risks by carrying out a 350 000 situ-m3 environmental bulk dredging operation using the dredging equipment that is normally used for maintenance dredging in the port. In combination with a dedicated monitoring programme, this project was completed against low costs.
The Haringvliet Estuary and adjacent waters are part of the delta in the south west of Holland. In this area, sediment originating from the rivers Rhine and Meuse became contaminated during the industrial revolution.
The estuary contains a huge amount of contaminated sediment (some 100 Mm3) and it was realized that creating a disposal site for this amount of sediment would be expensive and would certainly meet social and environmental opposition. However, environmental studies of the area indicated that some of the risks could be countered by taking a functional approach, i.e. by placing a layer of clean dredged material on top of the contaminated sediment. In 2003, an experimental dredging operation was carried out in the Haringvliet Estuary; Rijkswaterstaat succeeded in capping the contaminated sediment in a 16 hectare area with a 0.5 m layer of clean material.
The results of both operations were satisfying and it emerged that a complete clean-up operation would not be necessary.
Keywords: Environmental dredging, functional approach, capping, Chemiehaven, Haringvliet