FIELD MONITORING OF RIPENING OF DREDGED MATERIAL AT 3 SITES IN THE NETHERLANDS (PRELIMINARY-RESULTS)

Ripening of dredged material in a deposit is a natural 'drying' proces s by which raw dredged material transforms into soil. The aim of ripen ing is to obtain soil which complies with environmental legislations a nd geotechnical specifications for application in earthworks (e.g. dik es, noise reduction banks, landfill covers). The paper deals with the background and contents of a monitoring programme on the ripening beha viour of clayey, peaty, and sandy dredged material, and changes in che mical composition, especially of organic compouds, and leaching charac teristics during ripening. The main objectives of the monitoring progr amme are (1) to develop a management system for the ripening process, (2) to quantify the input and output volumes of dredged material, and (3) to develop guidelines for the design of (transit) deposits. The re sults of the monitoring programme will also be used for calibration an d validation of a computer model on ripening. Prelimanary results on r ipening of clayey material and biodegration of PAH and mineral oil are presented. On the basis of these results it is expected that large vo lumes of slightly to moderately contaminated dredged material are suit able for beneficial use after ripening. (C) 1998 IAWQ. Published by El sevier Science Ltd.