6 NATCHEZ ON THE WATERFRONT


Dredging and relocating dredged materials


By Dan Natchez* O


f all of the various issues that face the recreational marine industry as a whole, among the biggest


have to be dredging and spoil removal. After all, the obtaining, retaining, restoring and/or improving of water depths is a fundamental requirement for boating and it does not really matter if we are talking about in-water or upland boat storage, since those upland stored boats still can’t get anywhere without sufficiently deep water. Unfortunately, in many parts of the world, having meaningful navigation depths for boats is increasingly meeting challenges from the combined forces of Mother Nature and the regulatory bureaucracy. To be fair, Mother Nature for the


most part is simply up to her usual tricks, perhaps excepting what seem like her increasingly frequent temper tantrums and associated severe weather events that can wreak havoc on bottom profiles.


There’s nothing quite as frustrating as looking out the day after a storm to see a new shoal blocking your marina entrance. There are few other topics that


can conjure up as much emotion, controversy and polarisation as dredging, and particularly what to do with the sediments that have been dredged. Of course, it does not serve the industry well to refer to ‘dumping of dredge spoils’. Language is important and unfortunately there is a long history of using the terms dumping and spoils. More correctly stated, we should all be using terms like ‘relocating dredged materials’ or ‘relocating existing bottom sediments’.


Contaminants In most cases, the greatest concerns centre around potential contaminants within the sediments so regulatory agencies keep tightening the rules for testing


A model 5012 LP Versi-Dredge supplied by IMS Dredges carries out mainte- nance dredging in Poland.


the materials to determine their contents. As detection technology has improved, the degree of testing required has increased and the allowable levels of contaminants to be considered ‘clean’ have been


decreased. In many cases, where materials were considered clean 20 years ago, today, with the same basic tests, the materials are considered ‘of concern’, even though the raw data would indicate that


Owned by the US Government, this marina was created along the edge of an inland lake, but no account was taken of the multiple drawdowns of water. The unfortunate result of not taking a holistic approach to design is that the pontoons became grounded.


AUGUST 2018 • MARINA INDUSTRY SOUTH-EAST ASIA & PACIFIC


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