What is hydraulic fill?
Hydraulic fill is the process where sediment or rock excavated by dredgers from the seabed or other borrow areas, is transported
and ultimately placed into the designated reclamation area. For each of these phases of excavation, transport and placement, a
hydraulic filling method is used, meaning that a soil and water mixture is created to facilitate dredging, transport or placement of
the fill material. The fill material is then placed as a mixture of the fill (sand) and water into the reclamation site.
But this is the simple mechanics. Before a land reclamation project can commence, months or often years of research are
invested in determining the best possible work methods and the availability and suitability of the hydraulic fill. The question
that has to be asked is: Will the hydraulic fill be able to bear the buildings, the cranes and other infrastructure for the newly
How to build a land reclamation site
To begin with, the foundation of constructing a safe reclamation site is collecting a wide range of data. Data collection includes
desk studies, field work and laboratory testing. It means gathering bathymetrical and topographical data and geological and
geotechnical information in both the borrow and reclamation
areas. Add to that hydraulic, meteorological and environmental
data and then follow this with reporting on soil and rock
classifications and descriptions using various internationally
This data is used during the pre-construction, construction
and post-construction stages. Geostatistical methods will be used
to develop models of the borrow and reclamation areas. All this
information can ultimately be applied to an environmental impact
assessment, which in most countries is a requirement in order to
get work permits.