DREDGING AND SEA DISPOSAL SITES: GUIDANCE
ON CREATING A NEW SEA DISPOSAL SITE
Dredging and Sea Disposal Sites
1.
Background
Within the framework of the 1992 OSPAR Convention, dredged materials have been listed in
Article 3.2 of Annex II as being permitted to be dumped at sea. In the following, “dredged
material” includes sediments relocated due to hydrodynamic and sidecast dredging and
“disposal at sea” includes relocation of sediments due to these techniques. Where an
application is made for a marine licence to dispose of dredged material to sea, the applicant
will usually identify a preferred registered sea disposal site in the application. Marine
Scotland Licensing Operations Team (MS-LOT) will decide, with the appropriate consultees,
if this site is suitable to receive the dredge material and if not will propose alternative sites.
MS-LOT, when deciding on the appropriate sea disposal site will take into consideration
other dredging operations in the area, disposal site capacity, disposal restrictions (e.g. tidal,
seasonal), type of material for disposal (e.g. erodible, non-erodible) and location of the site
(i.e. distance from the dredging project). A successful application will result in issue of a
marine licence to dredge and dispose of the dredged material at a named, registered sea
disposal site along with conditions, where applicable. MS-LOT are required to keep records
and report to OSPAR on sea disposal site locations and the nature and quantities of material
dumped at sea in accordance with Article 4(1) of Annex II. The marine licence will therefore
stipulate that the applicant must submit returns to MS-LOT at designated intervals.
2.
Dredge Material Characteristics
If dredged material is poorly characterised and a proper assessment cannot be made of its
potential impacts on human health and the environment, it shall not be dumped at sea.
Physical, chemical and/or biological (including toxicological) characteristics of the material
need to be determined before disposal can be considered. The physical characteristics of
the dredged material to be disposed of are important, not only in determining the suitability of
a potential sea disposal site (e.g. erodible material will disperse over time into the wider
environment under normal conditions at a dispersive site), but also for determining the need
for subsequent chemical and/or biological testing (for further details see
http://www.scotland.gov.uk/Topics/marine/Licensing/marine/Applications, or e-mail MS-LOT
MS.MarineLicensing@scotland.gsi.gov.uk). The results of the physical/chemical/biological
characterisation will indicate whether the dredged material, in principle, is suitable for
disposal at sea. Where sea disposal is identified as an acceptable option, it is nonetheless
important to consider any available beneficial uses. The Best Practicable Environmental
Option (BPEO), carried out by the applicant and submitted with the marine licence
application should assist in establishing this. Particular attention should be given to dredged
material containing significant amounts of oil or other substances that have a tendency to
float following re-suspension in the water column. Such materials may have an adverse
effect on fishing, shipping, amenities and other uses of the marine environment.
In certain circumstances dredged material may be exempt from chemical and biological
testing, for instance if any of the criteria below are met:
a) it is composed of previously undisturbed geological material; or
b) it is composed almost entirely of sand, gravel or rock; or
c) in the absence of appreciable pollution sources, which should be supported by existing
local information so as to provide reasonable assurance that the dredged material has not
been contaminated, the quantity of dredged material from single dredging operations does
not exceed 10,000 tonnes per year.
3.
New Disposal Site
3.1
Requirement
Under certain circumstances there may be a need to establish a new sea disposal site. This
can only be designated after the applicant has undertaken characterisation of the candidate
disposal site, MS-LOT has consulted all interested stakeholders and that the new disposal
site is deemed to be acceptable. This process can take over a year, but this will be
dependant on the amount of information already available on the proposed area and the
requirement for site specific field work. Characterisation should be undertaken before an
application is made to dispose of the material at sea in order to avoid risk of the application
being withdrawn. In such cases where characterisation is not carried out the applicant will
have to resubmit the application once all the relevant information is received.
An assessment of the need for a new disposal site should be undertaken and include the
following:
Short and long-term disposal needs of the project;
Suitability and capacity of existing disposal sites nearest to the project;
Potential alternative disposal options (e.g. habitat enhancement, re-use within the
project); and
Determination of the acceptability of the material to be disposed of to sea.
For projects carried out in Scottish waters attention should be drawn to the Environmental
Liability (Scotland) Regulations 2009. These Regulations implement Directive 2004/35/CE
(Environmental Liability) of the European Parliament and Council on environmental liability
with regard to the prevention and remedying of environmental damage (to protected species,
natural habitats, water and land). They provide that, for certain economic activities, where
there is an imminent risk of environmental damage, the responsible operator must take steps
to prevent it. If environmental damage has occurred the responsible operator must prevent
further damage.
3.2
Selection
Principal factors to be considered when selecting a disposal site are listed in the London
Convention 1972 Annex III. The following (but not restricted to) should be considered by the
applicant/developer when identifying candidate disposal sites:
Determination of the area within which the material can be reasonably transported and
disposed of (consider economic and operational feasibility);
Fishing/shell fishing grounds (commercial and recreational);
Spawning, feeding and nursery grounds (commercial and recreational);
Fish migration routes (commercial and recreational);
Marine mammal feeding grounds and migration routes;
Aquaculture sites;
Present and potential areas of special importance for conservation (SACs, MPAs);
Potential effects on human health;
Other uses of the sea (renewable energy sites, cables and pipelines, oil and gas
infrastructure, MoD, shipping lanes, anchorages, amenities and recreational use); and
Marine archaeological sites.
It is important that the process of characterising a new sea disposal site is considered in line
with the National Marine Plan (Scotland) as this will provide information on the nature of
activities that may be permitted in any given area.
3.3
Assessment
An evaluation of the new site to determine potential adverse effects (remembering the
polluter pays principles) should also be undertaken by the applicant/developer (considering
spatial and temporal effects) including:
Nature of the seabed (topography, geochemical and geological characteristics, benthic
communities);
Physical nature of the water column (depth, temperature, currents);
Chemical and biological nature of the water column (pH, salinity, dissolved oxygen,
nutrients);
Type of disposal site, e.g. dispersive; and
Biological and ecological effects of the dredged material (toxicological and
bioaccumulation effects, changes in community structure, degradation of water and
sediment quality and alteration of sediment characteristics).
The assessment of potential effects should lead to a statement of the expected
consequences of the disposal operation (i.e. Impact Hypothesis) which will then provide the
basis for defining environmental monitoring requirements and whether to approve or reject
the disposal option. In order to achieve this it may be necessary to develop a baseline
survey to describe, not only the environmental characteristics, but also the variability of the
environment (i.e. sediment transport and hydrodynamic models). For a retentive site,
material deposited will remain within the vicinity of the site and therefore any Impact
Hypothesis should delineate the area that will be substantially altered by the presence of the
deposited material and what the severity of these alterations might be. The immediate
receiving area may be completely smothered and therefore the timescale for recovery or
recolonisation and the likelihood that recolonisation will be similar to, or different from, the
existing benthic community structure should be assessed. The assessment should also
specify the likelihood and scale of impacts outside the immediate receiving area. For a
dispersive site the assessment should include a definition of the area likely to be altered in
the shorter term by the proposed disposal operation and the severity of associated changes
in the immediate receiving area. The assessment should also specify the long-term
transport of material from this area.
The EIA Directive (85/337/EEC as amended by 97/11/EC and 2003/35/EC) should be taken
into account for all capital* dredging operations (and where applicable for maintenance
dredging operations) and an environmental impact assessment undertaken. For marine
renewable energy projects dredging and disposal of dredged material operations can be
covered under the overall project EIA. In addition, where applicable (i.e. where dredging or
disposal is likely to affect the conservation value of a European site), the EU Habitats
Directive (92/43/EEC) may require an appropriate assessment (AA) to be undertaken by the
licensing authority. The licensing authority may request additional information from the
applicant in order to be able to carry out an adequate AA. Where an EIA has been carried
out, the information can also be used for the AA. However, the level of proof that a
development will not adversely affect the integrity of the site is not required in an EIA, and
therefore this proof will be required by the licensing authority.
* Capital dredge: an area/depth being dredged either for the first time, or which has not been dredged within the past 7
years. Maintenance dredge: an area which is dredged annually or on a regular basis.
4.
Marine Licence
On submission of the disposal site characterisation report MS-LOT will undertake a
consultation exercise with all interested stakeholders and if the site is found to be acceptable
then MS-LOT can designate the site as open. A disposal site code will be obtained from
Cefas and the UK Hydrographic Office formally informed. The marine licence will manage
the disposal of dredged material at sea through appropriate conditions to ensure that
environmental change beyond the boundaries of the disposal site are as far below the limits
of allowable environmental change as practicable. The marine licence will contain terms and
conditions under which sea disposal may take place as well as provide a framework for
assessing and ensuring compliance, highlighting monitoring requirements and ensuring that
results are reported to MS-LOT. For instance, where appropriate, disposal vessels should
be equipped with accurate positioning systems and vessels may be inspected to ensure that
conditions of the licence are being complied with and logs checked to ensure that disposal is
taking place at the specified disposal site. In most cases, blanketing of a comparatively
small area of seabed is considered to be an acceptable environmental consequence of
disposal. However, if the dredged material is predominantly clean, fine grained sediment it
may be appropriate to deliberately use a dispersive strategy to prevent or reduce blanketing,
particularly of a smaller disposal site. In some cases it may be appropriate to add temporal
restrictions on dumping activities e.g. tidal and/or seasonal to prevent interference with
migration, spawning or fishing activity.
5.
Key Considerations
The applicant shall characterise any proposed new sea disposal site(s) as early as
possible to avoid delays in obtaining a marine licence for the dredging and disposal of
dredged material at sea;
All offshore projects generating greater than 1MW of energy must provide a statutory
EIA (projects generating less than 1 MW may require an EIA) which should include
information on any dredging and/or disposal of dredged material. Where appropriate,
the EIA should also provide the information required for the regulator to undertake an
Appropriate Assessment;
Chemical/physical analyses of the dredged and proposed new sea disposal site
sediments will be required. Guidance can be found on the Marine Scotland website at:
http://www.scotland.gov.uk/Topics/marine/Licensing/marine/Applications/predredge;
MS-LOT will undertake a consultation exercise on the Disposal Site Characterisation
report;
All consultees will be notified by MS-LOT if a new site is designated and the UK
Hydrographic Office formally informed;
MS-LOT will determine if the applicant is required to undertake monitoring at the new
disposal site and, if required, include this as a condition on the marine licence; and
A new sea disposal site does not have exclusivity rights.
Marine Scotland
January 2013