ENVIRONMENTAL CODE OF PRACTICE
Marine Structures
Overview
Boatyards and marinas, clubs and sailing schools which have
pontoons, pilings, moorings or slipways will be subject to various
requirements in terms of construction and maintenance, prevention
of fouling as well as some considerations in the materials used in
their construction. The Yacht Harbour
Association has produced a Code of
Practice for the design, construction and operation of coastal
and inland marinas and yacht harbours. This is a very valuable
document that covers a wide range of topics including marina
design, environment and pollution prevention and boatyard
operation.
Construction and maintenance
In planning and carrying out any work in or near rivers,
streams, ditches and other watercourses, precautions must be taken
to ensure their complete protection against pollution, silting and
erosion as well as interference with navigation.
Any work on or near foul sewers, (especially trunk sewers),
underground oil/chemical pipelines or fluid filled electricity
cables poses a major threat of pollution if damage occurs. At least
7 days prior notification of an intention to work on these
structures should be given to the relevant environmental agency,
enabling appropriate pollution prevention measures and emergency
procedures to be agreed. The use of industrial by-products at
locations where drainage from the material could directly or
indirectly enter surface or groundwater must also be discussed with
the Agency.
The Agencies
Pollution Prevention Guidance, PPG 5 details requirements from
works in, near or liable to affect watercourses. Any work carried
out in or near watercourses must be regarded as high risk with
significant potential to cause pollution. Potential pollutants of
concern include silt, cement, concrete, fuel, lubricating and
shutter release oils, petrol, sewage, bridge cleaning debris and
other waste materials. The guidance details the relevant legal
framework and general advice on pollution prevention, along with
the controls required to control these potential pollutants.
Compliance with this guidance should minimise the risk of
pollution occurring. Every site is different and will need to be
considered individually. Consultation with your local agency office
is advisable before any work is started. Construction work at
marinas should be undertaken with reference to the coastal and
marine environmental site guide (CIRIA publication number C584).
The Agencies have also produced specific guidance for pollution
prevention at construction and demolition sites (PPG6), which
should be followed in conjunction with this guidance if
applicable.
Environmental impact assessment
It is likely that those wishing to develop new or existing sites
for moorings and berths will have to satisfy ever more stringent
planning requirements, with the onus on them to show that their
proposals do not have an adverse effect on the environment for
which they are intended. Environmental Impact Assessments must be
undertaken if a scheme is going to have ‘significant’ effects on
areas such as a Site of Special Scientific Interest, Heritage
Coast, Area of Outstanding Natural Beauty or Marine Nature Reserve.
The assessments to accompany applications for both inland and
coastal sites may require professional expertise in their
preparation. Such EIAs should be prepared in conjunction with all
relevant public bodies and nongovernmental organisations and used
to minimise environmental impacts during all stages of construction
and operation.
Materials and design
Tropical hardwoods are often used for mooring walkways and
pontoon decking. It is estimated that the marine industry consumes
approximately 5% of the UK hardwood imports in both marine
construction and boat use. Balau, keruing, opepe and salang batau
have been popular choices for pontoon decking materials due to
their durability, easy maintenance and surface properties. It is
estimated that a marina with capacity for 200 boats will require
approximately 55m - 85 m of timber for pontoon and decking
purposes. The declining quality and reduced availability of certain
hardwoods for pontoon decking, such as keruing and opepe, is a
clear indication of the impact that timber extraction is having on
some of the world’s tropical rainforests. As timber species become
rarer, commercial extraction will tend to concentrate on more
marginal trees which previously would not have been sought. These
trees are likely to have been of inferior quality and this is
confirmed by some of the marina construction companies.
The damage to the rainforests is well documented and to avoid
further deterioration wood should be sourced from sustainable
forests carrying the appropriate certificate. For information on
buying certified timber and timber products the Forest Stewardship Council website
provides information.
Alternatives to tropical hardwoods such as preservative treated
softwood, concrete and recycled plastics have become more widely
available for use in marina pontoon decking. Some operators are
reluctant to use alternative materials, as their performance and
reliability cannot always be guaranteed. Other operators have,
however, successfully used alternatives in the past and as quality
tropical hardwoods become more difficult to obtain there is likely
to be a switch to alternative materials.
Additional issues when looking at materials and design is
avoidance of fouling. Consider, where appropriate, introducing new
surfaces which require less cleaning. Where possible, slipways
should be designed and constructed with ridges to allow for better
grip when people and vehicles are using them, even with some weed
growth. Likewise, link pontoons to the land can be designed with
ridges to avoid slipping.
Fouling of slipways, pontoons, and harbour structures
Fouling of harbour structures, such as slipways, steps, jetties
and pontoons, can result in surfaces becoming covered in layers of
bacterial and algal slime that must be removed. This essential part
of harbour management is required to ensure that they are both safe
to use and to prolong their longevity. However, even when no
chemicals are used in the cleaning and just water and elbow grease
is applied the runoff that enters the harbour may be contaminated
with oil, debris, heavy metals or sediments.
The use of chemicals, even those which have been ‘approved’ by
different bodies, can in certain quantities damage the local
environment causing low oxygen levels, altered pH and reduced plant
and animal diversity. Some chemicals, such as soaps and detergents
may actually encourage algal growth as they contain the nutrients
that they require to grow rapidly. These problems will be
particularly noticeable where wastes are washed into enclosed
waters, such as docks, or areas with low tidal flushing such as
harbours or estuaries.
The Agencies Pollution Prevention Guidance, PPG 23 details
maintenance of structures over water and focuses on the associated
environmental risks. The maintenance of structures over water
generates a range of pollutants, including metal particulates,
paint, polluted water, detergents and cement. These can directly
affect local water quality and can cause soil and groundwater
contamination, so the discharge of pollutants to surface waters and
ground waters must be avoided during maintenance activities. The
guidance provides information on how to plan for and carry out
these operations as well as giving information on containment
measures and waste disposal. It recommends adopting a risk
assessment approach in order to identify and assess the impacts of
the proposed activities so that suitable maintenance methodology
and pollution prevention measures can be selected.
A number of methods have been used to overcome the effects of
fouling of harbour structures with variable success. These range
from manual washing and scraping to the application of chemicals to
kill and remove the fouling organisms (biocides). Where possible
avoid the use of chemicals.
1. Manual removal, such as pressure hosing or scraping is likely
to be the most environmentally sound option; however it is labour
intensive and may not achieve a level of removal that is safe for
the public. Mini rotary tractors or pressure washers can however be
very effective for removing algae and weed from slipways and
jetties and their use should be explored before chemicals are
used.
2. Soaps and detergents are often used within harbours for
general cleaning operations. As a result of cleaning operations,
water entering harbour waters will have characteristics of
‘greywater’, containing significant amounts of nutrients, which has
the potential to contribute to excessive algal growth. Under
certain conditions, which depend on a number of variables
(including background water quality and season), when present in
low concentrations this can have the effect of enhancing plant
productivity. When detergents are present in high concentrations
the formation of algal blooms may occur. The breakdown of these
blooms causes the removal of oxygen from the surrounding waters,
which can disturb or suffocate sensitive marine animals within the
area. The tendency for algal bloom formation is highest during the
warmer spring and summer months. Where soaps and detergents must be
used, please use the minimum requirement and dilute to minimise
potential effects.
Maintenance dredging
Before dredging is undertaken check with the Marine & Fisheries Agency if a
licence or discharge
consent is required for dredging activity itself or disposal of
the dredged material. In most cases there will be a requirement and
you should refer to the Consents and
Planning section in the ECOP.
Maintenance dredging as an on-going periodic activity requiring
a licence/consent has been the subject of much discussion about how
to ensure the requirements of the Habitats Regulations are met. In
response to this discussion, a working group was established with
both industry and government representation.
The group developed a protocol on maintenance dredging in
European Marine Sites and other such protected areas has and is now
available from the Marine & Fisheries Agency, all be it in
draft form.
The aim of the protocol is to provide a methodology within which
a robust, but appropriate level of assessment of maintenance
dredging activity is achieved without imposing undue burden on
industry. Throughout 2004, the protocol has been trialed on the
Medina, Isle of Wight, Truro/Penryn in Cornwall and on the Humber
and led by the Harbour Authority in each region.
The BMF through its specialist dredging advisor has been
actively involved to assess how it works in practice and to
identify any potential difficulties. The outcome is likely to mean
that each estuary will have an agreed baseline document about
maintenance dredging activity taking place. This document will be
held by the Harbour Authority and periodically updated in
cooperation with marina operators and others carrying out
maintenance dredging. When maintenance dredging licences are then
considered by the MFA they will be referenced back against the
agreed baseline document as part of the licensing process.
Avoidance of repetitive consultation is a key driver for the
protocol. The pilots will highlight any changes that may be
required to the document prior to the document being more BMFwidely
adopted.
For more information on other consents required, click HERE.