Wetlands, Industry & Wildlife - a
manual of principles and practices
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Chapter 17 - Non-operational land
17.1 Potential constraints associated with non-operational land
Future land requirements
Staff perception of non-operational land
17.2 Attracting wildlife to non operational land
All but the smallest industrial
sites include areas, which have no operational functions and could be enhanced or managed
to encourage wildlife. Interim uses, such as nature conservation, are particularly
appropriate on areas of land retained to act as buffers from potentially conflicting
land-uses and on areas for which there are no plans for development in the medium term.
Areas where development is difficult, such as awkwardly shaped corners, poorly drained
sites, derelict sites and the periphery of a site, are all potentially suitable for
wildlife. Nature conservation should be seen as a means of putting these often forgotten
corners to good use. The very fact that land has no functional use may suggest to some
that it should be sold off, but the PR benefits gained from converting it into a wildlife
area may well outweigh its value as real estate. Industrial sites often have the advantage
of being enclosed by security fences, limiting human disturbance, and offering a safe
haven, even for shy wildlife.
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17.1 Potential constraints
associated with non-operational land
The constraints associated with non-operational land vary from site
to site. Some will have none of consequence, offering the wetland designer a free rein to
create something of real value to wildlife.
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17.1.1 Future land
As discussed in section 2.5 (Chapter 2 - Industry, wetlands and wildlife), probably the main factor inhibiting companies from encouraging wildlife on
their land is the fear that this may in some way jeopardise future operational use. Many
companies will produce five, ten or even twenty-year development plans which indicate the
likely need to utilise particular areas of land. Such plans can be used as an indication
of the time-span over which an interim use can be applied and therefore the appropriate
level of investment. On some sites local conditions might make the creation of wetlands a
simple affair, such as where water-tables are very close to the surface or the substrate
is composed of an impermeable clay. In such cases it may be legitimate to create wetlands
even if their future prospects cannot be guaranteed beyond five years. If, however, the
additional expense of a liner is required, it may be unrealistic to create anything more
than a small pond unless its future can be guaranteed for a longer period.
Of greater concern than expense are the implications of potentially
having to destroy a wetland of wildlife interest if operational requirements change. If
the site in question is within view of the public, then the PR message should be carefully
considered. It will obviously be important to gain the support of potential lobbying
groups, such as the county wildlife trust, before embarking upon such a project (see Feature 17.1). Support and understanding will be greatest where
there are likely to be opportunities in the local area to create alternative wetlands if
the site in question is needed for operational purposes. The ethics of creating habitats
which, possibly have only a temporary life-span should also be considered. The creation of
wetlands for less mobile species, such as amphibians, should not be promoted unless there
is a good chance that an alternative habitat can be provided for them if necessary. Mobile
species such as migratory birds, by contrast, are better adapted to cope with changes in
habitat distribution. See also 2.5.(Chapter
2 - Industry, wetlands and wildlife).
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17.1.2 Staff perception of
Corners of sites that have no operational use and are generally out
of view are often used as dumping grounds. It is, therefore, important that everyone
involved with a site is informed when such areas are adopted as wildlife areas so that
they respect them as such. Several areas within Shell's 720 ha Stanlow complex have
recently been designated as wildlife areas and will be identified on the ground by signs,
while margins bordering roads are to be defined with post and rail fencing. Noticeboards
and corporate magazines and news-sheets are other obvious means of bringing such changes
to the attention of the workforce.
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As discussed in 16.1.1(c) (Chapter 16
- Reclaiming industrial land),
derelict sites might be contaminated, in which case treatment of the contaminants and the
ethics of attracting wildlife must be considered.
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17.2 Attracting wildlife to non-operational
Theoretically, an area of non-operational land is like any other land being
considered for wetland creation or enhancement. Flat and low-lying sites, in particular,
should offer the potential to create a wide range of wetlands. Industrial complexes are
often located on flat land by the coast or adjacent to rivers. In such situations there
are often associated wetland habitats, such as ditches and saltmarshes, that can act as
reservoirs from which wetland plants and animals can colonise new habitats. Chapters 3 to
10 should help to guide any discussion of the potential options.
When judging the suitability of an area of non-operational land for wetland creation,
certain factors should be given particular attention:
1) Technical considerations.
The ease and expense associated with creating a wetland.
2) Operational considerations.
The current use of the site and surrounding areas. Implications of any medium and
long-term plans for the site.
3) Wildlife considerations.
Existing wildlife interest. The likely potential for creating good wildlife habitat
and the implications of any constraints.
4) Other benefits.
The ease with which the public could be allowed onto the site to appreciate, at
first hand, the company's good work. Potential benefits from improved visual amenity for
staff, visitors and people viewing the site from outside. Accessibility to staff who might
wish to. visit during lunch hours.
There are many examples of companies with wetlands, from small ponds to
intricately designed wader scrapes, occupying their non-operational land. The two sites
featured in this section demonstrate admirably how, with a little forethought, wildlife
can be encouraged without interfering with operational requirements. The ICI Brinefields (Feature 17.2) illustrate an industrial process which is spread
over a large area, and supports a matrix of areas available to wildlife amongst the
operational structures. Tophill Low (Feature 17.3) illustrates how a
company has converted the neglected corners of a site into features of wildlife interest
which the public are encouraged to come and admire.
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Portrack Sewage Treatment Works, Cleveland (Northumbrian Water)
Portrack Sewage Treatment Works lie on a 24.8 ha site adjacent to
the River Tees that has historically been occupied by marshland. The potential wildlife
value of the non-operational part of the site was recognised not long after the
construction of the works began in 1980. There was a series of shallow pools on this land,
ideally suited to a variety of waders and other waterbirds. The wildlife interest of this
site has been promoted by Northumbrian Water Limited (NWL) since the early 1980s, with
appropriate site management undertaken by the Tees Ringing Group with the help of other
local conservation groups.
In the early 1990s a more rigorous discharge consent was applied to the
site, requiring the works to be up-graded. The necessary additional secondary treatment
facilities required extra land which meant encroaching upon the marshland area. At about
the same time the northern margin of this spare land was given to one of NWL's subsidiary
companies to develop as the site for an incinerator (which, in the event, has not received
planning permission on the grounds that the facility is not required). The combined effect
of these two proposals was to reduce the size of the wildlife area from c.13.5 ha to c.4.5
ha. However, the company were keen that the remnant land should be used to retain the
existing wildlife interest. The design of the modified works was very compact and arranged
such that the loss of open water was minimised. In addition, new areas of open water were
excavated elsewhere on the remaining area of non-operational land to compensate for the
losses; the total area of standing water may now actually be larger than it had been prior
to the improvements, while the inclusion of islands in the main Pool A (see Figure 17.1) should make them more attractive to breeding
waterfowl. Some of the spoil resulting from this excavation work has been used to create
an earth platform and screened approach for a viewing hide.
While the recent conservation works are likely to raise the profile of
the site's wildlife interest, NWL has retained the option to develop the site. The company
uses a number of mechanisms to ensure that other interested parties are aware of their
attitude towards the site. On the ground, interpretative signs are to be elected at
strategic points where the public can view the site. In addition, the company has actively
involved local organisations with an interest in nature conservation. A 'Wildlife Advisory
Group' has been set up, consisting of representatives of organisations such as Cleveland
Wildlife Trust, Cleveland INCA (see 2.5 (Chapter
2 - Industry, wetlands and wildlife)) and English Nature. The terms of reference of this group are specified as set
i) to advise on the development and management of Portrack Marsh;
ii) to formulate and update a Conservation Management Plan for Portrack Marsh;
iii) to advise on the implementation of the Conservation Management Plan;
iv) to report annually to NWL.
The members of the group have endorsed a management plan that clearly
states: "Much of the area may be required.for future extension of the treatment works
to comply with any new water quality standards". In addition, NWL can use the forum
to keep members aware of any proposals that might affect the site. Thus, should the need
to develop the site arise, all parties should be sympathetic to NWL's requirements.
17.1 The layout of Portrack Marshes before and after a major modernisation
scheme implemented at Portrack Sewage Treatment Works during 1992-93.
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Feature 17.2 North Tees Brinefields, Cleveland
ICI has been extracting salt in the Teesside area since about 1950,
for use in its chemical plants. Its current operation extends over c.151 ha of low-lying
land that has been reclaimed from the Tees Estuary over the last hundred years. The salt
deposits, c.300 m below the surface, are abstracted by pumping in water and removing
saturated brine (26% sodium chloride). Up to 1.3 million m³ of brine is removed annually
from the field. Some of the underground cavities left by this process are used to store
hydrocarbons which are pumped from the nearby chemical plants and refineries. Some of the
brine is stored in reservoirs to provide a displacement medium for retrieval of the
The infrastructure associated with the brining operations occupy only a
small proportion of the total area; the flat, low-lying land is crisscrossed with
pipelines and access tracks and dotted with occasional well-heads. Amongst these man-made
structures is a variety of wetland habitats: pools of various sizes, reedbeds, swards rich
in orchids, ditches and extensive areas of grazing marsh. Of particular interest are the
scattered pools, which tend to vary in salinity from brackish to highly saline, owing to
brine spilling from the well-heads. These pools support a rich saltmarsh community; 20
different species of halophytic plant have been recorded on brinefields 4 and 5, having
colonised presumably from the nearby Tees Estuary. The pools are also very attractive to
waders; thirty-five species have been recorded. The wader species found feeding on pools
vary according to their salinity. Some pools are hyper-saline and support a very limited
range of invertebrates confined to chironomids and brineflies (Ephydra, Diptera).
However, these insects are very abundant during the summer months and can provide a
valuable food source for some of the smaller waders, such as Ringed Plover, Dunlin and
Little Stint. Larger wader species generally prefer larger prey which can be found on less
saline pools, thus reducing competition between species. Good numbers of waders nest on
the site; surveys in the late 1980s found maxima of 8 pairs of Redshank, 25 pairs of
Lapwing, 22 pairs of Ringed Plover, a single pair of Oystercatcher and occasional pairs of
Snipe (83 (Appendix 11 - Selected references and further reading)). The
site is the most important in Cleveland for Ringed Plover which nest on a variety of
artificialsites, including bare, stony areas around pools, hardcore around the well-heads,
and unsurfaced gravel roads. As well as supporting a high density of Ringed Plovers,
studies suggest that nest survival is higher than average, presumably owing to the lack of
human disturbance and the absence of tidal flooding which are a feature of many more
The extraction of the brine makes the land liable to subsidence (which
is the source of some of the pools) and consequently unsuitable for building development.
In recognition of this constraint, together with the site's wildlife interest, ICI have
started to implement active conservation measures in line with the broad ranging Company
Environmental Standards. Based on the various ecological studies undertaken on the
brinefields, a range of conservation action points have been drawn up:
1) Wherever possible, operations are planned to avoid damaging
or disturbing the important saltmarsh flora.
2) Wetlands and salinity gradients are maintained by controlled
releases of fresh water and brine. New wetlands have been designed to maximise the
benefits of having a variety of salinities.
3) Roads and hard core areas are kept to a minimum to limit the
loss of habitat.
4) Where access roads and hard core are essential, they are left
unsurfaced and with a substrate chosen to maximise their attractiveness to nesting Ringed
Plovers, Oystercatchers and Common Terns.
5) All nests found on the site are marked to prevent them from
being accidentally destroyed.
6) Grading and road maintenance are carried out in late summer
in order to minimise disturbance to nesting birds.
7) Opportunities are sought to add features for wildlife (e.g.
islands were created for breeding Common Terns in 1993).
Since 1990, a further brinefield (Number 6) has been developed, which
has enabled the company to consider the ecological implications of the process right
through from the design stages. An ecologically-based management plan was drawn up for the
field prior to development, in consultation with various outside organisations. Not only
has this ensured that the new field will be of maximum value to wildlife, it has also
avoided costly planning delays and enhanced the Company's environmental reputation. The
new brinefield contains a greater area of wetlands than existed before development
started. The latest innovation associated with this enlightened scheme has been to
re-establish a tidal regime around the well-heads in one operational area, providing
valuable additional habitat for waders. In the longer term, the intention is to turn over
large areas of this land to nature conservation once the brining operations cease. In
1993, ICI was presented an award by the Royal Town Planning Institute for its
environmental work associated with the development of Number 6 Brinefield.
|View across part of ICI's
North Tees Brinefields showing the matrix of infrastructure and wetland habitats
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Feature 17.3 Tophill Low Water Treatment
Works, East Yorkshire (Yorkshire Water Services)
Tophill Low Water Treatment Works not only supply water to the City
of Hull but now also offer an excellent wetland nature reserve. The 110 ha site occupies a
narrow strip of low- lying land sandwiched between the Barniston Drain and the River Hull.
The main features of the site are two concrete-walled reservoirs, which were completed in
1959. Two filter washwater lagoons (described in Feature 12.4 (Chapter 12 - Silt storage lagoons)) and some clay pits provided, until very recently, the only other wetland
habitat on the site.
The wildlife interest of Tophill Low has been recognised for many
years. Lying close to the east coast of England, the expanse of open water has proved a
magnet for migrant birds; a total of over 240 bird species has been recorded. The
potential appeal of the site to migrant birds is amply demonstrated by a concentration of
over 250 feeding Ruff that took advantage of the bed of a drained reservoir in September
1993. The reservoirs, despite their artificial walls and contours, have, in fact, been
notified as a SSSI in recognition of their wildfowl interest. The extensive arable
farmland surrounding the site provides feeding for dabbling ducks that roost on the
reservoirs, while the shallower 'D' reservoir (c.3.8 m deep) provides a feeding area for
large numbers of diving ducks (including up to 800 Tufted Duck). The extent and variety of
the wetland complex also makes it of value for other groups of wildlife. An area used for
small scale, ad hoc clay extraction, known as East Pond, supports 13 species of
Odonata, including the scarce Red-eyed Damselfly and Black Darter, while two locally
scarce water plants Greater Spearwort and Nodding Bur-marigold - grow in the South Marshes
and washwater lagoons.
In the 1970s a member of staff from Yorkshire Water, together with keen
volunteers, formed the Tophill Low Wildlife Group to encourage the development of the site
for wildlife. Early projects carried out by the group included flooding a marginal area by
blocking a drain and modifying the washwater lagoons. After many years of volunteer input
by the Wildlife Group, Yorkshire Water decided that nature conservation should be given a
higher profile on the site.
The opportunity to carry out a major habitat creation project presented
itself when the NRA came to Yorkshire Water needing clay to carry out flood defence works
along the adjacent river. It was agreed that the NRA could extract clay from specified
areas within the site and, in lieu of payment, they would re-grade the excavations to form
new wetland wildlife habitats. Various fairly large, but irregular-shaped blocks of land
towards the periphery of the site were chosen as they offered little potential from an
operational standpoint and little value in terms of real estate. The work was carried out
between 1990 and 1993, resulting in the formation of the North Marsh, the re-design and
enlargement of the South Marsh and further improvements to the filter washwater lagoons.
The largest component of these works was the excavation of the two blocks that make up the
large, shallow South Marsh. The East block lies on a peaty substrate which made excavation
and land-forming difficult. Around the edge is a ring-fence ditch, c.2m deep and c.4 m
wide, which prevents the planted Common Reed on the fringe from spreading, while the
shallow centre has been formed into a system of ridges and furrows. The value of this new
habitat to birds soon became apparent; in 1993 it supported about five pairs of breeding
Pochard, at least six pairs of Tufted Duck and a pair of Shelduck. The West block was
created in an area that had previously been tipped with clay spoil and planted up with
conifers that were of little value to wildlife. This shallow scrape still retains a clay
bed over much of its surface area; straw has been introduced to help to develop an organic
layer in order to increase the density of invertebrate prey for waders, such as the
breeding Little Ringed Plovers. The deeper North Marsh should provide additional habitat
for Odonata as well as nesting birds.
Wanting to capitalise on the wildlife potential of the improved site,
Yorkshire Water sought the advice of the RSPB on visitor access and facilities, and
wardening requirements. As a result of these recommendations, Yorkshire Water increased
the quota of hides around the site to nine and, early in 1993, took the enlightened step
of appointing a full-time warden to look after the, wildlife habitats and deal with
visitors. Schools will be encouraged to visit and the general public allowed to purchase
permits giving them access to the trails and hides and helping to offset the cost of
employing a warden. In October of that year a splendid new nature reserve was opened.
|Aerial view of Tophill Low Water Treatment
Works showing how wetlands have been incorporated into most of the marginal areas of the