Brymbo Reclamation
Project Introduction
Since the earliest planning stages in the
mid-1990s Scott Wilson has provided geotechnical advice and design
services to Brymbo Developments Ltd for the reclamation and
re-development of the 92Ha former Brymbo steelworks, near Wrexham
in North Wales. The project is partly funded by the Welsh
Development Agency and the fee value is around £800,000.
Project Background
The Brymbo ironworks were originally established in the late
18th century. The works buildings and slag banks were located on
one side of a steep valley, and the site area has been widely
undermined for coal and ironstone. Following closure in 1990 the
remnants left included a road tunnel, deep basements, heavy
foundations, and approximately 50m high slopes formed of end tipped
and hot poured slags.
In order to reclaim the derelict works for housing and industrial
development a massive earthworks operation was required. This saw
over 2 million cubic metres of natural and slag materials being
excavated and placed in compacted layers within the site boundaries
to form new development platforms.
Project Scope
The reclamation has required the design and
specification of both the geotechnical and infrastructure related
aspects. The geotechnical input has included earthworks
design and specification, treatment of abandoned mine-workings and
shafts, slope stability design and remediation, guidance on
construction over filled ground and complicated buried
topographies.
Issues that have been addressed include:
historical slope instability, complex earthworks, potentially
expansive steelworks wastes, temporary and permanent slope design,
foundation design including consideration of complex settlement
problems relating to deep uncompacted fills, and the investigation
and treatment of old underground mine workings.
One area of the site presented a significant settlement problem.
The underlying 40 metre deep opencast coal site had been restored,
some 25 years ago, by end tipping. Settlement analysis and finite
element modelling showed that the placement of a stiffer mantle of
engineered fill over this older fill would reduce differential
settlements to a level that would permit stable housing
development.
Value Adding Project Achievements
Close involvement by Scott Wilson’s
geotechnical experts from the earliest conceptual design stage and
throughout the reclamation has facilitated a major redevelopment
despite the very challenging risks and legacies posed by the
historical use of the site. This has given the client the
confidence to pursue similarly challenging and difficult sites
elsewhere in the country.
