Work continues at Swansea’s historic Hafod-Morfa Copperworks!

Black Mountains Archaeology has been proud to support Swansea Council in the UK Governments, Local Regeneration Fund, restoration of the Scheduled Monument and Grade II Listed Musgrave and Vivian Engine Houses and Rolling Mills (SMGm483; LB11697; LB11695) at the Hafod-Morfa Copperworks, Swansea. Our archaeological investigations have helped uncover remarkable evidence of one of Britain’s most important industrial sites, while informing the sensitive restoration of these internationally significant remains.

A world-leading Copperworks

At their peak during the mid-19th century, the Hafod and Morfa Copperworks were among the largest copperworks in the world. Together they employed over 1,000 people and produced a substantial proportion of the world’s copper and yellow metal. The two works were amalgamated in 1924 to form British Copper Manufacturers before being acquired by Imperial Chemical Industries (ICI) in 1927, becoming known as ICI Landore. Copper plate and sheet continued to be manufactured until the works finally closed in 1980, marking the end of the last operational copper plate mill in the United Kingdom.

More than four decades later, the surviving buildings are now being stabilised, restored and transformed into landmark visitor attractions, preserving an internationally significant chapter in Wales’ industrial heritage.

Over the past eight years, Black Mountains Archaeology has undertaken extensive archaeological excavations and community archaeology projects across the wider copperworks site. These investigations have revealed remarkably well-preserved remains of buildings, furnaces, flues, machinery and industrial floor surfaces, providing an exceptional insight into almost two centuries of copper production.

Investigating the Musgrave and Vivian Engine Houses

Since January 2024, Black Mountains Archaeology has been working with Swansea Council to support the restoration of the Musgrave and Vivian Engine Houses and the adjoining Musgrave Rolling Mill site. At the heart of the project is the Musgrave Engine, a nationally significant Scheduled Monument and the only surviving example of its kind in the world to remain in its original location. Together with the adjoining Grade II Listed Vivian Engine House, these remarkable structures represent some of the most important surviving elements of Swansea’s internationally significant industrial heritage.

The entire rolling mills site was subject to full-scale archaeological excavation (strip map record) to inform designs and interpretation for the proposed restoration. The investigations revealed extensive industrial archaeological remains across the whole area, which demonstrated all phases of development and industrial processes that were known to have taken place here. The archaeology was deeply stratified and very complex, with numerous examples of features built on top of, or cutting through, earlier features.

The Lower Swansea Valley, and the Hafod Works in particular, produced an extraordinary amount of the world’s copper at its peak, and formed a leading part in a vast global trade network in copper ore and copper products. In the 19^th century the mills produced copper plate for ship sheathing, thus giving the British Navy and merchant ships an advantage in international waters. In the 20^th century the installation of the Musgrave Engine enabled the production of larger, heavier steam train boiler plates to meet global demands for larger trains. Against this remarkable industrial backdrop, the archaeological discoveries are of international significance.

As with many former industrial sites, archaeological investigation was complicated by significant engineering challenges including water ingress, contaminated ground and deep deposits of unstable made ground.

Three Phases of Archaeological Investigation

The archaeological works were undertaken across three phases.

Phase I (January – March 2024) investigated the north-eastern half of the site and revealed:

• the remains of a drive shaft and belt wheel;
• masonry structures and a probable flywheel pit associated with the original 1819 beam engine house;
• the Vivian flywheel pit;
• two separate rolling mill lines, including a previously unknown inner line that was later confirmed by a newly discovered 1911 Musgrave engineering plan;
• substantial machine bases associated with the twentieth-century Musgrave rolling machinery;
• numerous annealing furnaces and extensive hot gas flues used during the copper rolling process;
• and extensive brick and concrete floor surfaces, machinery bases and industrial structures associated with successive phases of the rolling mill.

Phase II (October 2024) concentrated on the south-western area of the site and uncovered:

• the Musgrave rolling machine pit with surviving in-situ machinery;
• two annealing furnaces;
• major hot gas flues connecting directly to the Musgrave chimney;
• a steel water supply pipe serving the Musgrave Engine basement;
• and a substantial stone platform that may represent the boiler house for the original 1819 engine.

Phase III (June – October 2025) completed the excavation of the remaining areas and revealed:

• the remains of an early nineteenth-century rolling mill building;
• the full extent of a substantial stone boiler platform;
• a distinctive curved stone foundation that may represent an early engine bed;
• additional annealing furnace bases and an extensive network of interconnected flues;
• the complete extent of the Musgrave rolling machine pit, including a surviving balancing gear for a missing rolling machine;
• large industrial artefacts including rolling cylinders and riveted steel machine covers;
• and an intricate water management system comprising stone culverts, brick culverts, steel pipework and a substantial brick manhole chamber associated with the operation of the Musgrave Engine.

Together these discoveries provide an unprecedented understanding of how the rolling mills developed and evolved over more than 150 years of industrial production.

Preserving an Industrial Legacy

The archaeological remains uncovered during the investigations represent one of the most significant surviving industrial landscapes in Wales. Consequently, preservation of this nationally important resource became a central objective of the wider restoration project from the earliest stages of design.

Wherever possible, archaeological remains have been preserved in situ, ensuring that significant structures remain protected beneath and alongside the completed development. Where preservation could not be achieved, the archaeology was recorded to an exceptionally high standard through detailed excavation, measured survey, photography, specialist recording and high-resolution 3D photogrammetry and LiDAR. Together these records provide a permanent digital archive that will preserve the archaeological evidence for future generations.

The completed archive, including excavation records, plans, reports, survey data, photographs and digital models, will be deposited with the National Monuments Record of Wales (RCAHMW) and the regional Historic Environment Record curated by Heneb, ensuring the results are available for future research, conservation and public interpretation.

Preservation, however, extended far beyond archaeological recording. Throughout the project, Black Mountains Archaeology worked as an integral member of the wider design team alongside Swansea Council, Swansea’s Local Planning Authority, Cadw, Heneb, GWP Architecture, Mann Williams, the principal contractor Andrew Scott Ltd and other specialists, such as Ian Davies Plant, Pritchards Remediation, Coreus and SLR Consulting. Every design decision was carefully considered against archaeological significance, engineering practicality, construction methodology, programme requirements and project budget.

This collaborative approach required continuous dialogue between all project partners. Rather than archaeology acting as a constraint on development, archaeological understanding became a fundamental part of the design process, helping to identify where heritage assets could be preserved, where impacts could be reduced, and where engineering solutions could be refined to safeguard nationally important remains.

The result has been a carefully balanced scheme that delivers meaningful regeneration while retaining as much of the surviving industrial archaeology as possible for future generations.

Engineering Solutions Through Collaboration

Designing the foundations for the proposed Link Building presented one of the most technically challenging aspects of the entire project.

The site contained exceptionally complex and deeply stratified archaeological remains, together with voids, contaminated ground, water ingress and deposits of unstable made ground. At the same time, the proposed building needed to satisfy modern structural engineering requirements, remain economically viable and be capable of practical construction without compromising the wider restoration programme.

The original engineering proposal comprised an engineered fill and reinforced concrete raft foundation. While structurally robust, archaeological investigations demonstrated that this approach would have required the partial removal of significant archaeological structures and infilling of historic voids. Furthermore, the level of compaction required across the site presented an unacceptable risk of settlement within the surviving archaeological remains.

Recognising these challenges, Black Mountains Archaeology worked closely with conservation engineers Mann Williams and GOWN from an early stage of the design process. A detailed Heritage Impact Assessment was prepared that evaluated the archaeological significance of individual structures and assessed the direct impact of every proposed pile location on a feature-by-feature basis.

This was not a single design exercise, but an iterative process undertaken over many months. Successive rounds of design review saw pile positions repeatedly challenged, relocated and, where necessary, removed entirely. Every revision required careful consideration of archaeological significance, structural engineering requirements, construction practicality, programme implications and overall project cost. The process benefited enormously from the continued engagement of Swansea Council’s Local Planning Authority, whose professional scrutiny and constructive challenge helped refine the developing design at every stage. Working alongside Cadw, Heneb and the wider project team, this collaborative approach ensured that heritage considerations remained central to decision-making while recognising the engineering, programme and financial constraints of a complex restoration project.

The final foundation solution represents the culmination of this collaborative design process. A highly targeted piled foundation system was developed using diamond drilling together with ODEX and mini-pile techniques. This ‘keyhole surgery’ approach allows foundations to be threaded through the archaeological remains with remarkable precision, dramatically reducing disturbance while minimising vibration and protecting fragile buried structures.

Ground investigations undertaken using rotary coring further demonstrated the effectiveness of this approach, producing clean cores through selected archaeological structures with negligible disturbance.

The design process was informed by Historic England’s Piling and Archaeology: Guidance and Good Practice (2019), together with ongoing consultation between Black Mountains Archaeology, Mann Williams, Swansea Council, Cadw, Heneb and the wider project team.

The solution ultimately adopted is an excellent example of what can be achieved through multidisciplinary collaboration. By bringing together archaeological, engineering, conservation, planning and construction expertise, the project has succeeded in delivering a practical and economically viable engineering solution while preserving an exceptional industrial archaeological resource to the greatest extent possible. The final design is not the product of a single discipline, but the culmination of months of collaborative problem-solving, rigorous technical review and a shared commitment by all project partners to safeguard one of Wales’ most important industrial heritage sites.