Summary
The standing and buried remains of a chemical plant of 1908 producing soda ash (sodium bicarbonate) by the Solvay method, and of 1915 for the experimental manufacture and then production of calcium nitrate as an ingredient of munitions explosives.
Reasons for Designation
The former soda ash and calcium nitrate works at Plumley is scheduled for the following principal reasons:
* Rarity: the site is a rare example of a surviving ammonia-soda works (a key element of the alkali industry, one of the most important chemical industries in England with many technological developments made here), in particular as a competitor to the pre-eminent Brunner Mond company;
* Diversity: also including remains relating to calcium nitrate manufacture on an experimental and production basis, making a very significant national contribution to the manufacture of explosives for the First World War;
* Survival: the remains of both works survive well and are readable as earthworks and upstanding structures, with some buried remains;
* Potential: the surviving remains have strong potential to yield further information to specialist analysis and investigation, enhancing our understanding of both works.
History
The alkali industry is defined as the harvesting or mining of sources of potassium and sodium, and the processing of these materials to produce carbonates or hydroxides of the metals (known as potash or soda, for potassium and sodium respectively). Alkali was mainly required for the production of soap and glass. The combustion of wood or bracken in a potash kiln (also known as an elling hearth) originally supplied the need for alkali. In the C17 the production of alkali from seaweed was introduced into this country, burning the dried seaweed in a kelp pit, commonly situated just above the shoreline. From 1795 the LeBlanc process was introduced on Tyneside from France, producing soda (in this case, sodium carbonate) from salt (sodium chloride); thereafter, making soda using salt was firmly the basis of bulk alkali production. In the C19 salt was largely provided by salt workings in Cheshire, although later in the century Teesside salt supplied the alkali industry in north-east England. The alkali industry soon became one of the most important chemical industries in this country and many technological developments were made here.
The ammonia-soda alkali industry was based on a process first discovered in 1810, and first made commercially successful by a Belgian - Ernest Solvay - in 1865. It was introduced to this country by John Brunner and Ludwig Mond (Brunner Mond) in 1872, with production starting at their Winnington (Cheshire) works in 1873. It was based in the Northwich area of Cheshire, with only three works established elsewhere. The Solvay process carbonated brine (which first had been saturated with ammonia), to give sodium bicarbonate and ammonium chloride, from which the ammonia was recovered, leaving calcium chloride and water. The key feature of Solvay-type ammonia-soda plants were the distinctive carbonation towers, between 70 and 90 feet tall.
AMMONIA-SODA PLANT
Prior to 1926 (and the formation of the conglomerate ICI by the merger of Brunner Mond with three other companies), five other ammonia-soda works were built in addition to Winnington, Plumley being one of these. Most were short-lived, being either bought out by Brunner Mond, or closed down due to competition with them. The works at Plumley (also known as Plumbley) were established by the Ammonia Soda Company Ltd (Ascol) which was formed in 1908 by Ivan Levinstein, Arthur Chamberlain and others for that purpose. (It appears to be coincidence, given the later use of the site for manufacturing ingredients for explosives, that Chamberlain was the chairman of the Birmingham ammunition manufacturers G Kynoch & Co, as there is no known application for soda in the manufacture of ammunition propellant). In 1912 the firm became a public company. Brunner Mond bought out the land around this works, sank two brine shafts on the other side of the railway and pumped brine from there for their Lostock works, and also daily sampled the stream below the works in the hope of finding evidence of pollution. Possibly due to these activities, Ascol struggled and profits were disappointing.
CALCIUM NITRATE PLANT
The production of nitric acid (used in producing TNT) required ammonium nitrate, which was also used directly as an admixture for finished TNT to create Amatol, a cheaper alternative. The outbreak of the First World War and demand for high explosives therefore dramatically increased the requirement for ammonium nitrate. The conversion of sodium nitrate (mainly from Chile) into ammonium nitrate became a primary aim. In 1910 Dr FA Freeth (chief chemist at Brunner Mond) had devised a method which combined sodium nitrate and ammonium sulphate to give ammonium nitrate plus sodium sulphate. This was difficult in unpredictable English temperatures, and although a plant at Swindon produced over 24,000 tons in 1918, the Americans produced much more by this method, which was freely granted to them.
An alternative was to use sodium nitrate and calcium chloride to create calcium nitrate. This could then be treated with ammonia (in which Britain was rich) and carbonic acid to give ammonium nitrate. The Solvay process created calcium chloride as a by-product, and an experimental plant to produce calcium nitrate was established in 1915 at Plumley, which had come under the control of the Ministry of Munitions. This was quickly followed, beginning in 1916, by large-scale production, which was also established at the Salt Union’s Victoria Works near Northwich (Cheshire). These plants supplied Brunner Mond’s ammonium nitrate production, mainly at Lostock-Gralam, near Plumley. Overall, Plumley produced slightly less calcium nitrate than Victoria, but was only overtaken in 1918.
The importance of the supply of explosives has led the First World War to be dubbed ‘a chemist’s war’. The skill of a nation’s scientists was now as important as the valour of its soldiers in determining the outcome of the war. The size and sophistication of its chemical industry and research facilities were as critical as the size of its armies. After the First World War, Lord Moulton (Director-General of Explosives Supply in the Ministry of Munitions) wrote to Brunner Mond’s chairman, 'We have been indebted to your Company for the manufacture of the bulk of the largest component of the high explosives used by this country in the war.' (Dick 1973, 35). In total 216,120 tons of ammonium nitrate were made during the war (almost 90 per cent of it by Brunner Mond). The calcium nitrate process was used to create just under 60 per cent of the national ammonium nitrate output. The Plumley works manufactured 43 per cent of the calcium nitrate used, and thus directly provided vital ingredients for 25 per cent of all the ammonium nitrate used by this country to manufacture high explosives for the war. The manufacture of calcium nitrate at the Victoria works was only possible due to the successful initial demonstration and then scaling-up of the process at Plumley.
LATER HISTORY
The calcium nitrate plant was demolished immediately after the war, in 1919, but there was no attempt to level the site. Plumley continued in ammonia-soda production but Ascol was voluntarily liquidated in 1919 and Brunner Mond bought the site outright. Production continued until 1926, when much of the Solvay plant was probably demolished, again with no attempt to level the site. The railway sidings were removed between 1938 and the mid-1950s. From the mid-C20 the large warehouse which is the only standing building on the site was used by Associated Octel for storing sodium salts. This involved the demolition of the bagging plant in the southern extension. This use continued until the 1980s, since when the site has been disused.
Although annotated by the Ordnance Survey as a nature reserve, the site was never designated and the Cheshire Wildlife Trust never took over its management as was intended early in the C21. The eastern part of the industrial landholdings was used in the 1960s for dumping earth excavated in the construction of the M6. However, this is not thought to have affected the scheduled area, where the large pond that is still extant accords closely with that shown on the 1918 drainage plan and marked ‘effluent from ASC’. The soil tipping is thought to have been restricted to the easternmost part of the site which has since become agricultural land.
HISTORY OF INVESTIGATIONS
The site was identified as a former soda plant in the Monuments Protection Programme Step 1 report for the chemical industry, as part of the alkali industry. The Plumley site’s role as a test-bed for a new process by which the raw ingredients for high explosives could be obtained, and then as a major producer of those materials, has been underplayed in accounts given by the chemists responsible for munitions supply. Consequently it is not fully elucidated in the principal text on the archaeology of gunpowder and explosives manufacture (Dangerous Energy, Cocroft 2000), although this did note that the site had been used for the production of calcium nitrate to supply high explosives manufacture. The growing diversity of linkages with commercial chemical-industrial activity is characteristic of this period and leaves few monumental remains that can be isolated as specifically relevant to explosives production.
An initial archaeological survey completed in December 2001 and a detailed survey of the calcium nitrate plant carried out in 2002 established the detailed character of the site. The remains of both plants accorded to a high degree with the buildings shown on historical mapping, including a plan drawn by AW Tangye and dated 1910-1914, and a drainage plan and sketch plan, both of 1918. These plans allow the layout of surviving earthworks and building remains to be clearly understood and the detailed character of the plant, if not the full detailed processes, to be appreciated.
The ammonia-soda works stood on the western part of the site, although brine was pumped from a shaft in the south-east corner. The main building housed saturators and finishing machines. A boiler house attached to the west provided the heat for the processes. Attached to the north was a range annotated on the Tangye plan as ‘distiller tower shed’, which was in turn abutted on its north side by a ‘blowing and vacuum engine house’. To the east of these, running north-south and attached to the main building at the south, were the four Solvay towers where the ammoniated brine was carbonated. Railway sidings to the east and west separated the main building complex from a repair shed to the west and a crystallisation plant to the north-east. These sidings also led to the beds to the north-east where residual waste was dumped. An office and dressing rooms/canteen were sited to the north and north-east of the main plant. A long, shallow reservoir approximately 40x5m is also associated with the Ascol plant although its exact purpose is unknown. An effluent pond was sited to the north of the brine shaft, probably draining the waste beds.
The calcium nitrate plant is largely sited to the south-east of the Ascol works. It principally comprised five or six linear buildings running north-south, annotated on the 1918 sketch plan. The westernmost housed boilers, mixers and salt pans. Here brine from boreholes, which had been pumped via six-inch pipes, was passed through a succession of salt pans. Settling and evaporation purified and concentrated the brine until it was rich in sodium nitrate. From here it passed eastwards to another salt-pans building, where it was treated with calcium chloride (presumably recovered from the waste of the ammonia-soda plant) to give a solution of calcium nitrate and sodium chloride. The brine, now rich in calcium nitrate, was pumped back westwards for further refinement. Here it might also have been preheated before being pumped into the crystalliser building, which also had workshops and a laboratory to its south. Heavier waste material was discharged during these processes into cross-ditches and thence into two large north-south ditches.
The large warehouse was built for storage of the calcium chloride that was required in large quantities for these reactions, and of the finished calcium nitrate. The external buttresses were added soon after construction due to the inadequate strength of the thin walls, and quickly followed by a southwards extension with a bagging plant. The railway sidings allowed for efficient delivery and movement around the plant of raw and waste materials, and despatching of finished products to other works via the main line.
Details
PRINCIPAL ELEMENTS: an ammonia-soda plant of the Solvay type, and First World War experimental and production plant for making calcium nitrate, surviving above and below ground as steel floor joists, concrete building beds, some upstanding concrete structures, banks and ditches of evaporation beds, and drainage structures, comprising most elements of both plants.
DESCRIPTION: now (2018) largely unmanaged woodland, the site is located approximately 1km east of Plumley village and 500m south of the A556, from which it is served by a road named Ascol Drive, named after the company which founded the factory. It is approximately 500 x 500m, thus occupying approximately 25ha. A railway line runs along the south side of the site, which originally had sidings running from this line. The majority of buildings and infrastructure are in the western part of the site.
The ammonia-soda works mostly comprises the tight group of buildings clustered around a main building approximately 75 x 52m, aligned roughly north-south. The northern edge of this group is approximately 80m to the south-east of the site entrance at the end of Ascol Drive. In addition the crystal plant, office and dressing rooms/canteen are approximately 40m to the north and north-east of the main plant while the repair shed and reservoir (approximately 40 x 5m) are approximately 80-100m to the south-west. Extensive remains of most of these structures survive in the woodland, primarily as concrete beds (some with holding-down bolts and arched passageways running through them), metal I beams or low brick structures, with some stone footings; many stand approximately 1m high, but some of the concrete structures are up to 4m high. The brine shaft stands approximately 300m to the east, topped by an L-shaped building footing approximately 11 x 7m and 1m high, with smaller buildings nearby. The lime waste forms a large kidney-shaped mound approximately 150 x 100m and 8-9m high immediately to the east of the crystal plant.
The calcium nitrate plant is largely sited to the east and south-east of the Ascol works, in an area approximately 150 x 100m, aligned roughly north-south. The layout of the five or six linear buildings annotated on the 1918 sketch plan can be recognised in the pattern of earth and concrete platforms, ditches and banks, and large concrete blocks up to 4.5m high with internal chambers and passageways. To the west the line of the former railway siding now forms a linear depression approximately 100m in length, with the large warehouse to its west at the southern end. The warehouse stands to its full height of approximately 15m.
EXTENT OF SCHEDULING: this is focused on the known surviving remains of the ammonia-soda and calcium nitrate plants including their railway sidings, ancillary buildings, waste tips and effluent ponds. The scheduled area is drawn to the local authority boundary in the south-west corner and follows the property boundary for most of the western and northern boundary. To the east the boundary follows the eastern edge of the path around the waste beds and the woodland boundary to the east of the effluent ponds, taking in an area of managed woodland at the south-east corner on the site of a former railway siding spur. The southern boundary follows the northern boundary of the railway line.
EXCLUSIONS:
All fences and posts, and the above-and-below-ground structure of the large brick warehouse are excluded from the scheduling; however the ground beneath all of these features is included.
