PLUMLEY LIMEBEDS, Northwich, Cheshire Survey Report

Oxford Archaeology North (OAN) (formerly Lancaster University Archaeological Unit) were invited by Cheshire County Council Environmental Planning to undertake an archaeological recording programme of the remains of the industrial plant at Plumley Limebeds, Northwich, Cheshire (SJ 708 750). The programme was designed in accordance
with a brief by the Archaeology Officer (Development Control) for Cheshire County Council. The land is presently a nature reserve but is on the site of a former ammonia soda
works complex, which has been highlighted as being of particular importance in a recent step 1 report on the Chemical Industry for the Monuments Protection Programme (MPP) of English Heritage (D Cranstone pers comm). In addition, there are the remains of a munitions plant, constructed at the outset of the First World War, which produced calcium nitrate, an essential raw material for the production of high explosives. Munitions plants of
this period are extremely rare and the site is of considerable archaeological importance. An identification survey of the whole site was undertaken in November 2000, alongside a basic level of fabric recording of a surviving warehouse, the results of which were presented within an interim report. This was to be closely followed by a etailed survey of the munitions plant and a more detailed mitigation survey of the warehouse; however, in the
event this was delayed because of the outbreak of foot and mouth disease and was thus not completed until December 2001. As a result of the identification survey, the remains of the Ammonium Soda Plant (Ascol) and the ancillary industrial structures can be broadly equated with the buildings shown on the historical mapping. The detailed survey of the munitions plant, which followed on from the identification survey, established the detailed character of the plant and, in conjunction with the cartographic sources, it was possible to establish the overall processes of production; however, as much of the superstructure was dismantled and removed in 1918/9, an understanding of the detailed process has been limited. The detailed fabric survey of the warehouse has been able to establish its development and role within the production process. The building has large buttresses constructed around three sides, and it had been initially interpreted as a blast-proof warehouse, for the storage of explosives. However, it has been established that the plant produced calcium nitrate, a raw material for the production of explosives, but no actual explosives were ever produced at the site; it has also been established that the buttresses to the building were a later addition. It can therefore be confirmed that this was not a blast-proof warehouse. The
buttresses were in a second phase of the building's development and this was followed by an extension of a bagging plant on the south side (Phase 3). The extension is shown on a plan dated to 1918 and it is evident that the principal alterations occurred during the 1914 to 1918 period of activity the munitions works. The next phase of its development was when the building was adapted for warehouse storage by the nearby Associated Ethyl works (later Octel) at some stage after 1939, which involved the demolition of the bagging plant and the blocking of some apertures. The warehouse finally fell out of use in the 1980s.