Royal Naval Propellant Factory Caerwent Nitro-glycerine Hill

Cadw's description

Summary description and reason for designation

The following provides a general description of the Scheduled Ancient Monument.

The monument comprises the remains of buildings and structures relating to a Second World War nitro-glycerine plant (known as a nitro-glycerine hill) at the Royal Naval Propellant Factory, Caerwent. The site provided high-grade propellant for the Royal Navy and was deliberately located on a hillside so that gravity could be utilised in the manufacturing process. The Admiralty acquired land from 1938 and the factory became operational in 1941. The nitro-glycerine hill comprised of a mixed acids farm (Item A), a refrigeration, compressor and sub-station (Item B), a glycerine and soda store (Item C), a brine store (Item D), two charge houses (Items E and F), two nitrating houses (Items G and H), three washing houses (Items I-K), a waste acids farm (Item L), part of a paste sheeting and mixing house (Item M), three paste drying houses (Items N-P), two latrines (Items Q and R) and an intermediate house (Item S). The different process areas are separated by earthen bunds and linked by an extensive guttering system. Production at the site ceased in 1965 and decontamination was completed by 1968.

The monument is of national importance for its potential to enhance our knowledge of British Second World War munitions production and the effort required to sustain a total war. Nitro-glycerine plants are a relatively rare monument class. This example was one of the last to be built in the UK and represents the next generation on from the scheduled example at Holton Heath, Dorset. The survival of the intact plan form, including buildings, guttering, bunds and infrastructure demonstrates the industrial processes at the site. Together the structures form a readily understandable group and possess important group value. The remains of the individual structures are well preserved and retain significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits.

The areas scheduled comprise the remains described and areas around them within which related evidence may be expected to survive. Area A is centred on Items D and F at ST 4817 9195. It is an irregular polygon in shape and measures 420m WNW-ESE by 60m transversely. Area B includes Items B-C, E and G-R and is centred on ST 4824 9135. It is an irregular polygon in shape and measures 580m WNW-ESE by 240m transversely. Area C includes Item S and is centred on ST 4801 9173. It is rectangular in shape and measures 35m NW-SE by 30m transversely. Area D includes Item A and is centred on ST 4858 9156. It is square in shape and measures 40m NNE-SSW by 40m transversely.