Gretna, Hm Factory, Eastriggs Explosives Factory, Nitroglycerine Hill No. 3

Canmore ID: 373569

NY26SE 16.03

Centred NY 26609 64751

What remains of the buildings that once formed part of this Nitroglycerine Hill are situated on a ridge, the gradient of which eases gently as the topography levels off in boggy ground to the NNW. They comprise the remains of the blast mounds of the three Final Wash Houses (NY 26577 64586, NY 26661 64613, NY 26739 64665), the blast monds of six Paste Mixing Houses (NY 26535 64690, NY 26621 64718, NY 26704 64746, NY 26509 64766, NY 26596 64794, NY 26678 64822), the blast mound of a Dry Guncotton Store (NY 26572 64870), and the blast mounds of two Paste Magazines (NY 26517 65001, NY 26653 65007). In addition, the ancillary infrastructure includes, amongst other elements, the remains of a narrow-gauge and a standard-gauge railway network (NY26NW 46.23, NY26NW 46.24). As the processes involved in the production of Nitroglycerine relied largely upon gravity to enable the movement of the constituent fluids in a continuous direction, all these buildings are carefully arranged in an ordered sequence and so take account of the slope of the ground. In addition, they are deliberately spaced – the blast mounds of the Final Wash Houses and the Paste Mixing Houses being set 70m apart, the Dry Guncotton Store 40m from the latter, while the Paste Magazines are distanced about 90m from the Dry Guncotton Store and also from one another.

The grass- and gorse-grown remains of the two most westerly of the Final Wash House blast mounds measure 48m from ENE to WSW by 45m transversely overall within earth and stone banks measuring 14m in thickness and 3.5m in height. All have rounded corners. The most easterly blast mound is a little larger measuring 52m from ENE to WSW by 46m transversely overall within earth and stone banks up to 18m in thickness and 3.5m in height. They have all slumped a little both internally and externally. There are scarps outlining three sides of a rectangular feature, measuring about 3m from ENE to WSW by 2m transversely and up to 1m in depth, cut into the foot of all three blast mounds on their NNW facing slopes (NY 26583 64606, NY 26660 64631, NY 26733 64684). There is also a V-shaped gap on the SSE of the blast mounds measuring about 7m in width and 2m in depth. Two brick-lined tunnels, one for a narrow-gauge railway and the other for use in an emergency exit, are also cut through the blast mounds. The narrow-gauge tunnel in the most westerly blast mound is situated on the NNW facing slope offset to the ENE, while its two companions have similar tunnels offset to the WSW. The emergency tunnel in the more westerly blast mound is found on the WSW where it emerges into a network of ditches, while those of the others are situated on the ESE and emerge onto open ground. Each blast mound contains a later Nissen hut (NY26SE 16.06) constructed before the outset of the Second World War. The grass-and gorse-grown blast mounds of the six Paste Mixing Houses to the NNW are rectangular on plan and each measures up to 45m from ENE to WSW by 40m transversely overall within earth banks up to 15m in thickness and 3.5m in height. However, two have much sharper rounded corners (NY 26512 64771, NY 26595 64799) than the others. The two most easterly blast mounds have entrance gaps in the NNW side offset to the ENE, while their four neighbours have entrance gaps in the same side offset to the WSW. However, one entrance survives intact (NY 26512 64771) as a brick-lined tunnel, while its neighbour to the ENE (NY 26595 64799) has had the roof of this removed. Each is approached by the remains of a narrow-gauge railway embankment.

The grass- and gorse-grown blast mound of the Dry Guncotton Store to their NNW measures roughly 40m square overall within earth banks 15m in thickness and up to about 3.5m in height. There is an entrance tunnel on the ENE offset to the SSE and this is also serviced by the narrow-gauge railway network. The grass- and gorse-grown blast mounds of the two Paste Magazines are situated to the N and NNW of the Dry Guncotton Store. They are both rectangular on plan, but the more westerly measures 50m NNW to SSE by 42m overall transversely within earth banks 15m in thickness and up to about 3.5m in height, while that to its E measures 50m from N to S by 45m overall transversely within earth banks 17m in thickness and up to about 3.5m in height. The more westerly has an entrance gap on the ENE offset to the NNW, while its counterpart to the E has an entrance gap on the W offset to the S. They are also serviced by the narrow-gauge railway network which leaves these gaps to run towards the former site of the Off-loading Platform. However, the latter has been destroyed by the road running to the N of the Hills.

The structures associated with Nitroglycerine Hill No.3 are referred to in the report (MMW 1919, 145-163, plans in text) outlining the processes involved in the manufacture of the cordite propellant at H.M. Factory, Gretna (Site 3), which was established by the Ministry of Munitions during the First World War. This section of the factory comprised a complete plant for the manufacture of Nitroglycerine. Apart from the blast mounds of the three Final Wash Houses and those of the six Paste Mixing Houses, the Dry Guncotton Store and the two Paste Magazines, other buildings were also associated with the plant. These included a Chemists Hut (NY 26800 64513), a Glycerine Dump (NY 26654 64494), a Soda Solution Dump House (NY 26665 64400), an Acid Dump House (NY 26676 64505), two Acid Storage Tanks (NY 26679 64498), four Air Storage Tanks (NY 26734 64539), a Charge House (NY 26670 64516), a Brine Store (NY 26703 64500), a Nitrator Separator House (NY 26701 64532), a share of two Wash Water Settling Houses (NY 26476 64613, NY 26804 64705 shared with Nitroglycerine Hill No.2 NY26SE 16.2) and their Ponds (NY 26453 64673, c.NY 26809 64781 shared with Nitroglycerine House No.2 NY26SE 16.2), a Waste Collecting House (NY 26468 64804), two shared Rest Rooms (NY 26425 64771-shared with NY26NE 16.2, NY 26874 64881-shared with NY26NE 16.4), an Off Loading Platform (NY 26584 65041) and other minor structures such as a shelter and latrines. In addition to the report, an undated plan (SUPP 10-39), a series of descriptions of blueprints (SUPP 10-16 3075A, 3076, 3076A, 3077, 3090A; SUPP 10-17 3202; SUPP 10-18 3376; SUPP 10-19 3562; SUPP 10-20 3737), some actual blueprints (SUPP 10-24 3075, 3076, 3090, 3090A, 3097, 3196, 3208, 3211A; SUPP 10-25 3376; SUP 10-26 3507, 3562; SUPP 10-27 3737, 3798A; SUPP 10-28 3910; SUPP 10-31 4365), together with ground-based, contemporary official photographs taken during and after construction (MUN 5-297 pt2 158D, 222, 286, 286A, 286B, 333, 333A, 333B, 333C, 338; MUN 5-297 pt4 600.2.7.18; MUN 297 pt5 713), held at the National Archives at Kew, illustrate the character of the buildings on this Hill. These sources show that the chemicals were brought to the top of the Hill from other parts of the factory (see Hill No.2, NY26SE 16.02 for a description of the character of the buildings clustering around the Nitrator Separator House in this area). Elsewhere, the architecture of Final Wash Houses, the Paste Mixing Houses, the Dry Guncotton Store, the Paste Magazines and the Off-loading Platform are also described under Hill No.2 (NY26SE 16.02), except for the following differences. The small rectangular features noted above as cut into the foot of NNW facing slopes of all three of the Final Wash House blast mounds mark the site of turf-built safety shelters, while Hill 3 shared its westerly Wash Water Settling House, Pond and Rest Room with Hill No.2 (NY26NE 16.2) and those to the E with Hill No. 4 (NY26NE 16.4).

This Nitroglycerine Hill fell into lot 491, which was offered for sale by auction on 22-5 July 1924 (HM Treasury 1924, 89; Carlisle City Archives, DX 170/38), when it was purchased by Greenwood & another of Broomhills, Eastriggs (Carlisle City Archives, DX 2040/3). The foundations and perhaps the ruins of the Glycerine Dump, the Soda Solution House, the Acid Dump House, the Charge House, the Brine Store and the dwarf walls of the Air Storage Tanks are visible at the top of the Hill. In addition, the three Final Wash House blast mounds, the six Paste Mixing House blast mounds, the Dry Guncotton Store blast mound and the two Paste Magazines blast mounds, together with the foundations of the Off-loading Platform are shown on an aerial photograph (M124/13 04121) flown on 19 August 1940. However, Nissen Huts (NY26SE 16.06) had already been introduced into the blast mounds of the three Final Wash Houses, the six Paste Mixing Houses, the Dry Guncotton Store and the two Paste Magazines. Another aerial photograph (CAM/031 06211) flown on 13 October 1942 shows that all the buildings at the top of the Hill had been destroyed.

Visited by HES Heritage Recording (MMD and ATW), 7 September 2022.