Blast Shelter

The Department's description

Exterior description and setting

Building 1
This structure is located towards the south end of Fincarn Glen and is aligned NE/SW parallel with a small stream of the same name running northwards through the glen to its E.
When in use, it was completely covered with earth (except for its entrance at NE), all of which has now been removed. It comprises a horizontally-mounted metal cylinder fabricated from pre-formed curved corrugated metal sheets bolted together. Its two ends comprise vertical metal sheets slotted together. Both ends extend slightly beyond the curved roof/walls to retain the earth which formerly covered the structure. There are circular metal ventilation flues at its front and back end; the back one is complete, but only the base of the front one survives.

Setting:
The shelter sits just above the Fincarn Glen stream, with an unpaved track to its immediate west. It is located between an ammunition bunker 80m to its NW (HB01/06/019G Building 4) and another bunker 65m to its SW (HB01/06/019I Building 2). It would doubtless have been used should any of the bunkers at this end of the glen exploded, whether accidently or otherwise (there were 21 ammo bunkers in all in the glen).

Building 2
One of 21 ammunition bunkers erected in Fincarn Glen by American military personnel in 1941-42.
Situated towards the south end of the glen, this single-storey, single-bay structure is aligned NW-SE into the hillside with its entrance at SE. It is of rectangular plan and semicircular cross-section.
All its components are of pre-formed galvanised steel. Its roof and sides are of overlapping curved corrugated sheeting, all completely covered with earth.
The two end walls are of flat steel panels held together with flanges bolted together up their outside faces. These walls have flat tops and sloping sides which extend beyond the roof and sides to retain their earth covering. The back wall (at NW) is dug into the hillside and thus covered with earth as well.
There were formerly two outward-opening steel doors at its SE end, both now missing. Above the door opening are the painted figures '12' and '15' and three small square vents. On the wall to the left of the doorway is a metal bracket (for a fire bucket) and the painted figure '3'.
Right of the doorway is an identical painted figure and also an electrical junction box. On its cast aluminium cover is the legend: "100 amp 660 volt flameproof junction box/ Type Walsall" 9346BX/ Groups 2 & 3. PLP 2026/ Isolate supply elsewhere/ before removing covers/ Made in England". Below the top box are two smaller ones, the covers of which read: "This box must be/ entirely filled/ with sealing/ compound". There is no obvious platform in front of the door (but it may be buried).
The bunker is now disused and grassed over.

Setting:
All the ammo bunkers were widely spaced out along the glen to minimise collateral damage should one have exploded. The nearest to this one are 105m to N (HB01/06/019G Building 4) and 95m to SW (HB01/06/019I Building 3).
This example sits at the bottom of a grassy slope rising up the west side of the glen. The stream flowing northwards through the glen runs in front of its entrance, just beyond an unpaved track down the glen.

Building 3
One of 21 ammunition bunkers erected in Fincarn Glen by American military personnel in 1941-42.
Situated at the south end of the glen, this single-storey, single-bay structure is aligned NW-SE into the hillside with its entrance at SE. It is of rectangular plan and semicircular cross-section.
All its components are of pre-formed galvanised steel. Its roof and sides are of overlapping curved corrugated sheeting, all completely covered with earth.
The two end walls are of flat steel panels held together with flanges bolted together up their outside faces. These walls have flat tops and sloping sides which extend beyond the roof and sides to retain their earth covering. The back wall (at NW) is dug into the hillside and thus covered with earth as well.
There were formerly two outward-opening steel doors at its SE end, both now missing. The metalwork above this opening has also been removed. On the wall to the right of the doorway is a painted figure '3'. There is no obvious platform in front of the door, the entrance having been gravelled over to facilitate animal access (but it may be buried).
The bunker is now used as an animal shelter. A concrete-walled silo pit has also been built at the left-hand end of its front end. Its roof and sides are grassed over.

Setting:
All the ammo bunkers were widely spaced out along the glen to minimise collateral damage should one have exploded. The nearest to this one are 95m to NE (HB01/06/019I Building 2) and 105m to SW (HB01/06/019J).
This example sits at the bottom of a grassy slope rising up the west side of the glen. The stream flowing northwards through the glen runs in front of its entrance, just beyond an unpaved track down the glen.

Historical information

The Fincarn Ammunition Depot was constructed by American military personnel with the assistance of local labour. It was completed by May 1942 and used for the temporary storage of munitions shipped into Lisahally Port on Lough Foyle, 6km to the north. From Fincarn, the ammo was transferred to military bases such as the nearby Maydown and Eglinton airfields.
The steelwork on many of the ammo bunkers bear the legend "Armco Ingot Iron Manufactured by the American Rolling Mill Co Middletown, Ohio 2oz coating". 'Armco' is the acronym of the American Roller Mill Corporation of Middletown Ohio, founded in 1899 and a pioneer of continuous rolled sheet steel production. The name is still used generically to this day to denote cylindrical corrugated metal culverts under roads etc.
This bunker is essentially a standard Armco hut, the size of which was 50ft x 20ft x 10ft radius. Its heavy-duty galvanised steel sheeting and arched cross-section made it capable of being buried under several metres of earth. It is not unlike a Quonset hut, the American equivalent of the British Nissen hut, but without any internal framework and by a different maker.
C Company of the 1st Provisional Marine Battalion, an infantry brigade of the US Marine Corps, was based nearby at Beech Hill and performed guard duty here for a time. The bunkers may also have been used for as a chemical storage depot (known as C-910) between November 1943 and August 1944.
Although erected in the early 1940s, no buildings or structures are depicted in Fincarn Glen on the 1948-49 OS map, presumably for security reasons. All the features are, however, shown on the 1963 OS map under the caption "Disused Camp Site".

References - Primary Sources:
1. PRONI OS/6/5/14/5. OS 1:2500 map, Co Londonderry sheet 14-05 (1948-49).
2. PRONI OS/11/37/5/1. OS Irish Grid map sheet 37-05 (1966-67).
3. PRONI OS/11/37/9/1. OS Irish Grid map sheet 37-05 (1968).

Secondary Sources
1. A. Glenfield, Second World War in Northern Ireland, .
2. ARMCO history: ,, and .
3. Quonset huts: J. Decker & C. Chiei (eds), Quonset: Metal Living for a Modern Age (Princetown: Princetown Architectural Press, 2005), and .
4. Chemical storage, .

Criteria for listing: architectural interest

Not listed

Criteria for listing: historic interest

Not listed

Evaluation

This record has now been protected by scheduling under LDY014:014 and can be viewed on the NISMR database:

Building 1
A corrugated steel blast shelter built by the US military authorities in 1941-42 in connection with the Fincarn Glen ammunition depot.
Architecturally, this is a good example of a small emergency Second World War blast shelter. Its lightweight pre-fabricated components could be transported easily (across the Atlantic in this case) and quickly erected using unskilled local labour. Its cylindrical design did away with the need for an internal frame and no foundations were required as it was self-supporting. Pre-fabrication was extensively used during the war for military buildings and structures. Once fabricated, earth dug from its vicinity was used to give the store added protection against blast damage and also camouflaged it.
The shelter's setting is of special note - amidst numerous ammunition bunkers in a narrow glen which could be easily defended at both ends. It also has considerable group value with the 21 ammo bunkers with which it is associated and is one of two such shelters in the glen (the other is HB01/06/019B Building 2 towards the N end).
Historically, this shelter had a rare and unusual function. Its original fabric survives in an unaltered stare. It is a tangible reminder of the large American presence in and around Londonderry during the Second World War. The Fincarn ammo store complex is probably the largest such concentration of bunkers and blast shelters still surviving anywhere in the Province.
Because of its specialist function, American connection and survival as part of a larger group of military-related buildings and structures, this shelter is not only of local interest, but of provincial significance as well.

Building 2
A corrugated steel ammunition bunker built by the US military authorities in 1941-42 for the temporary storage of ammunition.
This ammo bunker is of architectural interest as a good example of a Second World War ammunition store. Its superstructure is of lightweight pre-fabricated components so that it could be transported easily (across the Atlantic in this case) and quickly erected using unskilled local labour. Its semicircular arch design did away with the need for an internal frame and no foundations were required as it was self-supporting. Pre-fabrication was extensively used during the war for military buildings and structures. Once fabricated, earth dug from its vicinity was used to give the store added protection against blast damage and also camouflaged it.
The interior is reasonably well preserved, and its historical significance greatly enhanced by the stencilled and handwritten inscriptions.
The bunker's setting is of special note - in a narrow glen which could be easily defended at both ends. The spacing between it and its neighbours - 95+ metres - also minimised any damage should one have exploded. It also has considerable group value in being one of 21 ammo stores and one of 24 surviving military structures in Fincarn Glen.
Historically, this bunker had a rare and unusual function. Virtually all its original fabric survives in an unaltered stare. It is a tangible reminder of the large American presence in and around Londonderry during the Second World War. The Fincarn ammo stores are probably the largest surviving concentration of their type anywhere in the Province.
Because of their specialist function, American connection and survival as a group, they are not only of local interest, but of provincial significance as well.

Building 3
A corrugated steel ammunition bunker built by the US military authorities in 1941-42 for the temporary storage of ammunition.
This ammo bunker is of architectural interest as a good example of a Second World War ammunition store. Its superstructure is of lightweight pre-fabricated components so that it could be transported easily (across the Atlantic in this case) and quickly erected using unskilled local labour. Its semicircular arch design did away with the need for an internal frame and no foundations were required as it was self-supporting. Pre-fabrication was extensively used during the war for military buildings and structures. Once fabricated, earth dug from its vicinity was used to give the store added protection against blast damage and also camouflaged it. The interior is reasonably well preserved, and its historical significance greatly enhanced by the stencilled maker's marks.
The bunker's setting is of special note - in a narrow glen which could be easily defended at both ends. The spacing between it and its neighbours - 95+ metres - also minimised any damage should one have exploded. It also has considerable group value in being one of 21 ammo stores and one of 24 surviving military structures in Fincarn Glen.
Historically, this bunker had a rare and unusual function. Virtually all its original fabric survives in an unaltered stare. It is a tangible reminder of the large American presence in and around Londonderry during the Second World War. The Fincarn ammo stores are probably the largest surviving concentration of their type anywhere in the Province.
Because of their specialist function, American connection and survival as a group, they are not only of local interest, but of provincial significance as well.