I'm not going to talk about the production areas as there are other reports on here of those. A couple of the reports say that the people would add the tunnels later but that doesn't seem to have happened (not as easy to break in as they expected......).
The best tunnel photo on here so far was taken by newage and posted about a year ago along with some other photos around the production site.
In October 1939 J. B. Edwards & Co. started work constructing a production site for I.C.I. (under contract to The Ministry of Supply) at Rhydymwyn. Known locally during WWII as "The ICI Site" it was to produce and store Dichlorodiethyl sulfide (or 1-Chloro-2-[(2-chloroethyl)sulfanyl]ethane if you prefer).
At the same time as the site construction started Halkyn and District United Mines Limited started work on the underground storage tunnels cut into the limestone at the side of the valley. To speed up the tunnel work HDUM ran a compressed air main across the fields from one of their existing compressor houses. Three bores were in operation six and a half days a week. Excavated material was used to level the valley floor on which the rest of the site was being constructed. Thirteen months later lead-lined mild steel tanks were being installed in the tunnels ready for material to be stored (some material was already stored above ground on the adjacent 'Antelope Field' site by this time.
Before the final tunnel arrangement was achieved two changes in required storage capacity had been made and changes made to the original layout.
At right angles to the three main tunnels are four cross chambers (you can find a plan diagram on the Rhydymwyn Valley History Society website). The central tunnel is slightly larger to allow access to 65 ton tanks. Each cross chamber had an overhead crane. Fans drew air down through gratings in the floor, which also served to collect water (and liquid spillages) and then up vent shafts at the end of the South and North tunnels. Fresh warm air could be forced into the system through variable ducts in a false ceiling from two fans in a plenum house outside the central tunnel entrance.
When the sulphur mustard liquid and tanks had all been removed part of the floor was strengthened in case the site was used to store part of the strategic gold reserve during the cold war. This storage never occurred. The tunnel condition is monitored annually and occasional remedial work done.
The RVHS has been fighting for the past seven years to try and get permission for public access to this interesting historical structure. Yesterday was the first public access permitted out of two days that were authorised this year (the day was fully booked as is the second one.....bookings are being taken for next years opening days).
Not a lot left but having fought your way this far down the waffle here are a couple of photos.
25 feet into the central tunnel (immediately behind me is a gate which marks the furthest people were allowed in before). 703 feet in the distance is the end of the tunnel.
Looking back to the entrance from the end of the concrete-lined section. A metal gate is visible either side of the sloping doorway which directed forced air up above the mild steel ceiling.
Chambers A south and B south each had single rows of storage tanks plus weapon storage. The butresses for the crane as well as the concrete edge support of the air tank ceiling can be seen as well as the air-vent/sump gratings
Chambers A north and B north each had single rows of storage tanks plus weapon. They were also extended 260 feet beyond the Northern access tunnel
Chambers C and D, both north and south were enlarged and had two rows of tanks
Rear wall
Looking back towards the entrance from the same point as the previous photo
The best tunnel photo on here so far was taken by newage and posted about a year ago along with some other photos around the production site.
In October 1939 J. B. Edwards & Co. started work constructing a production site for I.C.I. (under contract to The Ministry of Supply) at Rhydymwyn. Known locally during WWII as "The ICI Site" it was to produce and store Dichlorodiethyl sulfide (or 1-Chloro-2-[(2-chloroethyl)sulfanyl]ethane if you prefer).
At the same time as the site construction started Halkyn and District United Mines Limited started work on the underground storage tunnels cut into the limestone at the side of the valley. To speed up the tunnel work HDUM ran a compressed air main across the fields from one of their existing compressor houses. Three bores were in operation six and a half days a week. Excavated material was used to level the valley floor on which the rest of the site was being constructed. Thirteen months later lead-lined mild steel tanks were being installed in the tunnels ready for material to be stored (some material was already stored above ground on the adjacent 'Antelope Field' site by this time.
Before the final tunnel arrangement was achieved two changes in required storage capacity had been made and changes made to the original layout.
At right angles to the three main tunnels are four cross chambers (you can find a plan diagram on the Rhydymwyn Valley History Society website). The central tunnel is slightly larger to allow access to 65 ton tanks. Each cross chamber had an overhead crane. Fans drew air down through gratings in the floor, which also served to collect water (and liquid spillages) and then up vent shafts at the end of the South and North tunnels. Fresh warm air could be forced into the system through variable ducts in a false ceiling from two fans in a plenum house outside the central tunnel entrance.
When the sulphur mustard liquid and tanks had all been removed part of the floor was strengthened in case the site was used to store part of the strategic gold reserve during the cold war. This storage never occurred. The tunnel condition is monitored annually and occasional remedial work done.
The RVHS has been fighting for the past seven years to try and get permission for public access to this interesting historical structure. Yesterday was the first public access permitted out of two days that were authorised this year (the day was fully booked as is the second one.....bookings are being taken for next years opening days).
Not a lot left but having fought your way this far down the waffle here are a couple of photos.
25 feet into the central tunnel (immediately behind me is a gate which marks the furthest people were allowed in before). 703 feet in the distance is the end of the tunnel.
Looking back to the entrance from the end of the concrete-lined section. A metal gate is visible either side of the sloping doorway which directed forced air up above the mild steel ceiling.
Chambers A south and B south each had single rows of storage tanks plus weapon storage. The butresses for the crane as well as the concrete edge support of the air tank ceiling can be seen as well as the air-vent/sump gratings
Chambers A north and B north each had single rows of storage tanks plus weapon. They were also extended 260 feet beyond the Northern access tunnel
Chambers C and D, both north and south were enlarged and had two rows of tanks
Rear wall
Looking back towards the entrance from the same point as the previous photo
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