Site Records


The Valley Works
North Wales

[Source: Andrew P Smith]

Site visit report: Valley works complex.

Photo: Entrance to Tunnel 2 (main entrance).
Photo by Nick Catford

March 22nd 2001 saw 5 members of Sub Brit visit the former chemical weapons and food storage buffer depot at Rhydymwyn in North Wales. This visit was arranged with and fully sanctioned by the MAFF who own the site and we were met by 2 MAFF members of staff who would escort us around the site with the local civilian security guards.

Having duly changed and collected hard hats and luminous safety jackets we started our tour of the site. Starting from the guardhouse at the northern end of the site we walked down the main road passing a number of buildings on both sides of us including P4 on our right. All these buildings were empty and had all the windows and doors removed. It became obvious that the site is very overgrown in parts and is not in use and hasn't been for several years.

We passed a number of mounds and our guides explained how these were buildings that had been demolished and grassed over. There were a couple of shaft accesses from the site to the Milwr tunnel complex Halkin level but these have now been capped. The access points had suffered collapses and the cavers involved had not gained access into the Halkin level but had confirmed that it appeared that it once existed. There is no access to these `shafts' that are now mounded over and grassed.

We continued along the road which turned right then left at which point we came level with the northern access tunnel into the underground complex. This tunnel now functions as the emergency escape from the underground area. The blast doors have been removed and the entrance bricked up. A single steel security door with heavy-duty locks now provides access into this tunnel. Continuing along we reached the middle tunnel that is opposite the gap between P5 and P6 buildings. This is now the main entrance into the underground complex and has 2 heavy-duty steel security doors on it with the former blast door area being bricked up.

Further along the road on our right is the entrance to the southern tunnel and this entrance is now sealed but has ventilation grills fitted high up to assist airflow in the underground section.

At this point the group split in 2, as we were restricted to a maximum of 4 people at a time underground due to health and safety requirements. Two Sub-Brit members and the 2 MAFF officials went into the tunnels whilst the remaining 3 Sub-Brit members headed to the southern end of the site to view the former filling rooms and the old railway platforms. With the others going into the tunnels we continued along the road through the site heading south. The River Alyn runs through a culvert along the length of the site with a branch of it running underneath the tunnels (more on this later). As we passed P6 and entered the southern part of the site the road surface changed from concrete to Colas. This was to reduce the risk of a spark from something being dropped onto the floor igniting one of the weapons being filled. The filling rooms are small brick and concrete structures with roof and wall vents and many have blast walls to protect the entrances. These buildings still have their WW2 camouflage paint clearly visible on then particularly on the east side which is protected from the weather. We continued along the main path down to the southern boundary fence, which is topped with barbed wire. Here the Alyn flows over what's left of the weir following the floods last year and on to the Dee estuary.

We turned and headed north walking along the east path through the site. From this path we could see much more of the paint on the side of the filling rooms and we entered all the buildings. One of these had a sign reading 'cleanway to canteen' painted on the wall in excellent condition. Many of these buildings are in a very poor state with leaking roofs etc. Set in the middle of the filling rooms was the railway platform. Again this was covered in Colas and we could clearly see where the 2 railway sidings used to be.

Continuing North we walked along the edge of the site and turned west back towards the main pathway when we reached the old sewage works. These still had a lot of machinery in place but were very dilapidated.

Walking along the side of the sewage works our guides explained how in the bad flooding last year the site became awash as the Alyn overflowed and a substantial amount of flotsam and rubbish was washed onto the site. There were numerous piles of this everywhere awaiting clearance. We crossed the end of the sewage works and headed back towards the east fence and picked up the east path again. Continuing North we passed the rear of P6 and at the gap between P5 and 6 crossed the site back to the main tunnel entrance where the first party were just emerging from the underground workings.

Before entering the underground workings we received a short but comprehensive safety briefing and collected our emergency respirators. Large signs outside the entrance told us that the tunnels were dangerous and empty. Our guide then led us into the tunnels.

The main entrance tunnel is around 250M long and is concrete lined for the first half after which it is bare rock painted white. There is up to 3 inches of water on the floor of this entrance tunnel. This tunnel leads directly into chamber A that is transverse to the entrance tunnel. At this point it is possible to go left, right or straight on into chambers B,C and D.

Photo: Storage Chamber A.
Photo by Nick Catford

We decide to turn right (north) and are standing at the midpoint of chamber A. The chambers are all identical and have rough rock walls painted white. Along the centre of this tunnel set into the floor are a series of drain cover grills, which are all badly rusted, and we were warned not to step on these as they would collapse under our bodyweight. There were various puddles of water on the floor in this chamber.

We could clearly hear the sound of water running and this got louder the further north we headed. Reaching the northern most point of chamber A we could look down the tunnel to the northern door which was our emergency escape route. This tunnel was empty.

Attached to the walls high above our heads were the fixing points for the runners for the long gone overhead cranes. There is no evidence of railway tracks in any of the tunnels.

We turned left and headed down a short piece of tunnel into chamber B. Here we could see where the water noise was coming from.

From a hole high in the roof at the northern most point of chamber B a torrent of water was crashing down onto the floor below. This was causing the puddles that were to be found in various areas of the underground workings.

We turned south and headed down chamber B being careful not to tread in the grills set into the floor. We turned right and moved into chamber C which had sluice channels cut into the floor along each edge approximately 3 fete wide and 6 feet deep. The water tanks that stored the Runcol (Mustard Gas) filled shells were located in chambers C & D and the sluice channels were to remove water that leaked from the tanks into the drainage system that was below the tunnels (more on that later). These sluices were now filled with standing water and again the floor of these chambers was wet in places.

Moving into chamber D we moved to the northern end where we viewed the way through to the air shafts. In order to access the shafts it was necessary to cross a 6ft deep water pit. This used to be the way down into the drainage system beneath the underground chambers. The whole system was run by pumps that got rid of the excess water and the drains were up to 5ft tall in places. The pumps were switched off many years ago and these have now become flooded and access to them is not possible unless you have a wetsuit and breathing apparatus!

We continued south along chamber D and at the far end was the southern vent shaft access, which was identical to the northern one.

We crossed back into chamber C and then worked our way back to chamber B and eventually A.

In some of the chambers the consulting mine engineers employed by the MAFF have places measurements to check for shifting of materials in the chambers and this has resulted in loose rock being removed in a couple of places and a small amount of re-inforcing being put in at the southern vent shaft access.

We walked back to the main entrance tunnel and exited stopping to look at 2 vehicle gates that were rusted to the walls. These obviously provided an 'air lock' type gate for allowing vehicles in and out or the workings.

We emerged into the sunshine to be greeted by the 2nd Sub-Brit party making their way back towards us having toured the south of the site. We then all set off together to tour the rest of the site. We walked back across to the east path and continued along stopping to look in all buildings of interest. Building P5 used to house flour as part of the MAFF buffer stock and directly behind P5 is one of the sheds that used to house the shunter engines. There is a small amount of standard gauge track set into the floor outside P5 on its west side.

Continuing along we then visited the quality control labs where there were a number of yellow squares in the floor marked 'toxic drain'. In these buildings which again had no windows or doors there were remains of light fittings and a number of power junction boxes on the walls.

We left the labs and walked across the north end of the site passing the old powerhouse and garages that house an ambulance and fire engine arriving back at the gatehouse.

Throughout the site there are numerous boreholes that the MAFF use for monitoring whether there is any leakage from the significant number of toxic waste burial pits which are marked and fenced off on the site.

The site is a mile long and is totally disused the only presence being security guards from Citex who are contracted to the MAFF to provide site security.

No restrictions whatsoever were placed on us by the MAFF and we extensively photographed and video'd the site and the underground workings.

I would like to take this opportunity to thank the MAFF for their extensive co-operation and allowing us to visit this important site.

Many of the buildings on the site were demolished early in 2003. Some works are being done at the foot of the bank adjacent to the tunnel entrances to stabilise the bank where some small buildings have been demolished, at the southern end of the site a new bank has been built to replace the washed out river bank, this is stone faced and has new boundary fencing to close the gap in the original boundary. See last two photographs in the gallery.

[Source: Andrew P Smith]


Entrance to Tunnel 3 (emergency exit)

Entrance to Tunnel 2 (main entrance)

Entrance to Tunnel 1 (now sealed)

Looking along Tunnel 2 from the entrance

Storage Chamber A

Looking along Tunnel 3 towards the airshaft from the junction with Storage
Chamber A

The northern end of Storage Chamber F

Doorway leading to the airshaft at the end of Tunnel 3

The southern end of Storage Chamber D and the junction with Tunnel 1

Looking along Tunnel 1 towards the airshaft, from the junction with Storage
Chamber A

Looking along Tunnel 2, just before it’s junction with Storage Chamber A
Note the gate fixed to the wall


Building K5 (75) – Weapon charging and storage building

Inside Building K4 (85) – Weapon charging and storage building

Buildings K5 (75) on the left and K4 (85) on the right

Building K5 (75) – Weapon charging and storage building

Power House – Building 97

Building 96 (right) and part of Building K4 (left)

Engine shed – Building 95 with Building 96 behind

Building P4 (59) – Pyro production building

Building P4 (59) – Pyro production building

Building R3 (65), Runcol preparation building, left and P4 (59) right

Building? With Building P4 (59) behind

Building P4 (59) – Pyro production building

Building P4 (59) – Pyro production building

Building 17

Power House - Building 32

Building 126 with Building 117 behind

Building 123

Various buildings in the assembly area

Building 128

Various buildings in the assembly area with K4 (85) in the background

Sign referring to ‘Injured contaminated persons’

Building 149 – note the camouflage paint with the railway loading platform behind

Building 149 and Railway loading platform

Railway loading platform with Building 149 behind

Toxic burial pit close to Tunnel 3 entrance

Toxic burial pit close to Tunnel 3 entrance

A short History of` The Valley Works' is available here.

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Last updated 7th March 2003

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