Detailed Concerns






Nerve Gas and Unexploded Ordnance (UXO)

“Immediately after the war, because of its secure storage and rail connections, [RAF Llanberis (Glyn Rhonwy)] was temporarily used as a storage facility for 14,000 tons of bombs filled with tabun (a toxic nerve gas) which had been seized from German ammunition depots…
It should be noted that the RAF was unwilling to certify the quarries completely free of explosives, despite rendering safe each disposal area.”


The Applicant’s own  Zetica Report Zetica Report produced by their ordnance management consultants   told us more about the munitions history of the quarry complex than was ever made public when the Gwynedd Council Plannning Department considered and approved the smaller scheme.  But it raised more questions than it answered, and, with the help of material recently and fortuitously made available at Gwynedd Archives, we have delved deeper into the detail – some of which was oddly omitted from theZetica report.

See this Written representation from J Taylor regarding Munitions  , and this specially commisioned research Evidence to the Inquiry Dr Dave Preskett .

Note that most of the material referenced here is Crown Copyright and as such we are immensely grateful to the National Archives at Kew and to Gwynedd Archives, and acknowledge their kind permission in allowing publication.

We found proof of handling chemical weapons (something which Zetica initially seemed to have overlooked) such as mustard gas at Glyn Rhonwy as evidenced by this correspondence Ref. 71 MU 4111 3 11 MEA Porton Down Visit April 73 with Porton Down Chemical Weapons Establishment, inventories of very large bombs taken away for “practice” by the Defence Ordnance Disposal School  DEOD visit July 1973, and very strong and alarming circumstantial evidence of improper disposal of at least one Tabun Nerve Gas Bomb .. see this astonishing collection of photos of new Tabun bombs in a factory and an old one laying in a slate crevice KC 250 GR III bomb photos and KC 250 GR III bomb photos file- HMSO envelope  .  These photos were found in an envelope (also illustrated) marked “Sandcastle” – the name of the Tabun disposal operation –  in a pile of documents exclusively pertaining to Glyn Rhonwy.  These detailed and alarming accounts were in the same collection of documentation and physically close to other material  which Zetica had used as their source material for their “desk study”, so we were surprised that they had been “missed”.  Draw your own conclusions.

Our own sceptical conclusions about the severity of potential hazards posed by the site’s military history are, unsurprisingly,  disputed by the Applicant (they called it “seeking to create a narrative”) and you can read the exchange of views in the form of examiners questions and Applicant’s and Interested Parties’ responses at the  Planning Inspectorate’s  Examination Documents

Our views have not been changed by the discussion. And the Applicant’s attitude, as we perceive it, in seeming to want to gloss over some of the trickier (and expensive)  issues regarding management of these hazards does not inspire confidence.
The consequences of getting it wrong could be catastrophic for public health and safety in the local area let alone environmental conditions in the downstream water catchment areas.


“The bomb disposal areas are unlikely to pose a risk because:
We have no confidence in the Developer’s ability or will to effectively monitor their own activities for environmental compliance.
So this raises the question of whether even the Regulatory Authorities, let alone the Developers, are capable of ensuring proper compliance with Planning Permission/Development Consent Order/ self imposed conditions.
Correspondence regarding this is still ongoing.


The Planning Inspectorate have noted that the information provided by SPH is misleading. Their statement regarding connection via an underground cable does not relate to the grid connection onwards but rather “that this was the infrastructure to enable the generating station to be connected to the 132Kv connection and this was not part of the connection itself. The applicant will consider revised drafting to seek to ensure that this is clear.”

What is clear is that this seriously questions both the validity of the local consultation and the integrity of SPH and their application.
The Snowdonia Society are particularly concerned about the visual imapct of pylons see

They have had a lot to say about this in their written submission .. see  Glyn Rhonwy Deadline 4 grid connection Snowdonia Society WR 10031956.


You’d think that for a project of this size and for the money that has already been spent that the Applicant would have very clear ideas about how they propose to do it and who will build it.  But we are finding that their ideas don’t stand up to scrutiny.

We are very grateful for the expert assistance of one of our supporters, engineer Mike Vitkovich, who was intimately involved in the construction of the Dinorwig scheme.  He has analysed the proposal in detail and come to some surprising conclusions, supported by a  report from David Hobson, a Chartered Civil and Tunnelling Engineer with thirty years of experience building such schemes

In a nutshell, their conclusions are

  • the penstock as proposed is unbuildable – it is too steep to drill blast and remove the spoil uphill, so an intermediary vertical shaft would be necessary – something which has been ruled out on account of the environmental  requirement not to build intermediary surface strucures between the upper and lower quarry ponds
  • the proposed access to the upper quarry Chwarel Fawr, by simply (and cheaply because the Gwynedd Council will probably pay for it) widening the existing Cefn Du road from Waunfawr is undriveable.  It is too steep for the kind of vehicle loads required.  Mike Vitkovich proposed building a brand new access across Cefn Du of suitable gradient, or alternatively proposed constructing a temproary route up through the existing quarries from Q6 / Lower Glyn Rhonwy – the proposed lower pond.
  • The Applicant’s estimates of material to be moved and therefore vehicle movements and footprint of temporary waste slate heaps are grossly in error – there will be more vehicle journeys more disturbance more noise and more space taken up, with implications for the footprint of the dams and spoil heaps in relation to the site boundaries (and possibly impinging on the “bomb store” – see elsewhere)

see the supporting documentation here…..

Glyn Rhonwy Hydro assessment of construction – David Hobson

GR Access Roads Deadline 5 Submission Final

Glyn Rhonwy Access Roads and Penstock Design Deadline 5 Submission Final MV




Here also Mike Vitkovich was able to lend his experience to scrutinising the Applicant’s noise assessments

He found surprising ommissions in their assessment protocols, particularly in relation to Ground Borne Noise and Low Frequency Vibration – particularly intractable problems which belatedly became apparent after the Dinorwig scheme was built, and inadequacies in location of survey sensor locations

He sought the advice of a  noise engineer Rupert Thornely-Taylor of Rupert Taylor Ltd, a consultant in acoustics, noise and vibration and  Fellow of the Institute of Acoustics with 52 years experience in such matters

Here is Mike’s submission to the Inspector, and the consultant’s report

Low Frequency Noise and Ground Borne Vibration – Mike Vitkovich

Glyn Rhonwy GroundBorne and Low Frequency Noise review by Rupert Taylor




Prior to the beginning of the Inspectors Inquiry, which has been pleasingly inclusive open and democratic unlike the process whereby the smaller scheme was approved, there did not seem to be much  effective feedback or meaningful two way conversation between the Applicant and objectors to any aspect of the scheme.
Their efforts  seemed like a public relations exercise – not a consultation.


The scheme is likely to have a profound effect on the quality of life for residents close by .. particularly those living along the Cefn Du road which is proposed as an access route for construction vehicles from Waunfawr to the top pond (Chwarel Fawr) and to those living directly beneath the lower dam on the main A4086 road to Llanberis particularly Glyn Peris Guesthouse (whose business is likely to be destroyed by the scheme) and their close neighbours.
Llanberis Community Council did not submit a report to the scoping consultation and have pretty much remained silent on the issue other than to say early on they welcome the proposal, whilst Waunfawr Community Council having initially supported the scheme now appear to be against it.
The local impacts on a possible 300 days of blasting, should this turn out to be necessary, do not seem to have been properly considered.
Several homes and businesses are located below the site and they have expressed concern about landslip and flood risk during construction and operation, and also commercial impacts on their businesses during the construction phase.

Here are some of the submissions made by local residents in respect of this

Glyn Peris Guest House

Submission by Mads Huuse and Dr Jane Huuse

Objection – WaunfawrResidents



We have a lot of concerns regarding flooding

  • Residents along the Afon Seiont are already subject to rapid river level changes from unnanounced releases of water into the system from the Dinorwig scheme, and similar changes may result from the Glyn Rhonwy scheme.
  • Data about who is at risk from flooding appear to be confidential  .. we find this unacceptable and have said so
  • There is unsatisfactory assessment of risk of quarry wall instability leading to collapse and sudden overtopping of the proposeddams, particularly the lower Q6 / Lower Glyn Rhonwy quarry
  • there has been insufficient regard paid to the proximity of the tail of the lower dam to the bomb store and any potential for structural instability there impacting on dam integrity .. the Applicant’s attitude seems to be that its outside their development boundary so no ttheir problem

For more on this see this submission to the enquiry Glyn Rhonwy PINS representation J Taylor REGARDING FLOOD RISK

and this report from Gwynedd Council on the structural Integrity of the bomb store .. it hasn’t been surveyed since 1997 and there are no plans to monitor it other than by occasional visual inspection – it is within tens of meters from the proposed foot of the lower dam – and is the remaining part of a structure which collapsed in the nineteen forties GR Glyn Rhonwy bomb store structural report prob 1997

and also for the more detailed geological aspects, see the Applicant’s Hydrogeological report

And it appears  they STILL don’t really know in detail how water comes into or out of the quarry sytem .. in essence – and hidden within the verbiage – the plan seems to be to fill it up and see where it leaks….

One report amongst the pile of MoD documents discovered in Gwynedd Archives describes how, having pumped out Q6 to get access to some of the buried munitions there, the lake level rose by fifteen feet after  period of heavy overnight rain …







In their promotion of the scheme the Developers have consistently overstated the number of jobs likely to be provided, particularly during the construction phase of the scheme, with figures of up to 300 being mentioned in the press and 30 during the operational phase.
This of course is highly desirable and in terms of PR a very positive lever in favour of the scheme.
But the analysis in the Applicant’s   vol2b ch15 socio-economics issued suggests that the number of full time jobs in the operational phase could be as few as 20 (down by a third from the figure of 30 previously promoted), and of course no guarantee that these posts could all be filled from the local skills pool. It goes on to state that during construction  “between 78 and 118 local jobs could be created”.

These figures are at odds with the undoubtedly welcome job prospects that were touted by the developers of the scheme at early promotional events and press releases.

By way of comparison the local Spar shop in Llanberis employs about 28 people, although these are mostly part-time jobs.





The Llanberis area in general and Llyn Padarn specifically are very popular for outdoor recreation, including fishing and watersports for local people and visitors, and support a growing tourism industry.
Llyn Padarn is the focus for around 10 sporting events annually, attracting 1000 to 2000 competitors and a similar number of spectators

Any development which impacts the natural environment adversely will be detrimental to the activities above, with a negative financial impact.  Acces to Cefn Du itself will be altered by the proposal, and there is much dissatisfaction with the Applicants  mitigation proposals

The following are some of the submissions that have been made in respect of this

Common land access – Snowdonia Society

Outdoor Education Centres Glyn_Rhonwy_AHOEC_report

Glyn Rhonwy PINS representation Arfon Swimming Club

British Horse Society

Seiont Gwyrfai and Llyfni Angling Society response to UKPI






The Developers have gone about the promotion of this scheme in a piecemeal fashion
The Gwynedd Council prepared the lower platforms in 2012 in a way that suggests early foreknowledge and preparation for the present proposal
It  also seemed odd to us that the necessary environmental consents required from Natural Resources Wales were  applied for separately. Even NRW found this odd. A permit for abstraction has already been granted and as described  elsewhere on this site the dicharge consent applications have now been withdrawn.  And without these the scheme would be very difficult to implement. So it is strange that a Development Consent Order (DCO) is being sought before this hurdle is cleared.