Notes from Public Meeting – 30th July 2015 – Landslip

ST DOGMAELS LANDSLIDE 1994 – 2015

Public Meeting, 30 July 2015, 7pm, Memorial Hall

 

Present:

Mr Emyr Williams B.Sc. (Hons) M.Sc, Pembs CC

CC Mike James

Chairman of the Parish Council and meeting: Cllr E Rees

Cllrs: G Wislocka, M Thomas, J Elster Jones

Clerk to the Council

 

Members of the public: 17

 

Following introductions Mr E Williams of Pembs County Council proceeded to outline the development of the geographic area around St Dogmaels and how it contributed to the landslip in 1994.

 

In the immediate area of the St Dogmaels slip site, he stated that a valley, similar to that of Cwm Degwel, had been filled with glacial debris. There had, he understood, been at least 5 landslips in that area since the last ice age, the most recent of any size being the slip in 1994. However the problem of slippage, he advised was confined to the single valley and a few very much smaller pockets of glacial deposit, some of which had reacted in the 1994 incident.

 

This was described as a ‘rotational slip’ which meant that the bottom part of the unstable slope moved removing support for the upper slope(s).

 

He showed diagrams of the 1994 water levels which showed the artesian pressure to be ‘above ground’. The water pressure lifted the glacial deposits and allowed it to slide over the rocks despotised by the glacier.

 

The exploratory works introduced boreholes going some 5m deep and the remedial works removed water from the area to drainage channels reducing the pressure by 6m of head. He stressed that it was not volume of water which had caused the slip but high pressure of water.

 

He showed graphs of current water levels which showed the water pressures/levels fluctuating each year but remaining well below ground level.

 

43 boreholes remained at the site and the level of water was recorded each year. This information, along with visual surveys of the area, was compiled, by experts, to allow a comprehensive review of the area to take place. To date the annual surveys has supported the significant reduction in water pressure with the reassurance that the area was stable.

 

Concern was expressed that what appeared to be relatively minor maintenance works, highlighted in the reports, had not been undertaken. This was of serious concern to the community as it showed a lack of commitment by Pembs CC to the overall maintenance of the works at the landslip site. Mr E Williams assured those present that Pembs CC had monies allocated for the maintenance works in the Coast Protection Budget. Permission to enter the land to perform the checks and maintenance had been granted for 90 years.

 

The Community Council sought the commitment of Pembs County Council, and any subsequent authorities, to continued monitoring and maintenance of the site.

 

Mrs E Franklin, High Street, stated that her property had been damaged during the pile driving to install the culverts. The original damage had been repaired through the authority but was re-appearing in the same places on her property. Mr E Williams advised he would see what action might be taken and arrange for her property to be visited.

 

Cllr G Wislocka expressed concern that it appeared that wells were silting up instrumentation to record water levels could not be reach. She was assured that specialists had cleared some well and would continue to clear and maintain the wells.

 

The difference between land sliding and settlement in buildings was queried. Mr Williams advised that land creep could and would happen over millennia. It was unlikely that any current damage appearing in property was as a result of slippage. He would be happy to advise further if the property owner contacted him.

 

Cllr G Wislocka expressed concern that the drainage ditches associated with the remedial works had, at times, not been cleared efficiently and Himalayan balsam had spread down them.

 

It was also queried who was responsible for the fencing around the culverts as this was in poor condition.

 

It was advised that flooding from Pencnwc, near the reservoir was common. Engineers had visited the site but nothing had been done to maintain the area taking water to the culvert or clear to overflow ditch for approximately 5 years. Mr Williams promised to contact those affected to try to solve or alleviate the problems.

 

Mr Williams knew that there were ongoing problems in getting insurance in the area. He stressed that most of the village had very different geology to the landslip area and properties were not at risk. He himself had been responsible for writing letters to insurance companies following the slip. Mrs E Franklin had original literature from the period which named a company prepared to insure properties in the landslip area. It was agreed that the Clerk to the Community Council investigate if the company still existed. Concern was expressed that the situation would not get easier as time went by and information and expertise was not as freely available.

 

Mr Williams advised that planners should be aware of the landslip are in the village and should take this into consideration but it was down to Building Control to specify build standard requirements. Halcrow, the company which was monitoring the landslip area, should be able to supply information to planners and BC. There was also national planning guidance to reference.

 

It was queried is some sort of statement could be made to indicate that properties outside the known slip zone faced no issues, this in order to make insurance cheaper and easier to get.

 

The Chairman advised that there were moves to consult more extensively locally on planning and CC M James advised that the Pembrokeshire Local Development Plan was under review.

 

It was queried if the bank at Mwtshwr was a glacial head which raised queries about the development site opposite Berwyn and the site at Awel y Mor. Mr E Williams advised he had visited the Berwyn site and was aware of concerns with regard to the stream becoming blocked should the soil be eroded at the tip of the slope.

 

He noted that the partial collapse of the stream banks down towards the road culvert was the responsibility of the riparian owners of the land and not of Pembs CC.

 

It was queried if the Community Council could receive a copy of the report on the site annually and that Mr E Williams liaise with the Community Council with regard to a timescale for addressing the concerns of the meeting.

 

The Chairman thanked Mr E Williams for attending the meeting and thanked those present.