RESIDENTS in Llanerch have raised concerns over what they claim is a ‘sink hole’ on a road close to the proposed site for a new school on Llanerch field.
Residents of Heol Nant-Y-Felin said that the hole had grown in size over a few days, and were concerned over the possibility of an accident and further deterioration in the road.
We contacted Carmarthenshire County Council for a statement. They responded:
“The hole was cordoned off on Tuesday and made safe. Investigations will now be made to ascertain the cause.”
The response did not quell the fears of local residents. One resident who did not wish to be named said:
“I spoke to the Coal Authority today in relation to the sink hole at Heol Nantyfelin, they advised that they would have come out to investigate however they have filled in the hole and made any investigation impossible.
“I would have assumed that they were aware of the mine workings within the area, I would have assumed that they would have contacted the Coal authority in order for them to fully investigate the sink hole and why it appeared. I asked them to explain why they did not take this course of action in order to safeguard the residents in this area, and let the proper authority investigate this incident.
“This is a very serious worry for the residents of Nantyfelin.”
Another local resident with some expertise in the field of engineering said:
“This needs some serious investigation, the safety of the residents in the area should be paramount here and should be investigated by the proper authority.
“The lack of concern by Carmarthenshire County Council is very worrying to the inhabitants of the area, we have all seen what these can lead to, and indeed one of the workmen advised that they had seen one sink hole that would take a Mini.
“You would think that this would have an impact on the planning for the school which will house 480 young children.”
“I reported a hole in the road on Heol Nantyfelin on 22.06.18, there was a clear 6″ gap underneath the hole which was filled today, however I would like a report on the cause of the hole, especially in view of the Coal Authority Objection to the proposed development of Llanerch Field for a 480 pupil school.
“I have documented the photographic evidence day by day as the hole got larger. I understand that the workmen stated that this could be down to movement due to the mine workings throughout the area, as confirmed in the Coal Authority Report on your planning portal.”
The following are responses to the planning application for the proposed new school on Llanerch field.
CDN Planning Response
Perhaps of greater significance when considering the wisdom of siting a school on this land is the fact that it is being placed right next to, and partially over, a very large sewage tank.
The tank is 154m. (500 feet) long, 20m. (65 feet) wide, and 6m. (20 feet) deep, and it is fed by 750mm. diameter sewage pipes.
The risk of sewage overflow as a result of failure is noted in the Flood Consequences Assessment, and the topography of the area means that any such failure is likely to invade the site of the proposed school.
The Council has not taken account of the design life of the attenuation tank. DCWW has advised that it will be subject to periodic inspections. After 20 years (2028) it will be subject to minor works to correct any structural defects, thus causing unwanted disruption to the school; whilst in 50/60 years (2058/2068) it will need to be replaced altogether.
Both the bridge supporting Heol Goffa, and the support structures holding up the steep banks on the opposite side of the river are showing signs of distress. Any failure of these structures will inevitably result in local flooding and will clearly impact on the school buildings which are required to be sited close to the river.
Response from Coal Authority
The application site falls within the defined Development High Risk Area; therefore within the application site and surrounding area there are coal mining features and hazards which need to be considered in relation to the determination of this planning application.
The Coal Authority records indicate that there are two recorded mine entries (shafts, CA refs. 251200-047 and 251200-048) present within the application site and that the zones of influence of two off-site mine entries (251201-008 and 251201-038) encroach into the site.
We hold not details of any treatment of these shafts. In addition, our information indicates that a thick coal seam outcrops across the site which may have been worked in the past and that further historic unrecorded underground coal mining is likely to have taken place beneath the site at shallow depth.
The Coal Mining risk assessment prepared by Quantum Geotechnical
Shallow unrecorded mine workings
The Coal Mining Risk Assessment Report concludes at Section 5.0 that “the risk to the proposed structures on the southern half of the site, from any shallow or unrecorded workings, is considered to be negligible” and that “no further measures are required in the design and construction of the scheme to mitigate any such risk.”
In making the above conclusion, the Report indicates that the Rosy Coal seam is the shallowest workable coal seam present beneath the site. However, the Coal Authority’s information suggests that the Mynyddislwyn Lower Leaf coal seam (also known as the Bedwas, No.3 Llantwit, Four Feet, Big seam) outcrops in a north-south alignment across the easternmost part of the site (to the east of Heol Goffa) and dips in a westerly direction.
Building over or within the influencing distance of a mine entry (shaft or adit) can be
dangerous and has the potential for significant risks to both the development and the
occupiers if not undertaken properly.
NRW response – River Lliedi
There are various structures such as blockstone/gabions along the right-hand bank of the proposed site. We do not have any details on who constructed these structures. Unless these are known to be owned by others, the landowner of the site is presumed to own up to the centre of the river. We advise that as they offer a degree of protection to the school fields that if this proposal proceeds they should be maintained by the Local Authority. We previously advised that the developer discuss this application with your Authority.
These structures are falling apart with knotweed clearly visible growing through the cracks in the wall.