Sink Holes

The question asked of the Council - Has a survey or has anyone been employed to perform Geophysical imaging with cameras, drone helicopter, uav solutions or uav drones on the Hollins Cross Farm to ascertain if piling work with Continuous Flight Auger CFA or Driven Piles is undertaken that there will not be any sub-surface archaeological remains disturbed? And to ensure that there are no undisturbed water eroded pockets (sink holes) on the field.

No Answer has been received.

Mine
shaft Erosion

When groundwater and water courses are re-routed and water courses are forced into old mine shafts or rock strata that this can accelerate underground erosion and pollute the water table

Sink holes are more prominent where there are old mine workings, the Hollins Cross Farm site has very shallow coal mine workings as designated by the Coal Authority that are documented and underground water courses that if disrupted will undermine more of the already honeycombed sub-strata of the field. Visual examination of the topology of the field shows very sharp contours already cut into the surface due to settlement. And the glen View Golf Course has some very striking settlement contours that are due to the collapse of mine workings.

Ground Subsidence

The British geological Society website highlights how areas with "Old Coal Mine Workings" are very High Risk areas for Sink Hole. Here is an example of just what can happen when abandoned coal mine shafts are disturbed by water erosion.


We asked the council to confirm they have read this. As yet No reply has been received from the council.


What triggers Sink Holes
Building works
Construction and development are also potential triggers. Modifying surface drainage or altering the loads imposed on the ground without adequate support can caused sinkholes to develop.
Changes in water table level
In some parts of the world, drought or groundwater abstraction can cause sinkholes by changing the level of the water-table. This removes the buoyant support water provides to a cavity. Draining these cavities can cause them to collapse.
Mining
Mining can be a factor in causing sinkholes, either by dewatering and lowering of the water-table, or by intercepting clay filled voids which subsequently collapse. Several sinkholes in Norwich have been caused by old chalk mines intercepting otherwise stable sediment-filled voids.