04:55PM, Wednesday 16 September 2020
‘Rapid technology’ has been used to delve deep into a Wooburn Green sinkhole that first appeared in a playing field in March.
The 40ft void was spotted by a dog walker, forcing Sappers Field to shut and the area around the hole cordoned off.
Now, a laser scan has revealed a huge underground void beneath the surface in Wash Hill.
Wooburn and Bourne End Parish Council approached land surveyors, Geoterra, to carry out a 3D laser subsurface scan and video survey.
Using a handheld scanner called a ‘SLAM’ scanner, the Geoterra team was able to quickly assess the size and depth of the sinkhole. ‘SLAM’ stands for ‘simultaneous localisation and mapping’.
The site had formerly been used to excavate clay for brick making, before being decommissioned and backfilled with waste before being turned into a playing field.
The scanner was lowered into the centre of the void from a truck-mounted platform, and was able to record data from a depth of 45m.
The results of the survey were analysed by engineers and will be used to determine the best solution for the sinkhole and return the area as a safe site for the public to use again.
Mark Hudson, managing director at Geoterra, said: “The GeoSLAM tool was the only way we could safely carry out this laser scan survey and has produced a truly stunning 3D point cloud model, the likes of which we have never seen before.”
Sappers Field – which is owned by Buckinghamshire Council but previously leased to the parish council – has been closed since the hole appeared and remains fenced off.
Parish clerk Malcolm Silver says the council is working with the unitary authority and waiting for it to come up with solutions, which could involve a ‘significant cost’.
He also issued a warning to people breaking into the field.
“We have done the surveys, we have shut the field, and we have made it safe, although people are breaking into it and cutting the fence,” Malcolm said.
“It is very dangerous, if you fall in it, getting out is nigh on impossible.
“We are waiting for [Bucks Council] to come up with some solutions on how it can be fixed. But it is quite a significant cost to fix it.
“They have got it, and they are doing all they can to come up with alternatives.”
Mr Silver added there may be other ‘potential failings’ on land in other areas of the field.
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