More Sinkholes


Going Down Again - Hyde Heath

Photo - Gareth Williams

Another 'small area of ground movement' - this time beside (under ?) a footpath on the north side of Hedgemore Wood, off Hyde Lane. Councillors visited the site on Wednesday 8th (according to the BFP) , and posted an account on 'X' on 10th Nov about a visit 'earlier today' - saying they were notified 'yesterday' - which would be the 9th.

Bucks councillors reported that "On 8 November, before the sink hole appeared, the data from the TBM indicated that the machine could be passing through a geological feature." so it seems likely that the hole appeared on the 9th, and was first reported ( via X) on the 10th. It is not clear why it falls to Bucks councillors to report the incident, or what grounds they have to be so reassuring. The hole is above the northern tunnel, bored by Florence, the lead TBM; Cecilia is around 350m behind and yet to pass through the area. We would advise against picnics in Hedgemore Wood next week.

Any statement from HS2 is (as yet) unknown to Google - perhaps they are checking the hole for horses or pedestrians, before saying anything ?



Sinking in Shardeloes

Ruislip Mudbath - Here

(Photo - Stuart King)

1-Aug-2023 - Plans for reinstatement

In accordance with these access agreements, Align will carry out a photographic pre-construction survey of the whole route before any remediation works begin and our environmental experts will check trees in the historic parkland to ensure that the access route from the temporary compound to the ground movement area avoids Root Protection Areas (RPA) and adequate separation from any trees with nesting bats or owls etc. All grazing livestock will be removed from the field by the farmer during the period when works are taking place and Align will provide traffic marshals for the duration of the works to manage vehicle movements and pedestrians on the Public Right of Way. (More...)


HS2 have produced a document to answer frequently asked questions about ground movement and the sinkhole near Little Missenden,

8-Jun-23 Question to the Transport Minister, from Sarah Green

I’m pleased that earlier today the Transport Minister agreed to meet with me to hear concerns about the oversight of HS2 ...
I will happily (??) sit down with her & her constituents, to take her through what's been found (Mark Harper)


How it happened - statement from the Chiltern Society, following a meeting with HS2 and the contractors.


A spokesperson for HS2 Ltd said: "We are aware of a small (?) area of ground movement within a field above the Chiltern tunnels. Investigations are ongoing, but this is likely to be linked to pre-existing ground conditions above the tunnels." (Bucks Herald)

Would those be the pre-existing ground conditions we warned about in 2010 ? In a week or two, this could be underneath the River Misbourne - but its only a chalk stream, so who cares ? -
"as it is above a portion of completed tunnel, the HS2 spokesperson has confirmed it has had no impact on current tunnelling operations, which are continuing."

"current thinking  is that it is probably a pre-existing dissolution feature or fissure which has partially collapsed". However, an industry specialist has suggested that the ground collapse could be linked to the tunnelling work.(No, really ? New Civil Engineer )

The Chiltern Conservation Board is alarmed ...

EA to the rescue ??

An Environment Agency spokesperson said: “We are investigating a sinkhole ... to understand whether it has resulted in any pollution to the local environment." (Bucks Free Press)- but not to see if the tunnel represents a threat to the Misbourne ?

Mr Strachan (QC for HS2, at the Select Committee Hearings) quoted from a letter from the Environment Agency –
‘Before we can approve applications in line with the protected provisions within the Hybrid Bill, we’ll need to be satisfied that all potential risks to the river and surrounding environment have been mitigated, and this will need to be supported by evidence from your ground investigation programme and we’ll continue to provide advice to ensure the proposed mitigation will be acceptable and approvals can be issued.’
So, Mr Smart, in general terms you’re referring to the protected provisions, but the EA is identifying here that they will continue to provide an approvals process before anything occurs, to ensure the protection of the River Misbourne and the water supply in the area, is that how it would work ? (Evidently not ... see MEP)

Other reports - BBC, ITV, Guardian, Chiltern Society. Video - Stuart King

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