Dear Marrk

 

Enquiry regarding:  HS2/Bentonite/Chilterns - Reports on 18th June 2021
suggest that Bentonite was found leaching up to 100m from HS2 Ltd's
Chalfont St Peter Air Vent Shaft.

 

Thank you for your enquiry which was received on 27 July 2021.

 

We respond to requests under the Freedom of Information Act 2000 and
Environmental Information Regulations 2004.

 

We have a record of a report made by a caller to our national incident
hotline of a sewer flooding incident in Chalfont St Peter on 18 June 2021,
however this incident did not involve Bentonite. Thames Water attended the
incident and also sent a report of their findings. Copies of these reports
from our National Incident Reporting System (NIRS) database are attached
under reference 01956648 and 01957276 respectively. Please note that some
details have been redacted from these reports to protect personal data
only. For a fuller explanation of this redaction please refer to the
attached appendix one. Please also refer to the [1]Open Government Licence
which explains the permitted use of this information.

 

We are therefore not aware of any loss of bentonite at the Chalfont St
Peter vent shaft on 18 June 2021. Bentonite was used during construction
of the diaphragm wall of the vent shaft but construction activity was
completed on 5 March 2021.

 

We are however aware of a loss of bentonite which happened during the
initial walling activity in 2020. This is discussed in the report,
“Analysis on Bentonite Loss during Chalfont Saint Peter D-wall
excavation”, document number 1MC05-ALJ-GT-NOT-CS02_CL04-000001, dated 2
December 2020. I have attached a redacted copy of this report.

 

Please get in touch if you have any further queries.  If you want us to
review the information we have sent, please contact us again within two
months from the date of this email.

 

Yours sincerely

 

James Hammett

Customers and Engagement Officer

Direct dial 0203 0259058

Direct email [2][email address]

 

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From: Marrk Keir [[10]mailto:[FOI #777759 email]]
Sent: 27 July 2021 14:39
To: National Requests <[11][Environment Agency request email]>
Subject: Freedom of Information request - HS2/Bentonite/Chilterns

 

Dear Environment Agency,

 

Reports on 18th June 2021 suggest that Bentonite was found leaching up to
100m from HS2 Ltd's Chalfont St Peter Air Vent Shaft.  A report was filed
to Environment Agency. 

Please could I see a copy of this report (redacted if necessary), and
please tell me what you have done/intend to do about it.

Do you consider there to be health risks to river life, water abstraction,
human life and to the environment in general?

How did the leak occur, and how can we be certain there won't be a
recurrence here or elsewhere on HS2 and HS2 associated works?

Does this alter your position regarding HS2 works anywhere around the Mid
Chiltern Chalk Aquifer?

 

Yours faithfully,

 

Marrk Keir

 

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