3-Feb-2024

Muck in the Misbourne

HS2 restore flow to the Misbourne !!

24-Jan-2024 Water from the Gt Missenden siltbuster is still being discharged into the Misbourne, via the culvert under the A413.

23-Dec-2023

Water draining into the Misbourne above Boug's Meadow

Initial report, from local monitors -

There is currently a suspicious discharge of water from a conduit leading into the winterbourne section of the River Misbourne just north of Boug's Meadow. Groundwater levels are still below the stream bed level, so otherwise this would be dry.
The location is the meadow just north of Boug’s Meadow, gridref SP 89477 01627. A concreted conduit outlet is gushing water into the previously dry riverbed, the flow reaching the footpath bridge at Boug’s Meadow and starting to flow under early afternoon today, 18th. It is also backing up the river from the entry point.

Around the point of discharge, there is an amount of light brown sediment deposited (included in the water sampling) which appears to be different from the black silt normally seen in this section. There is also a small, c30 cm diameter “pothole” of water just by the discharge point and likely connected, with white foam.

This was reported to Thames Water, and the EA. The indident is affecting the winterbourne section of the river, in the watermeadows between the Black Horse PH & Boug's meadow, on the North side of the link road

The serious issue is that large quantities of water from elsewhere have been used for cleaning.  We do not know:

  • Where the water comes from, and what invasive species it might contain
  • What it has been used to clean, and what contaminants it might have dumped in the otherwise dry river bed.
  • We have samples of the water and the silt it has dumped. Can these be analysed?

19-Dec-23

Thames Water investigated -

The mostly likely cause is excess surface water, from the silt flowing out.  It tested negative for ammonia and chlorine, so isn’t sewage or drinking water. They can’t test for anything else.  They are linking with the EA, and plan for a site visit tomorrow (20th Dec) . 

Siltbusters ?

Siltbuster is renowned as the UK’s leading developer and largest supplier of high performance and rapidly deployable mobile Lamella Settlement Units (also known as Lamella Clarifiers or Settlement Tanks), for the effective continuous removal and storage of solids once held suspended within water – responsible for their dirty & discoloured appearance.

Left - Slitbusters at Gt Missenden; Discharge pipe.                          Right - Discharge into ditch beside A413

The source of the water has been traced back to the Siltbusters, installed beside the pond in the Missenden worksite. Water from the overflow pipe is discharged into the drainage ditch on the East side of the A413 (see pictures above), and then flows through a culvert under the A413 and into the Misbourne. This raises two obvious questions -

  1. Why is water from road runoff being diverted into a chalk stream ?
  2. Why is HS2 discharging water into the road drainage system ?

Will the EA investigate before Christmas ?

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