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The Jubilee River story (0948z30)

The unbelievable (but true) story of The Wraysbury Drain

An ancient watercourse closely defined by legislation over 200 years ago -
no longer able to fulfill its function due to
unauthorised culverting, deliberate blockage and lack of maintenance -
AND NOBODY CARES!

The Wraysbury Drain Problem - a report by Ewan Larcombe - first published 24/11/2018

The Wraysbury Drain Problem. (Yet another report) - Updated 6/1/2020

The Wraysbury Drain is about two miles of ancient and legally protected (over 200 years) watercourse that has recently gone dry and ceased to exist. It is not just a water flow and volume problem, it is a water level problem that has not been fixed even after £180,000 of RBWM expenditure! And what about the environmental harm caused by the total loss of a flowing stream? What was previously a flowing water filled channel became an overgrown and mainly dry ditch and the rear gardens of the adjacent properties have consequential security issues!

The above image is the almost dry Splash in Wraysbury in August 2019.

The Wraysbury Drain starts at Wraysbury Station and runs to Hythe End but the ground conditions, the routing and the flow control structures in the upstream area are totally 100% artificial having been rerouted and re-engineered in the 1980's and 1990's.

$C:\Users\Ewan\Pictures\2018-09-17\IMG_2827.JPG$

The above image (Sept 2018) is of the weir at Wraysbury Station. The weir is designed to share the incoming flows between the Wraysbury Drain and the Horton Drain but is non-functional at this time.

The above image (Sept 2018) records water bypassing the weir due to significant scour on the railway side of the wing wall abutments. Thus the weir is unable to retain the head of water required to feed the Wraysbury Drain.

The above image of the current state of the Wraysbury Drain at Hythe End was recorded by others and emailed to me (2018)

Recommendations:

� Backfill and reinstate the weir wing abutment to prevent water bypass. (ACTIONED JULY 2019)

� Wait for water level rise above crest of weir and confirm head for Wraysbury Drain stage and discharge (flow).

� Check length of Wraysbury Drain free and clear. Despite significant expenditure the Wraysbury Drain has not yet been cleared from the Dive Centre entrance upstream to the weir! This stretch of the channel requires urgent maintenance and may need reconstruction. (STILL WAITING JANUARY 2020)

� If no Wraysbury Drain flow - it may be necessary to raise weir by small increments over time and then check for Wraysbury Drain response.

As a last resort it may be possible to reinstate the Wraysbury Drain flow by relocating the weir a short distance downstream and/or constructing a minor re-routing of the channel.

END

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Below is an earlier report for local people who know the area and the issues.

Further report on the water level control structure on the Wraysbury/Horton Drain at Wraysbury Station.

The following describes and records the circumstances from 1988 to 2018.

The weir itself is positioned adjacent and to the South side of the railway line and some 150m upstream from the Station Road Bridge as indicated below. The weir is not easily accessible.

2008 image

2017 image

The purpose of the weir is to maintain sufficient water level upstream of the weir to feed the Wraysbury Drain. None of this area is natural due to gravel working in the 1980's. Both the Horton and Wraysbury Drains are entirely man made in this area.

Below is an image of the area in early 1988. Realignment of the watercourses and uncontrolled/un-monitored gravel extraction by means of dry working failed to conform to the agreed method statement. This resulted in repeated failures of the embankments.

Early 1988

In May 1988 floodwater undermined the foundations of the railway bridge (shown below before the event) at Wraysbury Station and the entire bridge structure and the end of the platform collapsed leaving two pairs of railway lines hanging in space.

Below is how the area looked after the event.

May 1988

On the morning of the collapse - machinery engaged in 'prompt reinstatement'!

May 1988

A temporary roadway was constructed from Station Road, the railway bridge was reconstructed and the previously quarried land eventually backfilled. Channels for the water courses were then constructed but not on the original routes.

Consequently the Wraysbury Drain immediately suffered from intermittent flow issues. After investigation and by agreement - the weir at Wraysbury Station was constructed to raise and maintain the upstream stage (water level) and consequently ensure that a sufficient proportion of the flow was diverted into the Wraysbury Drain.

The original design of the weir was in the simple stoplog style with a series of boards within slots used to adjust the height of the water upstream by manually adding or removing the boards. Throughout its life the stoplog weir often suffered from both leakage and unauthorised adjustment.

In 2004 the stoplog weir was refurbished to reduce leakage.

The image below records the condition of the stoplog weir in November 2006 prior to conversion to a radial gate style weir. There is no apparent water flow due to the creation of both a temporary earth dam upstream and the construction of a watercourse bypass channel that diverted the flow around the structure. Some of the stoplog boards are still visible - as is the slot in the brickwork on the right hand side - into which the boards locate.

$C:\Users\Ewan\Pictures\2006-11 (Nov)\HPIM1693.JPG$ November 2006

The image below of the radial gate that replaced the previous construction was recorded in December 2017 from a similar position as the image of the stoplog weir taken in November 2006. The same brick constructions (wing abutments) embedded into both banks are unaltered and clearly visible on the two images.

$C:\Users\Ewan\Pictures\2017-12\2017-12\IMG_1816.JPG$ December 2017

By September 2018 the weir has ceased to function properly as can be seen from the image below.

$C:\Users\Ewan\Pictures\2018-09-17\IMG_2827.JPG$

September 2018

The image below records water bypassing the weir due to significant scour on the railway side of the wing wall abutments.

$C:\Users\Ewan\Pictures\2018-09-17\IMG_2828.JPG$

September 2018

Recommendations:

NOTE) despite significant expenditure (>£125,000) the Wraysbury Drain has not yet been cleared from the Dive Centre entrance upstream to the weir! To be honest this stretch of the channel is currently unmaintainable.

1) Backfill and reinstate the weir wing abutment to prevent water bypass. (actioned July 2018)

2) Wait for water level rise above crest of weir and confirm Wraysbury Drain stage and discharge (flow). Check Wraysbury Drain free and clear.

3) Subject to stage availability if no Wraysbury Drain flow raise weir by small increments over time and check for Wraysbury Drain response.

Further thoughts on possible solution to Wraysbury Drain flow issues.

1) Install temporary weir at position '2' and see what happens.

2) Dismantle faulty weir at position '1' and reinstate at position '2'.

ADDED 14/7/2019

The leaking weir was repaired on 8th July 2019 and the upstream level returned to normal overnight. The water level in the Wraysbury Drain returned to bank-full by 10/7/2019 but the conveyance was negligible. Exploration downstream revealed that gravel falling off the Wraysbury Dive Centre bridge had blocked the watercourse. Minimal blockage clearance has enabled a small flow of about 5 litres per second to pass the obstructions. Further works to improve capacity at the Dive Centre and further downstream are still required. The Wraysbury Drain at Hythe End is totally blocked (still blocked 23/1/2020)

The now working weir is shown below in an image dated 9/7/2019.

Added 14/8/2019 Although the weir was repaired in July 2019 and the Wraysbury Drain cleared from Windsor Road upstream to and including The Splash on The Green. There is still a significant flow restriction either side of and below the Dive Centre bridge. The problem was reported to Wraysbury Parish Council in July 2019.

The Splash image below is dated 11-8-2019

The Wraysbury Drain – an ‘ordinary watercourse’?

A brief report to Wraysbury Parish Council from Ewan Larcombe 9/10/2019

Background: The Wraysbury Drain is over two miles of very ancient and legally protected watercourse that is an important part of the local network of land drainage infrastructure. Starting near Wraysbury Railway Station the channel takes a steadily curving route downstream running generally parallel to Station Road, the High Street and Staines Road and finishing in Hythe End. The channel is designated ‘ordinary watercourse’ but has dimensional cross-sections specified by legislation over 200 years ago.

Changes - starting in the 1980’s: The area between Douglas Lane, Station Road and the railway line was quarried for gravel and the channels entirely removed. After ignoring warnings the railway bridge collapsed in 1988. Upon completion of partial backfilling the local drainage channels were reinstated on different routes. It became necessary to install a weir in order to ‘drive’ (i.e. provide sufficient head of water) the now relocated Wraysbury Drain. The original stoplog weir was then replaced with an adjustable metal weir in about 2006.   There are images of the two weirs available.

The current situation:

a.      Despite expenditure of at least £125,000 and the recent best efforts of local volunteers the Wraysbury Drain is still not flowing.

b.     The failed weir at Wraysbury Station was identified as a major problem and reported in September 2018.

c.      After a long list of reasons why maintenance works could not be started the weir was eventually repaired (by RBWM?) in mid-July 2019.

d.     There is still no means of weir adjustment. A ‘key’ is required.

e.     The channel is blocked with gravel at both sides of and beneath the bridge at the entrance to the Dive Centre in Station Road. The gravel needs to be cleared. Who is responsible?

f.       The Diving Centre Bridge design/construction shortcoming allows vehicles to displace the gravel into the channel. The bridge needs fixing otherwise the problem will continue.

g.      From the Dive Centre Bridge upstream to the junction near the weir - flow is restricted by thirty years of tree growth. This new section of channel was created along a different route after the Wraysbury Station Railway Bridge collapse in 1988. This length of the Wraysbury Drain has not been maintained for 30 years. Who is responsible? Apart from the cost there will be issues relating to access and/or responsibility!

h.     At Feather’s Lane the channel is now entirely blocked, having been filled to ground level with rubble and fenced over. The channel has also been culverted without permission. Action is required now.

The big questions: Who is responsible for the monitoring and maintenance of the Wraysbury Drain?

Reach Identity

Monitoring

Inspection

Capacity

Level

Quality

(Riparian, Wraysbury Parish Council (WPC), RBWM (planning enforcement or designated LLFA), Environment Agency and/or Thames Water.)

My conclusion is: We still need to identify who is responsible for monitoring and maintaining this channel. Land ownership is an issue. The planned River Thames Scheme makes no allowance for what will be a number of truncated watercourses. If the Wraysbury Drain is not immediately evident and demonstrable as a living, working watercourse it will be lost forever. This will influence groundwater levels, land drainage capability, local ecology, visual appearance and security.

I intend to submit this report to the RBWM Flood Liaison Meeting scheduled for 31/10/2019. I now have copies of the Environment Agency booklet ‘Living on the Edge’ – the riparian owner’s guide.

The two images below show the Wraysbury Drain route both ‘before and after’ 1988. The two red arrows on the lower image indicate the positions of the current Dive Centre restrictions and the Wraysbury Station Weir. In my opinion the channel between the two arrows (about 250m) requires re-engineering in terms of channel width/depth and gradient. This is a major project.

Maps: Wraysbury Drain at Station Road, Wraysbury.

END

ADDED BELOW 6/1/2020

Good News: The Splash (image below dated 6-1-2020) and the water is flowing well