Certainly never a dull moment

I finished the last blog post with the comment that there is never a dull moment in the Drainage team. Very apt, as three requests came in in close succession.

First was a report from our Clearance colleagues (Wednesday team) regarding a french drain on the up side at Broadway headshunt that appears to have lost some of its stone.

A day later a phone call - usually a sign of urgency. This certainly was, the Bridge Engineer requested us to investigate Stanton Aqueduct where cracks had occurred in the inlet channel on the down side. Consequently the stream was flowing down the cutting side and into the cess.

Finally a note from the PW team working on the sleeper replacement at Didbrook. There was a large tree branch fallen onto the inlet on culvert 15A.

Obviously the second item was the more urgent; so it became the only item of work for the first Thursday of February.

Thursday 2nd February

A team of four collected various items of plant and materials which might be useful for a temporary or even a permanent repair of the aqueduct.

First two of the team took Thunderbird-1 to Working Lane to collect some plastic pipes which might be useful as a bypass to the inlet channel. The other two loaded various items of equipment into Thunderbird-2.

When we arrived at the aqueduct, John Sreeves and Pete Lewis from the bridge inspection team were already there. The inlet pipe from the adjoining field has a diameter of 300mm - unfortunately this is the diameter that we do not have any of in stock. So we first laid a temporary 100mm flexible plastic pipe from the inlet to well inside the trough; fixed in the inlet 300mm diameter pipe with clay. This stopped the water flowing out of the cracks in the inlet channel down the embankment side. Next was to use some of the quick setting cement to fill the larger cracks in the channel floor and brick sides. Loose brickwork was removed and cleaned up. Normal cement was used to make concrete to plug the void under the channel. Other brick joins with cracks cleaned up, ready for repointing.

Temporary pipe inserted in to inlet headwall of the aqueduct. Rapid setting cement ready for the reparis to the concrete base.

Lower portion of damaged brickwork replaced - strong plastic cat food bag in use as shuttering!

End of first day temporary repair - a dry inlet channel...

... and water flowing where it should, out of the up side end of the aqueduct trough.

John & Pete used the ladder we borrowed from C&M to check the rest of the structure. We cleaned out the exit ditch on the up side; also installed a row of slip marker posts on the down side either side of the aqueduct to monitor for any bank movement. Unfortunately our spray can of blue line marker paint choose this moment to run out!

Also we located the three land drains that enter near the crest of the cutting on the down side between the aqueduct and bridge 10. Probably inserted whilst the railway was closed. Like one we found south of Stanton Road bridge a few years ago, these need proper piping down the cess. Fortunately they appear to only flow in very wet weather.

Finally, one team member checked on culvert 7A by the B4632 road bridge. The repair made in October is working well; nothing escaping into the up side cess and a good flow noted in the ditch in the adjacent landowners overgrown wood.

Thursday 9th February

With three team members off sick and one away on a dumper driving course we had to re-plan the work for today. Essentially the brick replacement and repointing work at Stanton Aqueduct (bridge 9) had to be postponed for a week. Fortunately the last seven days have not seen any rain; so our temporary pipe at the aqueduct is still coping with the flow of the stream.

So it was a small team of three who first attended to the fallen tree branch on the down side (inlet) of culvert 15A at Didbrook. Fortunately it was resting on the low mileage wing and the headwall so had not created a blockage. Easily removed, so a good start to the day, one job ticked off by 09:30!

Culvert 15A inlet after removal of fallen tree branch. (A before picture is in the Heritage Herald post of 8th February.)

As we had the laser level with us, we took the opportunity to measure the difference between the bore outlet and the onward pipe exit on the up side of culvert 14B near Didbrook Brige No1. This is where the adjacent landowner diverted the stream a few years ago. The height difference between the bottom of the brick invert bore and the bottom of the plastic exit pipe the landowner inserted is 450mm, with the exit being higher. So we are always going to have a pond here. The depth of water by the failing high mileage wing wall is approximately 500mm. Will need to think about how to drain sufficient of this to repair the wing wall.

Next on to the former garden centre site at Toddington to count and check on the stacks of concrete chamber rings which are for the cross drain 11B outlet to culvert 11A diversion at Stanton. There are 48 rings; we devised a plan to move half of these to Stanton using the LWB transits with tail lifts. The second half will need the telehandler for loading.

Dave & Nigel discussing the cunning plan to move concrete rings from Toddington to Stanton.

Then back to Winchcombe for coffee break in a warm mess (and to collect the one item of equipment we had forgotten).

After break up to Stanton to bridge 11. The cleared area of the hardstanding on the low mileage side was extended, and all the undergrowth removed from the stacks of pipes there. These were delivered in 2019 before the COVID-19 pandemic. After lunch we used the laser level to check the lie of the land between the existing cross drain 11B outflow and the culvert 11A outlet under bridge 11. This diversion will run under the farm track, as 11A outlet is on the low mileage end of the bridge. The ‘new’ pipes under the farm track were laid back in 2019. Having the embankment cleared almost to the fence line between bridge 11 and cross drain 11B was a great help - thanks to Tom Clark's team with their robo flail. We checked access for the minidigger, the easiest and safeest route will involve access from the farm track for which we need to obtain the landowner's permission.

With all vegetation cleared we can see exactly what lengths of pipes and collars we have at bridge 11.

Dave and Nigel using the laser level to check the levels of the existing and new cross drain 11B outlet. Existing outlet is the small diameter pipe disappearing under the hedge and diagonally across the field. It is too small to cope with heavy rain fall.

Finally up to Stanton aqueduct to check on the temporary pipe on the inlet. It is holding, just a dribble of water through the clay in the inlet; the low mileage crest is now just damp and no water running down the cutting side. With a new can of blue marker paint the tops of the slip markers either side of the aqueduct were painted - and the posts checked that they are still in line and upright. So no detectable movement in the embankment in the last week. We have been able to source some 300mm internal diameter pipe to extend the inlet from the stream through the headwall and into the trough. Thanks to Jason from Walsh’s for those.

Temporary bypass pipe on the Stanton aqueduct inlet holding, just a wee dribble through the clay dam. 

Slip marker posts all still in a line and upright, and now with blue tops. (The wheelbarrow under the trough is not to catch any drips - it contains sand for the next round of repairs. We were not going to wheel it down just to push it back up next time!)

So next time the plan is to install these pipes and complete the bricking and repointing on the aqueduct; plus move concrete rings from Toddington to to Stanton. And after that take a look at the french drain at Broadway. As ever, the plan is flexible!