Upon arriving at Pulbrough Brooks I was immediately greeted with one of those moments that reminded me of why I joined Keystone. A picturesque view of one of the UKs wetlands unfolded before me. Teeming with life, a dramatic scene of a Red Kite wheeling away from a mob of crows, after a failed attempted raid on their nest, played out across the landscape. I resisted a momentary urge to disappear off on a pre-works recce to see what other mysteries the reserve had to offer. Instead I met up with an excited group of RSPB rangers, awaiting the delivery of the new sluice system I was there to install for them. The excitement was infectious. The project promised to make a real change for the wetland and the people that cared for it, and I soon found myself eagerly anticipating the start of my new project.
The mission
At the heart of the project was a clear mission: to replace the old tilting weir system that had been struggling for years with a solution both resilient and reliable. Working closely with the RSPB team, we set out to install three new sluices and a pipe dam.
The system had three vital functions :
- Give the rangers an easy, practical way to adjust water levels across the floodplains.
- Reduce the overly nutrient rich backflow from the River Arun.
- Hold as much fresh inland catchment water as possible through the drier months.
Together, these functions would mean healthier wetlands, more resilient habitat and a lot less work for everyone caring for the reserve. To top it off, we were to come up with a design for eel passes on each of the three sluices to enable the pilgrim like migratory movements of the European eel.
The pipe dam
Buoyed by the enthusiasm of the RSPB team, Hugo and I set off with the excavator and dumper loaded with everything needed for the first installation. The goal was simple enough: get the pipe dam in place before the week was out. As the most straightforward structure on our list, it felt like the perfect way to test the waters and spot any issues before tackling the bigger challenges ahead.
We began by desilting the ditch to reveal its true shape, then built coffer dams at either end to hold back water at levels much higher than we were seeing that day, the ranger had preemptively warned us that water on the plains could rise quickly.
After pumping the area dry, we left for the evening feeling confident.
By morning, our confidence had proved too optimistic. We returned to find the site was completely flooded. The Head Ranger revealed the culprit; a leaky authority-owned flood defence sluice, which would become a recurring nemesis throughout the project. Overnight, the tidal range of the River Arun had forced water through the sluice and over our coffer dam.
It was a minor setback. We pumped the area out again and pressed on, laying foundations with blue puddled clay, securing pipes that spanned the structure, and topping it with more clay to form the rough outline of the dam. Over the next couple of days, we added elbows to give the RSPB control over water levels, shaped the dam into its trapezoid form and pumped out more floodwater.
By the end of the week, the first stage of the project was complete. It was now time to move onto the next step, installing our pre-cast concrete sluices.
The sluices
The threat of bad weather hung over the project. After such a long, dry summer, we knew that a single heavy downpour could derail the schedule, so we wasted no time in tackling the toughest task first: installing the largest concrete sluice. This ditch was the widest, the most heavily silted, and the main artery carrying the reserve’s water to the River Arun.
The routine was familiar enough: desilt the channel, build coffer dams, pump out the water, and by the end of the day we left feeling confident that the site was ready for installation.
Morning brought a rude awakening. The site was flooded yet again, another leaking flood defence sluice to blame.
To make matters worse, a local fisherman pointed out that we had unknowingly chosen the highest tides of the year to begin this phase of the work. Twice a day, at 2am and 2pm, the floodgates would open, sending a surge of water straight into our ditch. Pumping it out quickly became pointless; the tides reclaimed the site faster than we could clear it. Instead, we were left with only narrow, unforgiving windows in which any work inside the ditch could realistically be done.
Undeterred by the end of that first day, we had laid the foundations, raising the bottom of the ditch with puddled clay and a layer of type 3 to create a solid base for the sluice. Into the banks, we dug keys to anchor the wing walls.
Just as we finished, water began to trickle back in, slowly swallowing the progress we’d made. Watching it rise underscored the scale of the challenge.
Final touches
The next day brought the most critical phase: lifting the sluices and wing walls into position. They needed to sit perfectly aligned and set at the correct levels. With a bit of assistance from the excavator, we managed to get everything in place just before the inevitable floodwaters returned.
By the following morning, I was sealing the concrete structure while Hugo installed the pipes, making sure the system would move water exactly as designed. He built a bund to reinforce the whole setup, and I concreted the pipes into place to secure them and close off a previously known weak point.
Over the next few days, we completed the final touches: fitting the sluice boards, installing an emergency release valve, adding the eel passes crafted by our Yard Manager, Chris Seymour, and finally preparing the handrail for safety.
The last step
The last step was the real test; releasing the inland coffer dam to see if the structure held water as it should. To our relief, it worked flawlessly. With the site tidied, we moved on to the next two installations.
Their ditches were far easier to manage — free from leaky flood-defence sluices and spared the worst of the weather. Without the constant battle against flooding, we moved quickly through the work and finished with a strong, reliable system. It felt like a well-earned reward after the challenges we’d faced earlier in the project.
Conclusion
This project tested us with tides, leaks, and setbacks, but each challenge only reinforced its importance. In the end, the structures stood strong, the wetlands gained resilience, and the rangers gained control. Pulborough Brooks is more than a reserve; it’s a living landscape, and being part of its story is exactly why I joined Keystone in the first place.
Joe Norman, Site Manager