A river runs through the restored channel at Acacia Hall/Central Park, Dartford.
The Central Park/ Acacia Hall River Restoration Project took a massive step forward at the end of March.
On the Thursday 25th of March 2021, after months of delay due to the pandemic, the (rather ugly but essential) cofferdams were removed from the upstream and downstream ends of the project area, and flow was returned to the restored western channel of the Darent that runs through Central Park then past the redeveloped Acacia Hall.
I can’t tell you how excited the SERT team is about this, after over 3 years of hard and very muddy work!
This is now a very different stretch of river compared to the one SERT found over 3 years ago. This section of the Darent had been subject to heavy modification in the past. When I took over the management of the project in 2018, I found an over-widened, dark and hidden backwater, choked with silt and vegetation, heavily shaded by dense stands of self-seeded sycamore, littered and cut off from receiving any significant life-giving flow.
The weir at the downstream end of the site formed a major obstacle to fish passage. All of these impacts had gradually impeded flow down the western channel, resulting in the eastern channel – modified for flood relief – becoming the main watercourse.
Developing and delivering in partnership.
We immediately recognised that this stretch of river desperately needed help to bring it back to health. We have worked in partnership with Dartford Borough Council, the Environment Agency and collaborated with CBEC to design and deliver a showcase restoration project that reintroduces chalk stream river form and function on the Darent.
This was done by removing the Acacia Hall weir and delivering nature based measures using natural materials to recreate the type of natural variation in channel width and depth found in less disturbed river systems. These measures “kick-start” more natural, variable flow patterns, creating a greater variety of habitats that attract and support wildlife. All of these measures had to be at worst flood risk neutral, which meant a lot of measuring and modelling to make sure there was no increase in flood risk caused by any restoration measures. The modelling results actually showed a slight decrease in flood risk. Win!
Nick, a Senior Project Officer at SERT and Site Manager for the Acacia Hall Project, wrote about the delivery phase which took place over the wet and muddy winter of 2020-2021 and the measures put into place.
Then the pandemic hit…
2020 was the year of lockdowns as was the beginning of 2021. This held up the final phase of project delivery. However, we carried out monthly maintenance walkovers to check everything was OK and we also cleaned some silt from the channel with a digger to reveal more of the lovely clean gravel we found under the silt during restoration.
Work along the Acacia Hall section of the project – managed by Dartford Borough Council – carried on after lockdown. In March 2021, all of the partners agreed on the date to remove the cofferdams at each end of the site and let the Darent flow down the western channel again.
Channel Opening Day…
We arrived early, everyone buzzing with anticipation and prepared for a busy day and a big event, a lot to do on a blowy, showery and distinctly cool spring day.
Perhaps most of all, we were all itching to see the river flow again once the cofferdams were removed. Clear water gliding over clean gravel down a restored reach of a bubbling chalk stream. A place for people and wildlife to enjoy, a valuable move forward in the push for restoration in the Darent catchment.
Martin Moore led the fish rescue from the western channel, working with experienced SERT and EA staff to minimise handling and stress. This was because the water level in this channel would fall which might have resulted in fish becoming trapped as the restored channel was opened up again.
In the meantime other team members cleared litter and pulled the ubiquitous shopping trolley [we wonder if part of the shopping trolley life cycle is, in fact, aquatic] from the channel. Others walked the channel to complete maintenance checks to make sure that all of the restoration structures built back in the winter of 2020 and early 2021 were in good shape, before the upstream cofferdam was removed.
By late lunchtime the upstream cofferdam was out and after many years, water started to flow back down the restored western channel. For me, it was a really moving moment.