Restoring Rennie's legacy on the Lancaster Canal

The inspiration of renowned civil engineer, John Rennie, the Hollowforth Aqueduct carries the Lancaster Canal over Barton Brook in Woodplumpton, Lancashire. Rennie’s unique design incorporates three barrel-shaped stone pipes – an ingenious solution to the problem posed by the relatively shallow drop from the canal to the brook below. 

Today, the canal is a popular spot for boaters, walkers and cyclists, but, sadly, time has taken its toll. As our director for the North West, Jon Horsfall, explains: “The Lancaster Canal is over 200 years old and, like so much of our historic canal network, it has endured centuries of use and been battered by the elements.”

In July last year, our emergency team responded to a call at the Grade II-Listed aqueduct. The canal had suffered a major breach, with floodwaters washing away parts of the embankment, towpath, and aqueduct wingwall.

The team acted fast to secure the site. They installed temporary dams across the canal to isolate the breach and prevent any further damage or water loss, and deployed bypass pumps to keep boats afloat and maintain water levels.

With the dams in place, the major task of repairing the canal could begin. But it was no easy feat. The breach had occurred at a relatively remote section of the waterway, far from local roads, so to get materials on-site, a temporary track had to be built up to the aqueduct and along the bed of the drained canal.

There was also the small matter of boat traffic. The Lancaster Canal is a busy waterway, connecting the towns of Preston, Lancaster, and Kendal. So to minimise disruption, during the planning phase, we devised a unique solution to enable boaters to safely negotiate the route and continue on their way.

As Jon explains: “We kept boaters at the forefront of our thinking as we carried out the works, creating an unusual three-sided dam to allow boaters to navigate across the aqueduct.

In early October, with everything in place, the aqueduct was once again closed to navigation, as work began in earnest.

Overseen by our engineers, contractors set about fixing the extensive damage, starting by repairing and relining the canal bed and installing sheet piles to reinforce the banks. Next, they turned their attention to the aqueduct itself, restoring the damaged aqueduct apron and wingwall, before installing a drainage system to enhance the long-term stability of the structure. Finally, we reinstated the towpath, replanted trees, and cleared debris from the brook below.

As Jon tells us: “We’ve been working hard on-site since last summer to repair the breach and get the canal back open for boaters and towpath users as quickly as possible. Hollowforth Aqueduct is a piece of living heritage, and we’ve taken care to protect its historical aspects while repairing the damage and making it safe for the future.”

As Jon says, every care was taken to restore the iconic triple-arched aqueduct to its former glory, using the same rock-faced sandstone and consulting original archive drawings to ensure all the masonry was replaced in its original position.

“Thankfully, all the hard work has paid off,” says Jon, “the complex repairs have been completed, new measures have been put in place to prevent future breaches and navigation has now re-opened for boaters.”

Thanks to the quick thinking of our emergency response team, and the hard work, diligence, and care of our engineers and contractors, the Lancaster Canal is once again open for boaters, walkers, and cyclists to enjoy. This beautiful waterway and its historic aqueduct can now remain open and accessible for many years to come.