Grantham Canal, Cotgrave Update
Background to the Project
The project, which commenced in February 1998, is funded over 5-years and the majority of the works being undertaken on the canal are due to be completed by March 2001 with a budget of £613k over the whole lifetime of the scheme.
Those with an interest in the Grantham Canal will recall that over several years there have been various studies undertaken to establish the feasibility of restoring the Grantham Canal. At the same time a Grantham strategy has been prepared, which recognises opportunities for other leisure uses over the whole length of the canal until such time as restoration can become a reality. The Cotgrave scheme is a good example of a recreation project linking to the country park, but which maintains the integrity of the canal at the same time as preventing the continued decline which has occurred in the almost 70 years since closure.
The Cotgrave Site
The scheme commenced with bank protection measures to renew and provide waterway approach walls above and below the locks, which would also act as moorings for craft waiting to use the lock. Boreholes taken from the design work downstream of lock 7 established substantial piles were required at that location due to poor quality of soil conditions or possibly of fill used to overcome the mining subsidence.
The inspection of lock 6 established that the lock had stood up remarkably well to the subsidence. The walls were generally in good condition, but there were substantial areas where facing bricks required removal and the remains of timbers from former wooden hollow quoins have deteriorated to an extent where total renewal was the only option.
The upper and lower lock approach walls were in a badly deteriorated condition and close to collapse when the concrete dams were removed. The lock floor (lock 6) required almost no remedial works.
Lock 7 - Who Swiped the Lock Floor?
Unfortunately to date I have not had the opportunity to undertake research to find out the history behind this peculiarity. Sufficient to say that our investigations revealed that the lock walls themselves have remained in good vertical alignment presumably as the buttress units to the rear of the walls are founded on good ground. At the low end of lock 7 we found the remains of a former swing bridge base, but no parts of the original bridge. The bases have been rebuilt as part of the works. A concrete floor was built into lock no.7 prior to commencement of the lock refurbishment.
Phase Two - Improving the Environment
To ensure that the site traffic could access the locks for the rebuilding works, 3m wide access roads were built into the site from Cotgrave Road and Hollygate Lane. The access track works, which were substantially undertaken in winter conditions were also required to minimalise the danger of the towpath collapsing from use by site traffic and cranes to lift in the lock gates. Between lock 6 & 7 a 2m wide canal towpath construction was placed, as this area was not required for site plant access.
Restoring the Lock Chambers
At lock 7 however, the concrete placed to from the cascade has not had any shuttering or other protection in the area of the ground paddle chambers resulting in blockage within the chamber inlet and lock gate paddles had to be used to avoid unnecessary demolition at the lock chamber. In the long term we will need to consult with specialist contractors to find a way of breaking out the concrete in the chamber inlet to reinstate re ground paddles without unnecessary lock wall demolition. New lock gates (constructed in ekki timber) had been fitted to both locks and an arched ekki accommodation bridge has been installed at lock no.7. This bridge provides a pedestrian access to link the canal and the Country Park. There is provision for the bridge's removal in future (if required) and for fitting footboards to the lock gates if the bridge obstructs navigation.
The Opening Ceremony
To Finish the Project
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