Proposals

The Ribble Link Trust Ltd. proposes to link the River Ribble and Lancaster Canal via a river navigation utilising the course of the Savick Brook.

The Link is more than a canal. It will provide, along with the waterway for cruising, an environmental and recreational corridor linking the Lancaster Canal and Victorian Haslam Park, through the urban fringe of Preston, to the salt marshes of the River Ribble.

The link incorporates four distinct types of waterways:-

1. Canal Commencing to the west of Cottam Mill Bridge (No. 16) on the Lancaster Canal, a contemporary steel arch bridge carries the tow-path over the entry to the canal section. A three-rise lock, running parallel to Tom Benson Way, lowers the level some thirty feet to a small basin. Here boats can turn to enter the tunnels under the road and railway.
2. Navigation For two miles the Link is a navigation, utilising the Savick Brook, which will be widened and straightened. A further four locks create navigable pounds and lower the level by twenty-four feet.
   The locks will be constructed outside the existing channel and weirs are located upstream of the locks to provide a by-pass channel to allow the existing watercourse to pass the lock. The range of flows in the brook varies dramatically from fifty litres/sec in the summer to a one in fifty-year flood of thirty-five cubic metres/sec. To cater for these huge flows the weirs need to be a hundred feet wide.
3. Tidal Navigation Although lock two is almost one and a half miles from the River Ribble it is the sea lock. Here flood defences are provided, including a sea gate and flood banks around the lock. The by-pass weir incorporates a floating crest to prevent saline water entering the upstream freshwater pound during extreme tidal events.
   Lock two lowers the level by six feet and the eight-tenths of a mile passage to lock one is a navigation based on the widened Savick Brook. The water level will be controlled by lock one during most states of the tide but at high tide it will be dictated by the state of the tide itself.
4. The Sea Passage Lock one is an unconventional structure incorporating a gate. The gate, when open, will lie horizontally in the bed of the lock and will be rotated into the vertical position to control water levels upstream when navigation is required.
   Downstream of lock one navigation will only be possible for some three to four hours around high tide. Only minimal work consisting of posts and signs to aid navigation will be installed in the half mile to the River Ribble.
   Passage on the river section will be subject to an operational regime for safety reasons. Once at the River Ribble it will be possible to turn east (left) and cruise to the Preston Riversway facilities or by turning west (right) to cruise to the Rufford Branch of the Leeds and Liverpool Canal and onto the main network via the River Ribble and the River Douglas.

Care was taken during planning to ensure that there was no possibility of flooding, particularly in view of the flashy nature of Savick Brook.

At present the brook measures on average three and a half metres wide and has an average depth of 400mm of water. In winter, after excessive rain fall, this increases by one to two metres. Due to the required widening of the waterway to ten metres this increase will be reduced to between 300mm & 700mm, but in reality this would not occur as the water between each lock is held in pounds. When water enters the top pound the level is raised slightly and overflows into the next pound as can be seen on all canals and navigations which incorporate locks. The boating season falls between Easter and October therefore during the winter, when the heaviest rainfall occurs, the navigation will be closed.

Should a flood situation occur during the summer, the navigation will be closed until the situation returns to normal, usually this is no more than two days. Boats already on the navigation will be notified by red warning signs, which will be located at the locks indicating that it is inadvisable to sail and that they should moor up to the emergency ring posts until the situation returns to normal. (This type of system is incorporated successfully on the Upper Avon Navigation.)

The navigation will require nine locks to lower the water level by approximately 17.5m from the Lancaster Canal to the River Ribble. The locks will be 22m (72') long by 4.27m (14') wide and will be constructed from steel sheet piles with steel-reinforced concrete bottoms, cills and gate mountings.

A footpath exists at present down a considerable length of the route and the aim of the Trust is to attempt to connect the route via new paths which will create a nine mile long circular route incorporating Preston's Riversway docklands.

The Trust realised that new navigation could have an impact on other issues such as the effects on people, flora, fauna, landscape and the general environment. These points have been considered and all these items have been addressed to some extent in the Environmental Statement which was produced by the Babtie group. Since then several more detailed surveys have been undertaken including an Aquatic Macroinvertbrate Survey, an Archeological Assessment, a Breeding Bird Survey & a Brackish Water Survey and the project has been amended accordingly.

Construction Details

Lock one and its adjacent weirs is located downstream from Blackpool Road bridge. This will allow craft to enter or leave the navigation at any time that the tide allows. Because tidal water rises above these lock gates, a situation in which traditional 'paddle gates' would swing open with tidal movement, this lock will have a single rotating gate which, when fully open, will lie on the bottom and allow the Savick Brook to flow freely into the estuary. The gate has the advantages of being self-cleaning and, when raised, remaining fixed in position at all tidal conditions.

The bottom of the lock chamber is 1.0m above O/D and the lock will be useable when the tide reaches 2.2m above O/D, giving a depth of 1.2m in the lock chamber. When the tide reaches 2.8m above O/D the gate can be lowered to enable boats to sail through until it ebbs to 2.8m again when a gate must be raised to maintain the level in the navigation.

The sea-washed turf in this area will be removed to a safe place during building operations and reinstated afterwards.

The weirs at lock one will hold the water level in the last pound at 2.8m above O/D unless the tide is higher than this level.

Savick Bridge (location A) which carries Blackpool Road (A583) over the brook, measures 8.5m wide and 4.5m high, therefore no modifications are required to the structure. With the weir at lock one set at 2.8 above O/D a draught of 1.2m will be maintained under the bridge with tides below 7.7m. On tides up to 8.6m sufficient clearance remains to navigate the bridge but on tides above this a light system will be introduced to close the bridge to boat traffic until the tide recedes.

The bed depth will require lowering in the section above Savick Bridge to the location of lock two and the sewerage pipe from the British Nuclear Fuels Limited works will need lowering 1.5m or raising by 3.0m using a siphon arrangement to give sufficient clearance.

Lock two which, although almost a mile and a half from the Ribble, is the sea-lock. It will be constructed from steel sheet piles similar to those on the Upper Avon navigation and will include an access bridge. Flood defences here include a sea gate, embankments around the lock and a by-pass weir, with a floating crest, located in the existing channel adjacent to the lock. This feature will not only maintain the water level above the lock but also be able to rise with the incoming tide to prevent salt water entering the upstream freshwater pound.

It has been found necessary to construct an extra lock (2a) a little up-stream from the farm access bridge to lower the level of the pound so that land drainage will be maintained.

The farm access bridge will require modification to allow sufficient clearance, this will done by replacing it with a swing bridge or raising it by approximately 1.6m.

The navigation requires widening of the brook in most parts although in the section from the River Ribble to Savick Bridge this is minimal. The proposed width of the navigation is 10m at water level and in this phase the widening and deepening works which are required to give a minimum freeboard of 1m will continue as far as the golf course bridge. (The dimension of 1m freeboard applies to the full length of the navigation but the profile has been altered to reduce the amount of material to be moved. The sides will slope more gently to the full depth which will now be maintained across 4m.) The excavated material will be recycled by utilising it in flood control measures on the banks.

Typical profile of the navigation

A sewage pipe, which connects with the main relief sewage pipe, crosses the route at low level and again the pipe will need to be raised or lowered using a siphon arrangement. A second pipe runs from the golf club to the main relief pipe this also will need to be raised by 1.5m using a siphon.

The footbridge by the golf course has now been raised by Lancashire County Council & WRG allowing 2.9 air draught.

The bed of the brook will be lowered by 1.2m below the golf course bridge which may expose its foundations, in which case underpinning might be required. The present measurements are 5.8m wide by 3.0 high. It is hoped that the parapet of the bridge can be rebuilt utilising the original stone which is believed to lie in the bed of the brook.

Lock three will be constructed just up-stream of this bridge in the meander and a weir will be located at the start of the by-channel.

A short distance up-stream is Leyland Bridge on Lea Road, which measures 6.8 m wide by 3.65 m high, with a water level of 1m sufficient air draught remains, therefore no modifications are required to the bridge.

A little further up-stream of Leyland Bridge, a new cut will be required in which lock four will be constructed along with a weir. The area to the north will be promoted as a wild life sanctuary providing nesting sites for swans, ducks, moorhens etc. all of which are attracted to navigational waters.

The Savick Way bridge measures 7m wide by 3.25m high and by the removal of 350-400mm from the bed, sufficient clearance will be gained for navigation without major modifications being made to the bridge structure.

Lock five will be constructed in the meander just above the large North West Water outfall, once again a weir will be installed to allow water to by-pass the lock via the existing brook. Bank edge protection will be installed where necessary.

The railway bridge measures 5.6m wide by 7.0m high and Tom Benson Way bridge, which is adjacent, measures 5.6m wide by 4.0m high. Both bridges give adequate clearance for the navigation without any structural alteration.

Before the right of way was extinguished, for the construction of Tom Benson Way, a pedestrian tunnel carried a footpath through the railway embankment. This tunnel was blocked up and it may be impractical for it to be re-opened and extended under Tom Benson Way so that it might be necessary to suspend a steel walkway above the navigation to provide pedestrian access through the railway bridge. Pedestrians and cyclists will cross Tom Benson Way by an 'intelligent' Toucan Crossing.

A small basin will be formed just beyond Tom Benson way so that boats can negotiate the sharp turn which is needed at this point.

Locks six, seven and eight will be built as a three-rise from sheet steel piles with steel-reinforced concrete bottoms, cills and gate mountings to raise the level the final thirty feet to the Lancaster Canal. A series of ramps, protected by Armco, will be provided to allow disabled access up and down the lock flight.

A footbridge, of contemporary design, will carry the Lancaster Canal tow-path over the entrance to the Link which is just west of bridge 16.

Although there will be a 60 metre by 30 metre hard-standing area, at the top of the locks, access will be restricted to British Waterways maintenance vehicles.