River still needs a good clean-out

Consequently, I went out with my camera on Saturday and walked the length of the river from one end of Morpeth to the other, returning on the opposite bank, in order to gain a better understanding of the problems. I was particularly taken by one of her comments, that the Bennetts Walk drainage system cannot cope, regardless of the level in the Wansbeck.

I would split my findings into three topics and have provided the Herald with a CD of photos to try and emphasise my points.
River Velocity. Ms Telford is quite right about the type of material deposited in rivers, depending on the flow of the river, hence at the stepping stones, where there is an average velocity, there are islands of sand and gravel in the middle of the river and the banks have been extended into 'gravel beaches'.

Between Oldgate Bridge and the weir at Olivers Mill, the water appeared virtually still, brilliant for the ducks and rowing boats and very pretty, however the river bed will be continually rising in level due to the finer silt and organic matter dropping out of the slow moving water.

After the weir at Olivers Mill, the velocity of the river picks up again due to the fall in level and from there on, the river is again heavily obstructed by gravel, all of the way round to the 'Gas House Lane Footbridge', and therein lies (in my humble view) the root cause of the drainage problems of the Bennetts Walk area.

Conclusion: I wholly agree with Neil Ingham, who wrote in these pages on November 13, 2008: Remove the man-made obstruction at Olivers Mill and allow the river to return to its natural level. The Mill is no longer there, so we don't need the weir to provide it with a constant source of water. Sorry ducks and rowing boat operator, but what Morpeth needs is a natural river that works as nature intended and at a lower level.

Gravel Deposits. What I saw as I walked along Bennetts Walk, a part of Morpeth I had never been to before, staggered me because the river 'bottlenecks' over a length of approximately 200m, due to the build up of gravel on the inside of the bend, pushing the river bank out 10m to 15m from where it used to be many years ago, which is evident by the location of the surface water drainage outfall, which would certainly have been right on the edge of the river at the time when it was installed. This gravel bank is not newly deposited by the floods, it is clearly visible on Google Earth, whose images are about three years old.

Consequently (on Saturday), the drainage outfalls from Bennetts Walk were right on the water level, which wasn't particularly high at the time, caused by the river having only half of its original width in which to run, if the gravel was removed from that stretch of the river alone. Just imagine what would happen to the water levels if you removed 3,000 cubic metres (6,000 tons) of gravel.

Also, I am not talking about creating a slow-moving pond in this stretch of the river, as Ms Telford suggests, but a 1m deep excavation gradually introduced upstream and downstream in order to maintain the velocity of the river and keep it flowing.

Conclusion: This gravel bank must be removed immediately. There is good road access to this area and it could be a quick win, at least giving some comfort to residents that something is happening. At the moment the EA is simply working on the flap valves on the outfall pipes (does that mean they weren't working?)

Surface Water Outfalls: I took photographs of six surface water outfall pipes which are not being maintained properly, although there is evidence that someone with a shovel has been round recently to try and clean out a route into the river from the end of each pipe — totally and utterly inadequate, the first flush of the river after a heavy rainfall will undo any good work that has been done and refill the trench, hence blocking the outfall.

It needs an excavator with a dump truck to remove all of the material between the outfall and the river, really open it up so that the surface water stands a chance, also, prove that the flap valves work.
Conclusion. Simple, routine maintenance could make it much easier for surface water to gain access to the river. I also saw evidence of blocked road gullies as I walked the streets and some areas where gullies simply did not exist.

Overall, I stand by my conclusion that the river needs a blooming good clean out, after that, maintenance should be 'little and often' and cost effective, as the river will naturally continue to deposit material in the same places, just lift that out every few years and keep the river flowing at a good velocity.

If the EA does its job right on the major capital works upstream, including a well designed, easy to maintain silt and gravel trap, then the risk to Morpeth in the future should at least be reduced.
Finally, I think the Highway Authority and Northumbrian Water should investigate the surface water drainge network, particularly in the Bennetts Walk area and ask themselves why the outfalls are so low (now that the river is so high).

Could new 'overflow' outfalls not be installed at a higher level? I am sure there is an answer out there somewhere, would just be nice to hear it.

GEOFF WOODCOCK
Widdrington Station
Morpeth