Mersey Basin Campaign Blog

Boom re-connected & back in operation

As well as cleaning up the River Darwen and its banks, the litter trap boom was also re-connected today.  The trap is now back online and in operation.  Hopefully the river will continue to look as good as it does today for a lot longer than it would have without the litter trap.

Of course, the trap is not the total answer to the litter problem in the River Darwen.  I have heard the litter trap likened to 'a sticking plaster on the problem'.  If litter and debris were disposed of properly, we would not need to have a litter trap in the river.  The litter trap is here to highlight and try to prevent these problems but the project’s success depends on people changing their habits and disposing of waste responsibly – in the bin or at the household waste disposal centre.

Modified runner re-attaches boom

I am pleased to be able to report that the litter trap boom was re-attached on 18th April 2008.  The modified boom runner attaches the boom to the wall on the bank opposite the litter trap itself.

Utilising a roller mechanism, it is intended that the boom will move up and down more effectively than was possible with the sliding runner mechanism. 

The boom should also release more effectively in flows that are too high to avoid damage to the litter trap equipment.

Watch this space and for once look forward to rain (?!) to see how the modified runner mechanism fares.

Civil works near Litter Trap

Blackburn with Darwen Borough Council has begun work to install hardstanding adjacent to the litter trap using a Sustainable Urban Drainage System (SUDS).  'Geo-block' is being used to surface the hardstanding.  Rather than rain water running straight off tarmac into the river, it percolates through the ground in a natural way.  Geo-block will also allow the area to naturalise and blend into the beautiful surroundings of Witton Country Park.

   

The River Darwen is an extremely 'flashy' river because it rises and falls so quickly following rainfall.  I have heard locals describing it 'filling and emptying like a bath'.  Most of the catchment upstream of Witton Country Park is culverted underneath or runs next to roads and buildings.  Without a natural 'buffer' of land to allow natural drainage, the river can torrent quickly, scouring banks, undermining trees, causing erosion and associated problems as well as bringing debris and litter downstream. 

The speed of flow in the upper catchment is beyond the design capacity for the litter trap and we are in the process of modifying and adjusting the equipment to cope.  Blackburn with Darwen Borough Council is leading the way in utilising SUDS. 

When Cotton was King Blackburn was the weaving capital of the world.  Mill towns like Darwen and Blackburn grew because they could harness the power of the river.  Quite fitting that modern day protection of the river is a priority.

For more information about the industrial heritage of the River Darwen see the Cotton Town Website [click here for link].

Litter Trap adjustments II

At a meeting with OPEC, APEM and Blackburn with Darwen Borough Council last week, we discussed how the litter trap should be modified to make it more effective in high flows.  There will always be times when the boom cannot perform effectively when the river is in high flow but we intend that it will be working for as much of the time as possible to minimise the impact of litter downstream.

 

 

image shows the boom being overtopped by rising water on 7th January 2008

Other alterations are also being explored to ease access for emptying and increase safety.  These include bracing the basket to strengthen it, adding eyelets to the basket so that it can be stabilised during lifting and strengthening the lifting bars.

On 21^st January 2008 the River Darwen was at its highest ever recorded (since 1976)!  The boom survived, which shows that it is capable of the force of water in the river.  We were lucky that nothing big was caught in the flood as this extra pressure could have broken it! 

The boom modifications to the sliding device made on 29th October 2007 have not enabled the boom to move up and down with the river level.  OPEC is looking into the possibility of using a different (roller based) runner to ease boom movement, which could widen the operating conditions for the trap.  We are also considering adapting the runner to bend over in an arc, aiding release at the top of the runner.

Boom temporarily released

The litter trap boom was released yesterday as a temporarily measure to protect the equipment as there have been problems with the boom movement in high flows.  Possible adjustments and modifications are being considered to ease movement of the boom.  We intend that the litter trap will be back online and working more effectively as soon as possible.

Since April 2007, we calculate that the litter trap has removed 21 tonnes of litter and debris.

Litter and debris the litter trap removes would otherwise spread downstream through Pleasington, Hoghton Bottoms and Higher Walton, into the River Ribble at Walton-Le-Dale.

Litter Trap trappings & lifebuoy lost?

There is a new webpage dedicated to posting photographs of the litter trap trappings.  I have been amazed at what is turning up - yesterday there was a life buoy in the basket !  If you know where the life buoy has come from, please let me know and I will ask our contractor to keep hold of it when he next empties the basket.

Trappings 3rd December 2007 - a lifebuoy, plastic drinks cups and bottles, branches, leaves and a huge bleach bottle (just off the photo).

Trappings 3rd October 2007

 

Here's what was in the River Darwen litter trap on 3rd October 2007 - a bannister rail, a tyre, footballs, plastic drinks bottles, fast food polystyrene wrappers.  For more information about the project click here.

Trappings 4th September 2007

Here's what was in the River Darwen litter trap on 4th September 2007- garden waste (conifer branches), plastic drinks bottles, fast food polystyrene wrappers.  For more information about the project click here.

Shortened runner now completed

The 'runner' on the longest boom was shortened on Monday 29th October, enabling automatic boom release as river levels rise towards flood conditions.  This means that the trap will operate during low and medium flow but that it will release in higher flows to prevent damage to the trap and minimise the potential for flooding.

Download litter_trap_project_case_study_project_details_both_pages1.pdf

Trap adjustments

On 18th July 2007 Bruce Bendell and I met OPEC Ltd, APEM Ltd and Alan Bretherton (the contractor who is emptying the trap) to determine why the floating boom had broken again. 

The weather has been extreme for the time of year but the flows seen in the River Darwen are not unusual in winter months.  We are learning quickly about operating extremes for the litter trap, which but this has caused a few 'teething problems' such as broken boom connectors (see image below).

Metal connectors have now been fitted to try and help prevent the breakages.

   

The floats on either side of the basket have also been adjusted so that the basket effectively floats higher in the river.

There are also plans for the 'runner' on the longest boom to be shortened, enabling automatic boom release as river levels rise towards flood conditions.  This means that the trap will operate during low and medium flow but that it will release in higher flows to prevent damage to the trap and minimise the potential for flooding.