Over the years Carlisle has experienced some severe flooding, but none worse than in January 2005 when over 1,800 properties in the city flooded. Power and telephone lines were disrupted; road and rail networks were closed.
I joined the Environment Agency in February 2005, right after the Carlisle and Cumbria Floods. On a personal note it was devastating to see the impact to people in my community, but on a professional level it was a fascinating time to start working for the Environment Agency; I spent most of the next 5 years working on the design and construction of the £38m improvements to the flood defences in Carlisle.
- The Carlisle Flood Alleviation Scheme was split into two phases:
Phase one, Eden & Petteril Rivers (Warwick Road area)
Phase two, the River Caldew & Carlisle City (Denton Holme, Caldewgate & Willowholme areas)
I spent 18 months working on site while the Eden & Petteril phase of the flood defences were being constructed. It was a relatively straight forward build, consisting of clay cored embankments and reinforced concrete walls which are used to stop flood water flowing into local homes and businesses. I remember the summer of 2007 being hot and dry, I was overseeing the building of the flood embankments behind Warwick Road and in Melbourne Park and diverting the Old Eden watercourse at the end of Johnny Bulldog’s Lonning.The biggest problem we faced was damping down the dust on the access tracks and keeping the clay moist enough to form the embankments – a very different picture to the heavy rain of winter 2005.
The two biggest technical challenges we faced were the construction of a pumping station at the end of Durranhill Beck, which has two fully automated pumps that can pump 0.5 cubic metres of water per second from the flood storage reservoir; and installing a ‘pali radice piling system’ next to the River Petteril beneath the road towards Riverside House. This was a relatively innovative technique, which knitted together the historic sandstone river retaining wall and added the additional strength required to enable us to install the precast concrete flood defence wall on top.
The second phase of the scheme was along the river Caldew and around the city centre. The design and construction of this phase was a much tougher challenge, which is why it was done second, to give us more time to carry out the investigations and make sure we got the design right.
The main aim of the scheme in Carlisle was to reduce the risk of flooding to residents and businesses, but we also took the opportunity to work with Cumbria County Council, Carlisle City Council and Sustrans to provide greater benefit. There are many elements of the Caldew & Carlisle City phase of the scheme that stand out to me, but might be less obvious to the general observer.
We replaced two footbridges over the Caldew in Denton Holme. The Nicholson Bridge was named after the former Area Manager of the Environment Agency who was instrumental in securing the £38m funding for the flood alleviation schemes in Carlisle, but who unfortunately passed away before they were started.
The wall alongside McIlmoyle Way is constructed from 10m long steel sheet piles surrounded in concrete. The novel thing about this wall is that in order to reduce the thickness of the wall we clad it in 1cm thick bricks. These bricks were glued together in a warehouse and brought to site in large panels which were then stuck onto the concrete wall.
Much of the ‘sandstone’ clad wall, such as alongside Viaduct Estate Road and from Elm Street to the Madford Retail Park, is actually coloured concrete. To make it look like sandstone we used coloured concrete and took moulds from the wall of the City’s Market Hall.
The railings in the old wall between Elm Street and the skew bridge over the River Caldew to Viaduct Estate Road are there to allow the flood water to spill onto the cycleway, increasing the width of the river when it’s in flood. The features built into the railings also reflect the former railway goods line that passed along there. The upstream section of railings depict the scene of a runaway train that partially demolished the bridge on 1st May 1984, the bridge was completely removed during the construction of our scheme, with some of the quoins (masonry blocks at the corners of the wall) from the bridge piers being left next to the path as seating.
Before we built the flood defences, there was no riverside path between Graham Street and Thomas Street. We managed to incorporate a footpath/cycleway which we nicknamed ‘the missing link’ as it connected up the footpath and cycle network so you can now access the city centre without having to pass along the busier roads. In terms of delivering a legacy for the City this is an example of where we tried to think outside the box and use it as an opportunity to provide more than just flood protection, and we’re very proud of the results.
The scheme was completed in 2010, shortly after the November 2009 floods that affected much of the county. In the days leading up to the 2009 floods we worked rapidly to put measures in place to temporarily raise the one remaining uncompleted section and I spent a long night in our incident room in Penrith monitoring the river level forecasts and speaking to our operatives on site. All forecasts were showing that the river level would peak a few centimetres below the top of our temporary measures and it was a great relief when the river levels started to fall.
The flood defences were tested again in June 2012 and May 2013, preventing in excess of £180m of flood damage to the city. So you can see why this has been such a challenging, but fulfilling time to work for the Environment Agency and I continue to look forward to the challenges that my work will throw at me.