Premier Engineering

Portsmouth Dredging

Portsmouth Dredging
Written by Roma Publications

Portsmouth Dredging

The Portsmouth International Port (PIP) is located within Portsmouth Harbour, to the North East of the Portsmouth Naval Base. It is the UK’s most successful council-owned port and the second busiest cross-channel port in the country. It provides a significant contribution to the council’s budget, which helps to support essential services.

With over two million passengers, 250,000 lorry movements and 900,000 cars a year coming through the port, it is critical that the infrastructure can meet the needs of customers. To continue with these movements, PIP required periodic maintenance to dredge to its berth and approaches to remove localised build-up of harbour silt. To cater for further deep draught and large vessels operating on Berth 2, a capital dredge and disposal of seabed materials – to 8.7 Below Chart Datum (BDC) was undertaken.

Within the eastern and western extremities of the dredge area, scour protection and mattresses existed. These are formed from concrete/grout and the existing mattresses had to be broken out, disposed of to the land and the East Scour Mattress replaced at lower level.

Speaking to Premier Engineering about the project, Anisa Koci, Project Manager at Portsmouth City Council said: “As a major UK port this vital work was essential to help drive ambitions to grow the business.  With dredging, and other associated works, the port will be able to handle cruise ships up to 253m in length. This could mean we are able to double the number of cruise calls for the port over the next few years, which means an increase in significant customer spend for the city.

“The Berth 2 Dredging scheme, part of the Portsmouth International Port development, was the first marine construction project that I was involved in, so it had significant importance to me. This project gave me a good experience of working with various stakeholders and maritime specialist contractors like Scour Protection Ltd and Proserve Ltd. Undertaking works on a live marine environment is a big responsibility but at the same time it gives you a lot of satisfaction during the delivery of the works.

“Portsmouth International Port is currently planning to replace the 30-year-old passenger boarding tower, which is required to get onto the ships. The Berth 2 Levelling project is currently in the tender process and will involve essential levelling works to take place on the cruise berth, which would mean that the port could accommodate many more cruise liners who find the current layout challenging.”

Scour Protection Ltd worked alongside WM Plant, Baker Trayte Marine and ML Dredging to complete the work, which was project managed by Portsmouth City Council.

Premier Engineering also spoke to Chris Drake from Scour Protection Ltd about the project in a bit more detail.

Portsmouth Dredging

What has this project involved?
“Portsmouth City Council, who owns the port, realised that there was a window for cruise liners to come into Portsmouth but they didn’t have a berth to put them on because they are too big. They asked me and my company to take on the project and dredge the berth as well as installing protection against the propellers.”

Have you worked with the council before or were they a new client for you?
“We have worked for them for about 25 years so we know each other very well and we do a lot of their marine projects.”

Would you say this was quite a big project?
“Yes, it was fairly big for us. We started in the middle of December 2018 and finished in mid-March 2019. We actually completed the project under budget and early so that was good!”

With a project like this, do you need to use any specialist equipment?
“Because there wasn’t a dredger available that was big enough in the UK and because all of the big dredging units in the UK where busy when we needed one, we had to make one. We used a company called Baker Trayte who supplied the barge, which was 25m long by 14m wide. We then put a 120 tonne excavator from WM Plant onto the barge and towed it round to the wharf to dig out the spoil to the required level. We used a special computer system that let us control where we were digging and then put the spoil into slip barges. The spoil was then taken out to the Nad Tower and dropped out to sea. It is such deep water so when they open the doors it spreads out so that means that there isn’t just a pile of mud sat on the seabed!”

Would you say there was anything interesting or unique about the project?
“It was a strange one because we installed something called Proserve Mats. If you imagine an Airbed full of concrete; we put these things onto the bed which is like a material and then you pump concrete into them. They then fill up and make a bed. We installed the protection on the bed port in 1994 and 2010 and they were in the way for the new berth so they had to be installed deeper. We had to take them out and that hadn’t been done before, especially with mats of that size so that was quite interesting. It all went well and very smoothly so there were no problems with that side of things.”

Were there any difficulties or challenges with the project?
“There were quite a few to be honest. One was working in winter. That was quite hard because of the bad weather and cold conditions. Also, working in the marine environment is difficult because of the tide, different conditions that make it problematic and the driver of the excavator couldn’t see what he was digging because of the conditions. To help with that we used a special computer called a Prolec which helped to show where he was digging and that was a big help. Overall it went well.

Is this something that will have to be done again in the future?
“It is a onetime thing for this berth. They may do other berths in the future if this is successful but it is something that does happen quite a lot in different palaces.”

What has it meant for you to be involved with this project?
“It has been nice to keep the relationship ongoing with client. We are lucky that we are a marine contractor that gets to work all over the UK but this time, it was actually very nice to be at home and working on home turf. We knew everyone, knew where everything was and knew where to get equipment from if something broke down and we needed it at short notice so that was good.”

 

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