Cunningham Construction Ltd were approached by one of our key clients Methanex NZ who were keen to do something a little different than they had done previously with a major refurbishment project coming up on 3 cells of their 18 cell cooling towers (an integral part of the plants system). The project involved full and complete demolition of the existing modules and the building of new modules.
We were challenged to provide a scaffold solution that was submerged in the sloping high mineral content Cold Water Basin (CWB) to enable the plant to continue normal operation and avoid emptying the cooling towers. Cunningham’s engaged Edgar from Layher who was instrumental in the success of this project. Some of the major challenges of this project were centred around the Health and Safety of our team and coming up with a design that enabled us to achieve the desired outcome without exposing anyone to the risk associated with the contaminants in the water and minimising the additional risks confined space work brings where practicable. Another consideration for us was the impact and exposure on the submerged equipment given one of the main chemicals was chlorine which is an oxidizing agent and prolonged exposure would cause expediated rusting; so while demolition works began a couple of components were submerged in the CWB for the estimated project time and tested afterwards for any impact. Layher Germany were intrigued by this experiment and information and knowledge sharing went around the globe since this was a special case (prolonged exposure to water with high mineral content).
What CCL and Layher came up with was donned the “Lily Pad” design meaning we could build mini towers on the MTG Pad and lift these into place. The extremely small margins of error when it came to swivel jack heights on the sloping floor meant this was a critical part of the job, with every Lilly pad (108 in total) at slightly different heights and only 100mm of play with height. A dummy basin was built outside the Cooling Towers with the exact degree of fall so Lilly pads were precise based on the sequence to avoid extra cranage and man hour exposure.
Some constraints we had to satisfy are listed below:
- Build scaffold that does not use cooling tower structure to support decking.
- Scaffold is to support the install of the new modules on top of the plinths in the CWB.
- Must be built under lower level of timber structure.
- Water level of cooling tower can be dropped up to 300mm.
- Must be removable when structure in place.
- Floor of CWB is sloped to the centre.
- Water treatment does include chlorine which is an oxidizing agent. Will cause expediated rusting.
- Quantity of 108 if all were required to be installed at the same time.
- Must incorporate a removable handrail to walk the width of the CWB.
The design Edgar put together meant execution of this project was seamless and without incident.
In terms of client satisfaction and testimonial, the proof is in the pudding with this one. CCL have just completed the 2nd lot of 3 cells, and have just erected the external scaffold on the next 3 cells, with Lily Pads remaining built colour coded and ready for the next basin once demolition gets to the bottom. This has revolutionised the way Cooling Tower refurbishment is done onsite and although seems like a simple project, overcoming some of the challenges was an achievement in itself, the reduction in labour costs and safety advantages were key wins for us. A big thanks to Edgar on this one.
“With the need to have a scaffold dancefloor 100mm above contaminated water, the Lilypad design was a perfect solution. The height of each Swivel Base Jack was precisely measured to counteract the gradient of the fall bay basin. Lily pads were lifted by crane in joined sections of three adjacently. These sections were then joined together producing a perfectly level floor. This allowed all work inside the area to be performed above water.”
"A unique project given to us by CCL. We had to design an access scaffold 1.50m high placed inside the cooling tower that has many closely spaced columns. This meant smaller bays (0.73m and 1.09m squares) were used to avoid clashes to existing structures and clever solutions to enable the scaffold to be built outside the cooling tower and then craned into position.
Adding to the challenge was that the cooling tower was not fully drained, and the water inside has very high salt content. We were asked by CCL to liaise with Layher Germany to pull any international experience and expertise. At the same time, CCL conducted a test on site, leaving a few Allround components submerge to the salty water for weeks and checking for any defects daily. It was a very interesting exercise, and we are very pleased to know that the Allround gear performed very well with the tests.
The whole project was affected by the COVID lockdowns, and we are happy to hear that all the gear survived the extreme conditions"