Demolition of Stretford Plant at Corus, Redcar Coke Ovens, Teeside
Introduction
Thompsons recently completed the demolition of the Stretford Plant located in Corus Redcar Coke Ovens. The project, described as extremely high risk by our client was completed without accident or incident and to programme.
The Redcar Coke Ovens are the primary coke production plant at Corus’ South Teesside Works. The process of distilling coal into coke produces coke oven gas, which must be cleaned to remove harmful contaminants at the RCO By-Products plant (which included the Stretford Plant). Refinements to the processes however made the plant redundant for several years until a decision was made to demolish the plant in 2007 / 08.
Pre-demolition inspection
As part of the pre-demolition planning, a type 3 asbestos survey was carried out. This helped to develop the dismantling procedure and identify equipment required to be manually removed before mechanising the demolition procedure. Due to the deterioration of the plant, not all areas were accessible for inspection, therefore these areas were mapped and the equipment inspected later when it could be made safe or brought to a safe location.
Demolition considerations
The plant had been mothballed for a considerable time and due to weathering the steelwork was structurally unsound. As such it was decided to mechanise the demolition procedure by using excavator machines fitted with shear attachments. This eliminated the need to expose operators to plant hazards.
As the project came under the jurisdiction of the CDM regulations, the area was secured and controlled by Thompsons. Control measures were developed between Corus and contractor with daily meetings held before starting work to discuss progress and the daily plan.
Demolition procedure
To control hazard assessment as the project progressed, the plant was divided into 7 discrete zones. Work progressed through the zones in a systematic manner. This created room for the machines to work safely, cutting material and processing it before removing it for disposal. Spread throughout the zones, were redundant services and equipment such as pumps, and separators which were removed as they became accessible.
Storage, layout and processing areas were agreed before starting work which controlled work activity and kept the work area tidy, preventing tripping hazards while maintaining an overall sense of order about the workplace.
Difficulties
Directly adjacent to the Stretford area is a Benzole plant producing highly flammable spirit and vapour. To minimise fire and explosion risk, cold cutting techniques had to be used wherever possible in the general area. This also required the excavator machines to be fitted with spark inhibitors which had the detrimental effect of increasing noise levels which could not be avoided.
Due to the large volumes of gas produced at RCO, it is classed as a top-tier COMAH site. This requires extra care to be taken during lifting operations and during work around services and (possibly) critical supplies such as steam and electrics. This was particularly relevant during the demolition of the HCN and H2S towers which were located in close proximity to a large pipe-rack transferring coke oven gas and high pressure steam.
An involved structural assessment on the towers could not confirm sufficient integrity to lift the towers individually as complete units. The alternative was to dismantle the towers in sections, a 500 ton crane would lift the sections each weighing approx 40 tons which again required cold cutting techniques – drilling, sawing and “rivet-bursting”.
To prevent puncturing pipework from falling steelwork a protective canopy was erected over the pipe-bridge, and to address the COMAH lifting and dismantling work, a specific risk assessment identified robust control measures including over-assessing the SWL craneage to 150% and cutting the sections into a total of 12 sections to minimise the weights of the individual sections.
In spite of the difficulties involved - working from MEWP and man-baskets, the demolition crew took this undertaking on board and after a lot of demanding work completed dismantling the towers.
RCO identified the Stretford demolition work as “extremely high risk”, yet thanks to a well planned and executed job, there were no incidents or accidents throughout the project.
