World Demolition Awards shortlists - Industrial Demolition
By Steve Ducker15 September 2021
Project Demolition of the Nanticoke Generating Station
Client Ontario Power Generation
Delsan-AIM completed the decommissioning and demolition of the Nanticoke Generating Station. In undertaking this large-scale project, the safety of the workers and the public and the protection of the environment were primary concerns. All the work on site, therefore, was carefully planned and engineered with a recovery of non-hazardous materials of 95%.
This former coal-fired thermal electric generating station, once the largest in North America, located along the north shoreline of Lake Erie in Ontario. It consisted of eight generating units that had a full capacity output of 4,000 MW. The powerhouse was the main building where the electrical generating equipment was housed along with the associated boilers, coal handling equipment, pulverisers, turbines and generators.
There were also two 198 m (650 ft) high reinforced concrete chimneys. Due to the height of the chimneys and the powerhouse building, which were beyond the reach of conventional high-reach demolition equipment. Delsan-AIM used explosives to cause these structures to fall in a carefully controlled manner.
Before any demolition work could begin, the buildings and structures were made safe. This was accomplished by ensuring that all services, such as electricity, had been disconnected and that all hazardous materials had been properly removed and disposed of. A specially trained crew of rappelers performed extensive abatement work in the powerhouse to remove asbestos-containing information from large, difficult to reach downcomers and suspended boilers. There was also existing live infrastructure that had to be protected including switchyards, power grids and county water intake.
Country United Kingdom
Project Tilbury Grain Store
Client Port of Tilbury London
Erith provided emergency response and immediate making safe works to the port at Tilbury following an explosion that occurred in July 2020.
Assistance was provided to Essex Fire and Rescue with its investigation into the cause of the explosion, which was found to have been a rare dust explosion.
The effects of the explosion caused structural instability to the remaining silos, so Erith was employed to carry out the specialist role of removing the grain from silos before taking them down to slab level.
Consultation was carried out with the Environment Agency and port appointed authorities to approve the safe systems of work and mitigate all risks and concerns. Works were carried out in an operational port, on the banks of the River Thames and adjacent to the port’s Command Centre. Key to the success of the project was ensuring that there was no re ignition of the grain.
All works were carried out under DSEAR (Dangerous Substances and Explosive Atmospheres) Regulations 2002 due to working within “a high dust environment with explosive elements.”
An emergency response plan was briefed to the site team daily, with additional sources of water suppression always readily available. All works were carried out with no health and safety incidents.
Project East Intercourse Island Stacker Demolition
Client Rio Tinto Iron Ore
East Intercourse Island is a Rio Tinto iron ore port facility on the north west coast of Australia that receives trains, unloads, stockpiles and loads to ship large volumes of iron ore.
Stockyard age, technology and productive capacity were limiting operational output, so Rio Tinto elected to replace three 400 t stackers and seven 90 t trippers. The stackers were complex structures requiring detailed engineering and a complex felling methodology to safely demolish the structures.
The project faced several challenges:
- Demolition completed in an operating port site near to live services and critical infrastructure, such as the rail and foundations, which could not be compromised
- Restricted to a 20-day period to complete zero energy, pre-works, demolition and scrap processing on each stacker
- Unknown structural integrity
- A detailed 3D model was created, and field verified, to allow multi-physics simulation of the felling and determination of the felling geometry and pull forces.
Full, non-linear finite element analysis was completed to confirm structural integrity during rotation; design slew locking devices to maintain centre of gravity; identify areas requiring local bracing or stiffening; design “frangible upon impact” connections to concrete counterweight restraints; model load path and design supports to protect rail from excessive compressive or lateral loads; and design certified attachment point to ripper body of bulldozer
Ultimately controlled felling was completed with a pull force from two D10 bulldozers operating in unison.
The high-risk task was completed three times strictly in accordance with safety, environmental, engineering and schedule requirements.
Project SRP Navajo Generating Station Decommissioning and Demolition
Client Salt River Power
Independence Excavating performed the demolition of the 2,250 MW Navajo Generating Station for the Salt River Project (SRP), in 2020 and 2021.
The 404 ha (1,000 acre) plant in Arizona was a coal-fired power plant constructed in the early 1970s, with dedicated mine, landfill and railroad facilities to service it. The ultimate decommissioning programme was to demolish the plant, restore the property from any environmental impacts and return the land to the Navajo nation.
The demolition scope encompassed 121 ha (300 acres) and included three 236 m (775 ft) stacks, three 20,000 t boilers, precipitators, turbines, cooling towers, rail unloading facilities, and environmental treatment units.
Much of the project was performed with conventional demolition working through the plant units with shears, grapples, hammers and torches. Each of the 17 buildings or units was evaluated by a structural engineer regarding the demolition and the safety of the workers in executing the demolition. The project also included Navajo hiring preference goals.
Over 100,000 t of material was intricately demolished, sorted and shipped off site, mostly for recycling, with very little solid waste requiring landfill disposal. More than 92% of the demolished material was recycled, including metals, concrete and liquids.
Project Demolition of Voronezh unfinished nuclear power plant
Client Rosenergoatom Concern JSC
The Voronezh nuclear power plant was built from 1981 to 1992 for the needs of the city of Voronezh but when ready, 90% was mothballed. In January 2020, Rosenergoatom Concern JSC signed an agreement with Volgaspetsstroy to dismantle the station.
The contract provides for three stages. At the first stage, the reinforced concrete structures of the special water treatment building are dismantled, the structure of which consists of precast-monolithic reinforced concrete, the maximum height of the structure is 17.7 m (58 ft), the thickness of the main walls and floors of the building is 0.6 m (2 ft), and individual structures, such as mines and wells have a wall thickness of up to 1.5 m (5 ft).
At the second stage, the outbuilding of the reactor compartment is dismantled, a structure made of precast-monolithic reinforced concrete in a permanent formwork of reinforced concrete slabs-cells and is a square with dimensions in the axes of 63 x 63 m (206 x 206 ft), symmetrically covering the shell, with a maximum height of 33.2 m (109 ft), the thickness of the main walls and floors 0.6 to 0.9 m (2 to 3 ft).
The third stage includes the demolition of the main building of the reactor compartment, a construct made of a hermetically sealed reinforced concrete shell of a cylindrical shape, installed on a base plate with dimensions of 64.2 x 65 m (210 x 213 ft), the shell of the reactor is made of monolithic reinforced concrete of a cylindrical shape with a diameter of 33 m (108 ft) and a height of 54.8 m (179 ft).
The upper part of the reactor compartment is a metal dome, the height of the top of the dome is 67.1 m (220 ft). The thickness of the walls of the cylindrical shell is 1.6 m (5 ft 3in).
All reinforced concrete structures of the station are made of heavy concrete of the M800-M900 grades, which, over the years, has additionally gained its strength characteristics.