Demolition of the former Bargate Shopping Centre, Southampton

Southampton

Client

Bargate Property Limited

Services

DemolitionSite ClearanceSoft-Strip

Industry

Commercial

Hughes and Salvidge were appointed to the role of Principal Contractor for the demolition works at Bargate Shopping Centre in Southampton in 2017. The project involved the full removal of the 1980s structure, aside from its art deco frontage which remained. All the buildings sat on a site dating back to the 14th Century.

The 35-week programme included multiple stages broken down into different phases.

Prior to works commencing welfare facilities (including fire muster points and first aid locations) were installed and 2.4m timber hoardings set up around the entire site boundary ensuring the area was safe and secure. A bespoke protective scaffold was also installed surrounding the ancient town wall.

The protection of the ancient stone wall was one of the major phases within the project, the Structural Engineer designed the protective system for the wall which consisted of scaffold boards and ply wood to protect the wall. This ensured that no debris could land on or strike the wall during demolition works on other areas. The scaffold was fixed to surrounding walls in order to prevent the need of scaffolding being attached directly to the wall itself.

Not only did the ancient wall have to be protected during the process of demolition at Bargate, the High Street façade was also to be retained. The building was cross braced with timber and a steel frame was fixed to the façade by the steelwork specialists using mobile craneage and cherry pickers. All of the temporary works are to now remain until the façade is returned onto a new structure.

After the façade was protected and the ancient wall too, the three phases of the demolition could begin on site.

Phase one consisted of multiple structures, the MSCP (multi-storey car park) consisted of reinforced concrete and the main shopping centre was reinforced concrete and steel with face brickwork. The high reach excavator started demolishing from the south east side by starting at the top and crunch out one bay at a time in order to allow it to fall on to intermediate floors, then the floors were scraped in order to reduce overloading and prevent collapsing. Once the building was reduced, the standard height 45 tonne Hitachi excavator used the same method in order to finish demolishing the car park. The demolition arisings were segregated and loaded by a third machine into waste streams. During these processes, dust suppression tools such as a Dust Boss and hoses were used to mitigate dust pollution. Once the building was to ground level the basements had to be cracked into with a machine to break the surface then the excavator could create a ramp in order to get down and into the basements minimising risk and enabling the basements to be demolished successfully.

The canopy was also removed adjacent to the high street parking area, this method included the use of hot cutting. The steel framework was left in place in order to gain access for scaffolding to be erected however the metal work cut out in order to release the canopy was safely dropped to the floor and cleared away once cooled.

Demolition work carried out next to the façade consisted of saw cutting, BROKK work and hand demolition techniques.

All works were carried out to an extremely high standard in order to prevent damage to the façade. The techniques used ensured the works were carried out successfully, therefore contributing to safe works and keeping to the schedule.

Phase two consisted of three- and four-storey buildings of 1940’s construction with the majority of the works using demolition excavators to remove the buildings structures. Manual demolition was used from scaffold with breakers in order to remove the buildings masonry. All works were safely and successfully carried out to finish phase two of demolition works.

Phase three of demolition works consisted of two- and four-storey buildings, with steel framework and face brickwork. The excavator crunched out one bay of the roof and allowed it to fall onto the floor below this was followed by folding the walls below the roof slab onto the floor below. The arisings were scraped off of the lower levels to reduce overload. The method was the same throughout these buildings until the basements were backfilled with the arisings from the demolition.

After demolition works had been completed the substructure works of foundations, floor slabs and basements were broken up with impact hammers, removed with the bucket and then the concrete-containing reinforcing bar was pulverised by another excavator.

The stockpile of concrete slabs was then loaded into the concrete crusher on site and crushed to 6F2 and stockpiled on site making use of the arisings from the demolitions works.

During the works, Archaeologists came to site and discovered a 14th Century cannon ball, a 15th Century jar which held liquid mercury, a 17th Century plate and a 1000 year old completely intact pot. There were allocated times for archaeological digs within the demolition programme, however the time was extended due to the great finds within the site.