The hospital originally opened as a convalescent home for children in 1909 and was reconfigured as hospital during the Second World War in order to provide medical assistance for injured soldiers. In December 2006 the hospital was closed and plans were submitted to clear the site and develop 780 new houses.
777 Group was awarded the contract to demolish all but a handful of the facility’s 73 buildings and remediate the land they stood on. Because of the hap-hazard nature of the hospital’s growth over the last century the demolition phase of the project presented several key challenges according to contract manager, Dave Willcott, “The hospital was a sprawl of randomly placed structures from different eras that took different forms. A 25m-high chimney stood amongst five-storey office buildings from the 1960s, post-war accommodation blocks and older, antiquated buildings housing the hospital’s utilities such as boilers and generators. Most of the buildings contained asbestos and all had suffered damage due to vandals and thieves. The site housed a one mile-long, three metre deep utility tunnel as well as numerous unmarked water pits. All these factors meant the demolition stage had to be well-thought-out and closely managed”.
Before demolition began all residual asbestos had to be removed from the condemned buildings. These works being carried out by 777 Groups, Environmental Division. This was no easy task with an estimated 315 tonnes of the material having to be handled and ultimately disposed of. With the asbestos removed, the buildings were stripped of their interior fixtures and fittings. 777 Group then deployed 18 pieces of demolition machinery en-mass to clear the site of its antiquated structures.
The demolition process produced high volumes of inert material including 800 tonnes of wood and 600 tonnes of metal, all of which was segregated and recycled. A trio of crushers were utilised to process in excess of 15,000m3 of rubble with a third of the crushed arising retained on site for re-use in the future housing development.
With a majority of the site’s buildings demolished, the task of remediating the land began. During the war it was reported that munitions were taken from nearby railway sidings and stockpiled underground. Analyzing the ground generated several areas (Hot Spots) showing likely areas containing munitions, these areas were carefully excavated with a Banksman in attendance at all times and work ceasing periodically for the area to be fully inspected by operatives.
Away from the footprint of the buildings the drainage had been changed many times, some drain runs contained clay, cast iron, steel and non-notifiable asbestos. This also had to be removed by 777 Groups, Environmental division, this was carried out in access-restricted areas ensuring contamination was contained. Other environmental considerations included several listed trees which remained unhindered by the work.
Despite the threat posed by vandalised, asbestos-riddled buildings, and contaminated, explosive-ridden ground, the job of clearing the site and remediating the ground proved a challenging but ultimately successful for the Surrey-based firm.