777 Wraps up Woolwich with Safety Blanket
Demolition and Dismantling specialist 777 Group has recently deployed an innovative new protection system during the demolition of a seven storey office block in East London. The company successfully suspended a giant ‘protective blanket’ in between the condemned building and an area of ongoing construction work immediately adjacent to it.
The entire undertaking was something of a rarity as felling tall structures that are in close proximity to other buildings is usually the preserve of ‘top-down’ demolition techniques whereby the building is demolished floor by floor using small plant and labourers. This is often perceived as a slower, more expensive task but one that is normally necessary to prevent nearby buildings being damaged. The new technique found favour on the site in Greenwich where the blanket allowed the principle contractor to continue, unhampered by the adjacent demolition work, with the construction of Woolwich Central — a mixed use development that will include 1000 homes, a superstore and new council offices.
The innovative technique consisted of suspending a 28 metre long section of rubber matting in between the tower block and the ongoing construction project located immediately behind it with the assistance of a mobile crane. One of 777 Group’s Hitachi EX1200 ultra-high reach machines then demolished the structure in a conventional fashion with the rubber mat ensuring any debris that threatened to fall behind the tower block would not damage the adjacent construction work.
Produced specifically for the task in Greenwich by Lifting Gear UK Ltd, the giant mat is made from 7 metre wide sections of rubber conveyor belt which are clipped together. The clips allow the mat to be adjusted in length according to the task in hand. Complete with four half-tonne ground anchors located at the bottom of the mat, as well as its own block and tackle, the entire ensemble tips the scales at just over five tonnes. The task of suspending the entire blanket aloft during the project went to a mobile crane operated by Baldwins. Reaching into the London skyline, the crane was able to suspend the mat in a suitable position at the rear of the building.
With an estimated two hundred and fifty construction personnel working on the adjacent redevelopment, a series of safety mechanism were brought into play by 777 Group, crane hire firm Baldwins, and the company responsible for the nearby building work. With 777’s mammoth Hitachi EX1200 ultra high reach demo rig ripping down the office block piece by piece, an exclusion zone was established around the entire structure. Further to this, five banks men were positioned behind the building, just outside the exclusion zone to observe the undertaking. Equipped with walkie-talkies, the team could, if necessary, radio the Hitachi operative. Other considerations included wind speed and direction, both of which were monitored to prevent the suspended mat from tangling itself or impacting on the two structures.
Despite the use of the protective mat, the demolition of this 1960s tower block inevitably generated a degree of dust; a side effect that was mitigated by the use of a Dust Boss dust suppression unit. This pint-sized unit discharged a fine mist across the site ensuring clouds of dust did not affect business and homes nearby.
With just four weeks allocated by the principle contractor for 777 Group to surgically remove the council office building and the postal office immediately in front of it, the deployment of this ingenious protective blanket proved a godsend to those working on the demolition of the Greenwich’s past and those just a few metres away who are busy building its future.
Protective blanket doing its job
One of our 1200's hard at work