Tesco, Woolwich

Despite the immediate area having been earmarked for regeneration since the late 1990s, the recent extension of the Crossrail scheme to Woolwich has provided renewed impetus for a redevelopment scheme which includes the building a supermarket, 1000 flats and Greenwich council’s new civic offices on the site where Peggy Middleton House once stood.  With the green light finally given to developers, 777 Group was given just eight weeks to break-out and recycle the building’s foundations; a task which proved more challenging that it sounds according to 777 Group’s Business Development Manager Daryl Pearce, “During our initial examination of the site it was difficult to tell the depth and strength of the building’s concrete foundations. These unknowns, coupled with a time restriction for completing the project meant we had to deploy our machines and operatives en-masse at the site. Suffice to say, it was a good job we have the in-house capability for such undertakings as the foundations have proved tougher and deeper than first thought”.   

Instrumental in 777 Group’s ability to break-out, crush, back fill and compact the concrete foundations has been its extensive fleet of demolition machinery which includes two heavyweight Hitachi EX1200 excavators. Equipped with mass-excavation arms the EX1200s weigh in at nearly 140 tonnes each. Whilst one machine utilised a 7m3 MST bucket made from Hardox steel, the other hosted a brand new Atlas Copco hammer. Reputed to be the largest volume produced hammer in the world, the 10 tonne Atlas Copco HB10000 was used to good effect to break out over 50,000 m3 of reinforced concrete. The attachment housed a 24cm wide pin which can smash against concrete at a rate of 380 times a minute. According to Daryl the breaker’s performance played a vital role, “The combination of one of our EX1200s coupled with Atlas Copco HB10000 breaker really sped up the demolition process. With the Hitachi’s strong hydraulic power pack supporting the giant hammer the concrete came free at an impressive rate. Of course, having a second machine which can shift the giant slabs of broken concrete also helped things along”. 

Although the two EX1200s have been the undisputed heavyweights of the project, 777 Group also managed to field an impressive array of other demolition equipment including numerous 20 tonne, 45 tonne and 70 tonnes excavators as well as a mobile crusher and dust suppression unit. The extensive array of equipment deployed ensured the basement was removed in an expeditious manner whilst minimising noise and dust.

The number of vehicle movements into and out of the site was significantly less than most operations of this size thanks to an on-site recycling programme. Approximately half of all the concrete arisings generated by the foundation demolition were crushed, backfilled and compacted in-situ in order to facilitate a level change for the base of the new building. “Had the requirement been to simply break out the foundations and take them off to our recycling facility the project would have been completed in an even shorter period of time. However, in order to reduce the number of journeys to and from the site and the amount of primary aggregate required for the new development, it was decided to recycle some 25,000m3 of concrete and reuse it on site. Utilising the Terex Pegson crusher and our heavyweight EX1200s the material could be crushed, backfilled and compacted in an expeditious manner”, said Daryl. Further to this, some 200 tonnes of rebar was extracted from the concrete foundations and removed from the site. 

With the project completed on time and on budget, 777 Group’s ability to rapidly and safely remove irksome, stubborn structures such as the foundations of an uninspiring office have again been proven thus ensuring the long overdue redevelopment of central Greenwich starts without delay