Client : City & Provincial
Value : £901,000
Existing Structure & Location:
A redundant nuclear ‘cold war’ bunker, protecting the governments old secret underground war room. The site was surrounded by residential units and barristers chambers in the legal heartland of London.
Scope of Works
- Demolition of the bunker down to the top existing base slab, 4m below ground level.
- Provide ventilation and protection to the shaft, whilst maintaining the existing water and fire mains supply to the tunnels below.
- The proximity of the surrounding buildings & depth of excavation required, necessitated underpinning sections of adjacent properties.
- The concrete was 2.8m thick and crushing strength 90N/mm2.
- The team diamond drilled and hydraulically burst off the outer 1.2m layer of the bunker.
- A 9 tonne NPK concrete cracker with a 2m wide jaw span, specially purchased for this job, mounted on a 55 tonne Liebhere 954 excavator was utilised.
- To remove the remaining 4m of below ground structure, we used hydraulic breakers fitted to excavators.
- To combat the noise pollution we erected an independent scaffold frame and roof, which completely boxed in the site & clad it with 2 layers of plywood and a layer of 100mm thick rock-wool insulation in between. The result was an impressive reduction of 30db outside of the enclosure. Work continued all day without any disturbance to neighbours from noise or site activities as everything was completely contained.
- The plant was fitted with catalytic converters to reduce the contained fumes and a constant change of air was provided by installing large air handling units fitted with dust filters.
- All concrete was recycled at an East London Static crushing facility.
- Demolition was completed within the 22 week programme and within the £901,000 contract sum.