Erith were employed by Barratt London to carry out the demolition of a former 6 storey government office building in Camden, London. Surrounded by 4 conservation areas, the building is situated amongst a variety of commercial and residential units. The demolition and basement works will pave way for the construction of 164 affordable homes, ranging from 1-4 bedroom apartments.
The works in summary consisted of:
· Erection of site hoarding
- · Scaffolding
- · Removal of all asbestos containing materials
- · Strip-out of all non structural elements
- · Structural demoltion
- · On-site processing, segregating and crushing
- · Infilling works
- · Installation of piling mat
- · Piling works
- · Deep excavations
- · Falsework and formwork
- · 2 levels basement construction
Prior to demolition commencing, Erith erected flame retardant scaffold monarflex to both the front and side elevation alongside Rochester Place. This provision ensured when demolition was occurring all debris would fall within the fabric of the structure preventing dust migration and safeguarding the surrounding stakeholders.
The roof consisted of asbestos cement sheets which required a methodical and diligent approach. To mitigate the potential of working at height, Erith utilised a ‘wet and drop’ method which involved establishing an exclusion and respirator zone.
Works at Camden presented an array of sensitive receptors with a variety of stakeholders at each elevation of the structure. Of particular note was the tenants of Building 102 which housed Channel 4’s editing suite. To ensure disruption was kept to a minimum, Erith erected an acoustic screen to mitigate the potential of noise migration. Demolition works were carried out via mechanical means.
Plant utilised to deconstruct the building included a long reach, 60 , 40 and a series of 13 tonne excavators. The structure itself was demolished down to the underside of existing ground floor slab following the strip-out of all non-structural elements.
Temporary works were carried out to 2 existing basements that had walls adjacent to the site boundary. The existing retaining walls were then removed along with any other associated remaining concrete slabs and walls. Following this, PU-22 Sheet pile walls were installed which encompassed the full area of the site. ‘Zero’ or skinny piles were used in areas that were sacrificial and left in after the main works have been completed. The basement of the building was conducted to a Grade 3 water tight finish due to the sensitive nature of the surrounding area.
Arisings from the demolition works were processed on site to a 6f2 grading and utilised in the installation of a pile mat. After the pile mat had been installed, 600 No 450mm bearing piles were installed through the middle of the site.
Once the piling works had been completed, 12,000m3 bulk excavation works were be carried out to the formation of the lower basement slab. This commenced with localised excavation for the bases and placements of 2 tower cranes which were utilised throughout the project.
During the excavation, the installed bearing piles were broken down to a cut off level and cleaned between the perimeter sheet piles. Installation of below lower slab drainage and attenuation tanks with Cellcore were also placed to prevent ground heave, along with a waterproof membrane that was placed under the slab and up the face of the sheet pile wall.
Construction works took place from the lower ground floor slab, this in total included the lift and stair cores, drainage, lightening protection pits, rods and connection of earth tape to the reinforcing.
Further construction works included the floor deck falsework and formwork and fabrication of the ground floor slab.
Areas of the above mentioned works remain on-going and are due for completion in January 2016.