The Limes residential housing development – Phase 1
Formerly a nursing home, the Limes closed to residents in 2016 following over 50 years of service to the local community.
Located within a built-up area, adjacent to a busy arterial road into town and situated on a major roundabout, the site requires focused planning and attention to work within constraints presented.
After demolition of existing buildings on the site, the development will deliver 40 x one bedroom, 83 x two bedroom and seven x three bed residential units along with underground parking and landscaping.
BGR have been contracted to provide all piling services for The Limes development, which includes:
- 288 x foundation piles installed using the Full Displacement Piling (FDP) technique (see specialist techniques below for more details).
- 8 x 720mm diameter crane base piles using the cased bored piling method to secure the site’s large tower crane (see specialist techniques below for more details).
- 50 x linear metres of temporary works to create a so-called ‘Berlin Wall’ installation, requiring the sinking of King Post piles installed at 1.8m centres along the adjacent Green Street using normal cased bored piling techniques. Once installed, excavated bays between the King Posts were filled with wooden railway sleepers (see specialist techniques below for more details).
Specialist techniques employed:
The Full Displacement Piling (FDP) technique is a specialist service provided by BGR, which results in all pile spoil remaining in the ground rather than being brought to the surface. The key benefits of this method are:
- Speed of installation: FDP can install up to 20 piles in a single working day.
- No disturbance of contaminants: any contaminated soil present will remain under the ground.
- Disposal savings: no pile spoil means no need to remove from site for dumping, saving in both costs and eliminating impact on La Collette tip site which has a diminishing capacity.
Creating foundations for the large tower crane required the installation of piles capable of bearing the heavy load. BGR were able to minimise the number of piles needed through using a method capable of drilling into the bedrock and installing a 2-metre rock socket ideally suited for managing the expected high-tension loads.
By using wooden railway sleepers installed in between the King Posts as temporary works, it enables the Main Contractor to lower the piling platform level 3.5m excavation depth along Green Street, thus allowing the installation of the foundation piles from the lower level. The resulting reduction in concrete usage across 288 piles will lead to considerable financial savings.