CASE STUDY: RESTRICTED ACCESS PILING, LOWESMOOR VAULTED CELLARS.
Project: Piling on the site of the old Worcester Maltings to provide foundations for the new retail development.
Location: Lowesmoor, Worcester
Client: Carillion Richardson
Project Overview
The Lowesmoor area of Worcester has been in desperate need of regeneration since the end of vinegar production and the decline of porcelain manufacture over 40 years ago. The £75 million development scheme, proposed by Carillion Richardson, was given the unanimous endorsement of the city planners.
The project began in 1998 when Carillion Richardson began working with architects to find a practical use for the 7.5 acre site which had become synonymous for drug use, vandalism and arson and separated from the city centre only by City Walls Road. Integrating the old fermenting shed and restoring the 2 listed buildings on the site, The Infirmary and The New Filling Shed this scheme also retains the St. Martin's Gate Offices, Grainger's Porcelain Works Offices, The Counting House, The Cooperage and the basements under the old Furniture Store. All are being sympathetically restored back to their former glory integrating their original charm and architectural features into the new design allowing all to appreciate this historical site and it's heritage.
To date, this project has been split into 3 parts as far as the foundations are concerned, however, there is still much of this scheme yet to be developed.
Unit 17 - The new Asda customer restaurant
Being built on the site of the old malting factory, the piling through the existing vaulted cellars was particularly complicated.
Carillion were first required to locate the exact position of the 52No. 800x800mm underground brick piers. These had to remain completely independent of the new above-ground structure and it's foundations so a 300mm diameter diamond core was drilled above each to a depth of 4.5m and a 273mm diameter permanent liner inserted. This ensured that all the load was carried on these piles and wasn't transferred to the existing columns.
A 250mm diameter sectional flight auger was then used to bore through the toe of the liner creating piles between 11 and 17m deep. As an added complication, some of these piles were as close as 500mm from the newly rendered party wall of an existing building.
Due to the 5 ton structural capacity limit of the supported cellars beneath, a Klemm 702 was used.
Material was removed from above the cellars so a layer of polystyrene could be put down to support the new RC slab on the piles.
Unit 19 - Storage and Refrigeration apparatus for the new Asda
As opposed to the previous unit, we were now required to form piles and pile caps to support the store above from inside the existing cellars.
Due to the confined area we were working in, the rigs' power packs, the grout mixers and all other powered equipment was located above ground to prevent the build-up of diesel fumes.
We were installing 350mm diameter sectional flight auger piles to a depth of 8m from within cellars with a headroom of 2.4m. There were 3 to 6 piles to each cap, to be formed at floor level, and the main contractor was then going to install steel columns through the roof of the cellar to be fixed to the caps. This would ensure the load would be distributed evenly between all the piles under each cap.
Unit 12 - Multistorey Car Park
This structure was to become the new 535 space multi-storey car park. To date, this is the only part of this project to resemble a normal open site project and as there were no existing structures beneath this location we were able to utilize the Soilmec CM50, a much larger and heavier rig than those used previously. We installed 450mm diameter CFA piles with 800kN compression and 40kN horizontal loads and 300mm diameter CFA piles with 350kN compression and 40kN horizontals.
Our client, Carillion Richardson, is very happy with the work we have carried out and the timeframe in which we have done so. This project has posed a number of unusual, restricted access challenges and by working closely with the project team, we have been able to propose, and implement, the most cost effective solution for each part of the works.
