Pre-Prep School, Bishop’s Stortford

Due to expansion, Bishop’s Stortford College needed to enlarge the capacity of their pre-prep facilities. To make this requirement possible proposals were laid to accommodate an additional 180 places plus associated staff in a single storey structure designed by Hollins Architects on a vacant fallow site to the south west of the college.

The project was secured under a design and build contract procured by Grehan Contractors Ltd. Contractors Design Services were pleased to provide them with Structural and Civil engineering services in connection with the design and specification of the new load bearing masonry structure and its foundations together with a third of a kilometre of access road and 1750 square metre car parking facilities.

CDS were also charged with the design of the drainage that serves both the building and the roads, etc. where a solution had to be found to store the foul water generated by the new school facility during the day before discharging same via the college's existing drainage system over night to prevent overloading.

Hartley Jam Factory

Contractors Design Services were appointed by Squibb & Davies to design the temporary works to the contiguous bored pile, lined underground car park and provide logistical advice on excavation sequence and methodology.

The overall plan size of the new car park was approximately 60m. long x 30m. wide by up to 11m. deep containing 3 levels of car parking for the new residential apartments at the site of the former Hartley’s Jam Factory in Bermondsey, South London.

Two levels of internal propping were provided using high grade tubular steel sections and two lines of temporary kingpiles to reduce the span. The permanent reinforced concrete capping beam to the contiguous piles was used as a top waling, whilst twin heavy U.B. sections diaphragmed together were adopted for the lower.

The sequence of excavation had to be carefully assessed to minimize asymmetric loadings on the temporary works whilst maintaining an efficient and practicable means of spoil removal to achieve a tight schedule. The removal sequence and details were tightly co-ordinated to ensure various criteria were achieved for the Managing Contractor, Mansell, such as * Water proofing details * Maintaining acceptable stresses in the contiguous piles * Limiting pile deflection * Allowing economic progress of the formwork contractor * Ensuring the part constructed structure could sustain the applied temporary loadings * Allowing installation of continuous sections of services

Notting Hill

Major re-development of a period family residence in the exclusive Notting Hill area of London.

Works consisted of demolition of the existing 3 storey detached property with the exception of the feature rendered façade and the two masonry flank walls: construction of a new 3 – 4 metre deep basement including pool and two upper floors in steel with either concrete or timber floors

Contractors Design Services acted as specialist design consultants to Principal Contractor, Westgreen Construction Ltd for the temporary façade retention and for the support of the new basement excavation. An internal flying shoring system using proprietary components (Mabey System 160) was adopted to temporarily stabilise the retained external walls prior to demolition. Working closely with Mabey Hire, CDS oversaw its design and installation issuing Permits to Load to comply with current good practice.

For the new basement construction, CDS offered an alternative support solution based on Giken Europe BV’S patented ‘Zero’ sheet piling system. This realised several key advantages over the original contiguous bored pile and underpinning design, not least being the vastly improved construction period.

CDS designed the sheet piling and its temporary support to minimise ground movements during excavation to the satisfaction of the client’s consulting team and those of the adjoining owners. A structural monitoring system was also established under CDS’s control to confirm that movements were in line with predictions and to give confidence to adjoining owners.

Oxford Castle

Archaeological investigations indicate the site of Oxford Castle, latterly Oxford Prison, has been occupied since the time of the Norman Conquest. The original wooden constructions were replaced with stone structures that eventually formed the western defences of the city of Oxonforde. Having played its part in the 1642-1646 Civil War the castle fell into disrepair.

Picture engravings dating back to 1769 indicate the presence of the City Gaol on the site. From that date onwards the prison facilities were enlarged upon until the latter half of the 19^th century when they reached their present stage of development. The prison finally closed in 1996.

The Castle buildings are currently undergoing substantial renovation by Oxford Castle Ltd, an Osbourne Group Company, in partnership with English Heritage and Oxford City Council to convert them into hotel accommodation that will include museum facilities. The total out turn cost of the development has been put at £35m.

Due to their historical importance the buildings have been given the highest grade of listings by English Heritage. Contractors Design Services were pleased work in conjunction with GDG Management Ltd, architects The Architects Design Partnership and Jeremy Dixon Edwards Jones and structural engineers Alan Baxter Associates to provide sympathetic temporary works solutions to support the existing structures during the alterations.

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CDS, Unit 74, The Maltings, Roydon Road, Stanstead Abbotts, Ware, Herts, SG12 8HG
Tel: 01920 877077, Fax: 01920 870011, Email: enquiries@contractorsdesign.co.uk