In an exclusive Bristol suburb, Vinci Construction is building a new private health facility and redeveloping a listed building while keeping noise and vibration to the minimum.
Project: The Chesterfield Hospital redevelopment
Client: Nuffield Health
Contract value: £11m
Main contractor: Vinci
Architect: Kendall Kingscott
Start date: March 2012
Completion date: August 2013
Senior project manager at Vinci Construction Martin Cocks knows he has a job on his hands.
As if building a new 30-bed private hospital with all the bells and whistles expected of a top-class hotel wasn’t enough, he also has to oversee the redevelopment of a 250-year-old Grade II*-listed Georgian merchants villa, juggling the demands of renovation officers with those of state-of-the-art hospital facilities.
It’s a difficult task to bring in the £11m construction and fit-out phase of the £20m project anyway thanks to the site’s location, hemmed in on a tight parcel of land surrounded by some of the most expensive properties in Bristol.
It doesn’t help that the knoll of rock into which the piles and basement of the new-build section are being dug happens to be some of the country’s toughest. Although the carboniferous deposits are fractured and friable on site, it has still been tricky to install the forest of piles that cover it.
Don’t upset the neighbours
“Clifton is one of Bristol’s most exclusive suburbs and we are working right alongside a number of expensive, historical properties, not least the villa itself,” says Mr Cocks.
“Because of that and to make sure we don’t upset the neighbours, we are being extremely careful throughout the process to keep noise and vibration to a minimum.”
Vinci first tendered for and won the £11m design-and-build contract in October 2011 but didn’t really get started on site for another six months at the beginning of March 2012.
“By choosing the King Post solution, we were able to cut down on noise and install the precast planks as we excavated”
Martin Cocks, Vinci Construction
There has been a hospital on the site since the 1930s, and the demolition and site clearance work included asbestos removal and demolition of a cluster of supplemental buildings to the villa.
The construction phase will see the refurbishment of the Georgian villa and the construction of a three-storey-plus-basement 30-bed hospital and diagnostic centre.
“Our client Nuffield had owned it since the 1950s and ran it as a hospital until seven years ago. It’s been empty ever since,” says Mr Cocks.
“There was some asbestos strip-out but the main issue during demolition was to keep dust levels down.”
Considerate piling reduces impact
The design of the piling and basement has been carried out with a view to minimising impact on the neighbouring properties, too.
Instead of installing a contiguous piled wall to form the basement, the team elected to use a King Post solution. This involved placing 450 mm-diameter piles at 2 m centres and augured into the rock at 8 m below basement slab level, which itself is 4 m below existing ground.
Precast concrete planks were then installed between each of the piles as the basement was excavated, providing support to the sides as the dig progressed.
“The piles were socketed around 8 m below basement level,” explains Mr Cocks. “The rock here has lots of faults and fissures running down through it at an angle of about 30 degrees.
“By choosing the King Post solution, we were able to cut down on noise and install the precast planks as we excavated.”
In all, 100 King Post piles have been installed around the building’s perimeter with a further 100 bearing piles, also at 450 mm-diameter, installed throughout its footprint.
Minimal vibration appeases residents
Vibration was monitored throughout the piling process and kept to a minimum, part of a raft of good housekeeping measures the Vinci team has introduced to help appease the neighbours.
“We couldn’t have the plant on the roof because of the noise and height restrictions under the planning consent”
Martin Cocks, Vinci Construction
The structure of the new-build section sits at the back of the villa and is cast in situ reinforced concrete with 300 mm-thick slabs.
Grid pattern across the columns is at nominal 7 m centres, but these vary where there are specific client requirements such as smaller diagnostic rooms or where the team has needed to futureproof the building and provide room for the installation of replacement MRI scanners or X-ray equipment.
The basement itself will house both the building’s plant room and diagnostic equipment such as the MRI scanner. An access pit has been set aside so the scanner can be manoeuvred into position.
Trading up a merchant’s villa
Alongside the new-build hospital, the Vinci team is refurbishing the existing Grade II*-listed early Georgian villa into reception rooms, waiting rooms and offices for the new facility.
Originally built in the 1740s as a house for local merchant Nehemiah Champion II, who made his money in the brass production industry, the house features the ornate cornices, fireplaces and stair balustrading typical of the period. These are earmarked for preservation under the star listing.
The main structure is also being retained, with a slight extension to the original stable block annexe, which will become the kitchens and medical gas storage for the new hospital.
One elevation of the original building features black slag blocks, thought to be a by-product of Champion’s brass production business.
“There is some death watch beetle and some damp but it’s stood the test of time very well,” says Mr Cocks.
A new Welsh slate roof is being installed with rafters, and purlins being replaced and repaired as required.
Brick work will be repointed and rendered using lime mortar and lime render so that the building can ‘breathe’ a little to prevent any damp.
The stable block extension will be completed sympathetically with the rest of the building but won’t be built to look exactly the same.
The ground floor will feature three operating and diagnostic theatres as well as the reception areas. The first floor is dedicated to patient bedrooms, with the consultant treatment rooms on the top floor.
“We couldn’t have the plant on the roof because of the noise and height restrictions under the planning consent,” says Mr Cocks.
Requirements restrict deliveries and pours
Other planning conditions have affected the build. In a mainly residential area with narrow roads, work has been restricted to 8am-6pm in the week and 8am-1pm on Saturdays.
Deliveries can only reach the site on a pre-set route and Mr Cocks and the team limit the size of the concrete pours so that there is no fear of running over the standard working hours.
“The relationship with neighbours has gone from protests to talking about how good and proactive we have been”
Andrew Hutchings, Vinci
Waterproof concrete has been used in the basement area with material for the columns being skipped in by the 27 m-high, 45 m-radius luffing crane and pumped into place for the slabs. The largest pour the team has accommodated so far is 200 cu m, but Mr Cocks admits that was starting to push the time constraints.
“We were cutting it a little fine on that one,” he says. “The concrete comes from Tarmac’s local batching plant and we look to have one wagon being unloaded, one waiting and another on the way.”
With work due to finish at the start of August 2013, and the hospital opening soon after, there is still plenty to do before the first patients start to arrive for their consultant check-ups.
Team turns tide of anti-development locals
It’s fair to say that this project is being carried out under closer scrutiny than any Martin Cocks and senior quantity survey Andrew Hutchings have been involved in during their long careers.
A fervently anti-development neighbourhood association fought the project all the way through the planning process. Now the Vinci team is on site, the focus has shifted from planning concerns to practical objections.
“I think really the neighbours just don’t want a building site at the bottom of their gardens for 15 months. I can understand that and it’s down to us now to make sure we do as much as we can to keep disruption to a minimum,” says Mr Cocks.
But by keeping the residents on-board through sticking to the planning conditions and implementing a self-imposed noise level of 0 dB above ambient, the team has managed to turn the tide of neighbour frustration.
“From the very beginning we have explained what we are doing and focused on what we can control,” says Mr Hutchings.
“Our first assessment under the Considerate Constructors Scheme gave us a mark of 37.5 from 40.
“In terms of the relationship with our neighbours it has gone from protests and picketing to talking about how good and proactive we have been.”