Barrett Byrd Associates

Thousands of metres of piles and beams are being installed on a former Royal Ordnance factory site in Lancashire in a quiet manner, with due regard for the concerns of new residents living nearby. Mike Walter reports

Delicate community relations are being employed on Europe’s largest brownfield regeneration scheme – a new housing and commercial hotspot in Lancashire known as Buckshaw Village. The 160ha site is an ongoing development comprising 2000 homes with parcels of retail activity, and works often take place within metres of newly occupied houses.

Buckshaw is not so much a village as a vast new sustainable urban community. Sandwiched between the M6 and M61 near Leyland, the site once housed a Royal Ordnance factory used to manufacture artillery for the military services during the Cold War. Bunkers and warehouses have since been demolished and the site remediated. The land was bought by a consortium comprising Redrow Homes, Barratt Homes, Redrow Commercial and Barratt Commercial which is developing the site for factory use and domestic properties.

It is on these residential developments that foundation specialist Roger Bullivant Ltd (RBL) is using its Quiet Hammer fleet of piling rigs to help to alleviate any concerns from nearby residents with regard to noise and vibration. The company has a rolling programme of installing foundation piles, placing beams and improving the bearing capacity of ground.

RBL contracts manager Kevin Doyle says: “One resident who lived nearby complained about the vibration and noise our works would cause before we had even begun to install piles near his home.” Kevin duly set up vibration and audio monitoring devices on the homeowner’s doorstep. “Our works were found to be well within acceptable tolerances for noise and vibration and when we stopped piling, a truck drove by and recorded a reading twice that of our rig.

“We are happy to talk through our work processes with residents to allay any fears they may have about interference or disruption it may cause them,” he adds.

The Quiet Hammer rig on site at Buckshaw Village is currently driving precast concrete piles into variable ground containing peat, inert fill material, sands and clay to depths of up to 14m, without so much as a gentle thud resonating from the works site. A patented ‘muffling’ device within the hammer keeps noise levels down and around three quarters of RBL’s driven piling rigs now incorporate the Quiet Hammer.

The issue of noise on construction sites is timely. A new European Directive on the minimum health and safety requirements of workers exposed to noise will tighten existing legislation and is set to form part of new UK Regulations to be introduced in April 2006.

Selected areas of the site that require ground improvement but do not necessitate a piled solution are being strengthened using RBL’s suite of ground improvement techniques known as ‘SystemFirst’. One such technique involves creating vertical columns of clean stone that are compacted using a vibrating lance and installed every few metres beneath plots reserved for housing and on commercial developments.

RBL’s ground improvement manager Brian Derby explains: “A charge of stone is tipped into a void and the lance reintroduced to compact the stone until refusal. Stone is built up in layers of half a metre or so, depending on the condition of the soil. At this site, each column is designed to support a load of 125kN/m².”

A second ground improvement technique being used where new warehouse units are to be built at Buckshaw is known as NRG Compaction. This involves dropping a 10t weight with a pointed base from a height of 10m.

Completion of parcels of ground improvement and piling for housing is followed by the placing of foundation beams for perimeter and party walls. RBL is using two types of precast concrete beam on site: its inverted ‘T’ beam to support load bearing walls on properties up to two storeys high and rectangular ‘R’ beam for buildings of three storeys and above.

Each beam spans two precast pile caps and changes in level of up to 300mm can be accommodated by placing small concrete ‘spaces’ with a crushing strength of 40N – equivalent to that of a beam – onto a pile cap. Between 60m and 80m of precast beam are being placed for each house, before concrete slabs are lowered into place between the beams to form a solid floor.

The Buckshaw Village development includes not only typical family homes of brick and blockwork construction, but 71 ‘entry level’ one and two bedroom properties constructed using a lightweight steel frame. Redrow’s ‘Debut’ range of steel framed homes on the site are erected quickly and secured directly into RBL’s concrete floor slab and will be available to first time buyers.

BOX: Drilling down deep to heat new homes

An innovative method of transferring heat from deep underground into hot water for central heating is currently being trialled on a handful of properties at Buckshaw Village. Barratt Homes has agreed to use a system of geothermal heating developed by foundation specialist Roger Bullivant Ltd (RBL).

Geothermal heating systems generally involve pumping fluids down into the ground through heat transfer tubes and then back up to hot water storage cylinders to provide central heating. RBL has joined forces with heat pump specialist ECR and storage cylinder supplier Gledhills to form Geothermal Heating & Cooling Systems Ltd (GHCS) and provide a complete geothermal heating service for house builders.

"Geothermal heating has traditionally been too expensive and there have been insufficient incentives for house builders to install it," says Paul Smollett of GHCS. "We have found a way of making the technique less costly and new building regulations designed to reduce energy consumption will come into force next year."

The service is based on RBL's drilling technique, which according to Smollett, is dramatically reducing the cost of installing a geothermal hole down to 30m where the ground is warm enough to heat a house.

The method involves augering the hole with a hollow drilling head and 'string', which allows coiled tubing to be passed down into the hole while the drill string is still in place and supporting the surrounding ground. After the tubing is fed into the hole, a bentonite grout mix is pumped through the drill string, which is then removed and the hole topped up with grout.

"Geothermal heating is very efficient. We have calculated that for a typical four bedroom house, it will reduce heating bills by up to two thirds each year," says Smollett.

April 2006 is when a revision to Part L of the building regulations is expected to come into force. Heating all new houses built from that date must be made 22-25% more efficient, either by greatly increasing insulation or by using renewable sources of energy, and the use of geothermal heating could help many homes to meet that target.

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