Issue 9 - Summer 2006

Pennine Meets its Public

Keeping clients informed about latest developments and innovations in ground improvement is an important part of Pennine's customer relations strategy - which is why you'll find us as at all the leading conferences for the industry.

In June, principal geotechnical engineer Colin Serridge presented a paper on the use of recycled aggregates in stone column techniques to the ISSMGE 5th International Congress on Environmental Geotechnics.

The Cardiff event, organised by the Geoenvironmental Research Centre at Cardiff University and supported by the Transport Research Laboratory and the Building Research Establishment (BRE), was on the theme of Opportunities, Challenges and Responsibilities for Environmental Geotechnics.

More than 300 delegates attended from over 40 countries and Colin's paper, entitled Sustainability in the Context of Vibro Stone Column Ground Improvement Techniques, was very well received, generating a considerable amount of interesting email discussion.

Pennine were also one of the sponsors of the DFI/EFFC 10th International Conference on Piling and Deep Foundations, held in Amsterdam in June.

Geotechnical specialists from Europe met to compare industry developments with fellow professionals from the USA and Pennine shared a stand at the exhibition with sister company Stent.

Next up on the conference calendar is our attendance at the Housebuilding 2006 conference at the Business Design Centre, Islington, London, on October 10 and 11.

Now in its third year the event brings together an exhibition, Housing Market Intelligence Conference, seminar programme, free briefings and the Housebuilding Innovation Awards - please come and meet us at stand m21.

And on November 22 and 23, we'll be at the Thames Gateway Forum 2006, Excel, London - the place to be for all companies associated with redevelopment of the Thames Gateway and/ or the preparation for the Olympics in 2012.

Also, civil engineers can't afford to miss the Civils 2006 exhibition at London's Olympia on November 28 to 30. It covers all aspects of the industry, with daily conferences themed on regeneration, transport and environment - see you there!

Sister Companies Provide One-stop Shop for Ground Improvement in South West and South Wales

Pennine's Gloucester office has become the first in the group to offer joint representation with sister company Stent, providing a one-stop shop in piling and ground improvement.

The office, opened two-and-a-half years ago to serve the South West and South Wales, is now run by both Pennine regional manager Graham Ellery and Stent regional manager Graham Bartlett, with more than 60 years geotechnical experience between them.

Ellery said: "We are both well known in the area we both have vast experience of piling and ground improvement and of the soil conditions that exist in South Wales and the South West.

"Together I believe we offer a formidable combination of knowledge for the complete range of piling and foundation techniques available."

The two companies have recently won a raft of prestigious contracts including work for the Gloscat project in Gloucester for Bovis Construction, an industrial project in Newport for Encon Civil Engineering, and a project for Wessex Water Authority at Maundown.

Pennine Downsize Dynamic Compaction

Pennine have downsized traditional dynamic compaction (DC) to prepare ground for development of a new school in Gateshead.

Usually only areas of ground larger than 3,000-5,000m_ are considered suitable for DC, which involves using the energy from the fall of a 5 to 20 tonne weight landing in free-fall from a crane.

But at the Highfields site - part of a new Gateshead Schools PFI project - Pennine have successfully employed the technique on a small treatment area of just 2,100m2.

Principal geotechnical engineer Colin Serridge explained: “The first choice for improving the bearing capacity and settlement capabilities of a site like this would normally be to insert vibro stone columns into the ground.

“But the problem was that the made ground contained quantities of demolition arisings, including significant cobble and large boulder size concrete and brick masonry obstructions.

“It would have been very difficult to penetrate the ground without the costly and time-consuming removal of these obstructions.

“Fortunately, principal contractor and developer Sir Robert McAlpine Ltd and consulting engineers Connell Mott McDonald called Pennine in at an early stage in the project and we were able to help them develop a practical and cost-effective DC foundation solution.

“This involved undertaking two DC treatment passes using an 8 tonne weight from a height of up to 12-15m, followed by a continuous tamping pass which involved dropping the weight over the building footprint from a height of around 5m.

“Increasingly, conventional DC is being applied at geotechnically complex sites, but a high degree of process control and data feedback is essential.

“The fact that we were involved at an early stage meant we were able to carry out all the necessary testing and vibration monitoring, as well as being involved in a public relations process to reassure the site's neighbours - including users of a nearby community centre - that the process would not be detrimental to them.”

Pennine Provides Support for Rochdale Business Park

Pennine is helping meet significant geotechnical challenges at the Kingsway Business Park, Rochdale - destined to be an area of regional and national importance.

The £225m, 420 acre site off junction 21 of the M62 will be one of the largest mixed-use parks in the North West, but its situation on the very wet western slopes of the Pennines means large areas of the site are covered by waterlogged marshland.

Designers and builders of its infrastructure, White Young Green and Costain Limited, are therefore building a series of attenuation ponds in some of the poorest areas of ground.

Pennine's contracts manager Ralph Cook explained: “To ensure the integrity of the pond linings, Costain is improving the ground beneath the ponds by digging out the compressible peat and alluvium layers and replacing them with granular material.

“But at Pond 1C they discovered the alluvium beneath the outlet area was more than 6m thick. It would have been very expensive to excavate beneath the ground water table to this depth.

“So we worked with White Young Green and helped develop a piling solution using vibro concrete columns (VCCs) and a load transfer platform (LTP) that provided the required stability at a fraction of the cost of excavating.“

In a four-week contract, worth £100,000 to Pennine, the team inserted 396 VCCs to depths of up to 10m, providing a safe working load of 150kN.

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