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To attract developers to take on proposals to redevelop a large brownfield site in Essex, Capita Symonds was chosen to assess hurdles and solutions.

In late 2009, Thurrock Thames Gateway Development Corporation embarked on a procurement process to regenerate a 57ha brownfield site in Purfleet, Essex, to deliver a new centre. Financed and delivered by a public-private partnership, the ambitious Purfleet Centre project proposes the construction of more than 3,500 homes, a health and community centre, shops, work spaces, a primary school, a public square and open space, and could generate more than 1,100 jobs.

Recognising that in current market conditions securing the right private sector partner for a site of this scale and complexity would be challenging, the Thurrock Thames Gateway Development Corporation (TTGDC), which is charged with delivering the Purfleet Centre project, realised that it was essential to catalogue all of the site's potential risks and then identify solutions to them.

Following a tendering process, the Corporation appointed Capita Symonds to examine the site. "For the Corporation, spending money to assess the land as far as possible before they sold it made complete financial sense," says Paul Landsborough, Associate Director at Capita Symonds. "The assessment work provides certainty and is much more likely to bring forward good quality bids from development consortia."

The site

The Purfleet site comprises a number of fragmented plots in the south-western part of West Thurrock, an area historically known for its chalk quarries, but which has been home to other industries since the late 19th century. A former paper mill still dominates the waterfront site and the central area houses a range of businesses, including warehousing, haulage and waste storage firms. Purfleet also includes a disused wharf on the waterfront and a former oil storage tank in the central quarry area. Many of these factors could complicate development.

However, the site has enormous potential due to its excellent transport links. As well as being just 20 minutes by train from Fenchurch Street station in central London, it is close to the M25 London orbital motorway and the site's southern portion is on the north bank of the river Thames in the shadow of the iconic Dartford road bridge.

The Corporation's vision for the area is outlined in the Purfleet Centre Development Framework. The document, drawn up in 2009 by consultancy Urban Initiatives, proposes a new urban centre that would increase the town's population from around 5.000 to 12,000, with the opportunity to provide a broad mix of homes, jobs, shops and services.

Procurement

Capita Symonds was one of ten consultancies that bid for the lead technical role through the Homes & Communities Agency multidisciplinary framework. Prior to the formal tendering process, Capita Symonds met with the Corporation to gain an early understanding of its requirements. This enabled the consultancy to establish a working relationship with the Corporation and to tailor its bid documents to reflect exactly what the TTGDC was looking for in a lead consultant.

"The Corporation was very proactive in letting consultants know that it would be tendering," says Mark Hirst, Director of Development, Transport & Environment at Capita Symonds. "We took advantage of that and started talking to the Corporation before the tender went out."

Following the bid stage and interview process, Capita Symonds was appointed to the project team as the technical lead consultant advising on environmental issues, engineering and infrastructure.

Baseline assessment

Capita Symonds' initial role was to develop a comprehensive set of data about the site, which was used to ensure that developers bidding to become partners on the project knew as much as possible about the risks and opportunities involved. The team set about identifying technical, commercial and financial risks, as well as recommendations on how these risks could be managed. This involved input from a number of disciplines including air quality, archaeology, ecology, flood risk, geotechnical engineering, ground contamination, noise and vibration, traffic and transport assessment, and utilities and services.

The baseline review confirmed the Corporation's original thinking: that the site, while having excellent development potential, had various potential technical problems that would require further assessment and management. A programme and budget for further survey works was agreed to fill in the identified data gaps and better understand the key development considerations.

Further survey works

The first issue the team examined was flood risk. The Purfleet development, although well protected by flood defences, was planned for a zone that the Environment Agency defines as being at "higher risk" of flood. It was clear that flood risk mitigation needed to be incorporated into the development proposals to satisfy current planning guidance. Drawing on its existing relationship with the agency and its detailed knowledge of the site, the team quantified the level of existing flood risk and developed several flooding scenarios to assist in the creation of a workable and cost-effective mitigation strategy.

As with any site containing former industrial works, assessing pollution was a major area of programme and cost uncertainty. The Capita Symonds team linked all of the existing information with the future development proposals, identified higher risk land plots and managed a programme of ground investigation works. These works covered approximately three-quarters of the site and involved approximately 400 boreholes, more than 1,000 soil samples and 200 groundwater samples. Using this information, the team was able to assess the extent of the ground contamination, identify how much it would cost to make the land fit for development and propose a timetable for remediation.

In tandem with the ground contamination investigation, a programme of geotechnical testing was undertaken which confirmed the accuracy of published information about the site's geology. Using this information, Capita Symonds developed possible designs to ensure that the foundations of a range of low and high-rise buildings that would form part of the Purfleet Centre masterplan took into account the geology.

"Carrying out such a comprehensive assessment enabled us to work out how to piece the jigsaw together," says Landsborough. "It enabled us to work out strategies for combining solutions to different problems. This will save costs in the long-run."

Outcome

In the end, Capita Symonds produced a suite of 30 technical reports tailored to a commercial audience and provided data on a range of common development issues including flood risk, ground contamination, geotechnical, acoustics and drainage and utility provision.

The complete data set, which was finished in April 2010, provides an invaluable tool in support of the procurement process. The data enabled Capita Symonds' team to develop costs for dealing with key potential development hurdles and advise the Corporation on the significance of technical constraints to the emerging masterplan. Ultimately, the quality and quantity of data will enable all parties involved in the procurement process to know what issues and opportunities they are talking about, which should help to ensure that a technically and financially robust scheme is brought forward.

Simon de Vere, Programme Manager at the Corporation, says: "I am delighted with Capita Symonds' contribution to this project. The technical and environmental issues that are involved are extremely complex. The commonsense approach being adopted by the team has made significant benefits to the overall programme, and will add value to the discussions to be held with potential partners."

Capita Symonds management team for the Purfleet Centre (l-r)

• Mark Hirst, Director of Development, Transport and Environment
• Paul Landsborough, Associate Director
• Nadia Dew, Project Manager