Surveying service pinpoints buried hazards on brownfield sites

As available greenfield sites become more scarce, house builders and developers are facing increased pressure to build new property on brownfield sites. In addition to the inherent remediation issues of each site, significant problems exist with buried services. In a special contribution, IETG outlines the role of a newly formed, dedicated utility location company that is providing innovative solutions to the problems.

The requirements of the contaminated land regime, environmental assessment, IPPC and ISO14001 require landowners and users to be more pro-active than ever before about investigating the condition of land being acquired or developed. In response to these requirements, 40SEVEN was recently launched as the first dedicated underground utility surveying company within the UK marketplace. It operates on a nationwide basis and has the largest team of surveyors in the country.

Spearheading the latest non-destructive testing (NDT) technology, the joint venture is a collaboration between IETG (Integrated Environmental Technology Group plc) and LTU (Lord Technical Utilities Ltd). It combines the operational experience of IETG with the technical expertise of LTU to provide a comprehensive surveying solution and has developed an approach to sustainable urban development that is gaining widespread acceptance.

Underground hazards

The development of brownfield sites carries with it a significant amount of risk and to aid compliance with the HSE's guidance document, HSG47, Avoiding Danger from Underground Services, it is now recommended that a utility scan is carried out before any on-site digging commences. In addition to the costs associated with the remediation of contaminated land, where considerable understanding has already been gained on the dangers from contaminants, the effective location and identification of buried services can affect the feasibility of any brownfield site development and, surprisingly, is often overlooked.

Historically, existing data on buried assets, found within statutory records, is normally the sole source relied upon although they can often be inaccurate, incomplete or out of date. Subsequently, the resulting failure to establish the accurate position of a buried utility or other potential hazard is not only costly, but has serious health and safety implications.

40SEVEN has been assisting local authorities in all aspects of underground service location prior to the design stage of projects. With the production of accurate utility maps, councils have been able to plan and avoid utility diversions and identify clear or unused space below ground. This is definitely a change from the normal practice where, within the engineering industry, uncertainty was widely accepted and, in a number of cases, the costs of striking underground utilities and subsequent diversions were built into the project costs prior to a spade being put into the ground.

Survey in North West

A recent survey was carried out by 40SEVEN in the North West of England to assist both the local council and the developer to plan the redevelopment of an old council estate. To carry out the successful location of underground services, surveying was divided into two discrete stages.

Firstly, a desk study was carried out using the historical information (that was previously the sole information source) to establish the past uses of the site and the surroundings. The information gathered and reviewed included not only the land usage but also information from statutory bodies and local authorities about the site and the surrounding area and data regarding the location of existing utilities.

Secondly, non-destructive testing (NDT) was carried out on site to locate and plan out the route of underground services. Using "Best Available Technology", such as the new Mala Ground Penetrating Radar, surveyors identified not only the precise location of utilities, the relationship between them and their depth from the surface; they also identified the unused space below ground. This enabled planners to map out the routes of the new pipelines and cables and decide where foundation and substructure work could be carried out.

As a result of the survey, the local authority in question was able to demonstrate an overall cost saving through the provision of accurate plans. This enabled the contractor's fees to be reduced as they did not have to carry out any investigations before work started on site. Also, unexpected surprises were avoided which would have led to both the expense of redesigning plans and suspending work on-site until the correct utility layout could be determined.

The surveying techniques adopted by 40SEVEN can be used by local authorities for other applications such as highway maintenance and construction, resurfacing schemes, flood defence schemes, drainage and land drainage location and long distance pipe and cable tracking. Using non-destructive technology to provide accurate utility maps is both cost effective as it is quicker, more reliable and reduces the need for "digging" permits. It is also more convenient as there is less of a likelihood of utility customers having their supply interrupted by "accidental strikes".

Recent targets set by the government state that 60% of new homes need to be built on brownfield sites. Combined with figures from the National Land Use Database that estimate that there are 17,300 hectares of derelict land nationally which would need some form of remediation before it could be re-developed, and the necessity of adopting up to-date surveying technology that is both cost effective and reliable becomes a paramount issue for planners and developers.

For further information contact Peter Ashcroft, Sales Director for 40SEVEN.

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