Site investigation - the maximization of data

In most instances, contaminated land management conjures up in people's min ds varying degrees of remediation practices. These may vary from dig and du mp, in situ or ex situ processes, volume reduction, containment, or even na tural attenuation. The key word, however, is 'management', in that, while a site may exhibit contamination, it may not necessarily pose a hazard. It i s only through conducting a site investigation and possibly a risk assessme nt that the hazard and associated risk can be determined. According to the International Commission on Radiological Protection (ICRP), 'the primary ai m of radiological protection is to provide an appropriate standard of prote ction for man without unduly limiting the beneficial practices giving rise to radiation exposure'. Of equal importance is the general ICRP definition of intervention as 'an activity that decreases overall exposure by removing existing sources, modifying pathways, or reducing the number of exposed in dividuals'. Interpreting these definitions is key to the provision of safe and effective management of contaminated land. Site investigation is theref ore the tool through which the supporting and underpinning information is d erived. Invariably, it is an expensive exercise and, if not carefully desig ned, has the potential to involuntary mobilize contamination or even cross- contaminate geological strata. An investigation therefore needs clearly to address the overall objectives and must be designed first and foremost with this in mind. The importance o f the desk study phase in collating existing information prior to design is often underestimated and requires special attention. Of equal importance i s the necessity to ensure that the site investigation process does nor negl ect human safety or environmental protection. While it is possible to maint ain an overall generic approach, it is important carefully to target known drivers and objectives. An investigation may be used to support any of the following, and most, if not all, are inextricably linked: (a) optioneering studies (b) delicensing part or all of a site (c) decommissioning work (d) to provide time-series data (e) to gain a quick appraisal of the problem (f) to prove safe management of the site (g) to underpin a risk assessment (h) to fulfil regulatory requirements (i) to undertake remediation. While a number of these issues will be discussed, the paper will concentrat e primarily on the maximization of data arising from geotechnical investiga tions. On nuclear licensed sites, the majority of site investigation work i s targeted at civil engineering projects, where geotechnical information is the primary aim. This data is invariably of limited use for contaminated l and appraisal and it is therefore important to design a dual or multi-purpo se site investigation of these additional requirements are to be met. Such an approach allows the follwoing: (a) maximization of the potential data set (b) alleviation of the requirement of re-drilling or sampling at a later da te (c) the collection of time-series data (d) increased environmental protection (e) reduced costs over the long term. BNFL is currently undertaking a number of pilot investigations whereby geot echnical and environmental aspirations are being merged. It is hoped that t hrough this process an increased understanding of environmental aspects of our sites can be established, thus allowing safe and effective management t o take place.