Diesel spills on the highway may reduce skidding resistance and lead to long term damage to the road structure if not removed promptly. Clearing up diesel spills causes road user delay when carriageways are closed for operative access and generates contaminated materials from the clear up. If not removed in a timely fashion, both the spilled diesel and the contaminated sorbents can pollute the environment. Diesel fuel spillages of varying degrees occur daily on the highway and are typically associated with significant road-user delay; Figure 1 and Figure 2 illustrate two typical incidents that closed lengths of UK arterial routes for several hours. Diesel fuel on the road surface not only has the potential to reduce the skidding resistance but can lead to the permanent damage of bituminous materials if not removed promptly (Balwin, Carmody et al. (2005)). There are many products available for use in the UK that may, or may not be, appropriate for diesel removal since there is little if any technical information concerning their performance. British, European and American standards already provide appropriate tests for the assessment of the various characteristics of granular diesel sorbents, however these were not immediately accessible to road network stakeholders: thus there were no simple means of knowing how well diesel sorbents performed on the road. The UK Highways Agency (HA) contracted Atkins to undertake a combined research project both to produce a specification for the performance of diesel sorbents for use on diesel spills and to undertake timeline analysis for diesel spillage incidents recorded in the HA’s Command and Control (C&C) during the period of the task to better understand the broader dynamics of the diesel removal process. Both solid and liquid products are available to neutralise, stabilise or soak up spilled diesel, however the introduction of non-solid materials on to the road surface may introduce the potential for pollution of watercourses and the UK Environment Agency advocate the use of mechanical recovery and/or sorbents to remove oil (Environment Agency (2010)): “We prefer the use of mechanical recovery and/or sorbents to remove oil from surface waters. These methods for removing oil don’t add to the water pollution and are designed to remove the oil from the water.... alternatives often require the introduction of further products to the water environment, some of which are pollutants in their own right.” Thus only solid sorbents were studied in this work. The research identified a number of tests which can be used to benchmark, in a nonsubjective manner, the performance of any granular diesel sorbent. It has also provided a simple guide to the terminology used to classify sorbents and provided a valuable insight into the components of road user delay associated with diesel spills (and how these delays might be further reduced). (Author/publisher)
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