Mihael Brencic% Andrew Dawson, Lennart Folkeson, Denis Francois and Teresa Leitao
Abstract There is often a risk of pollution entering or moving in the road environment. This may give rise to problems of various severities dependant on the local environment around and under the pavement. Therefore the risks have, first, to be assessed and then appropriate action taken to minimise the movements and/or the impacts. This chapter describes the criteria to be applied when considering pollution mitigation schemes and the constraints that must be taken into account. Both traffic considerations (which often form the driver for pollution supply) and economic considerations are included in the coverage of the chapter together with some comments on site sensitivity. In particular, the chapter provides a framework for considering alternative mitigation strategies against a background of the benefits and limitations of each. Pollution mitigation measures are only mentioned where they are identifi — ably different from conventional drainage measures which are covered more fully in Chapter 13.
Keywords Pollution control ■ impact mitigation ■ flow disruption ■ site sensitivity
Roads and road traffic can act as serious sources ofvarious types ofpollution. Pollutants spread to the environment through different pathways, with different transport agents and mechanisms. Once pollutants are transported away from the road and traffic sources they can reach various environmental compartments where they can have detrimental effects. Pollution from roads and traffic must be managed and its harmful affects prevented at all stages, especially in environmentally sensitive areas.
The objective of this chapter is to describe general principles of prevention and mitigation of pollution that originate from road and traffic operation and that can influence the water environment. Consideration was taken mainly of mitigation of [27] deleterious effects caused by seepage water. Pollution prevention and mitigation is associated with several constraints that can be classified in five major groups; site sensitivity and vulnerability, risk and hazard to pollution, traffic characteristics, economic and legislation constraints.
In the second part of the chapter general principles of mitigation methods are described. A new classification of mitigation approaches based on the pollutant fate model that consist of the chain sources — pathways — targets is described. Classification is described based on the ex-situ and in-situ mitigation methods and descriptions of intervention and non-intervention mitigation measures are also introduced.
The content of this chapter is very much connected with the next chapter “Recommendation for the control of pavement water” where design and technical measures for pollution prevention are described.
