As noted by Dasgupta [13], the theory of social coste benefit analysis has been developed over the past 50 years, and is now, for all intents and purposes, complete [14e16]。 Following Karmokolias [17], costebenefit analysis e including externalities e has been used to evaluate public sector investment projects since the 1930s, although the practice became more widespread in the 1960s [18,19]。 Guidelines for the valuation of environmental impacts in project appraisal can be found in American manuals for inter alia water projects and recreational use of forested areas [20]。 In Europe, the history of environmental valuation in SCBA is much shorter, and the existence of such guidelines is quite limited [20]。 Manuals for SCBA can be found in a few European countries mainly for transportation projects, but most often, they do not provide guidelines for economic valuation of environmental impacts。 How- ever, these methods are applied at an increasing rate and certain studies have been carried out, particularly in the UK, Germany, Scandinavian countries, and the Netherlands [21]。

As far as the mining sector is concerned, in many countries, an SCBA of a proposed mining investment has to be submitted during the environmental permitting procedure。 Nowadays, there are cases in which the absence of an SCBA has resulted in the cassation of mining investments (e。g。 Decision Record 613/2002    of

the Greek State Council with respect to the TVX gold project in Northern Greece)。 However, there  are  no strict methodological frameworks available for conduct- ing an SCBA of mining projects。 Hence, mining practitioners should prepare SCBAs, applying com- monly accepted guidelines developed by international organizations [10,17,22e27]。 In general, the starting point for an SCBA is the financial cash flow of the project。 This cash flow is adjusted (Table 1) in order to reflect the external effects of the project and to estimate the Social Net Present Value (SNPV) and the Social Rate of Return (SRR) [24]。 From the external effects, monetary valuation of environmental impacts on neighbouring communities holds, perhaps, the most challenging position。

2。2。Environmental  liability

Environmental liability (also known as natural re- source damage assessment e NRDA) is of great significance for companies engaged in the mining sector。 Those who are involved in managing releases of contaminants to the environment may soon find themselves employed in an exhaustive regulatory pro- cess that can result in millions of dollars in expense to compensate for the lost values of environmental resources [28]。 In the US, legislation for NRDA was introduced in 1973, when the Trans-Alaska Pipeline Authorization Act identified strict liability for damages from oil spills。 The liability was extended beyond the oil industry following implementation of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) in 1980。 In 1986, the Superfund Amend- ments and Reauthorisation Act (SARA) added a new dimension to mining activities。 The economic framework for estimating the non-market value of environmental resources  was further processed by the  Department   of

Table 1

Financial cash flow  adjustments

Category of impact Influence

1。Impacts on employees

a。Wages above opportunity  cost Positive

b。Expenditure  on training Positive

2。Profits of complementary  goods Positive

3。Profits of local suppliers Positive

4。Impacts on neighbours

a。Environmental impacts Negative

b。Impacts on infrastructure