Realizacija projekta službeno je otpočela u septembru 2008, osam mjeseci nakon što je bivša bugarska koalicija na vlasti pod vodstvo socijalista potpisala sporazum o tome tokom posjete Sofiji tadašnjeg ruskog predsjednika Vladimira Putina.
The implementation of the project began officially in September 2008, eight months after Bulgaria's former Socialist-led ruling coalition signed an agreement on it during then-Russian President Vladimir Putin's visit to Sofia.