After he graduated the courses of the Faculty of Industrial Chemistry, Dan Ioan Popescu remained in the County of Prahova where he worked first as an engineer for the Production Company Valea Călugărească (1971–1972), then as an engineer at the Institute for Research and Process Engineering in Petrochemistry and Refinery of Ploieşti (1972–1973).
On its first segment, from Ploieşti to Valea Călugărească it runs through one of Romania's most important wine regions and the site of many inns (hanuri) and historical cellars, many of which were built in the 18th and 19th centuries.