Complex sentence: The town developed during the communist regime as part of the industrialization program, being built here a phosphates factory in the 1970s, that polluted the Black Sea and the Lake Tasaul with toxic dumps.
Split into simpler sentences: The town developed during the communist regime as part of the industrialization program. Here, in the 1970s, a phosphates factory was built that polluted the Black Sea and Lake Tasaul with toxic dumps.