Вся эта работа будет стоить примерно 1.6 млн.дол.США.

Cost of these works will make about 1.6 mio USD. ??

estimated cost of work "is" USD 1.6 million

Monetary amounts are formatted as numerals preceded (with no space) by the three-letter currency code set by the International Standardization Organization (ISO), Standard ISO 4217.
USD5000 (US dollar)
CAD80,000 (Canadian dollar)
GBP145 (UK pound sterling)
EUR620 (European Union euro)
RUB10,000 (Russian ruble) (NB! RUR is now obsolete and refers to rubles prior to 1997 denomination)
A legal convention requires to repeat a spelled-out number in the numerical form. Always put the numeric representation in parentheses after the spelled out quantity. (Note that in Russian legal documents this order is reverse).
Incorrect
USD20,000 (twenty thousand)
Correct
Twenty thousand US dollars (USD20,000)