The expansion includes installation of two new GE 7EA gas-fired turbines with duct burners, a low-density polyethylene unit, a third olefins plant and a propane dehydrogenation (PDH) unit.
EPA said in a statement: "The expansion alone will bring more than $2bn in capital investments, create 1,800 construction jobs and 225 long-term operations jobs in the local area."
EPA regional administrator Ron Curry said: "Today is a major milestone in the work EPA has done with businesses and the state of Texas to ensure our economy continues to thrive while promoting cleaner, more efficient energy production and use.
"We share our success with TCEQ and the joint permitting programme our agencies started last year to process business’ applications for permits."
The GHG permits are part of regulations finalised in 2010, which require projects that increase GHG emissions to obtain an air permit.
EPA said that it has to date issued 50 GHG permits in Texas out of the 83 applications received since 2011.
