(KMOV) -- A billion-dollar expansion at the Conoco-Phillips oil refinery in Roxana, Ill. could lead to big economic growth in the Metro-East.  

There are already about 2,000 construction workers working on the site right now.  By this autumn, that number is expected to double. 

The River Bend Growth Association, which is the economic arm for 11 communities in the Metro-East, says the project will create $19 million a year in local and state tax revenue to go along with 500 long term jobs once it is complete in 2011.

After recent reports of poor air quality in Madison County, Conoco-Phillips says pollution will decrease with this new addition to the refinery.