The best way is to siphon it out. The 1961 shop manual has detailed instructions on how to do this. Followed these and it worked fine.
It is in the gas tank.
The gas tank on the 2012 Chevrolet Impala holds 17 gal..
The gas tank on the 2002 Chevrolet Impala holds 17 gal..
The gas tank on the 2009 Chevrolet Impala holds 17 gal..
The gas tank on the 2005 Chevrolet Impala holds 17 gal..
The gas tank on the 2014 Chevrolet Impala holds 18.5 gal..
The gas tank on the 2006 Chevrolet Impala holds 17 gal..
The gas tank on the 2001 Chevrolet Impala holds 17 gal..
The gas tank on the 2004 Chevrolet Impala holds 17 gal..
The gas tank on the 2007 Chevrolet Impala holds 17 gal..
The gas tank on the 2011 Chevrolet Impala holds 17 gal..
The gas tank on the 2008 Chevrolet Impala holds 17 gal..