1998 Chevy Blazer Fuel line

Where is the leak located in refference to the gas tank? In order to change the fuel pump the gas tank must be removed or dropped down from the blazer. On the fuel inlet and outlet lines at the pump, there are two small o-rings that seal each of the fuel lines at the pump. They should be changed when the pump is replaced because it's very easy to damage them when you remove them from the pump and it is a lot of work to get to them, so while they are disconnected they should be changed.
However, considering that the blazer is ten years old, and the fuel lines are steel , the leak also may be a rotted out fuel line. Yes, the fuel line may have been bumped but this probably was not intentional or intended. If it was rotting away this would have happened anyway. Also check the fuel hose inlet ( where the fuel enters the gas tank from the gas pump ). Sometimes removing the gas tank loosens the hose up...or breaks it...
You are right in being afraid of driving it. A gas leak is very dangerous and should be fixed immediately. However, if the mechanic gives you the bull that the gas smell is normal or something like that change mechanics!! Do not let this guy touch your vehical.. Ask him if he would put his own kids in a vehical with a gas smell.. That is just crazy. If a good mechanic changed a fuel pump, and smelled gas afterwards , the problem should be solved before the vehical is even allowed to run let alone leave the garadge! I'm willing to bet that this guy changed the fuel pump with a lit cigar in his mouth --didn't he---?
If the fuel lines need replacing MAKE SURE that steel fuel lines or high pressure fuel injection hoses are used, because the fuel pressure in your engine is very high. Regular fuel hose cannot stand up to this high pressure; and if it's used it will burst. Fuel injection hose is around a dollar fifty a foot, regular fuel hose is about 20 cents a foot. Big difference but VERY IMPORTANT! keep me posted