Here are a list of engineer units that took part in the Normandy invasion.  As you can see it is very, very extensive.  I don't think that people realize the scope of the operation for D-Day.  These are JUST ENGINEER units, period.  It kind of brings things to focus.
 
Of course we would have to go in and eliminate units and narrow it down to just those who landed on Omaha for you.  But as you can see, it would be helpful to have a bit more info, even a patch or something to go on...   
 
Divisional Units
 
1st Engineer Combat Battalion - 1st Inf Div
 
121st Engineer Combat Battalion - 29th Inf Div
 
4th Engineer Battalion - 4th Inf Div
 
307th Airborne Engineer Battalion - 82nd Airborne Div
 
315th Engineer Battalion - 90th Inf Div
 
326th Airborne Engineer Battalion - 101st Airborne Div
 
Here are the non-divisional units...
 
HHC, 5th Engineer Special Brigade 
 
HHC, 6th Engineer Special Brigade
 
20th Engineer Combat Battalion 
 
37th Engineer Combat Battalion 
 
38th Engineer General Service Regiment (less Band) 
 
49th Engineer Combat Battalion 
 
112th Engineer Combat Battalion 
 
149th Engineer Combat Battalion 
 
234th Engineer Combat Battalion 
 
237th Engineer Combat Battalion 
 
238th Engineer Combat Battalion 
 
254th Engineer Combat Battalion 
 
299th Engineer Combat Battalion
 
336th Engineer Combat Battalion 
 
348th Engineer Combat Battalion 
 
502d Engineer Light Ponton Company 
 
503d Engineer Light Ponton Company 
 
531st Engineer Shore Regiment 
 
582d Engineer Dump Truck Company 
 
602d Engineer Camouflage Battalion 
 
610th Engineer Light Equipment Company 
 
612th Engineer Light Equipment Company 
 
819th Engineer Aviation Battalion
 
991st Engineer Treadway Bridge Company 
 
992d Engineer Treadway Bridge Company 
 
996th Engineer Treadway Bridge Company 
 
RHC, 1106th Engineer Combat Group 
 
HHC, 1121st Engineer Combat Group 
 
HHC, 1171st Engineer Combat Group 
 
1219th Engineer Fire Fighting Platoon 
 
1340th Engineer Combat Battalion 
 
1605th Engineer Map Depot Detachment 
 
2013th Engineer Fire Fighting Platoon
 
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This list identifies Army units that were awarded assault landing credit for the Normandy invasion, 6 and 7 June 1944. It includes all units except for platoons and detachments that were a part of larger organizations and is based on the following War Department and Department of the Army General Orders: WD GO 70, 1945; WD GO 75, 1945; WD GO 116, 1946; DA GO 23, 1947; DA GO 72, 1948; DA GO 6, 1950; DA GO 37, 1950; DA GO 32, 1953; and DA GO 28 1956.