At the part of flood gate when your back at the the beggining of the level before
it, there is 3 blocks and you hyave to get on top of them so instead of using 
gernade jump just wait for one of you team mates to stand right next to them and
jump on the lowest one and if you look to the right when ur on it you will see 
one of the corners on the block underneath the lowest one, jump onto it and gernade
jump onto the highest block and look to ur right there is a angle on the wall that 
you can walk on, jump onto it and look to your left and keep on walking when you 
get to the part whenu have more room to walk turn around and go up the other ledge
and when u get up top of there turn around and go up the bigger angle on a diagonal
case its a bit patched so u have to scale the patch but when you get up there you 
can't jump so just walk and there are a lot blank spots that are hollow and you 
can't walk on so just go on the ledge until you get to a big red crane type theing
and jump ontop of it cause you can jump now. u just keep going until you reach a 
gap, jump over it and go until you hit a wall then look to your left there is a 
small trench that has no floor but if you stay next to the wall you can scale 
until the end then you around the corner and you walk on air now so just explore!