This is the only mission where you have to split up the entire team into Alpha and Bravo. Have Alpha command one engineer and Bravo command the second. Then you have to split the teams so that you can control each team individually. Use the catwalk with one of the teams to get back over to the farthest pumps safely. Take your other team and have them protect their engineer as they kill the other soldiers as they head to the closest pumps. One thing you must keep in mind is you HAVE to keep both engineers working at the same time. I would highly recommend that once you get the engineers to start defusing the first bombs that you position one SEAL facing a different direction and turn on Fire at Will. Keep an eye on the engineers because if they are hit, they WILL stop defusing the bombs and then you have to start again.
Once you start defusing the bombs, you have 3 minutes to get all four defused. There is not enough time only have one engineer working at a time. They must work at the pumps simultaneously. Once the are finished and all the bad guys are dead, then your good. But if once engineer is killed or if the timers run out, HQ will say "What were you doing out there? Those engineers were important to us. We are pulling you out immediately. You are lucky we don't have another team to replace you." This obviously means they were killed and the mission is failed.