I found the fastest way to do this go into a private match, single player easy. The 4th New York stage has a ton of mines not to far into the level. Crouch to approach the mines and not set them off. This level also has a few turrets at the start you can take over for the turret achievement. You will have to reload a few times for that one, but can get the defuse mine achievement in two runs problems. I am pretty sure you can just get to the mines, diffuse, quit out, and do it again.