Move on up and watch the quarians get take out by the geth dropship. Things just can't ever be easy. We need to blow that pillar up with some explosive charges. Push forward and turn into the little garage on the left. There are a lot of geth in here, so don't just charge in. Hang back on the first wall and start shooting. There should be a geth hunter inside, so take him out first. You squadmates won't shoot at him when he's cloaked, so you're the only one who can bring him down.

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Once the garage is clear, advance up and play Tali's journal. You can get some medi-gel in back and also grab the first of the demolition charges. Try to move out, but then stop and take cover. A few more geth will drop in to cover the exit, so we need to bring them down. There's a Geth Prime too, so put down a lot of heavy fire and abilities on it.
Advance and turn to the left. There will be a few more geth ahead, but the area should be fairly clear. Get into the bunker at the back and grab the charges. We're not even close to done though. A huge wave of reinforcements will drop in outside the door. As one of your squadmates should point out, you're not in a good position. Move out to the left quickly and get up the stairs. You can then flank the two rocket geth on the bridge and use this position to mop up any stragglers on the ground. Your squad should do fairly decent damage while you're handling this though. Just keep an eye on the destroy and stay low.
Run back to the pillar and plant the charges. Get clear and then head into the bunker. The area is full of dead geth. Loot them all, loot the safe, and scan the rifle. When you're ready to go, play Tali's journal and the access the comm console. She'll confirm her location and open the door up to the second half of the ruins. Go through the door and get behind cover again.