To complete the AG Center quests you'll need to shut down the irrigation system. Here's how.
From the main lobby take the corridor north of the entrance, taking out any pods as you go. Hit them from a distance so you're not getting infected, and go all the way until you get to the central basement.
Entering the basement, you'll need to use the Computer Science skill on the large computer up against the wall. If your skill is higher enough you should have no problem unlocking all the airlocks. If not, you'll have to do them one at a time, coming back to the computer to unlock them as you go.
Open the eastern airlock and send someone with Lockpicking skills to open the door on the right. If you have no decent Lockpick skills send Angela Deth and she can Brute Force her way in. There's a poison cloud here, so make sure you enter Solo mode using Space otherwise the whole team will get in trouble. Whoever you send, make sure they have plenty of bandages and Pain Relievers.
Once inside click the last switch on the wall ignore the rest for now. When the fans shuts down send Angela or another character to use Brute Force on the door down the corridor to close it. They will take damage again from the poison so make sure they have some protection. Now go back down the tunnel into the room with the switches and flick them all on. The fans will begin to clear the eastern tunnel, but there's one left to take care of.
Go down the hallway, around the corner to the closed door. Open is and use a weapon to cut the vines on the remaining fan. Now turn them all on and clear the eastern tunnel.
Explore the room directly opposite the switch room. There are enemies to kill and loot to pick up, but be careful of any boobytrapped boxes. Use the Demolitions skill to disarm them. Now take the whole party down the eastern tunnel where you'll find a ladder.
The Eastern Fields are full of enemies and pods. Go outside the building you've started in and you'll fight some enemies on the right. Now turn back north and destroy the pods in the way before going down the path, past the wrecked car and up the ramp. The researcher here can be saved if you use Outdoorsman of Surgeon skills to free him. If you don't help he will die
Go down the otherside of the platform and you'll see someone trapped in the fence. Fight the enemies and free Dr Larsen's assistant, Ryan. He will tell you that Dr Larsen went to deal with the irrigation valves. Now head back out of the gate. Just to the northwest of Ryan are boxes in a corner. Kill the enemies and use Perception to make sure the boxes aren't trapped before looting them.
Now go on the east path through fences where you will come across a small field of giant rabbits attacking cows. Once all the cows are dead, fight the rabbits. Loot whatever you can and head to the small pen of dead pigs. You'll see a dead man outside a small building and something written in blood. Use Perception and you'll see he was shot to death. Loot the box to his right (check for traps) and go inside the building.
Dr Larson is laying on the ground, surrounded by wildlife. Kill the enemies and use Perception again to discover all the bodies were also shot. Heal up your party before talking to Larsen, who will end the conversation and start a fight.
Larsen has a lot of action points so you'll need to make sure the party is as healthy as possible or they run the risk of bleeding out. After the fight Kathy will tell to close the valve in this room and go on through the western fields. with that done, head back to the Central Basement.
Side Quest: Find Serum to Complete Cure
Kathy in the lab will tell you she needs a serum from the mushroom cave in Central Basement. Open the airlock to the Fungal Mushroom Cave and go inside to fight some enemies. Be warned that attacking one enemy will bring them all into the fight, so make sure you have plenty of ammo and health.
Once they are dealt with, go to the eastern wall and you'll come across a small door to a storage room. Inside are two dead bodies, one with an energy rifle. Click on the closed door and you'll begin a conversation with Skinner, who's drunk.
When he lets you in you can find out some more information about the breakout. We let him join our party because more hands make light work. To get into the room at the back of the storage area you'll have to Lockpick or Brute Force your way in. Inside you'll find chests and Fungicide, which you should take back to Kathy.
Matt now gives you a key to his office, the first door on the left down the eastern hallway. Loot it and go back to the Central Basement.
Central Basement – Headed to Western Fields
Just like the eastern tunnels, the western hall is flooded with gas. Go to the door on the right side of the tunnel and use someone with Computer Science to open the safe at the back. Ignore the dead bodies.
Again, you need a single party member to brave the gas, preferably someone with Computer Science skills. Use the skill on the robot so that it clears the vines blocking the path. If that's not possible, Brute Force will work on the cracked wall past the locked door.
Note: If you don't yet have the western maintenance keycard go back to the main Central Basement entrance and loot the box and safe there.
If you used Brute Force or attacked the cracked wall you'll have to fight the enemies inside the cave and then break down the other cracked wall, switch the fan on and run to the ladder that leads to the west fields.
If you opted for Computer Science you can send the party running through the poison once the robot has done his thing, and they can switch the fan on before climbing the ladder.
After your conversation with Kathy, chop the vines off the door and go outside. Head towards the man shooting rabbits and he'll tell you where the irrigation controls are. You'll need to find spare parts to shut it down as you Kathy has asked that it doesn't get completely destroyed.
Now is a good time to level up if any of your party needs it. Press the Call button on your radio and grab the extra skill points. Now head to the door southeast of your position.
Use Brute Force or Lockpicking on the door, then Perception on the boxes to look for traps. Go back outside and past the sandbag bunker. Unlock the next door to access the generator.
If you have Rose or a high enough Computer Science skill you can hack the control panel to turn off the generator. This will save time exploring although you may miss out on loot.
If you don't have a high enough Computer Science skill you'll need to find the spare parts. Go out of the building and towards the western side of the area to find two boxes.
Check for traps (this should become second nature by now) and move up to fight some more giant rabbits. Check the rest of the boxes here. Go southeast to the door you entered after picking up the old man and grab the Flow Regulator. Use it on the generator and then go back to the main level.