This side-mission can be found by entering the Normandy’s galaxy map and having the ship travel to the following location:
Hades Nexus > Shiol > Gei Hinnom.
Scan the planet and locate the anomoly to begin the mission.
After you land, look behind the crates to the right for some Refined Palladium . Have a look at the log on the table to the left if you are interested and pick up the Medi-Gel off the ground. Head through the small passageway at the far side of the camp and you will exit into a large area. On the left you will find a wounded Quarian.
Examine the Quarian to trigger the appearance of several waves of Varren. The Varren are pretty keen to eat the Quarian and will attempt to attack it. In turn, you will need to defend the Quarian from their attempts. There are three caves the Varren will enter the area from. The first two to watch out for are on the wall directly opposite the Quarian and the third is further down the wall to the left. After you have killed around twenty Varren, your shuttle will land. Use the action button on the door to complete the mission.