The sewers are accessible by either a manhole between two ruined buildings in the southwest corner of town, or by stepping upon a grate in the northeastern part of town, two blocks north of the fire station and directly north of the barred up building with the dead mercenary on the stairs. Note that the sewers, much like the city above, are infested entirely with deathclaws.
Entering through the manhole, one can either head south through a large metal door or follow the sewer northwards.
The large door in the south leads to a room with a generator. A small door in the east allows access to a hallway, whose doors gives access to two rooms and a partly collapsed tunnel; the first room on the left (E) has a workbench, the second room (A) holds various loot, a deathclaw and three wall safes in the back, and the partly collapsed tunnel (B) has several bodies, among them a Brotherhood of Steel initiate with a unique power armor. The tunnel has been breached on its southern side, leading to a skeleton (C) holding a spoon and a skill magazine underneath it.
Following the sewer northwards leads to multiple deathclaw encounters. After the first curve, one can either head through a large metal door in the east or follow the sewer northwards. The large metal door leads to a small room with an average locked safe and a closet (D) with a very hard lock. Heading north instead, leads to a collapsed wall with a ladder on the left leading to the Old Olney underground (only with Broken Steel), and a door on the right leading to a maintenance room.
Inside the room, a skeleton holding an ID is located next to a locker on the western wall and an average locked terminal, found on the eastern wall, can be used to activate a Protectron. Heading through the northern door will lead to a blue door leading back the surface. Back there, one will seemingly be trapped in a small pit. However, if the grate above is lowered, one can "climb" out of the pit by facing the northwestern corner and jumping continuously while also moving forward.
- Bottlecap mine - On the workbench, in the first room to the left after heading through the southern metal door (E).
- Nuka-Cola Quantum - Next to an ammunition box, in the second room on the left after heading through the southern metal door (A).
- Fat Man - On the ground underneath the safes, in the second room on the left after heading through the southern metal door (A).
- Prototype medic power armor - On the corpse of the Brotherhood of Steel initiate, located in the partly collapsed tunnel (B).
- Medic power armor manual - On the corpse of the Brotherhood of Steel initiate, located in the partly collapsed tunnel (B).
- Duck and Cover! - Under a skeleton, at the end of the small dig south of the partly collapsed tunel (C).
- Mini nuke - On a shelf behind the very hard locked closet (D), in the room with the single average locked safe.
- Utility worker ID - Next to the skeleton in the maintenance room with the terminal.
- The utility worker ID will be scanned by the Protectron and removed from the inventory, if one gets too close to it.
- The Protectron is a unique variant, as it has yellow markings around its "ankles" and "wrists". The same markings extend to its head casing, which also has a black and white checker pattern on it.
- Upon starting the "Maintentenance Routine" via the terminal, the Protectron will detect a "critter of unusual size" and run an "extermination program".
The Olney sewers appears only in Fallout 3.
Behind the scenes
The "critter of unusual size" line could be a reference to the line "rodents of unusual size", which is also mentioned in Fallout 2 and Fallout: New Vegas. The "rodents of unusual size" line itself is likely a reference to the book and movie The Princess Bride, wherein R.O.U.S. (rodents of unusual size) are prominently featured.
- Sajag: "Well, let’s see. All sorts of things going on in town lately. (counts on his fingers) There’s brahmin-mutilating bugmen, rodents of unusual size, a walking spirit, and a missing hunter."
- The Courier: "Rodents of unusual size? I don't believe they exist."
Lady Jane: "Oh I assure you, sir, they are very real and very large. Please do be careful."
(Lady Jane's dialogue)