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- "X-Ray Zulu, are you there? We need backup in the waste sector! There's some sort of worm creature! Tower and Inney are down and I've lost contact with the rest of the squad! We need backup now! Now, dammit, now!"
- ―HECU Marine
Waste Processing Area 3 is a Black Mesa Research Facility area, located topside and in lower levels of the facility. It is first introduced at the very end of the Half-Life chapter Surface Tension, and is seen later in Half-Life: Opposing Force, where it covers the chapter Pit Worm's Nest.
Waste Processing Area 3 in Half-Life
In the section seen in Half-Life can be found a Tactical Map originally manned by Cooper, a now dead HECU soldier, and used by Gordon Freeman to defeat the chasing Gargantua and clear the way ahead, leading to the Sector F. The other side leads to the Topside Motorpool, linked to Waste Processing Area 3 through a large tunnel leading to an underground parking lot where the Gargantua is met.
An underground section of Waste Processing Area 3 is visited in Opposing Force. That area comprises several Waste Stations and a main Toxic Disposal Basin, where Adrian Shephard discovers the Pit Worm. It also includes two garbage compactors; the G-Man can be seen in one, observing Shephard's movements. In that area Shephard must use toxic waste to defeat the Pit Worm. To do so, he must activate the steam vent (located near the creature), the main pressure valve (also located near the creature, and to be accessed thanks to the hand-held Barnacle and Spore Launcher spores on the wall, since the ladder to access the valve is broken) and the primary pump gearbox (located in Waste Station 02, another area, and by using an emergency override button) to unlock the toxic waste arrival, then release the toxic waste with the waste flush button, flooding the room with toxic waste and killing the creature.
The Pit Worm in the Toxic Disposal Basin.
After that, Shephard merely has to activate the bridge previously blocked by the Pit Worm, and cross the Toxic Disposal Basin room to proceed further, in sewers leading to hangars in Sector G. Mostly filled with Pit Drones, a few Bullsquids and dead HECU soldiers, that section is connected from one side to Specimen Observation Area 03 in Sector E's Biodome Complex by the ventilation system; the other side is connected to a series of Black Ops-controlled Sector G hangars leading to the Hydro-Electric Dam. It is unknown how it is connected to the Waste Processing Area 3 section seen in Half-Life.
 Behind the scenes
- The Pit Worm obstacle is similar - albeit less challenging - to the Tentacle puzzle in the Half-Life chapter Blast Pit, in that the player cannot simply use his weapons to defeat the creature, but must use the surrounding environment.
- The valve and the gearbox to be activated are obvious references to Valve Software and Gearbox Software, left there as Easter eggs. The reference to Steam is likely a coincidence, as it did not exist back then.
There is a rather large bug in the mapping of the second garbage compactor featured in Opposing Force. If one stays in the control room above after pushing the button closing the compactor, it is occasionally possible to die when the plates are moving, possibly because they are very close to the ground of the control room. The two Pit Drones met there may also be subject to that bug, and die as well.
The Tactical Map in Waste Processing Area 3, from above.
Cooper lying dead near the Tactical Map.
 Half-Life: Opposing Force
Dead HECU soldiers in a corridor.
One of the two Star Wars garbage compactors.
Ditto, with the G-Man looking above.
The Pit Worm firing its eye laser.
Bottom of the basin, showing that the Pit Worm came from the ground.
The Pit Worm standing lower in the basin.
The flooded Star Wars garbage compactor near Pit Worm's nest.
Near the primary pump gearbox.
The primary pump gearbox emergency override button.
The gearbox and the valve shown to be activated.
The toxic waste starts spreading in the water, the Pit Worm wondering what is happening.
The Pit Worm starts being hurt by the toxic waste.
The Pit Worm sinks into the toxic waste.
Shephard summons the moving bridge to leave the area.
 List of appearances