Although this article is based on official information, the actual name of this subject is pure conjecture.
The Hazardous Environment Combat Unit Dam Turret, commonly referred to as the HECU Dam Turret, is a stationary turret fully protected by sandbags, used by the HECU.
Overview[]
This turret is seen only once in the series, at the end of the Hydro-Electric Dam, where it fires a slow-moving explosive round once every several seconds.
Defeating it is difficult, as firing most weapons at the front opening is ineffective. The most common way of destruction is a well placed grenade or other explosives, though a direct hit with a fully charged Tau Cannon or five crossbow bolts fired into the barrel will also work. It will completely destroy the main sandbag pile where the turret is located.
The turret is supposedly manned by a single soldier, but it cannot be seen.