  We present the resolved properties of the $z=2.82$ Hyper Luminous Infrared
Galaxy (HyLIRG) HS170850.1, the brightest 850$\mu$m source found in the SCUBA-2
followup to the Keck Baryonic Structure Survey fields (S$_{\rm 850 \mu m}=$19.5
mJy), and amongst the most luminous starbursts known at any redshift. Using the
IRAM-NOEMA interferometer in the highest resolution A-configuration, we resolve
the source into two components separated by $\sim$8 kpc, visible as blue
shifted and red shifted $^{12}$CO(5-4) lines, exhibiting the expected kinematic
properties of a major merger between two gas-rich galaxies. The combined merger
system is traced over 2.3$''$ or 18.3 kpc. Each component of the merger shows
ordered gas motions suggestive of a massive, turbulent disk. We measure the
masses of the blue and red disks as (1.5 $\pm$ 0.2) $\times10^{11}$ M$_\odot$
and (0.71 $\pm$ 0.22) $\times10^{11}$ M$_\odot$ respectively. The more massive
disk component shows broad wings in the CO line, offset by $\sim$3 kpc from the
disk centroid along the major axis, and extending to velocities $\sim\pm$1000
km $ \rm{s^{-1}}$ from systemic velocity. We interpret this as either a
possible bipolar outflowing component, or more likely a warping or tidal
structure in the CO disk. Comparing the properties of HS170850.1 to other
submillimeter detected galaxies with comparably bright 850$\mu$m luminosities
suggests that ongoing gas-rich mergers, or at least a clustered/group
environment lead to these most extreme starburst phases.
