from the H2O Galactic Plane Survey (HOPS) and additional Mopra mm
observations have been used to search for dense gas toward
unidentified Galactic TeV gamma-ray sources seen by the High Energy
Spectroscopic System (H.E.S.S.). Previous searches for counterparts
concentrated on large scale molecular and atomic gas, aiming to determine if they arise from acceleration cosmic-rays and/or electrons. However the morphology and dynamics of dense gas can provide additional insight into the conditions of the ISM towards the gamma-ray emission. In this work, dense and disrupted molecular gas traced at 12 mm wavelengths has been used to provide further insight to the origin of several bright unidentified TeV sources.