I believe the trenching is from artisanal mining currently active on the site. The Maniema project has had quite a bit of historical mining in different areas going back to the 1960s. Some basic trenching and mine infrastructure is on site, and from that, VEC has identified some new targets.
In short, the trenching in this new area was not done by VEC, nor for the purposes of assays, but you can expect lab results back on the visible gold they did find. If that's promising, they'll move to drilling.
If you're wondering what the deal is with those artisanal miners, they're local miners who work independently on the site and I believe pay a tribute to the local entity that owns the remaining 30% of the project.
Happy to be corrected here, I'm going off my recollection of some of the original ANN on this.
EDIT: the historical mining on the project demonstrates there is gold, it's just a matter of how much