  We characterize the physical properties of star-formation driven outflows in
a sample of 29 local dwarf galaxies drawn from the Dwarf Galaxy Survey. We make
use of Herschel/PACS archival data to search for atomic outflow signatures in
the wings of individual [CII] 158 um spectra and in their stacked line profile.
We find a clear excess of emission in the high-velocity tails of 11 sources
which can be explained with an additional broad component in the modeling of
their spectra. The remaining objects are likely hosts of weaker outflows that
can still be detected in the average stacked spectrum. In both cases, we
estimate the atomic mass outflow rates which result to be comparable with the
star-formation rates of the galaxies, implying mass-loading factors of the
order of unity. Outflow velocities in all the 11 galaxies with individual
detection are larger than (or compatible with) the escape velocities of their
dark matter halos, with an average fraction of 40% of gas escaping into the
intergalactic medium (IGM). Depletion timescales due to outflows are lower than
those due to gas consumption by star formation in most of our sources, ranging
from hundred million to a few billion years. Our outflows are mostly consistent
with momentum-driven winds generated by the radiation pressure of young stellar
populations on dust grains, although the energy-driven scenario is not excluded
if considering a coupling efficiency up to 20% between the energy injected by
supernova (SN) and the interstellar medium. Our results suggest that galactic
outflows can regulate the star formation history of dwarf galaxies as they are
able to enrich with metals the circumgalactic medium of these sources, bringing
on average a non-negligible amount of gas into the IGM. Our findings are
suitable for tuning chemical evolution models attempting to describe the
physical processes shaping the evolution of dwarf galaxies.
