  Following the recent theoretical interpretation of GRB 090618 and GRB 101023,
we here interpret GRB 970828 in terms of a double episode emission: the first
episode, observed in the first 40 s of the emission, is interpreted as the
proto-black-hole emission; the second episode, observed after t$_0$+50 s, as a
canonical gamma ray burst. The transition between the two episodes marks the
black hole formation. The characteristics of the real GRB, in the second
episode, are an energy of $E_{tot}^{e^+e^-} = 1.60 \times 10^{53}$ erg, a
baryon load of $B = 7 \times 10^{-3}$ and a bulk Lorentz factor at transparency
of $\Gamma = 142.5$. The clear analogy with GRB 090618 would require also in
GRB 970828 the presence of a possible supernova. We also infer that the GRB
exploded in an environment with a large average particle density $<n> \,
\approx 10^3$ part/cm$^3$ and dense clouds characterized by typical dimensions
of $(4 - 8) \times 10^{14}$ cm and $\delta n/n \propto 10$. Such an environment
is in line with the observed large column density absorption, which might have
darkened both the supernova emission and the GRB optical afterglow.
