  We forecast the ability of bispectrum estimators to constrain primordial
non-Gaussianity using future photometric galaxy redshift surveys. A full-sky
survey with photometric redshift resolution of $\sigma_z/(1+z)=0.05$ in the
redshift range $0.2<z<2$ can provide constraints
$\sigma(f^\mathrm{local}_\mathrm{NL})=3.4$,
$\sigma(f^\mathrm{equil}_\mathrm{NL})=15$, and
$\sigma(f^\mathrm{orth}_\mathrm{NL})=17$ for the local, equilateral, and
orthogonal shapes respectively, delivering constraints on primordial
non-Gaussianities competitive to those from the cosmic microwave background. We
generalize these results by deriving a scaling relation for the constraints on
the amplitude of primordial non-Gaussianity as a function of redshift error,
depth, sky coverage, and nonlinear scale cutoff. Finally, we investigate the
impact that photometric calibration errors on the largest scales will have on
the constraining power of future experiments. We show that peculiar velocities
reconstructed via kinetic Sunyaev Zeldovich tomography can be used to mitigate
the impact of calibration errors on primordial non-Gaussianity constraints.
