  We report the studies of detailed magnetic relaxation and isothermal
magnetization measurements in the vortex state of the 112-type iron-pnictide
Ca$_{0.82}$La$_{0.18}$Fe$_{0.96}$Ni$_{0.04}$As$_2$ superconductor with $T_c$
$\sim$ 22 K. In the isothermal $M(H)$, a well defined second magnetization peak
(SMP) feature is observed in the entire temperature range below $T_c$ for
measurements with $H$ $\parallel$ $c$-axis. However, for $H$ $\parallel$
$ab$-planes, the SMP feature is suppressed at low temperatures, which might be
due to 2D Josephson vortices forming at low temperatures and high magnetic
fields in such an anisotropic system. A rigorous analysis considering the
magnetic relaxation data for $H$ $\parallel$ $c$-axis suggests an elastic to
plastic pinning crossover across $H_p$, which also seems accompanied with a
possible phase transition in vortex lattice near $H_p$. Moreover, point
disorder and surface defects are likely to be the dominant sources of pinning,
which contribute to the $\delta l$-type of pinning in the sample. A high $J_c$,
in access of 10$^5$ A/cm$^2$ observed could potentially make this material
technologically important.
