  We present evidence of large-scale outflows from three low-mass
(log(M/M_sun)~9.75) star-forming (SFR >4 M_sun/yr) galaxies observed at z=1.24,
z=1.35 and z=1.75 in the 3D-HST Survey. Each of these galaxies is located
within a projected physical distance of 60 kpc around the sight line to the
quasar SDSS J123622.93+621526.6, which exhibits well-separated strong
(W_r>0.8A) Mg II absorption systems matching precisely to the redshifts of the
three galaxies. We derive the star formation surface densities from the H-alpha
emission in the WFC3 G141 grism observations for the galaxies and find that in
each case the star formation surface density well-exceeds 0.1 M_sun/yr/kpc^2,
the typical threshold for starburst galaxies in the local Universe. From a
small but complete parallel census of the 0.65<z<2.6 galaxies with H_140<24
proximate to the quasar sight line, we detect Mg II absorption associated with
galaxies extending to physical distances of 130 kpc. We determine that the
W_r>0.8A Mg II covering fraction of star-forming galaxies at 1<z<2 may be as
large as unity on scales extending to at least 60 kpc, providing early
constraints on the typical extent of starburst-driven winds around galaxies at
this redshift. Our observations additionally suggest that the azimuthal
distribution of W_r>0.4A Mg II absorbing gas around star-forming galaxies may
evolve from z~2 to the present, consistent with recent observations of an
increasing collimation of star formation-driven outflows with time from z~3.
