The generator matrix

 1  0  1  1  1  1  1  0  1  1  1  X  1  1  1  X  1  1  1  1  1  1  0  X  1  1  1  1  1  1  1  1 2X 2X  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1
 0  1  1  2 2X+1  0  2  1  X 2X+1 X+2  1  X X+1 X+2  1 X+1  0  X  1  2 X+2  1  1 2X 2X 2X 2X+1 X+1  1 2X+2 2X+2  1  1  0  0  X  X 2X+1 2X+1 X+1 X+1  X X+1  0 2X+1 2X  1 2X  1
 0  0 2X  0  X  X 2X 2X 2X  0  X  X  X 2X 2X 2X  X 2X  0  0  X  0  X  0  0  X 2X 2X  0  X  0  X  0  X  0 2X  X 2X 2X  X  X  0  0 2X  X  0  0 2X 2X  X

generates a code of length 50 over Z3[X]/(X^2) who´s minimum homogenous weight is 99.

Homogenous weight enumerator: w(x)=1x^0+164x^99+72x^102+2x^108+4x^126

The gray image is a linear code over GF(3) with n=150, k=5 and d=99.
As d=99 is an upper bound for linear (150,5,3)-codes, this code is optimal over Z3[X]/(X^2) for dimension 5.
This code was found by Heurico 1.13 in 23 seconds.