The generator matrix

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

generates a code of length 10 over Z3[X]/(X^2) who´s minimum homogenous weight is 18.

Homogenous weight enumerator: w(x)=1x^0+108x^18+108x^21+18x^24+8x^27

The gray image is a linear code over GF(3) with n=30, k=5 and d=18.
As d=18 is an upper bound for linear (30,5,3)-codes, this code is optimal over Z3[X]/(X^2) for dimension 5.
This code was found by Heurico 1.16 in 0.000364 seconds.