The generator matrix

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

generates a code of length 11 over Z3[X]/(X^2) who´s minimum homogenous weight is 18.

Homogenous weight enumerator: w(x)=1x^0+474x^18+648x^21+918x^24+146x^27

The gray image is a linear code over GF(3) with n=33, k=7 and d=18.
As d=18 is an upper bound for linear (33,7,3)-codes, this code is optimal over Z3[X]/(X^2) for dimension 7.
This code was found by Heurico 1.16 in 0.197 seconds.