The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1
 0  3  0  0  0  3  3  3 3a 6a+3  0  3 3a 6a+6  0 6a+3  6  3
 0  0  3  0  0 3a+6 6a+6 3a  6 3a+6  3 3a+6 3a 3a+3 3a+6  0 3a+3 3a+6
 0  0  0  3  0 3a+6  3 3a+3 3a+3 6a+6 6a+3 6a+6 6a+3 6a 6a+3 3a  0 6a
 0  0  0  0  3 6a+6  6 6a+3  3  3 3a 3a  3 3a+3 3a+6 3a 3a 3a+6

generates a code of length 18 over GR(81,9) who´s minimum homogenous weight is 108.

Homogenous weight enumerator: w(x)=1x^0+552x^108+2384x^117+4928x^126+10688x^135+490024x^144+15808x^153+7056x^162

The gray image is a code over GF(9) with n=162, k=6 and d=108.
This code was found by Heurico 1.16 in 19.1 seconds.