The generator matrix

 1  1  1  1  1  1  1  1
 0  5  0  0  0  5  0  5
 0  0  5  0  0 15 10 15
 0  0  0  5  0 15 20 15
 0  0  0  0  5 15 15 15

generates a code of length 8 over Z25 who´s minimum homogenous weight is 15.

Homogenous weight enumerator: w(x)=1x^0+84x^15+160x^20+464x^25+780x^30+12500x^32+980x^35+656x^40

The gray image is a code over GF(5) with n=40, k=6 and d=15.
This code was found by Heurico 1.16 in 0.0218 seconds.