Toodyay Bin History

The Toodyay Bin History (TBH) series follows the Living History Walk Trail in the centre of town. The caches are all off set multis and the final co ordinates for each cache can be obtained by visiting the bins at each GZ and doing some simple sums to locate containers a few kilometres away.
 

To locate the final, a year is mentioned on the sign, this becomes ABCD:

S31 28 (D-2) B (D-1) E116 30 (A+1) C (D-1)