The cache:
S 38° 04.970' E 145° 27.115'
The starting coordinates listed above will lead you to where you need to gather a few clues.
The following relates to the coloured poles sculpture:
Number of poles = ABC
Number of different words displayed on the poles = D
Number of letters in the artist's surname = E
The following relates to the playground:
Number of poles supporting the spider web = FG
Number of large rocks at the sandpit = H
Largest number displayed on the path in the playground = JK
The final location is at:
S 38° CD.(E+F)H(B-A)' E 145° (J-G)(B+A).C(K-F)(D-4)'
Well done to KTCvic for the FTF