A walking track leads from Waterworth Park (adjacent to Goth Withlam Park) along the river. You need to keep your eyes open, the path is not sign posted, but if you follow along the river (keep it to your left) you can't miss it. Ignore the sometimes aweful smell of the river and the likely toxicity of the sediments (not a place to go swimming), but instead look at the usual great bird life.
You will come to a bridge with three large pipes, they are sewage pump pipes. The pipes are under pressue, so no hitting them, you can only imagine what would happen if they burst... (I leave that thought with you). The cache is hidden under the bridge. Check out the hint if you need it.