"We've got a responsibility to clean up substances like that - both for hygiene and safety reasons.
"It's important to clean it up while it is still in one place, before tyres start to track it all over the place.
Our maintenance crews had gone home so it was important that we called the appropriate clean up crews and they needed to get to the site and ensure that the offending material was removed.
"We are very pleased we had it open comfortably before 7am so the morning commuters were only effected minimally."
Mr Frith said he imagined a "very similar protocol" would be followed if an animal was to leave its business behind.
"It would still be a safety and a hygiene issue."
Mr Frith said it was fortunate that today's incident was an "anomaly".
Police said the identity of the man who did the offending act remained a mystery, however they would review CCTV footage in the hopes of identifying him.