However he said footing the additional costs would not be easy for residents.
In fact, some residents have had to dip into their superannuation.
"It's not a rich list here, it's a lot of different family people who have had to come up with $300,000," Mr Orth told 9News.
"At the moment the contribution from state [government] and council is only based on construction, which is once you physically start building the wall. Prior to that, there's a lot of costs [such as engineer and legal fees].
Collaroy homes were almost consumed by huge king tides in 2016.
Residents were evacuated and temporary retaining walls to stabilise properties.