Sewer work on the island is shaped by sand, salt water and very little space to work in.
Groundwater and salt water get in
Folly sits low with a high water table, and on a barrier island that groundwater is brackish. Where an older lateral has cracked joints, that water gets into the line and brings fine sand with it. Over time the sand settles in low spots and the line silts up — which is a different problem from a blockage, and it needs a different fix.
Tight lots, limited access
Island lots are small and often have parking, decking or a neighbouring property right where the line runs. That is exactly the situation trenchless lining exists for, and it is worth asking about before accepting a quote that assumes digging.
Older cottages
The original beach cottages may still have their first sewer line. Age alone makes a camera inspection the sensible starting point rather than guesswork.
Ask to see the footage
Silting, roots, a sag, a crack and a collapse cost very different amounts to put right. You should be able to see what you are paying to fix.