Is it a soils issue or something less serious?

However, you need a permit and the town inspects it once the hole is dug, and if there is any smell or visible sign of oil you must stop and bring in another company to take soil samples and dig up all the soil that is contaminated. 

But, it's very very likely you'll have to deal with one or multiple of:Drainage issues that have caused undiscovered damageAge and material of sewer lines and water supplySettlement or expansive soils causing problemsCentral systems (not having sufficient or central heating / ACJust some examples. 

Soil settlement caused foundation movement and cracking which took about a week to repair between foundation company, carpenters and painters.

If the roof is not well insulated, or you have a nice resonance chamber underneath (i.e. a good sized attic) it can be loud.

Maybe take the legs off the sink and build a  shelving unit underneath.

Getting clear on what's underneath the property is key, we have been held up since there were abandoned utilities we needed to get a public hearing and sign-off's on all the utility companies to allow us to build and that just takes time and has slowed progress.

Underneath that, you'll see different topics.

During inspection, we discovered there is an abandoned oil tank and soil contamination.

To remove this pool the right way (demo concrete, back fill, compaction, soil test) is very expensive.