French to English Tech/Engineering Environment & Ecology Soil pollution checks

This term appears in a document discussing, among other hazards of a building site project, procedures to be followed for investigating potential soil pollution on a 'brownfield' industrial site being re-developed.

"Sondages préalables à réaliser par l'entreprise de terrassement."

and

"Dépollution du sous sol (zones repérées par les travaux préliminaires de sondages effectués par XXX)"

and a few other very similar occurrences, referring also to hidden underground services.

I have found various entries in the glossary, including 'bore hole', 'survey', 'sample', 'analysis', and a few others that seemed to me less likely. I'm just a bit worried about the way of fitting it into my sentence, as I can't quite swallow "Prior hole-boring to be carried out..." ;-)

I think 'survey' may be the best solution albeit leaving out as it does the idea of boring holes (which I feel quite sure is involved here), but is there a term to refer to a 'survey using bore-holes' — and specifically, is there a dedicated term for this in this particular field?