Iron ochre is a rust coloured sludge that accumulates and clogges perimiter drains in certain soils. It is often found the Eastern Townships of Quebec. It is a very complex problem which can be controlled but not solved. In fact the real solution in regions known to have iron ochre is to not build a basement but build on a slab-on-grade to avoid deep drainage tiles altogether.
I will not go into detail here because the best information available is on the Régie du bâtiment du Québec web site -- in both English and French. Follow this link: https://www.rbq.gouv.qc.ca/en/citizen/buying-a-new-house/particular-problems/iron-ochre.html