Lac Saint Pierre, Quebec

CLIENT: Canadian Department of National Defense

PROBLEM: Contaminated Sediments

Lac Saint Pierre, once used as an experimental firing range, is a widening of the Saint Lawrence River downstream from Montreal. Between 1952 and 2000, about 500,000 shells were fired into the lake. 300,000 remain on the bottom, 9,000 contain high explosives but are unfused, and 2,000 were armed and fused when fired but did not explode and are considered to be Unexploded Explosive Ordnance (UXO). Safe and economical UXO clearance is critical.


  • Will buried UXO become exposed (and where)?
  • Conversely, will UXO on the surface become buried (and where)?
  • Can UXO be transported elsewhere (and where)?
  • Will UXO clearance activities disturb sediments that may be already contaminated?
  • If so, where did the contaminants come from and who might be liable?