Two-Hundred UXO Retrieved from 87-Year Old Shipwreck

HMCS Thiepval
Example of munitions found on HMCS Thiepval
Publication Date 
27 Dec 2017

Last June, the Royal Canadian Navy retrieved a collection of 200 unexploded explosive ordnance (UXO) from an old shipwreck off the coast of British Columbia. Operation THIEPVAL was carried out by a team of 15 Royal Canadian Navy (RCN) Clearance Divers, Port Inspection Divers, and support staff from the Fleet Diving Unit (Pacific). For four days, the team operated from the Yard Diving Tender SOOKE anchored near the wreck site for the duration of Operation.

In 2004, Public Works and Government Services Canada contracted Golder Associates to conduct an assessment of the potential presence of underwater unexploded ordnance in the Maritime Forces Pacific area of responsibility. HMCS Thiepval was listed as a potential UXO site.

In 2010, the discovery of munitions during a recreational dive on the Thiepval was reported in the Underwater Archeological Society of British Columbia newsletter “Foghorn”. Underwater photos of munition items were provided to ADM(IE)’s UXO Program. As a result of these photos, the Program began to engage in risk management activities for this site.

In October 2012 an Environmental Assessment was prepared in support of a UXO clearance of the HMCS Thiepval. The Environmental Assessment confirmed that the project was not likely to cause significant adverse environmental effects.

In March 2017, navy divers surveyed the wreck site to estimate how many UXOs were present and how long the task would take, as well as figure out how to execute the operation safely. However, when June came around, the team was in for a surprise.

“The largest hurdle encountered was that there were significantly more ordnance munitions in the wreck than was originally discovered in March. To overcome this, the team increased dive time to remove all the ordnances in the planned time frame,” said Lt(N) Sebastian Harper, who was a part of the RCN diving team.

The UXO – varying in size and type – were removed from the HMCS Thiepval, which sunk in 1930. The UXO were then transferred ashore to a designated disposal site, where each item was disposed of by detonation, in a safe manner in line with policy governing ammunition and explosives.

When asked if any interesting artifacts were found during the dive, Lt(N) Harper said, “Aside from the removal of the UXO, divers left the wreck undisturbed as it is an important historical site.”

As the ship has been in West Coast waters for the past 87 years, the majority of the wreck and its artifacts have been severely weathered.

The wreck now makes up a large debris field in the Pacific Rim National Park.

The HMCS Thiepval was a battle- class naval trawler used by the RCN. She was launched at the end of WWI and went on her first tour in 1918. She was decommissioned in Esquimalt, British Columbia, on March 19, 1920. She was then transferred to the Department of Marine and Fisheries as a patrol vessel before being reacquired and recommissioned by the RCN in April 1923. On February 27, 1930, Thiepval struck a rock, which led to her demise.

The wreck will be released to Parks Canada once the final report has been handled, and the site will eventually be open to the public/ recreational divers.

Operation THIEPVAL is a good example of cooperation between the RCN and DND. In general, ADM(IE)’s UXO Program is tasked with mitigating UXO risk on UXO legacy sites. The Program uses its expertise to conduct risk assessments and generally contracts out these types of UXO clearing projects. In the case of Operation THIEPVAL, ADM(IE) funded the RCN to carry out the work.