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CNHS - Removal of Ripple Rock - Seymour Narrows, British Columbia
N 50° 06.708 W 125° 20.613
10U E 332442 N 5553691
Quick Description: On April 5th, 1958 at 9:31 AM, one of the world's largest peacetime non-nuclear explosion removed the navigational hazard known as Ripple Rock.
Location: British Columbia, Canada
Date Posted: 4/6/2008 1:06:13 AM
Waymark Code: WM3H2K
Published By: Groundspeak Regular Member skottikus
Views: 118

Long Description:

Ripple Rocks were 2 mounds (900 metres long and 100 metres wide) that rose to within 3 metres (9 ft) of the surface of the ocean during low tides. This hazard had claimed 119 vessels and 114 mariners up until 1958 and was located in the narrowest section of the Inside Passage. Seymour Narrows is a 3 kilometers long by 750 metres wide section of water located 14 Km North of Campbell River and between Vancouver Island and Quadra / Maud Islands.

A couple of attempts had been made to remove them by drilling down from the ocean surface but these were failures because of the tide that can move through the Narrows at 10 to 15 knots. A plan then was developed to drill a tunnel under Ripple Rock and destroy it from below. It took 28 months for a crew of 75 to drill a shaft 174 metres (570 feet) deep and then a tunnel 762 metres (2,500 feet) long out under the ocean floor. When they got below Ripple Rock they drilled two vertical shafts 91 metres (300 feet) up into both of the mounds.

Once this was completed, 1,400 tons of explosives were packed into those 2 vertical shafts inside Ripple Rock. When the blast occurred, 700,000 tones of rock and water were thrown into the air close to 350 metres (1000 ft). There was a real fear that a tsunami would be created from the explosion but thankfully that didn't happen. The project was a success, reducing the rocks from 3 metres (9 ft) below the surface of the water at low tide to 14 metres (47 ft).

Large and small craft can now transit Seymour Narrows with out the fear of hitting Ripple Rock but it still can be a challenging area to navigate. Even the up to 20 cruise ships that pass this way on a daily basis time their transit for slack tide.

This is one of the newest National Historic Sites created and at present there is no plaque. The planned location for it is at this site.

Much of the information for this waymark came from the BC Provincial plaque at the site, articles and news reports about the 50th anniversary celebration of the event, along with discussions I had with a representative from the BC Provincial Parks service and Bill Roozeboom. Bill was the cameraman PWGSC hired to create a documentary of the project.

This was also one of the first Live TV shows done by the CBC. A great clip of the explosion can be seen here.

B.C.'s deadly Ripple Rock blown up. The CBC Digital Archives Website. Canadian Broadcasting Corporation. Last updated: July 26, 2012. http://www.cbc.ca/archives/categories/science-technology/applied-science/general-12/bcs-deadly-ripple-rock-blown-up.html [Page consulted on April 6, 2008.]

Classification: National Historic Event

Province or Territory: British Columbia

Location - City name/Town name: Campbell River

Link to Parks Canada entry (must be on www.pc.gc.ca): [Web Link]

Link to HistoricPlaces.ca: Not listed

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