HISTORICAL NEWS SEARCH - Government of British Columbia

ased RCMP helicopter was standing by for medical emergencies. Greenville also reported minor flooding. In the lowlying
areas, some basements were flooded.
Washouts closed the back road between Kitwanga-Cedarvale. Near Terrace, about 30 families in the lowlying
areas of Dutch Valley were threatened with flooding. On October 27, the back road between Kitwanga-Cedarvale
reopened. Highway crews repaired about 450 m of washed out road to the Nass Valley communities.
By October 28, flood danger receded. Provincial emergency officials did not have to evacuate homes in any
of the flood-affected areas.
November 28, 2003
Event type: Clay flowslide.
Precipitation: Not available.
Source: The Province, November 30, 2003; Lebuis et al. 1983; Viberg 1983; Cruden and Varnes 1996; Hungr et al.
2001; Schwab et al. 2004
On the evening of November 27 at about 12:30 a.m., a clay flowslide (classification of Hungr et al. 2001)
came down on the Khyex River, 35 km east of Prince Rupert. *1) The slide severed about 350 m of the Pacific
Northern Gas natural gas pipeline and heat source to that city and Port Edward. The 200-m wide slide, triggered by the
snowstorm, rolled some 300 m down the valley, blocking the river. Initial fears the diverted river could cut Highway
16, the only road link between Prince Rupert-Terrace were allayed by November 29.
The low gradient extremely rapid, liquefaction earthflow (classification of Cruden and Varnes 1996) caused
displaced material to flow up and down the river for a distance of 10 km. The slide, located 6.8 km upstream from the
confluence with the Skeena River, was characterised by a steep main scarp 45 m high by 345 m wide that consists of
glaciomarine sediments mantled by rubbly colluvium. It covered an area of 32 ha, of which 13 ha in the zone of
depletion. About 4.7 million m 3 of material was displaced. The estimated retrogression from the riverbank, back to
bedrock of the valley wall, was about 480 m.
The landslide occurred in uplifted glaciomarine sediments along an outside river bend. Pre-landslide bank
height was between 5-10 m. The landslide area was logged in December 1959. In 1968, the natural gas pipeline was
installed mid-way through the present zone of depletion. The most likely trigger appears to have been bank erosion,
considered the most common trigger of retrogressive flow slides (Lebuis et al. 1983; Viberg 1983). The role logging
played in bank disturbance and in any increase in bank erosion is likely minimal (Schwab et al. 2004).
With temperatures descending towards freezing point, an emergency social services centre was set up in the
Charles Hay Secondary School. The 14,600 local residents were urged to cut back on gas usage as the reserve tank was
quickly depleted. About 4,000 homes in Prince Rupert and Port Edward were left without natural gas service for 10
days.. The estimated cost for the city of Prince Rupert alone in emergency food and shelter over the 10-day period was
about $300,000. A temporary gas line placed over the landslide to restore service cost in excess of $1,000,000. The
cost for a permanent repair to the line may have exceeded $5 million. Repairs were not completed by the summer of
2004.
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*1) Roads, railways, pipelines and utilities are located in British Columbia’s north coast valleys on glaciomarine
sediments, which are common in river valleys. Consequently flowslides pose a high risk to infrastructure within these
valleys flanked by the sensitive glaciomarine sediments. Over the previous four decades, four other large clay
flowslides occurred in this general area. See events of May 24 and June 7, 1962 (Lakelse Lake), September 17, 1969
(Kitsault) and late December 1993 (Mink Creek) (Septer and Schwab 1995; Schwab et al. 2004).
December 24, 2003
Event type: Storm surge and flooding.
Precipitation: Not available.
Source: The Observer, January 1 and 8, 2004; June 10, 2004; CBC newscasts December 29 and 30, 2003.
On December 24, 100-kmh wind, huge Pacific waves and heavy rain hit the Queen Charlotte Islands. Longtime
residents called the storm “the worst in half a century.” Water and debris on the road closed Highway 16 between
Skidegate-Tlell. The waves carried away sections of asphalt and riprap. In Tlell, a dozen families temporarily left their
homes. One Sandspit house had a flooded basement and the cabins at Copper Bay took a beating. In Skidegate, waves
threw debris over the seawall and came close to the base of the new poles at the museum. At Mariners Point in Tlell,
the access road, camping site, and fire pit all washed away.
The fierce winds and a high tide that battered the coast of the Queen Charlotte Islands caused damage on a
scale many islanders said “not been seen in living memory.” In Queen Charlotte, a floathouse was swept into the
ocean. High water flooded the lower rooms of the Spruce Point Lodge. The residents of a house at Tlell moved after
the ocean chewed away the bank that had stood between their house and the ocean. The couple lost a strip of land 15-
20 ft. (3.5-6 m) wide.
On December 24, the highway between Skidegate-Tlell was closed for approximately nine hours. Huge
waves washed across the road in several places, depositing massive chunks of driftwood, rocks and other debris. After
the highway was closed around 12:30 p.m., the situation kept getting worse until the high tide at 1:45 p.m. The storm
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