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Multiple factors led to Nov. 15 landslide: Ministry

Community Forest to adapt practices for climate change; ELF says report misses the mark
Debris and downed trees near the Sechelt-Dakota forest service road after the Nov. 15 landslide

Work by the Sunshine Coast Community Forest (SCCF) “may have been the tipping point” for a Nov. 15, 2021 landslide that affected Burnett Creek and the Sechelt-Dakota forest service road. That is according to a report prepared by the Ministry of Forests’ Sunshine Coast District dated Jan. 17.

The slide occurred at about kilometre 35 on the road, upstream from the Coast Gravity Park and Sechelt’s Burnett Falls park during the mid-November atmospheric river. The report details that the slide originated just outside of SCCF’s recently harvested Block AN12 and below a section of road used to access that site. The slide moved about 2,800 square meters of trees, rock, and soil. A debris field was deposited along the road about 20 meters wide and 70 meters long, with an average depth of 1-1.15 metres.

In her conclusions, report author and ministry senior area engineer Shelley Higman wrote that it is “hard to say” if the slide would have occurred without SCCF’s logging and road work. She visited the site on Nov. 23.  Her report identified that the road, originally built prior to 1985, did “not appear to have been upgraded to current road construction standards” when it was put back into service by SCCF to access the cutblock. SCCF operations manager Warren Hansen, who took on that role after the road was reactivated, said in an interview with Coast Reporter on Jan. 25 that it was his understanding that the road had been assessed by a geotechnical consultant.  He said that there were no indications of any problems with the drainage system when it was reactivated.

SCCF had finished logging on AN12 in April 2021 but had not completed deactivating the road when record-setting levels of precipitation hit the areas. The report says that a combination of that weather system, saturated groundwater conditions and land disturbances from forest harvesting activities in the area likely caused the slide. Two culverts on the road, which has grade slopes of between 10 and 17 per cent, failed. Ditches overflowed and water meant to be directed through the culverts and ditches “liquified the receiving slope,” Higman wrote.

Hansen issued a written response to the report on Jan. 21. “We take this report to heart. We accept the conclusions and recommendations and will be acting on the recommendations made. The road and culverts at the site of the landslide were repaired immediately after the slide with planting of trees and grass-seed to occur in spring.” 

SCCF undertook about $68,000 worth of repair work to reinstate the forest service road. Hansen said it will not be compensated for that expense as repairs were undertaken on an emergency basis before the forest service was able to visit the site or authorize the work. SCCF will also be covering the replanting costs.

The report recommends that the ministry look at requiring drainage systems on reactivated roads to meet current standards and consider the effects of climate change. A suggestion was also made that roads with grades greater than ten per cent be seasonally deactivated.

“We’re going to be embracing that for sure,” Hansen said. “As a policy, we have kept our road systems open in the past for community firewood access, and to go back in, to plant and do rehabilitation work. Seasonal road deactivation may limit some community access but we are going to be doing things that look at the environment first and to ensure that the roads and culverts are weather-resilient.”

Higman went on to suggest that for work in areas with Stability Class 3 terrain, forest planners carry out more stringent terrain stability assessments. Those areas are defined as having a low likelihood of landslides following harvesting or road building but that minor stability problems may develop. The area outside the block where the slide occurred was rated as Class 3. Cutblock AN12 was assessed as Class 2; a very low likelihood of landslide initiation. Hansen said that the majority of SCCF’s tenure is in Terrain Class 3 and less. 

“The report will help reshape our SCCF management to move to improve and adapt our practices to respond to climate change with resilient roads and better water management,” Hansen wrote. As operations manager, Hansen said he is able to implement practice changes and has the full support of the SCCF board to do so.

The report also states that AN12 harvesting likely created a higher groundwater table, which it assessed as “the greatest contributing factor” causing the slide. “Substantial evidence of flooding through the harvested area” was observed.

Elphinstone Logging Focus (ELF) representatives were on site Nov. 16 and provided a report to the ministry within days of the slide’s occurrence. “Our documentation and field visit located a stream generated from poor water management entering the mid slope which would have saturated the soil and likely being the main reason for the failure at this location…All across this area there were no other landslides in areas where there was no road building or logging above,” ELF spokesperson Ross Muirhead wrote in an email to Coast Reporter.

In comments forwarded to the ministry on Jan. 24, ELF wrote that Higman’s report “glosses over the elephant-in-the-room – which is a description of the impacts of the 2019 clear cut logging and road building operation…The assessment missed a critical opportunity to map the clear cut and road area which was the source of the surface water flowing into the slide. A calculation then could be made of the additional volume of water flow as a result of the logging.

"The Sunshine Coast Forest District along with all other provincial forest districts (thus a structural issue) all fail to employ available hydrological formulas to fully understand water runoff volumes generated by logging and road building.”

In Dec. 2021, ELF also sent a written request to SCCF asking that it “cease and desist” from work in all future blocks that involve clearcut logging and road building. “This means re-doing the 5-year operational plan where clearcut openings and road building has been planned and that Ecosystem Based Management be implemented for future harvesting in previously cut areas, including a ban on industrial-scale road building. In the meantime, the operational focus must immediately shift to maintenance on all SCCF roads,” Muirhead wrote.