Landslides Ahead!

This landslide overflowed onto a mainline.
It measured about 3/4 hectare or 3 acres.
Yreka Main.

Culvert overflow.
Teeta 500.

Okay so one should know a little bit about what causes landslides. WATER! Well look at that when it rains a whole bunch the soil can become saturated and liquefies and gravity moves it downward!  It is particularly common in areas with steeper slopes, thicker soils, and exposed soil.  While logging can exacerbate landslide frequency proper forest management and road building can help lessen the impacts.   Over the last 100 years logging practices have changed a whole lot.  Heck in the last 20 years they have changed drastically!  So when the land is exposed and saturated the likelihood of landslide occurrences increases.  As land managers we can do our best to mitigate impacts.

Yreka Main road failure. 1of 3 in close proximity.

At Western we abide by a guide of TRMS or Terrain Resource Management Systems.  This guide differentiates high-risk terrain areas and requires professionals to follow a detailed list of measures to alleviate risk.  A geotechnical professional is hired to walk all of the blocks highlighted as potential risk.  They look at the rock formations, soil types, old slides, new/old road placements, steep terrain, streams, and everything in between. The goal is to minimize risk for debris flow especially that would impact fish bearing streams and habitats with high values environmentally and economically.  A combination of reports and thorough interpretations of the landscapes engineers and foresters develop plans to reduce risk and hazards for equipment operations and land movements. 

Matt & I on heli

Randy & I on heli.

Landslides happen but management is key.  For instance, this last October the North Island experienced a heavy rain event.  In fact it was 223 mm or almost 9 inches of rain in 24 hours!  As you can imagine a few landslides occurred. When 100mm of rain in 24 hours happens operations are shut down. The areas that this occurred in experienced enough slides that delayed logging and safe access to many parts of Jeune Landing. 

My place at the bottom of the slides to survey.
Really muddy!

The following week after the rainfall shutdown was lifted I accompanied the area engineer; Chris, forester reporting landslides; Matt, and operations foreman; Randy in an Astar Helicopter to check things out.  Our purpose was to record and summarize the events and damages obstructing equipment and block access.  For two hours we flew taking pictures and points of slide and road damage.  The more we knew the more efficiently we could delegate clean up tasks to the crews.  We recorded well over 50 incidents that either required clean up attention or was greater than ¼ hectare to be reported to the ministry.

The slide went all the way to the ocean!
Yreka Main.

Matt the modern day forester. Heli + Ipad. nbd
Jeune Landing.

Rock truck and hoe before much work was done.
Teeta 500.

Later on I was on site for one such clean up.  A road fill failed a corned on Teeta 500.  The road was likely originally built in the 1930s.  It is used as a mainline to connect the East to the West coasts of the island.  Hauling was occurring prior to the storm and was not safe to afterwards.  An outside engineer used a design to plan out a new fill to best suit the road.  The fill was situated on an 80% slope and required significant rocks to replace and hold up. We did not know how far we’d have to dig to find a bench to lay a new road or if we’d be luck and find bedrock.  The new fill was built up on huge pieces of rock blast out of a nearby bluff. Many truck loads of rock and fill was removed to expose the bench and set the proper road prism.  The project took almost 4 days to complete.  It closed the mainline for at least a week. There was a rock truck, excavator, and rock drill present to assist in the clean up project. 

Survey equipment and Rock drill preping to blast!
Teeta 500.

In addition to assisting with the road repair, I recorded the significant landslides to present to the ministry.  It became my job to measure the areas using pictures and Google Earth.  I had to identify the cause and effect of each incident. The tracking of these occasions are documented for further analysis for a more complete understanding of the geology and landscape reactions to landslides and debris flows.  They are associated with particular storms and can prove how severe the storm was and where it was focused.   

Improvisation at its finest!
The rock drill's boom was bent and the hoe's bucket straightened it out.

Giving the heated metal leverage.
Good thing a welder was around! Ha.