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Versant Nord/North Side, Chemin Charles Duncan
Entrance Flood/Washout Damage - Summer 2024.



The purpose of this entry is to archive a weather
flood event that had catastrophic impact within
the Resort domain, for historic record keeping.

i.e.: “Can you remember... What year did that happen?"

This flood damage occurred at the creek crossing
on the Versant Nord/North Side entrance road
Chemin Charles Duncan.


The date of this deluge was Friday August 9th, 2024
when Tremblant got 134mm of rain in this single event.
In Montreal this storm generated 153.8mm and there
was widespread flooding throughout the city. This event
broke the Montreal daily record set back in 1996 by
over 60mm. The highest rainfall amounts in Quebec
were Northeast of Quebec city at Lanoraie, where
220mm was recorded. This system was the remanent
of Hurricane Debby.



What you see below is the washout as it existed
at September 10, 2024, plus a record of where
the high water mark came to at the time of the
flood.





9.10.24.Versant.Nord.North.Side.Entrance.Flood.Damage.Observations.a.jpg



Obviously there was an immense and sudden
flow of water that generated sufficient hydraulic
pressure to push 100’s of cubic metres of earth,
rocks and road-bed.

Just as obviously, there will be substantial repair
required to reopen the Versant Nord/North Side
parking zone via this Chemin Charles Duncan route,
however, for repair crews there is other access to the
Nord Base side by either a small service road back around
the corner off of Chemin Duplessis or even over the top
of the Mountain by the network of Alpine service roads.

Consider these pic’s as “Before” and when the season
starts we’ll add “After” to illustrate the scope of repair.




9.10.24.Versant.Nord.North.Side.Entrance.Flood.Damage.Observations.b.jpg


We suspect that one of the reasons the “High Water” mark
got to where it did is that the shape and the amount of
volumetric capacity through the original flow path(which
subject to verification, we recall as being a large culvert)
actually created a dam-like effect when overwhelmed by
water it could not effectively flow fast enough.



As usual, when Mother Nature takes out things that
were there for decades before, Tremblant typically
upgrades the infrastructure to modern standards
that should be able to accommodate extraordinary
future events, so we will not be surprised to see
a substantial increase in the capacity of water flow
at this crossing.







Here are some Environment and Climate Change Canada(ECCC)
record stat’s for this weather event:







Summer of 2025 New Bridge Construction Detail.



Please Note:

This bridge was replaced in the fall of 2024 however
we were not able to attend until after the first snow
had fallen last winter, hence the delay until we could
get back for uncluttered, snow bank/covered, free,
full and easy summer access.



The new bridge represents a substantial upgrade to the
flow capacity of this drainage point by means of increase
of the volumetric potential here that we would estimate
at roughly 10 times the old and narrowest restriction that
was directly under the road.






The new bridge has what we would call a crib based foundation
on each side, spanned by very heavy steel beams capable of
highway heavy transport truck weights, as well as heavy
industrial earth and snow moving equipment.

The end unit cribs are constructed of very heavy wooden
timbers making a square frame that is filled with very large
rocks that are well beyond the open dimensions of the frame.
This system is open to the flow of water through and around
it so there will be far less likelihood that the potential for high
water pressure could be held back by embankments to the point
that it could generate any burst force to push earth to support
failure the way the flood took the old bridge out.

Everywhere you look, the timbers and steel are fastened by
galvanized bolts that are secured side-to-side, through-bolted,
thereby generating maximum structural clamping force. This
is a very heavy duty assembly with what seems to be a rather
obvious “overbuilt” quality that should have a life-span measured
in decades.








In our opinion, one of the advantageous features of this
construction is the openness of the crib’s wooden framing
to airflow at normal water levels that should enhance the
ability of the wood to dry quickly and stay dry and strong
through years of seasonal adverse wet weather cycles.



The very large rocks are also used for the entire surrounding
creek/river embankments where their immense weight and
aggregate surface area should be easily capable of buffering
huge volumes of water flow reliably. In this shot below, taken
on the east side of the bridge facing towards the P-Nord,
North side parking lot, you can see there is additional drainage
coming into the creek here on the upstream side from the parking
lot that has also been embankment stabilized by large rock
placements for peak volumetric flow capacity.








The “V” shape of the water passage to, under and past the actual
crossing should also allow for reduced river flow speeds as high
water levels occur just because there is so much additional progressive
width that can help handle larger volume without any narrow restrictions
or pressure points.






The placement of additional large heavy rocks into the
downstream flow should help reduce both direct flow
speed and erosive force beyond this point as the water
heads for the next bridge on the creek.



The approach to the new bridge from both sides is
a lot more obvious than the old bridge that you could
pass over almost without notice.








One major difference from the old to the new is that the
surface over the old was paved, where the new is a wooden
deck. In that sense the new has a far more formal presence
as a real bridge, but overall, the impression can still only be
described as “solid”.








There are wooden framed bridges in Eastern North America
that are well over 100 years of age, of course with ongoing
and proactive maintenance, so we expect that history will
reflect very kindly on this very fine new bridge that enjoys
the latest in structural design as well as surrounding flow
management as a complimentary enhancement.









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