Water Damages Newly Paved Slocan River Road at the base of Perry Ridge South of Winlaw
The Slocan River back road was temporarily closed for a day due to trees sliding across the road and hung up on power lines. Although the road is now open to one lane traffic the water is being funneled through black plastic pipe into the culvert. One lane has slumped and the cutslope above is also moving and held back with a cable. There are several cracks along the pavement in this vicinity.
The Geological Hazards Mapping of the Slocan Valley, done by Apex Geoscience Consultants Ltd. dated Dec 30, 1998 states:
“Mass movement processes involve the downslope movement of surficial material due to gravity. Material moves downhill by rolling, sliding and slumping.”..In most cases the failures appear to be caused by:
1) High pore water pressure between sediment layers (Primarily clay) or possibly along pre-existingfractures or faults within the clay and,
2) Over-steepened scarp faces in places aggravated by recent undercutting of the scarp by the river or road construction.”
Perry Ridge Water Users Association has requested a copy of the geotechnical assessment of this earth movement from Ben Tanasichuk is the Highways Area Manager for this Area.
Fortunately there are no homes in close proximity on this section of the road. This is not the case on the majority of the back road. Many Perry Ridge residents travel this route regularly and the school buses use this road. The school buses are no longer driving the road until it is repaired. Winlaw, Brent Kennedy and Mt. Sentinel High School students must now meet their school bus where the Little Slocan River Road meets the Slocan River Road. The water damage and increased rainfall demonstrate the impact of increased water on the sensitive soils of Perry Ridge. A main road like this is monitored by the citizens driving to and from their homes and YRB. However, once resource extraction roads are constructed and resources removed, these roads can have similar earth movements that can descend to the valley bottom, where many people live and travel. Old logging roads are a major concern for safety due to lack of up keep and monitoring.
Dr. June Ryder, Geologist, in her letter to the Ministry of Environment, (letter dated September 20, 2000)
“Even the most careful planning of roads and cutblocks cannot guarantee that accidents (slides, debris flows, floods) will not occur. A single such event on Perry Ridge, where steep slopes and steep creeks descent to highly sensitive terrain with dense rural settlement, could have disastrous effects.”
Dr. Lee Benda, a geologist with the University of Washington, wrote a report that said harvesting can increase soil water “on the order of 20 to 35 percent”.
Perry Ridge Water Users Association received a letter dated February 8, 2017 from BC Timber Sales, Kootenay Business Area. Tara DeCourcy, Woodlands Manager stated that BC Timber Sales are not planning to go back to extract resources on Perry Ridge for 5 – 7 more years. BC Timber Sales has stated they do not intend to collect precipitation data and plan to continue using the Equivalent Clearcut Area (ECA) methodology to assess risk.
Allen Isaacson Hydrologist, the co-author of the ECA method states:
“The ECA methodology was not designed for this type of terrain..Without the basic data, how is a statistical analysis of risk possible? What is a 100 year event in this area? What is the annual precipitation or runoff.”…The basic information needed for any type of risk analysis is lacking. In summary, the whole process (planning) should be done
with proper data collection and analysis…or it should be admitted that Perry Ridge is a unique area and not suitable for development”.
(Allen Isaacson, Hydrologist, “Comments on Perry Ridge,” Sept. 18, 2000)
Our Association insists that in the next 5-7 years BC Timber Sales collects the data – how much water is there to begin with? What is the precipitation? What is the snowfall? What is the melt rate? These all have to be answered, and then an analysis of how much change from the natural will occur with a road or a cut block. If this data is not going to be included and an analysis of how much change from the natural will occur with a road or a cut block then BC Timber Sales should admit that the remainder of Perry Ridge is
not suitable for logging and road building and set the area aside to protect the citizens that live below.
Marilyn Burgoon, President