The drilling program and the Bathymetric Survey were both completed last on June 30.
Four core holes were drilled, two on the Weir island and one on each side of the river. We had anticipated reaching bedrock at 25-30 meters, but we found it at 37m on the island, and 47m an 50m at each abutment area. Testing and sampling were performed throughout the boreholes so now we have very, very good geological and geotechnical data to perform design analyses that meets all the provincial and federal requirements including seismology.
Glaciers on Vancouver Island about 15,000 to 20,000 years ago helped form our Cowichan Valley. As the glaciers receded they cut and formed and deposited materials throughout the valley. It is these glacial deposits that we are finding above the bedrock. Understanding the characteristics of these deposits are key to understanding design options.
A bathymetric survey exactly measures the lake and river beds. We performed a detailed survey on either side of the existing weir on June 30th. This is also necessary to inform the design.
The Public Survey has been coming in steadily with over 160 received so far. It’s too early to share the information, but it is providing valuable insight into what you think – Thank you for responding.
First let me introduce myself. I am a retired geotechnical engineer who came out of retirement to help manage this important project and I am pleased to be able to contribute. Born in Edmonton, but I grew up in Duncan and graduated from ‘Cow Hi’ many years ago. My wife and I have a house on Cowichan Lake since 1995 and understand the beauty and the opportunity such a privilege provides.
We have noticed the impact of climate change over the years with longer, hotter dryer summers and how the river has had to endure extra low flows throughout the past few summers.
This project to design a new weir and understand the impact of that change on the perimeter of the lake is an important step to ensuring sustainable future healthy flow down our heritage Cowichan River.
Through this website, I will be providing you with my updates.
I would have liked to meet in a more public face to face forum, unfortunately COVID-19 has not made this possible and has changed the way we think and how we currently do ‘business’.
Please take part in the survey so we can understand your thoughts as we start to design your new weir.
It has been an interesting and successful start to our field program. There is small island at the existing weir between the concrete weir and the control gates. With little geologic or geotechnical information available, we wanted to get out there and drill a couple of boreholes.
With a lot of planning and ingenuity, we were able to source a local barge and load the 38,000 lb drill rig and all the supplies and transfer it over to the island – that was a win. Drilling started on Tuesday afternoon and we reached 30 feet by end of the day.
We really, really wanted to find bedrock in this area as it has not been done before and it is critical to our design process. We anticipated bedrock at 75 to 90 feet, but at the end of the day Wednesday we finally found bedrock at 138 feet. Yahoo! The second island hole started on Thursday morning. 2 more holes, one at each abutment will also be competed over the several days.
It only been one week but it seems like the message is getting out there and you are responding! Although we have had a few glitches with the survey, overall the input has been excellent – thank you. As we are slightly behind schedule the survey will be extended to July 12 so we can hear from anyone who wants to contibute.
Stantec Engineering is doing the work for us and we are at the stage where we need to fill in some information gaps. Therefore, you should see some drilling activity in the area around the weir in the next week or two. This will give us much more detailed geological information and geotechnical data to help with the design parameters.