Soil Classification System in Canada? 5

[geotechlab]

Can someone please tell me what soil classification system is mostly accepted by engineering/environmental companies’ in Canada or more specifically in Alberta? I have recently started a geotech lab in Alberta, Canada and I'm currently using the ASTM D2487 and ASTM D2488 procedures to classify soil for engineering purposes. Both ASTM standards use the USCS for its soil classifications. One of my new clients uses a modified version of the USCS. This modified version recognizes the group symbol CI (inorganic clays of medium plasticity, silty clays). Cl is classified as Liquid Limit of 30 to 50 and is above the A-line. CL is 0 to 30 (modified system). They also use different adjectives for the field soil classifications (ie. trace = 1-10%, little = 11-20%, some= 21-35%, and = 36-50%). Any input would be greatly appreciated.

 

[Focht3]

Is your client a geotechnical engineering firm?



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.

 

[geotechlab]

Focht3,
They specialize in environmental remediation but they also have a geotechnical engineering department.

 

[Focht3]

Never heard of such a system; and it's a bit troubling - our use of a common system for over 5 decades has greatly improved our ability to communicate and share. Fragmentation of the USCS would be a real disaster.

This one has the odor of an environmental guy trying to "improve" the USCS...



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.

 

[cdh61]

geotechlab,

Are you originally from Canada? The reason I ask is it is common to use the "modified" USCS in several provinces in Canada. Hence, CI, I us it all the time and it is common practise. I normally use the adjectives "trace, some, with, and" instead of the terms you mentioned, with the same percentages you have stated.

regards

 

[geotechlab]

cdh61,

Thanks for the info.

No, I have been working in the states. Who exactly developed this modified system? Do the majority of the provinces use this system of classification? Which provinces use it? What other systems are being used in Western Canada? I have contacted some of the major Universities but nobody has replied yet. Thanks.

 

[SirAl]

Hi geotechlab

I believe that the classification system adopted is the USC as modified by the PFRA (or Prairie Farm Rehabilitation Association). This agency was created through an Act of Parliament in the 1930's to deal with severe drought conditions. The PFRA was responsible for the construction of numerous earthen dams, reservoirs, and irrigation systems on the Canadian Prairies. It has since faded from the Canadian geotechnical scene but has a prominent place in the heritage of Canadian geotechnique. I recall archive photos published in a special anniversary issue of the Canadian Geotechnical Journal showing an entourage from the PFRA at Harvard University, taken with 2 of the grand masters of our field - Arthur Casagrande and Karl Terzaghi. WOW.

 

[SirAl]

I got a little off topic in previous post. The USC as modified by the PFRA is by far the most frequently used classification system in Alberta. Alberta Transportation (Provicial Road Authority) uses this system. I have also used AASHTO from time to time.

 

[geotechlab]

SirAl,

The info is greatly appreciated!

 

[BigH]

The modified system is L for LL<30, "I" for LL between 30 and 50 and H for LL>30. I never used the "I" term.

It was always standard practice in the pioneering geotechnical firms in Canada to use:

0 - 10% : trace
10 - 20% : some
20 - 35% : adjective (e.g., silty)
35 - 50% : and

Another difference in Canadian geotechnical is the use of the term "firm" for cohesive soils (rather than medium stiff) and "compact" for cohesionless soils (rather than medium dense).

 

[dirtguy4]

Some firms in Canada use the modified USC that was done by the PFRA. Other firms are using the Canadian Foundation Engineering Manual (CFEM), 3rd Edition put out by the Canadian Geotechnical Society in 1992. Chapter 3 in the CFEM deals with the description of soils.

From a liability point of view you may want to use the CFEM as I think it carries a little more weight in Canadian courts, however, most of the research done by the PFRA was performed in Saskatchewan/Alberta when developing the modified USC. So it really is what you feel more comfortable using, both are good resources.

 

[BigH]

WRT Dirtguy4 - he has good points. One way about the classification system you are using is to spell it out in your report. Our reports used to have an "explanation" page where we indicated what the classification system we were using, the "adjectives" in soil description, the estimated consistency to Su, N to Su and N to relative density. By spelling out what you are using very clearly, you will be on solid ground should someone wish to differ - or use a slightly different or modified system.

 

[BigH]

I thought this was an appropriate thread given it's title(Please don't red-flag me!) but for all the Canucks out there:

Best wishes for a great CANADA Day - July 1st.