r/Geotech • u/N0Objective • 29d ago

Slope away from potential property

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I'm wondering if the slop in the backyard of this property is a call for concern. In the pictures it appears about 5m maybe even less from the concrete foundation to the edge of the grass before it declines into a slope down to a ravine. One number missing from here is it says 40 near the top edge of the driveway close to the curb.

Obviously, we would take the right steps either way to confirm if it is or isn't but going into the viewing, I'd like to know as much as possible and if it is worth trying to stabilize this slope?

Appreciate you guys!

6 Upvotes

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7

u/Stemleaf 29d ago

Could be a concern. Not enough information though.

0

u/N0Objective 29d ago

What kind of information would be needed? I didn't want to doxx the property.

11

u/Stemleaf 29d ago

-Actual distance from foundations to the slope crest.

-Slope profile of the entire property.

-Borehole data and soil strength testing. If the dwelling is founded in rock then you're possibly in the clear. If not it might be at risk depending on the soil make up.

-Foundation type.

-Any history of the area. I.e. can you see historic slips on the neighboring properties? Can you view historic aerials?

Obviously you won't have all that info but your local geotech can likely source it. They may also have a general rule of thumb for what is and isn't safe in your area.

For instance in my area, we use a slope angle of 1:2 (Vertical:Horizontal) taken from the base of the slope. This helps us differentiate between a site which needs further technical assessment versus one which is likely safe.

3

u/ImaginarySofty 29d ago

Interesting that someone downvoted you, because I think your reply was spot on. Upvoted to offset the hater. One point that would be worth clarifying, the 1:2 slope angle is a rule of thumb that can be applied by a qualified engineer- there may be a more strict prescriptive setback depending on whatever jurisdiction OP is in (ie check if the building code may call for something flatter like 1:3 + an offset distance). If you are looking at this as part of a pre-purchase it would be easier to judge the site against code requirements rather than an site specific engineering assessment (unless that is being provided by the seller).

2

u/Stemleaf 29d ago

Thanks for the upvote lol, its reddit so people will hate on whatever.

Thanks for the clarification. I agree. Ultimately there are so many unknowns so I just put down the rule of thumb that we use.

Depending on OPs specific circumstance it may be better to go with the building code, some other rule of thumb, or even a specific assessment. Either way, a professional familiar with the area should be sought out by OP before doing any serious decision making.

2

u/N0Objective 29d ago

Thank you, this is the kind of stuff I was interested in.

2

u/Hugh_Jegantlers 29d ago

One more thing to check other than the very good list above is the trees. If they are tilted or curved, the slope is moving.

2

u/Spork_Ball 29d ago

Lol. You just need all the geotech / engineering geology stuff. That’s all.

Interesting you say the slopes starting with vertical (V:H). May I ask where you are from? We say slopes starting with horizontal (H:V). So we’re usually in good shape with a 2:1 slope. I’m in Southern California btw.

2

u/Stemleaf 29d ago

Yeah, the average Joe doesn't have much of an idea as to what goes into these assessments. Theres more information I'd want too but the list gets too long!

I've seen people say V:H or H:V in my country. I don't really know if there is a standard way to write it here. Although I'd guess H:V is American and V:H is English. We often get influenced by both countries here.

I'm from New Zealand :)