Applying Tosoil to a Buttress
Applying Tosoil to a Buttress
(OP)
Gentlemen:
The site being developed has a rock buttress on sound bedrock which is retaining a public road. Just below I am making geotechnical recommendations for construction of a home. What objections should I have to applying topsoil over the buttress (for landscaping). Any? I am troubled because I have never seen it done like this in my previous highway career.
The site being developed has a rock buttress on sound bedrock which is retaining a public road. Just below I am making geotechnical recommendations for construction of a home. What objections should I have to applying topsoil over the buttress (for landscaping). Any? I am troubled because I have never seen it done like this in my previous highway career.





RE: Applying Tosoil to a Buttress
RE: Applying Tosoil to a Buttress
Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.
RE: Applying Tosoil to a Buttress
Buttress dimension-length: 120 ft, height: 13-15 ft, built upon l.s. bedrock, 1.5:1 slope, app. 20' width. Adequately designed by others (colleague-competition...) with proper drainage.
The undeveloped site is on a hillside lot. Owner wants to build house on downslope. The entire parcel was subject to colluvial landslide in 1998. You can imagine quite steep.
Buttress constructed for purpose of stabilizing the road only in 1999.
I have no problem with buttress itself. I am recommending quite conservative geotechnical parameters for a SE to build a basement wall on the site.
Back to the buttress. Are there any drainage consequenses I should be aware of (and are not)of landscaping soil over the graded rock.
RE: Applying Tosoil to a Buttress
Keep all new construction at least 25 feet away from the buttress - preferably 50 feet, but I realize the lot may not be that deep. Construction of the basement is my biggest concern - not so much the wall pressures. You don't want to destabilize the buttress during construction... How will the contractor excavate for the basement?
With regard to the topsoil and drainage: I'd be inclined to use a lightweight geotextile and sand bed below the topsoil. This should reduce the risk of clogging the rock fill, resulting in drainage problems within the buttress. If the topsoil will cover the entire face of the buttress, you will need to provide positive drainage from behind the topsoil. (The slope appears too steep to be covered with topsoil.)
Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.
RE: Applying Tosoil to a Buttress