Site walls vs grading
Site walls vs grading
(OP)
I have seen a lot of site walls on plans and have designed the walls structurally, but I have never really thought about their placement.
When are some situations where you are required to use site retaining walls instead of just appropriately grading the site? In other words, when are you required to use a site wall? Is the choice on using a wall normally property line driven?
I would think appropriate grading of the site would be more cost effective when it is possible.
When are some situations where you are required to use site retaining walls instead of just appropriately grading the site? In other words, when are you required to use a site wall? Is the choice on using a wall normally property line driven?
I would think appropriate grading of the site would be more cost effective when it is possible.





RE: Site walls vs grading
I don't know what you mean by 'property line driven', but you can't grade on the adjoiner's land without permission. If you can't finish erosion resistant grading before you get to the line (or a street, bldg, parking lot, transformer, etc.), you need a wall.
RE: Site walls vs grading
And yes, that is what I meant regarding property lines.
RE: Site walls vs grading
RE: Site walls vs grading
Earlier I said 2:1 w/ matting. That should only be proposed in cut (not fill) without geo analysis.
Grading is the hardest thing to learn in civil drafting. Don't give up, just keep erasing and redrafting, you'll get there...I'm still erasing and redrafting after 9 years!!!
RE: Site walls vs grading
RE: Site walls vs grading
This is a good example of how experienced civil engineer designers can add much value to the design process, an inexperienced engineer might have to redesign a site's grading several times to "optimize" the use of the site with the minimum use of retaining walls. Retaining walls add costs but increase the usable land on a site. Experienced civils can usually identify unusual site grading constraints early in the design process so the site layout can be adjusted and decisions about retaining walls made early in the project.
RE: Site walls vs grading
Your points are true, but use circular logic - the reason why one uses retaining walls is to use more land, but the reason one has to use retaining walls to use more land is because the slopes would be too steep to resist erosion.
The maximization of land use is incidental to constructing erosion resistant slopes. Construction of erosion resistant slopes is the requisite action; if done correctly, it may incidentally lead to an increase in developable land area. Or it may not.
Retaining walls may lead to more developable land, or they may not. Erosion resistant slopes are always physically developable.
RE: Site walls vs grading
RE: Site walls vs grading
NPDES permits might also imply topo down to nearest or adject water sink or stream/pond, lake.
Also remember to provide for utilities and maintenance access when designing your retaining walls. Fire codes, and public traffic interests might also prevail. Turning site distances from nearby intersections might influence wall design.
We use 5:1 slope where a blanket statement is used. 3:1 token height to professionals, 2:1 to Civil Engineers working in the area, and Geotechnical report scrutinized in othr cases. This is for mountainous desert with sparse vegetation and angular soils.