Courtyard Drainage
Courtyard Drainage
(OP)
I have a project where the one story building is in the shape of a "C". i have to pad out the full expansion plan in which the facility expands and becomes an "O" in the future and a courtyard is formed. what guidance do y'all have for designing the storm line that will eventually be covered by a building and the courtyard area will have no overland relief? this is from a Civil site design perspective. thanks
RE: Courtyard Drainage
RE: Courtyard Drainage
i could boil down the question to,,, how do you design storm drainage under a building. my firm doesn't like the liability. I'd like to get more experienced on it.
I understand that pipes under foundations need to meet IBC. I will research it. Where does MEP design scope begin and a civil site design scope end when it comes to situations like this? we usually say that our design ends 5' from the foundation,,, what if that foundation is delayed 10-20 years and may never get constructed.
thanks
RE: Courtyard Drainage
I'd belt-and-suspenders the pipe. Even though the Q will probably be low, you wouldn't want a leak under your foundation. Maybe put it inside a sleeve, so it could be replaced without busting up the floor.
My glass has a v/c ratio of 0.5
Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/
RE: Courtyard Drainage
sub-surface retention using either HDPE or CMP pipes.
perforated with sand or gravel bedding to allow infiltration below
overflow gravity drain to allow drainage if it fills
design for clogged inlet
provide some way to maintain and remove any sediment or debris (manhole?)
use 100-year rainfall, not 5-year and add a large safety factor.
RE: Courtyard Drainage
RE: Courtyard Drainage
im leaning towards class IV RCP, water tight with manhole on either side of the future building expansion footprint. type 1 bedding.
RE: Courtyard Drainage
I would recommend against this if at all possible. If a dry well overflows on a site, it's no big deal. If it overflows in a courtyard, it's a very big deal. There's also the issue of wet feet for your foundation. Infiltration measures usually have a setback from foundations for safety reasons.
To answer the overall question, it really depends on the municipality what they'll let you get away with. My home has a fully enclosed courtyard, and it drains fine with a 3" PVC pipe that's buried under my foundation slab. I wouldn't specify that on a project I was designing though. If I could get the design to show that an 8" or lower pipe can handle the flow, I'd do it with DIP, personally. RCP isn't a bad option, as long as its water tight, but if it's under a load bearing foundation you'll need your structural / geotech folks to weigh in. Under any differential settlement the bells in the RCP could shift and allow infiltration/exfiltration. You definitely don't want a sinkhole under your building. In Atlanta, I have seen this sort of thing done with an RCP pipe encased in concrete. I've also had structural designers design "cut outs" into cast in place load bearing concrete walls, where they make a kind of a rebar diamond around a hole for my pipes to go through.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: Courtyard Drainage
My glass has a v/c ratio of 0.5
Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/
RE: Courtyard Drainage
RE: Courtyard Drainage