Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Courtyard Drainage 2

Status
Not open for further replies.
ClemsonVet

ClemsonVet

Civil/Environmental
Joined
May 12, 2016
Messages
31
Location
US
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
 
Sort by date Sort by votes
If they intend o\to put a glass ceiling on the courtyard, they will plant things or put in a fountain. there will be less water. but you have to design for phase 1. Check the rainfall data back at least 5 years and then add 25% for climate changes. They may never put up Phase 2 and roof.
 
Upvote 0 Downvote
There will be no glass ceiling, it will be come a courtyard enclosed on all four sides, which increases the importance of assured 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
 
Upvote 0 Downvote
How pervious is the soil? If it's sand or gravel, and you direct the roof runoff to the outside, you may be able to get by with rain gardens or drywells in the courtyard.

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. -
 
Upvote 0 Downvote

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.

 
Upvote 0 Downvote
I would run a properly sized RCP pipe underneath the level of the proposed foundations with a manhole/inlet at each end just outside the building. Coordinate with the structural engineer for a stepped footing or run your pipe through the footing (probably stem wall above footing).
 
Upvote 0 Downvote
ACtrafficengr & cvg, the IPC says to use 100 year 1 hour storm event so yes, i'll over design it for sure. jgailla, the pipe will be constructed and then some time in the future will be covered by the building so we can't go through the footing unfortunately. Sleeve encasement is a decent option, i'll have to explore that a little more.

im leaning towards class IV RCP, water tight with manhole on either side of the future building expansion footprint. type 1 bedding.
 
Upvote 0 Downvote
How pervious is the soil? If it's sand or gravel, and you direct the roof runoff to the outside, you may be able to get by with rain gardens or drywells in the courtyard.
Click to expand...

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 -
 
Upvote 0 Downvote
beej67, good point, especially since severe rainfall events are becoming more common.

My glass has a v/c ratio of 0.5

Maybe the tyranny of Murphy is the penalty for hubris. -
 
Upvote 0 Downvote
You asked about MEP because you go under a building. You won't connect to the building, so no MEP. You don't want them involved anyway.
 
Upvote 0 Downvote
The point of entry into the courtyard for yard equipment should be where the storm drain line is to be buried as there should no foundation to penetrate.
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

ClemsonVet
  • Locked
  • Question Question
Site Design Drainage in a closed courtyard
Replies
2
Views
672
CarlB
CarlB
ojmGA
  • Locked
  • Question Question
Detention outlet culvert directly drainage system
Replies
0
Views
677
ojmGA
ojmGA
T-jay
  • Locked
  • Question Question
Inquiry Regarding Flattest Slope for 44m PVC Stormwater Drainage Pipe at Fuel Dispenser
Replies
4
Views
1K
KaBone
KaBone
Althalus
  • Locked
  • Question Question
Drainage Before and After Development
Replies
2
Views
716
beej67
beej67
zahid106
  • Locked
  • Question Question
Stormwater Drainage design for Cloud Bursts
Replies
6
Views
747
cvg
cvg

Part and Inventory Search

Sponsor

Back
Top