Car parking drainage / flooding in basement

[123131415]

Dear member,
My new building(area 355m x 125 m) of 7 story and 3 story (level 0 level -1, level -2) below the grade and used for car parking purpose. Dry – wet well arrangement (located in level -2) is to be considered to dispose parking drain, to avoid flooding. Rain fall intensity is in my area is 4 inch .i am using rational method to calculate peak run off Q= C X I X A. My doubt is

1. how i will decide wet well or dry well arrangement to be used
2. formula for calculating effective volume of pit V = (pumping rate x pumping time)/ 4 can be used
3. if i use a rational method to size pit for rain fall intensity 4 inch , sump size will be too high. for duration of 10 mints
4. I have to consider which one area, level 0 , level -1 , level -2 separately and add discharge of each floor to get total volume of pit
5. Any data available in code for seepage rate from basement
6. For design oil separator based on IPC 2012, 1003.4 and UPC 2012, I have to consider area of level i.e level 0 ,level -1 and level -2.

 

[PEDARRIN2]

Make sure you are not mixing storm with sanitary.

The garages I have designed, only the drains open to above (getting direct rainfall) would go to storm. Everything else goes to sanitary.

For your pump, make sure the flow rate of the pump(s) with the storage volume of the pit exceeds what you would get from the rain fall. If you want to reduce the size of the pit, you will need to increase the flow rate of the pump(s).

 

[123131415]

Mr. PEDARRIN2
Thanx for prompt useful advise. i will elaborate more to have better understanding of my problem. as i mention that 7 story building , strom water from roof , waste water and sewage up to level 1 are directly going to existing manhole at level 0.from level 0 ,level -1 and level -2 waste + sewage are collecting in single pit at level- 2 & then pump to existing manhole at level 0. strom water at roof will be deisgn for 4 inch water fall intensity and run - off will discharge at level 0. my doubt is for car parking storm water design . i have to design for half of rainfall intensity, area for one floor or all level area etc... seepage from basement.

 

[PEDARRIN2]

Where I design, the authorities having jurisdiction state we can take drains that receive "drippings" from vehicles, to sanitary, but first goes through an interceptor to pick up sediment/oil from the vehicles. The only drains this would not apply would be drains which are on a level open to rainfall. If you have a roof, then this would be none. But if you have parking on the top (open) level, then these would go to storm.

Seepage from the basement - which I am assuming would be infiltration from around the foundation - should go to storm sewer.

You need to start a conversation with the code authority in your area and ask them what they will require.