Storm Sewer Grate Intake Capacity
Storm Sewer Grate Intake Capacity
(OP)
1.) I'm trying to compute the intake capacity of a storm sewer grate that is 2' in diameter that is near a the curb of the parking lot.
2.) Does it seem reasonable to have 60,150 sqft of parking lot tributary to (1) 2' diameter intake?
I calculated approx 8 cfs for the peak flow to the intake for a 10yr storm, but I'm not sure how to calculate the intake capacity.
Peak flow using:
Using Q=CIA with I=5.8 in/hr (this is in northern IL).
Sorry if I'm leaving info out, but I'm trying to get a rough idea if enough drainage has been provided.
2.) Does it seem reasonable to have 60,150 sqft of parking lot tributary to (1) 2' diameter intake?
I calculated approx 8 cfs for the peak flow to the intake for a 10yr storm, but I'm not sure how to calculate the intake capacity.
Peak flow using:
Using Q=CIA with I=5.8 in/hr (this is in northern IL).
Sorry if I'm leaving info out, but I'm trying to get a rough idea if enough drainage has been provided.
EIT
RE: Storm Sewer Grate Intake Capacity
http://isddc.dot.gov/OLPFiles/FHWA/015808.pdf
RE: Storm Sewer Grate Intake Capacity
Speaking from my florida experience, I, as well as many other florida engineers rely on FDOT criteria and inlet capacity tables. I believe these tables are based on the principle of flow through an orifice and use an equation similar to an orifice equation. I beleive this is correct, but I'd have to look at the FDOT document to confirm for sure. At any rate, I typically use the tables. I don't have the tables open in front of me, but my intuition tells me that you will need more than one 2' diameter inlet for 8 cfs. You can probaly search for the tables on the FDOT website and access them. I would also imagine that other state DOTs would have similar tables.
RE: Storm Sewer Grate Intake Capacity
RE: Storm Sewer Grate Intake Capacity
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RE: Storm Sewer Grate Intake Capacity
RE: Storm Sewer Grate Intake Capacity
The answer to question 2 is easy - a two foot diameter grate is usually not enough for an acre and a half of parking lot drainage. I've occasionally seen inlets designed that sparsely when the client is large, private, and cheap, such as an owner of an industrial warehouse facility who doesn't really care if their parking lot floods out routinely, but even for those guys you need to show clearly on your construction documents the limits of ponding for design storms to cover your own butt.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: Storm Sewer Grate Intake Capacity