Grading for sheet flow of stormwater
Grading for sheet flow of stormwater
(OP)
For a proposed parking lot, the engineer we are working with drew up a site plan which has sections of the parking lot graded at what I believe is a 1% slope (6" over 30'). We aren't in disagreement, but we question whether or not this is sufficient. I'm aware that this is acceptable, but afraid that no one will be able to pull asphalt level enough to keep the grade at 1%. Should we be concerned, or should the water be able to flow consistently accross the asphalt without 'puddling?' I'm not an engineer, nor do I have a solid background in engineering. I'm just seeking advice for a development project. Thank you in advance.





RE: Grading for sheet flow of stormwater
RE: Grading for sheet flow of stormwater
RE: Grading for sheet flow of stormwater
RE: Grading for sheet flow of stormwater
I am in a coastal pain where the land is quite flat. One cannot run steeper slopes very far. Either one is getting too low for drainage or creating too much of a fill condition. Contracters here don't seem to have a problem paving 1%.
RE: Grading for sheet flow of stormwater
RE: Grading for sheet flow of stormwater
RE: Grading for sheet flow of stormwater
I've spec'd bituminous at 1% many times. I've never had an RFI from the contractor regarding the slope, so there must be no problem laying it at that.
On one warehouse we did, the owner actually spec'd 0.5% at the docks. Don't know why, but we graded to .005. I can say, though, that that project (now complete) does have very small low spots with standing water. Not enough to pose a hazard, just a little ugly.
Remember: The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
-Steve
RE: Grading for sheet flow of stormwater
RE: Grading for sheet flow of stormwater
RE: Grading for sheet flow of stormwater
Just to note - the 8.33% grade for ADA is only for curb cut ramps or building access ramps, and then only for a maximum distance of 12-16 feet before a landing is required. Across the HC parking spaces, 2% slope is the maximum.
RE: Grading for sheet flow of stormwater
RE: Grading for sheet flow of stormwater
RE: Grading for sheet flow of stormwater
RE: Grading for sheet flow of stormwater
I almost never go over 4% in commercial shopping centers, because that's the slope that shopping carts start running away with groceries, kids in child seats, and crash into car doors (liability).
RE: Grading for sheet flow of stormwater