Min Slopes on Gravel Parking lots

[Will007]

Can anyone tell me what the standard slopes are on a gravel parking lot?

I believe we can use slopes of 1.5% to 4%.

Is this okay or far off.

please advise.

Thanks

 

[oldestguy]

Usually 2 percent is the least.

However, rmember any standing water is a place for pot holes to form. They are caused by the splash effect of the tires.

Depending on how fancy the lot is for use, the steeper you can make slopes, the less chance of pot holes. I'd go for 4 percent if I had a choice.

 

[fattdad]

Wouldn't the minimum slope be contingent on the permeabilty of the underlying soils (just asking here, not really sure. . .)? Recognizing that for asphalt/concrete pavement there is truely a need to limit birdbaths and a corresponding need to have a minimum slope, would the same be true for gravel pavement underlain by some texture class I or II subsoil? I'd think that 8 inches of gravel with a porosity of 0.33 would provide full infiltration to quite a nice rainfall event (i.e., 2 1/2 inches or so) if then underlain by sandy or gravelly subsoil, where would the birdbaths be?

Comments?

f-d

¡papá gordo ain’t no madre flaca!

 

[cvg]

it has to do more with the accuracy of the grading as well as the possibility of settlement than it does with infiltration. If you start out with flatter slopes, you run the chance of eventual birdbaths. with steeper slopes, you more often can avoid this problem

 

[fattdad]

This I get, but it's a gravel parking lot - that's where I wonder whether birdbaths are a likely problem if the underlying soils are relatively pervious. . . .

f-d

¡papá gordo ain’t no madre flaca!

 

[CarlB]

Gravel parking lots usually need a surface course of crushed aggregate, which includes some (usually ~8%) binder (read silt & clay). So it may not infiltrate water so well. And ofter other soil tracked in can lessen its infiltration capacity over time. Puddles may well infiltrate/dry out sooner than in pavement, but in the meantime damage is done. The standard design for gravel roads I've seen has a 3% crown.

 

[cvg]

even if damage is not done, nobody wants to see standing water especially your client. However, generally with standing water and traffic, the puddles always get deeper, they never seem to fill themselves in...