Storm Water Drainage through Accessible route

[Mech]

Existing building
2009 ICC A117.1 & ADA

The existing parking lot slopes away from the building and away from the road towards the white drainage path. The building floor is lower than the road. Grade is higher on the left side of the sketch than the right, establishing the direction of water flow.

The purple accessible space and striped out area are proposed. The existing entrance door at the purple striped out area is existing.

Is the parking spot and path permitted to slope as shown and have storm water run as shown? The only restrictions I saw are for a maximum slope of 1:48. I did not see anything about valleys being created.

Water going through the space could easily turn to ice in the winter. The slopes are noticeable enough to see with the naked eye, without surveying the area or seeing any waterflow.



Thanks!

 

[Yikes]

There is nothing in the code that prohibits storm water flow over an accessible stall, access aisle, or adjacent paths of travel. Rainfall can be expected on outdoor areas, and wheelchair users pass through water on flow lines at curb ramps all the time.
Accumulation of water ponding, or ice, is a property maintenance issue, just like accumulation of leaf litter or other debris.

It is highly unadvisable to create a situation where ice will form and not be immediately removed. If it were me, I would either not put the swale there, or I would have some kind of pavement heating system, such as is often done on college campuses, to keep it ice-free.

 

[Yankee Chronicler]

The gradient within the accessible stalls and the adjacent access aisles can't exceed 1:48 for any part of the stall or aisle. As long as the slopes don't exceed 1:48, I don't think the codes prohibit allowing surface water to drain across an accessible parking space.

That said, if the stall is 20 feet in length and the swale is at the center, a slope of 1:48 over a length of 10 feet means a change of elevation of 2-1/2 inches. It's unlikely that it would pond to that depth but in heavy rain it's possible. It's not good design.

 

[Jean Tessmer-HI]

Existing building
2009 ICC A117.1 & ADA

The existing parking lot slopes away from the building and away from the road towards the white drainage path. The building floor is lower than the road. Grade is higher on the left side of the sketch than the right, establishing the direction of water flow.

The purple accessible space and striped out area are proposed. The existing entrance door at the purple striped out area is existing.

Is the parking spot and path permitted to slope as shown and have storm water run as shown? The only restrictions I saw are for a maximum slope of 1:48. I did not see anything about valleys being created.

Water going through the space could easily turn to ice in the winter. The slopes are noticeable enough to see with the naked eye, without surveying the area or seeing any waterflow.

View attachment 13210

Thanks!

I would strongly recommend you obtain a copy of the Americans with Disabilities Act DOJ 2010 Standard for Accessible Design. Here is the link: https://www.ada.gov/law-and-regs/design-standards/2010-stds/ There are a number of issues with your diagram: (1) you don't say what the cross slope will be over the entire parking area. If it is more than 1:48 anywhere in two directions the stall will not meet wheelchair accessibility. (2) The entry door needs to be at least a 36-inch-wide door x 80 inches high and the wheelchair clearance on the pull side of the door needs to be 60 inches deep in front of the door and at least 54 inches wide to provide the 18-inch latch side clearance to the door. This is basic stuff. You also do not show signage or wheel stops to prevent the vehicle hitting the window. You could raise just the accessible parking stall area and install ADA grating in the area of the drainage path to allow the water to go under the raised accessible parking surface. You will need to pay very close attention to any vertical transition or gaps such grating would pose.