Downspout Under Driveway and Drainage Questions

[AldeanFan]

I'm saving up for a new and larger driveway, probably next summer.

Before I go to the town and start looking for an asphalt contractor I want to make sure what I want to do is feasible and that I'm using the correct terminology so I don't sound like a dumb *** and bet taken advantage of.

The existing driveway is 20' wide, 50' long. The garage is 20' x 20'. There is a strip of grass 25' wide on the West side of the garage. The house is on the East side of the garage.

I'd like to widen the driveway to 30' wide with the additional 10' wide lane extending to the back of the garage, so I'd be adding 10'x70' beside the existing driveway area and the garage.

My lot slopes from West to East with a ditch on the East side of the garage.
The garage faces north.

The driveway and street are at the same level. The driveway slopes down from the garage toward the street, then 6' from the road it slopes up to to meet the road. As a result water flows over the driveway. The driveway is basically a ditch. There's a ditch on the east side of the driveway but not the west side. The lowest point of the driveway is 10" below the road.
To fix this issue I'd add a culvert under the new driveway with a catch basin on the West side and the culvert exiting in to the existing ditch on the East side.

The next issue is the downspouts. There are two downspouts on the West side of the garage which drain on to the grass. This area would be paved over.
The plan here would be to connect the downspouts to an underground drain line under the driveway, exiting in to the ditch on the east side of the driveway.
The underground drain could either travel from the north west corner of the garage, diagonally under the driveway from the corner of the garage to the ditch, or zig zag under the driveway and travel down the east side of the driveway to the ditch.

I'm in Canada so freezing is an issue.

What's the required slope for underground drainage pipes?

What else am I missing?

Thanks!

 

[jetnow1]

if the drain lines are properly done there should be no standing water, so no freezing. Be sure they run to daylight and have enough slope to keep it moving, usually 1/4 inch per
foot is safe but as little as 1/8 inch per foot will work depending on size and material. Your local contractor can probably give you more help with what will work locally more than someone several hundred miles away.

 

[thammel]

I have all my downspouts tied to drain lines that are buried and take all the water far from the house. This is a very smart thing to do. I used 4" thin wall pvc. Mine are probably at least 1-2 feet down. I know some places they are more like 3' down and eventually due to the sloping ground emerge - I have them dumping into the woods behind our house, but one does actually emerge in the middle of the lawn.

Tom

 

[rsanter]

I would add a little more than the minimum slope in the pipe to make sure the water moved and does not freeze up.
Use rigid smooth wall pipe and not that corrugated stuff if you can

2% slope in the pipe would be nice. A little more if you can get it

Bob

 

[AldeanFan]

Thanks,
I'll makes sure to slope the runs as much as possible.
Definitely going with smooth wall pipe so I can clean it out if necessary.

Next questions, how much stone (how deep) will I need for a base under the new driveway? I may or not be doing some of this work myself but I want to make sure it gets done right either way.

And the big question, any ideas on cost? I have no idea how to estimate these kind of things. A co-worker just got her roof done, quotes were between $3,000 and $25,000, good thing she got multiple quotes.

 

[larry_g]

My son has been quoted a dollar a square foot to have asphalt put down on his. However his is near 200 yards long. A smaller job may be more per sq'.

lg
no neat sig line

 

[jhelrey]

Use solid PVC and go at least 6-8 inches. Put rodent cages where they daylight.

Doesn't take much to clog them or freeze up.