Trench Drain Under Asphalt?

Question

My question is regarding a trench drain I am running down the side of my home to divert runoff water from a downspout. This drain will pass under the driveway and I was curious as to what depth will allow a vehicle to pass over without damage? I am planning on cutting the apshalt with a concrete saw and keeping the width as narrow as possile. I am hand digging this trench so I can keep it as narrow as the Sch 40 4" pipe. Also, in one portion of the yard the drain will run through is driven on or parked on occasioally, will this still be possible after running the drain underneath to woodline?

Answer 1

Above all keep your project "KISS" friendly,paying attention to slope.A good rule of thumb is 1" drop per 10'.I have installed at much less (I call sleepy drains).

I have installed drains that came out to street/sidewalk using this pop up (see link).I dig hole beneath,using 5 gal bucket and fill with gravel.When water rushes out it pops up and when it equalizes it perks back to ground.

I just hate to see you make an unnecessary repair.

Good luck

Answer 2

Use schedule 80 and it won't have to be very deep.  I buried some schedule 40 about 8 inches under my drive and covered with road base, then asphalt, have had no problems.

Answer 3

You should be more concerned with making sure that your run of 4" has the needed slope to not back up and hold water. Make the slope as steep as convenient with a minimum drop of about 2 inches from one side of the (one car) driveway to the other. Use 1/4 inch gravel to back fill and make sure that it is well tamped and even to support the pipe and keep from crushing. If you want you could use concrete but that is a bit overkill. You might put concrete on top though before you redo the asphalt. I would go a couple inches minimum from the pipe top to the asphalt bottom with 4 inches being better and enough. You must see if you can put a clean-out at least on the low end, both ends still better and if you live where it freezes you need to be really sure that you have that good slope and drainage ability or you may find you have a speed bump next January and a tire eating ditch next March. P.S. You can get theses drain spout lawn waterers that keep runoff from the house foundation and spreads water over the lawn to save on water use. Some roll out when full and roll back when empty of rain.

Answer 4

You will need to bury the 4" pipe at least 3' below grade, making sure you bed the pipe properly and compact around the pipe well. You may want to consider using sch. 80 under the driveway and areas where you expect traffic. Deeper will be better, but I am sure you will be limited by the outlet elevation for your drain. The line should be sloped to the outlet by at least 1/4" per foot. If you can not get the burial depth needed, consider switching to a metal pipe (ductile iron) or encasing the pipe in concrete.