Looking for help with drainage

[gml1998]

I need to find out the correct way to drain a section of the yard at my son's house.
Attached is a sketch of the situation, I am looking for info size of drain tile, which sections need to be perforated.
The green line on the left is the south wall of my son's place. The purple box near the bottom is the lowest spot in the yard ,found with neighbor's laser transit. The area shaded is approximately where water stands after a decent rain. The red box at the top is city storm drain. The lowest part of the storm drain is about 9 ft below the low spot in the yard, so the drain tile can be pitched with no problem. The city said they would do the hook up to the storm drain .
The two 39 foot red lines indicate two lines we would like to tie in to the drain tile for the 2 down spouts on that side of the house. Also there is a sump pump discharge we would also like to tie in. The sump currently rejects on the surface about 20 feet from the house.
The main drain tile would be about 193 feet long (80+30+83)
My son's neighbor is an operator so we have someone that can run a mini excavator.

So the questions are what size drain tile, where should we use perforated , how deep and do we use gravel in the trench. And can we run the down spout and sump into the same pipe. Also where the purple box is on the sketch (The low spot) can we put in a catch basin?
Thank you for any help.

 

[Bretny]

It sounds like you have a good plan alreaty. As for how deep a foot below ground is good enough. Dont use the black poly pipe. Use something like sch20 at least.

You can run gutters and sunp pump in the same 4in pipe but i would run a second pipe. If you dont your gravel bed/french drain may act as a drywell or fill up with water. Thats not what you want, you want that gravel bed collecting surface water not water that is alreaty collected. Also pipe is cheap, redoing the job isnt.

 

[Bretny]

Also use perfirated pipe with gravel and filter sock in the wet/low areas. Everywhere else isnt really needed.

 

[doctordirt]

Without seeing it, but knowing it would drain catch basin and 2 down spouts. Would run 6" sdr 35 for the main line and laterals running to Downspouts in 4 " sdr 35. No black corrugated, would also be my reccomendation.

 

[gml1998]

What type of gravel for the gravel bed and should the trench be lined with a landscape fabric then filled with gravel, to help keep particulates from the gravel bed?

 

[ard]

Just wanted to say I *love* a plan drawn on paper.



(I often read about people than are stuck, due to 'not having any decent drawing programs'!)

Also, not sure it matters, but whats the frost depth there?

 

[gml1998]

42 inches ,give or take

 

[cantupshift]

Thoughts on my own project yet to be done.

Use pvc pipe pipe, not corrugated pipe. Put in cleanouts every ** number of feet so you can rent a line cleaning machine and daylight it if it gets plugged.

Pipe with the drain holes down at the bottom of the trnch so it can fill from the bottom.

Solid pipe above it for you gutter down spouts and sump pump. Again drain cleanouts with these too.

In TN I plan on going with landscape fabric and back filling with stone. Also glueing the joints to keep roots out.

 

[gml1998]

how much pitch should there be for best drainage?

 

[Bretny]

What type of gravel for the gravel bed and should the trench be lined with a landscape fabric then filled with gravel, to help keep particulates from the gravel bed?

3/4 crushed and washed is good stone for this. No fines in it.

how much pitch should there be for best drainage?

1/4in per foot of run. Will be fine. More wont hurt. Less can allow fines to settle in the pipe and clog it.

 

[bad_idea]

Doesn't take much. 1" per 8' is about all you need, or 1/8" per foot, or 1% slope (all three are the same thing).

I am a DIY type with plenty of drainage issues living in the southeast. Apple Drains on youtube said it best in regards to when to use perforated vs solid pipe. Perforated is for capturing water. Solid pipe for water you have already captured - you don't want to lose any of the water you already caught.

Use perforated in a gravel trench for the low spot and transition to solid pipe once you are out of the low spot. French drains (gravel filled trench with perf pipe) are for capturing water. Solid pipe is for moving water. Use solid pipe for everything else. Run a separate line for the downspouts - don't tie them into an existing drain tile around your foundation. That would over saturate the ground around the foundation and work the sump pump excessively.

I can't speak to depth to bury as we do not have a frost line. I am not sure how you would handle that. My assumption would be you'd want to bury the pipes below the frost line to avoid the lines freezing. Considering the storm drain is 9' down and you have an excavator available, I would think you'd go 4' down. Again, I have no experience with freezing ground. We don't see snow every year, maybe an inch or two every other year or so.

 

[Bretny]

Dont burry your pipes below frost. Spring is going to be when they are most used. I have a 4ft frost depth and only havr my gutter drains 1ft under ground. They wont freeze because there pitched properly. Moving water hardly ever freezes.

Also if you havr any clay or fines your not going to collect much water in a french drain thats 4ft below ground.

 

[rburke65]

Pretty interesting topic as this project in coming soon.