Drywells should not be positioned near the house. Otherwise the collected water may find its way back to the foundation and basement perimeter drain (French drain) system.

 

Thanks. I am planning to install drywells at recommended minimum distance of 10 feet.

 

Another option

I just wanted to add a second option I've been mulling. Minimize the use of french drains and use catch basins at strategic locations instead. The catch basins would help to alleviate surface flooding and also serve as a cleanout. Debris could be removed from the catch basins periodically to help maintain the dry wells. I would still need a french drain at the low point of the house, that's where surface flooding occurs.

Picture below:

 

If the house is built into a hill, aren't you better off using the french drain to bring the water around the house to the hill?

As someone with extreme water problems, I didn't find the dry wells helpful and ended up aborting the plan after digging and testing the hole. I hope you have done a test hole? (Dig a hole, fill with water, make sure it doesn't just sit there). In your case, your house will still be in between the dry well and daylight.

I've had more success with finally using a swale in order to have proper grading near the house. I just went as far from the house as i could and dug a V into the ground, allowing me to have the house graded to the bottom of the V. If you place the french drain there, even better.

If you are dealing with downspouts, you could just bury solid pipe to run everything around to the hill side of the house, in my case this allowed me to run everything to daylight.

 

What type of soil do you have? I would also figure out how much water you would be collecting on some of the larger areas of the roof to see with the system can handle the volume.

 

Response to questions

To respond to above two responses (thank you for your feedback).

1) I have sandy/silty soil. Very little clay. At the lowest spot (where I'll have a puddle after very rainy weather) the puddle drains itself within two days max. There's no where for the water to go at this spot, so I think my drainage must be fairly good.

2) I'm having difficulty assessing whether my system can handle the downspout volume. Three drywells could handle about 165 gallons at one time (55 gallons times 3). An two of rain (which is a lot for my area) would be about 1,500-2,000 gallons. But this would not be the norm. For those heavy rains, I believe a pop-up emitter is going to be necessary, but better to have the rain pop up 10 feet away (or more) from my house than the current three feet from the downspouts and trickle back to the foundation.

3) I have considered the swale. The problem is, given the siding of my home is very close to the ground, I would essentially need to dig a very deep hole in the middle of my yard in order to create the "V." It would severely disrupt the appearance of the yard. And would also be difficult to preserve the turf given the amount of regrading that would be necessary. Also, I'm now thinking the french drain is overkill. I only have issues with water running along the side of the house when the downspouts are flowing heavily due to heavy rains. I think by addressing the downspout flow, I'd be addressing the vast majority of my issues.