if you have been to my house it is at the bottom of a large hill and just past the left dog leg turn
my driveway is for the past dozen years now 3 cars wide and 2 deep in length
so when I got tired about 8 years ago of pumping water from my garage after these 100 yr storms I went and put in a full length drain across the bottom of the driveway
The drain feeds into two 4 inch pipes that flow downhill to the back of the property and exit thru a loose boulder wall to dump on the folks further down the hill behind me
A few years ago we had that tornado pass just south and the water from that storm was 10 inches plus in the garage, and that was in just 10-20 minutes of waterfall like rain so I dug the yard up and replaced the 2 4 inch pipes with 2 6 inch pipes That is I am told TWICE the capacity of my supposedly over engineered project
At the time I put in the drain I had our downspouts fed into 2 new isolated 4 inch pipes that parallel the others running thru the side yard about a foot below the surface. That is 2 4 inch pipes and 2 6 inch pipes !!
Today I saw the unimaginable Water flowing out of every manhole and sewer in the street and a tsunami wall of water goes over the driveway lip and down my driveway and overwhelmed my drain masterpiece. Last fall I made a bypass at the fenceline in case of such calamity and the water once it got to 3-4" in the one car garage began flowing on its own until the rain let up but I still had to shovel water from the garage for an hour
Looks like I need to find the next bigger sizes of pipe
I am thinking that 12 inch pipe which comes in lengths twenty feet long may do the job Cant make the lip at the top of the driveway higher as I already bottom out sometimes and that aint good for the mufflers etc.
And to think when I bought this place all we had was a dry well
