"tim birr" wrote in message
...
My house is about 50 years old. All downspouts from the gutters go
into underground piping and exit "downhill" from a four-inch black
plastic pipe into a drainage ditch.

Near the end of last winter, noticed that water was pooling up from
"underground" near one of the downspouts.

Being lazy and clueless, ignored the problem. But as rain season
approaches, figured I better fix this -- we get about five feet of
rain per year.

I will dig out and see what is going on (I suspect a hole
underground). I will patch if I can, but if I need to run a new line,
any advice?

I was planning 3-4-inch plastic pipe running in a shallow trench (not
much freeze problem here) downhill to the ditch.

However, when I installed a french drain behind a storage shed a few
years ago, all the manuals were very specific about "drop per inch" --
ie -- the pipe should gradually slope away.

That would be difficult here, as I would have to run the line about
200 yards at a diagonal to do this from my house on a hill.

If I run the drain pipe straight downhill it will be about a 30-yard
run, but quite steep. Is that a problem?

It might be worth it to rent a camera and inspect it internally. You could
have collapse, clogging with dirt/sand, or roots. If it is as simple as
dirt, you can just flush it. If it is a collapse, at least you know where
the problem is, and don't have to dig up the whole thing.

Even at 50 years, clay or good plastic may be still "good enough". You
could cut an access hole, insert a small hose, and push it down to jet
through the clog, or even come up from the bottom to flush out the
obstruction. Those sewer guys have a high powered jet that would blow it
right out while the camera is in there.

Build you a critter barrier on the end of the pipe, as sometimes when it's
not raining, this is a place where critters nest. 1/2" hardware cloth works
good.

Fast slope is good. Helps keep if flushed out even during slow rains when
sediment and gook might tend to settle with slow flowing water.

Try free first. Use one of those little conical sprayers that you would use
to spray off your driveway. $1 at the Dollar Store. I'd try from the
bottom first. You'll know if you're flushing it out, or if it hits
something and won't go any further.

Steve