Downspout Drainage
Pipe Installation Tips
Frequently I see builders install downspout
drain lines close to the foundation of a new house. They do this long before the
backfill dirt around your house has compacted. This is a mistake.
Piping installed in uncompacted ground will
often develop negative pitch. This means that the pipe drains the wrong way! In
many cases, the stress on the pipe caused by compacting soil actually fractures
the pipes or cause joints to leak. This is unacceptable.
The better choice is to install this piping
in virgin soil which was undisturbed by the original foundation excavation. This
may mean staying 5 or 6 feet away from the foundation. What a small price to pay
for long term peace of mind!
Always try to lay the pipe in a bed of sand
or gravel. Don't allow an underground pipe to act as a beam. If a pipe has a
hollow spot beneath it, it will become a beam just as soon as dirt is piled on
top of it. The weight of the dirt (often 100 lbs per cubic foot!) will cause the
pipe to bend or break.
If your soil is rocky, be sure to cover the
downspout drain pipes with sand or smooth gravel. Sharp rocks can crack piping
materials.
How Deep are They Buried?
Downspout drain lines do not have to be
deeply buried. In fact, if your lot is fairly level, you must be very careful as
to how deep they are installed. If you go too deep, the pipe may still be
underground when you get to the discharge point!
Think about starting the installation at the
point where the pipe will discharge. Work backwards towards your house. Keep in
mind that you may have to pass under sidewalks or driveways. Never install a
"trap" in a downspout drain line. A trap is a low spot where water or solid
particles can collect. The solid particles may eventually clog the pipe. If you
live in a cold climate, trapped water may freeze and burst the pipe.
In many instances, I would dig a trench only
16 inches deep. This trench would follow the natural contour of the ground. A
trench this deep allows you to have a foot of dirt over the pipe in many
locations. Trenching machines work great! Set the depth and it follows the
contour of the ground for you. Watch out for buried electric lines!
ZOT!
