Curtain Drain Function
Curtain drains are essentially trenches filled with gravel covering perforated pipe which act like an underground gutter to solve your drainage problems. The ditch is lined with filter fabric to ensure that the perforated pipe does not eventually clog with silt and dirt, thus rendering the curtain drain useless.
For curtain drain installation you will need the services of a large piece of digging equipment such as a Caterpillar 303 excavator, which you can rent at a local equipment rental store. You will also need enough gravel to fill the ditch along with either rigid PVC pipe—which is crush resistant—or flexible black plastic piping, which is much cheaper but not as durable. Also, think ahead and purchase some Wye fittings or sanitary tees to allow for easy clog removal without replacing entire sections of pipe.
Before getting started, drill holes into the full length of PVC pipe four inches apart on either side.
How to Install a Curtain Drain
Before you begin digging, call 811 to find out if there are any power lines running beneath the ground where you will be digging. Once the area has been declared safe, use the heavy digging equipment to dig a trench 18 to 24 inches deep along a place where the water seems to be standing—or draining to—the most. Be sure to slope the ditch in the direction you would like the water to drain.
Line the ditch with quality filter fabric such as Typar landscape fabric. Place one or two inches of gravel (three-quarter inch percolates work well) at the bottom of the ditch and install your PVC pipe, inserting Wye fittings every 12 feet or so (making sure to mark where the Wye fittings are placed). You may use the gravel beneath the PVC pipe to fine-tune the pitch of the trench.
Cover the PVC pipe with more gravel, leaving three inches or so at the top. Fold the filter fabric over the gravel, allowing the filter fabric to overlap. Fill in the top of the trench with decorative gravel or grass to cover the curtain drain.
If you run into clogging problems later on, you can dig down to the Wye fittings, remove the caps and then use a snake to blow out any clogs.