PARTS AND LABOR
Installing drainage pipe is a straightforward job that any homeowner can handle. It's typically done in three phases: digging the trench, laying the pipe and backfilling with soil.
What's involved.
Depending on the trench length and, more important, the type of soil, digging the trench with a shovel can range from relatively easy to downright impossible. For our installation, we dug a 70-ft.-long trench by hand through rocky soil, a job that took three weekends.
A quicker, easier alternative to hand digging is to rent a trenching machine or hire a backhoe operator. The backhoe will cost $75 to $200 per hour; the average job can usually be done in under two hours. To minimize damage to the landscape, have the operator use a 12-in. trenching bucket.
The trench must be at least 10 in. deep, but be aware that in cold-weather regions the pipe occasionally will clog with ice during periods of heavy precipitation. This condition most often occurs when the air temperature is mild during the day but drops below freezing at night.
The only guaranteed way to keep the pipe from freezing is to bury it below the frost line, which ranges between 32 and 48 in. in most areas of the snow belt. Digging a trench that deep is only practical when the end of the pipe drains into a dry well or is connected to an existing drain line.
Pipe types.
The drainage pipe used for extending downspouts is nonperforated
4-in.-dia. Schedule 40 PVC pipe; you can find it at any plumbing-supply house,
lumberyard or home center in 10-ft. lengths ($12 each).
Some jobs will also require flexible drainpipe, which is invaluable for getting around obstacles or following uneven terrain. For our installation, we used it to snake around a few large boulders we couldn't pry out. A 100-ft. roll of nonperforated flexible pipe costs about $28.
Along with the drainage pipe, you'll need an assortment of PVC elbows, T-fittings, couplings, adapters and other specialty fittings that allow you to connect together the pipe sections. Also, purchase a 16-oz. can of PVC primer ($4) and PVC cement ($4) for gluing together all the parts.
Backfilling basics.
There's not much to know about backfilling a trench. Just shovel the dirt back in, then compact it around the pipe. But, there is a trick that can make this phase go much more smoothly. Before you begin digging, lay down wide pieces of cardboard beside the proposed trench. As you dig out the dirt, shovel it on top of the cardboard. Then, when it's time to backfill, you can easily scrape or slide the dirt back into the trench without messing up the lawn.
