In Drain Language
If recent rain has turned your backyard into a swamp, it’s time to think about drainage. Whether yours is a new house with no landscaping or an older one with established plants and lawns, drains are not that difficult to install. And they pay off by helping prevent lawn- and plant-killing fungi and erosion or standing-water problems that can damage house and fence foundations. Basic steps to a street-drainage system:
PLAN
On graph paper, draw a scale plan of your lot, showing house, driveway, existing or planned porches, walks, patios and buildings. Avoid running lines under patios, walks or construction areas unless you need a drain there.
* Drains need to fall only 1 inch per 100 feet.
* Keep system as straight as possible; use 45- and 90-degree turns or a simple Y when turning corners or splitting a branch line.
* Grade yard so water will flow to drain openings; fill low spots and use a rake or 2-by-4 to level them. In a landscaped yard, install drains in low spots and plan system to move water away from them.
* Use powdered chalk, gypsum or a can of upside-down spray paint (sold at most hardware stores) to mark drain lines on turf.
THINK IT THROUGH
If you’re draining through a curb and into the street gutter, the outlet for your system can’t be lower than the street surface. All drain openings in lawn, planters, patios and walks must be higher than the outlet. Run a taut piece of nylon cord from a stake at the outlet to the beginning of the system in the backyard. An inexpensive string level will show the downhill run.
* A through-the-curb system may require a city permit. Check with municipal offices about costs and other requirements before you start digging.
* An alternative is to end the line inside the curb and install a pop-up emitter. Gathering water forces the top to open, allowing drainage.
* In most cases, cheaper 3-inch-diameter pipe will be enough.
DIG
Trenches should be at least 6 inches wide and 8 to 10 inches deep. Fittings such as couplers are 3 inches in diameter and usually need 2-inch clearance for drain-opening stubs.
* Use a narrow-bladed trenching shovel and a pick mattox. A power trench digger--Ditch Witch is available at most rental yards--will accelerate the process.
* Allow room for your hand on each side so you can manipulate pipe.
INSTALL
When laying pipe, work back from the curb outlet. Notice each section has one flared end that serves as a slip-fit coupler for the next piece. You don’t have to glue sections, but there is a glue for pipe. Before gluing or filling trenches, put a garden hose in the opening farthest from the outlet and turn on the water to check the entire line for leaks.
* If test water doesn’t make it to the outlet and there are no leaks in the line, you may have a low spot impeding flow. Check section levels to ensure a downhill flow.
* If you must cut a pipe, use a straight coupler or a T or Y to connect. The T legs should point straight up with a short section of pipe inserted to create openings at ground level for drain grates. If the start of your system is going to be a drain, use an elbow and you won’t have to plug one end of the T.
FINISH
Once your flow works, fix loose fittings (push firmly together, wrap with duct tape or glue) and fill the trenches. Put tape over drain openings to keep out loose earth while filling the trenches.
* Tamp earth thoroughly as you fill; water for several days and retamp to keep the surface flat and prevent shallow furrows.
TOOLS
Trenching spade: Has a long, narrow blade and is easier to dig with than a normal shovel.
Hack saw: To cut pipe.
Tape measure
Long level or string or line level: To ensure continuous downhill slope.
Chalk, gypsum or spray paint: To mark drain layout.
Tamping tool: Rent or make one (short 2-by-4 nailed to longer 2-by-4 handle to form a capital T; use crossbar
Parts
Pipes and fittings needed will depend on design:
Pipe
10-foot lengths, 3- or 4-inch diameter, rigid or flexible.
Fittings
* 90- and 45-degree elbows
* Ys; Ts
* Couplers to join cut pieces
* End caps
* Square or round grills
* Atrium grates (cone shape)
* Catch basins (9- and 12-inch square or 6-inch round)
* Plugs for catch-basin openings
Options
* Flex downspout diverter (when drain is not flush with wall)
* Adapter for rectangular downspout to round pipe
* 90-degree pop-up emitter (if not cutting curb)
* 4- to-3-inch straight adapters
A Catch Basin
Think about using a catch basin at the low end of your line. Basins are built with a sump--a floor lowered below the pipe inlet-outlet holes. Debris collected in the sump can be removed after a storm. Or you can flush the pipe with a hose several times a season.
Source: Orange County Farm Supply Co.;
Researched by JOHN O’DELL and TOM REINKEN / Los Angeles Times
