I dug a trench about 6-8 inches deep against the edge of my patio and about 10 feet into the rain garden.
I then laid the pipe in the trench, using a long level to make sure the pipe sloped steadily. The ground slopes in this direction naturally, so that task wasn’t difficult. I buried the pipe except for the last 5 feet or so, which still needed a bit of work.
Where the pipe stopped, I continued the trench for about five more feet. I lined the trench with landscape fabric, tucking the ends up underneath the mouth of the drainpipe, and anchored it in points with rocks scavenged from other parts of the garden.
I had a length of pipe sleeve, a tube of fine mesh fabric made to slip over perforated drainage pipe that allows water to drain in but stops mud from clogging the pipe. I cut a short length of the sleeve and knotted the end, and slipped it over the mouth of the drainpipe to prevent leaves (oh, myriad leaves!) from clogging the pipe. Using a pipe clamp, I secured the sleeve to the pipe and tucked the knotted end out of the way.
Scavenging more rocks and fine gravel from elsewhere in the garden, I began to create a dry streambed that will channel the flow of water from the pipe to the rest of the bed. The rocks will interrupt the flow of the water and allow it to move at a slower pace into the garden. The entry point of water into the garden is actually higher than the central 70 square feet that I excavated to the greatest depth, but the water will percolate in and continue to flow downhill.
Wouldn’t you know it? The day after I finished this segment of the garden, it rained. Time for a performance evaluation.