Driving to Perfection

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Allowing for Drainage

The rain that flows off your drive has to go somewhere or the drive will waterlog and turn to mud. Where the drive is flat, dig a two-foot-deep trench along each side. Pour a gravel bed and then set in a perforated drainage pipe or drain tiles, surrounding each joint with tarpaper. Cover with coarse gravel and top with excavated soil. Be sure the drainpipe slopes down as it runs, and that it empties into the roadside ditch well below your drive surface.

Open ditches along each side of the drive — bottoms the better part of a foot lower than both the road surface and the surrounding ground — are better (and easier) for sloping drives and cuts. (Most fills will slope to each side and drain naturally.) Make ditches a foot or more wide, as deep narrow ditches ask for rapid water flow and erosion. Prevent erosion in steep ditching by laying in rock sides and bottoms. Or build a series of baffle dams of rocks or logs, held up by lengths of pipe hammered into the ground.

Installing Culverts

Install culverts to channel water beneath the drive and to run the drive across the roadside ditch. The simplest way is to lay in tarred corrugated steel tubing (of a size appropriate to the depth and width of the ditch) and build the drive over it. Lay soil around the culvert in thin layers, compacting each by hand. If your area is prone to gulley washers, get really big culverts even if you need them only a few times a year. Avoid the most common mistake of home road-builders: Don't get culverts too small or set them so shallow that a heavy flow of water will undermine or overflow the tubing. A heavy rain can carry it away, leaving you with a flowing ditch at the foot of your drive.

Sink culverts deep enough below the ditch bottom or creek bed so that the water can lay an inch or two of gravel bed at their bottom. Culvert is available in sizes ranging from a few inches to several feet in diameter, with cost appropriate to size. When we broadened the entry of our own drive, I had to extend the existing foot-diameter culvert by four feet to the east. But I managed to scavenge a length of pipe from materials discarded when a local highway was broadened.

You can buy precast end-baffles for smaller-sized culverts to keep the drive from falling out, to help keep the culvert in place, and to break the force of occasional floods. It is better road craft, however, to dry-lay stone buttresses around each end of a culvert. The stonework looks better than a plastic or concrete flange or the tip of a bare metal pipe. It adds a finishing touch to the drive.

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