Factors to Consider on a Driveway Drainage System
When planning a driveway, driveway drainage requires special attention. There needs to be a system to it to ensure that the water doesn’t remain on the driveway. Another aspect of driveway drainage that’s vital is considering not only how it gets off the driveway but how it drains through the ground, rather than down into drains.
The gradients of the driveway are the most important factors in driveway drainage. There are two of them: the endfall, which is the gradient along the length of the driveway, and the crossfall, which is the gradient across the driveway.
Neither gradient needs to be steep (about 1 foot in 60 feet is perfectly adequate) but it does need to be factored into the design of the driveway. Where the driveway is seemingly flat, having the design much like roads, with a crown or higher area in the center, allows water to run off to the sides.
On extremely long driveway, considering having small gulleys or drainage pipes at the sides of the drive for the runoff of moisture. These will carry it away. However, it’s important to consider where it will be carried. Unless the ground is damp or marshy, creating drainage from crushes rock and pebbles, with a porous or drilled pipe above will allow the water to drain into the ground. This is better than carry it away to a storm drain. You can also use this system to direct the water away toward an area of your property that might be able to handle it.
The material you use for the driveway surface has a huge effect on the driveway drainage. Non porous materials, for instance, will mean that the water has to be carried away. By using porous materials, or fitting brick (for example) without mortar, you’re allowing the water to drain between the bricks and directly into the ground. As long as the driveway is on a good base, there will be no problems from this.
Allowing excess water to drain into the ground offers one huge advantage-it can help stop localized flooding. The water drains naturally rather than large amounts being directed to the city drain system, where it can overwhelm facilities in periods of torrential rain. Letting the water go into the water table stops that table from being drained completely by increased demands for water that are so common these days.
Under the Driveway
For excellent drainage you need to have the right materials under the driveway. What you use will depend on the driveway surface. For good driveway drainage, however, you’ll need to ensure that the aggregate isn’t packed too tightly. Some space will encourage drainage. At the same time, the gaps shouldn’t be large enough for water to accumulate, or it could freeze in cold weather which might cause driveway cracking. Be certain to use the right materials on top of the aggregate for the bedding courses of the driveway, too, as these can have an effect on driveway drainage.