Open drainage systems, also called natural drainage systems, consist of uncovered channels or ditches that pick up wastewater flows. These systems are often unlined, but perform better if lined with concrete, brick or mortar. Apart from wastewater, open drainage system also serve as stormwater run-offs, and should be designed to accommodate heavy flows. These systems are not suitable for transporting sewage. Open drainage systems are more often used on farm lands than in urban areas.
The Advantages of Open Drainage System
1. Cost
Unlined open drainage systems are easier and less expensive to set up than covered piping. Installation is also less labor-intensive, as a farmer can create channels and ditches on his own, provided he has the right equipment. Maintenance of these systems is also not as labor-intensive as pipes that need to be dug up for reparations, so it works out cheaper in the long run too.
2. Surface Drainage
Open drains can receive overland flow and thus have the advantage of serving as surface drainage. These drains collect more silt and rubbish than pipes and allow increased residency of water to break down pollutants. Open drains parallel to roads can be used to guide water off the roadway, ensuring road safety in wet conditions.
3. Maintenance
As open drains are more easily accessible than pipes, maintenance of these drains is simple. Inspections and cleaning operations are easier to perform as these drains are not buried. If open lined drains are correctly designed, they should not require expensive or major repair. Regular inspections prevent major issues from arising. Grass or other vegetation should be planted along the sides of the drains to prevent erosion.
The Disdvantages of Open Drainage System
1. Expensive
Installing a open drainage system is a costly investment. You’ll end up paying a high price, especially if you hire a professional to install your open drainage system. You may also need a permit to install open drainage systems, especially if your particular project requires multiple channels and deep excavations.
2. Maintenance
Regular maintenance of your open drainage system will ensure that it functions properly at all times, says the University of Illinois. You have to ensure that the outlet ditches of your subsurface systems are free from blockages caused by sediment buildup. You’ll need to check that debris does not seal the inlet covers. If a tile of your drainage system breaks, you have to replace it. Removing water-loving trees, such as willow, elm, soft maple and cottonwood, from within 100 feet of the drain will keep your drain from blockages caused by overgrown roots, fallen leaves and branches coming from these trees. Ochre, an iron oxide that can block your drain pipe, may also build up; therefore, you constantly have to be on the lookout for it.
3. Can Contaminate Bodies of Water
A research conducted by the University of Illinois has shown open drainage systems can also contribute to contamination problems, especially when not properly maintained. According to the study, subsurface drainage systems can carry nitrate through the drain pipes, channeling it directly into the bodies of water such as streams, rivers and lakes.