Drainage systems are especially important in Louisiana and Mississippi, where the land is more vulnerable to water damage from flooding and erosion than other places in the country. The reason for this is the low elevation of the ground because of its proximity to the Gulf of Mexico. Because the land is lower the water table is higher, with water very close to the surface. Excessive rain from tropical systems, hurricanes, stalled storm systems, and frequent rainfall cause the water to pool on top of the ground and stay there, causing rot and damage to foundations and structures, as well as yards, parks, sports fields and more. In addition, Southeast Louisiana has more clay-heavy soil which retains water instead of porous soil or sand, which would allow the water to drain through it.
Planning a drainage system in Southeast Louisiana and parts of Mississippi can sound like an overwhelming task with lots of complicated terms, but you, as the property owner can typically implement one or two common sense measure to get water flowing in the right direction – away from your home or building, leaving the remaining land high and dry.
Types of Drainage Systems
- Natural drainage, such as bayous, canals, retention ponds, and rain gardens
- Surface drainage which are ditches, swales, culverts, trench drains, and grading and sloping practices
- Sub-Surface drainage, which the main drainage system are French drains
Large commercial drainage systems in cities like New Orleans utilize flumes. A flume is a surface drainage device usually fabricated out of concrete that is used for stormwater runoff. There are many different types of flumes designed based on the ground in which they are installed and the rate of the anticipated storm water deluge that is expected. Flumes can be incorporated into commercial and city designs, often being constructed as part of sidewalk and walkway systems with residents unaware they are part of a storm drainage system.
Types of Drainage Techniques
- Grading and sloping of the land for water runoff
- Excavation of trenches for swales, culverts, trench drains, & French drains, as well as ditch and canal excavation
- Pond excavation for both traditional and retention ponds
Less invasive depressions can be dug in your yard or property for rain gardens, which are spaces typically about 6″ lower than the surrounding ground. Rain gardens are filled with mostly sand, but also some soil and compost. Plants and trees which are natural water sponges are then planted to soak up the excess pooled water and help the drained water dry up much more quickly and naturally. Additional drainage control can be attained by strategically building retaining walls to block water flow and keep it off of lower land area.
Surface Drainage
Ditches & Canals
Ditches and canals are dug deeper and longer to accommodate a prolonged and fast moving water flow away from your home or commercial building. Ditches are used a lot in Southeast Louisiana for drainage of not only rainwater, but also the drain from septic systems.
Swales & Culverts
Swales are natural trenches that are excavated out of the land to match the slope of the land. They are usually dug shallow and wide to accommodate a slower rate of water drain off. A lot of swale design includes the planting of vegetation on the sides of the swales to camouflage it as part of landscape design. Culverts are typically installed underneath driveways, sidewalks, and walkways to handle water drainage to the street.
Trench Drains
A trench drain is below the ground, but is used to drain off surface water by collecting heavy rainfall from parking lots, gravel lots, and other flat surfaces. The trench drain is covered by a grate aboveground and is connected to underground piping to drain the water away from the area.
Sub-Surface Drainage
One of the most popular and simple drainage techniques for houses in Southeast Louisiana is the French drain. A common misconception because of its name is that this system is a French design. It is actually named after Henry Flagg French who originally used it for agricultural drainage. In simplest of terms, a French drain is perforated pipe covered by gravel that is installed underground to transport water that sinks into the ground to the pipes below. French drains are extremely effective in that the gravel encourages water to filter through it quickly, and the pipes trap the water and move it quickly and efficiently away. They can be integrated into any space with minimal disruption, another reason they are so useful and popular.
In order to correctly install your French drain, you will need to consider the following factors:
Trench Size
Proper depth and width of the trench to accommodate the volume of water.
Trench Position
Consistency and positioning of the slope to ensure maximum drainage effectiveness.
Trench Filtration
Using quality and durable filtration material, which prevents sediment from collecting in the pipes, as well as root infiltration.
Trench Material
Gravel size and consistency to most efficiently drain the water flow quickly and effectively.
French drains are designed to be low maintenance and to last for many years. However, water erodes most things in Southeast Louisiana and Mississippi, so paying attention to the behavior of water on your land and having your drainage system inspected is an important part of being a property owner.
