Gravitaatioviemäri

Gravitaatioviemäri, or gravity sewer, is a type of wastewater collection system that relies on gravity to move sewage from its source to a treatment facility. This is the most common and traditional method for transporting wastewater. In a gravity sewer system, pipes are laid with a specific downward slope. This slope, known as the gradient, ensures that the force of gravity pulls the wastewater through the pipes.

The design of a gravity sewer system is critical. The gradient must be sufficient to maintain a flow velocity that prevents solids from settling out of the wastewater and causing blockages, but not so steep that it creates excessive turbulence or erosion. The size of the pipes is also important, as it needs to accommodate the expected volume of wastewater.

Manholes are typically installed at regular intervals along the sewer line. These provide access for inspection, cleaning, and maintenance. They also allow for changes in direction or elevation of the sewer pipe. In some cases, where gravity flow is not feasible due to topography, other methods like pumping stations may be required to lift the wastewater to a higher elevation before it can resume its gravity flow.

The simplicity and low operating cost make gravity sewers a preferred choice where the terrain allows. They require no energy to operate, unlike pressurized sewer systems. However, they are susceptible to infiltration from groundwater, which can increase the volume of wastewater to be treated, and exfiltration, which can contaminate the surrounding soil and groundwater. Regular maintenance is essential to ensure the continued efficient operation of a gravity sewer system.