What Are Rainwater Infiltration Facilities?
Rainwater infiltration facilities are designed to enable rainwater to percolate into the soil or underground. With guerrilla rains and linear precipitation zones causing rapid water flow into sewers and rivers, these facilities have become crucial in preventing floods and inundations. By promoting underground infiltration of rainwater, they also contribute to groundwater nurturing, especially in urbanized areas where farmland and wooded regions are diminishing.
Uses of Rainwater Infiltration Facilities
These facilities are utilized for allowing rainwater to infiltrate the ground, aiding in flood prevention and groundwater recharge. They are installed in various locations, including buildings, residences, schools, and city halls. In some regions, municipalities subsidize the installation of these facilities to mitigate flooding. Often inconspicuous, resembling manhole covers, they are typically buried underground.
Types of Rainwater Infiltration Facilities
There are various types of rainwater infiltration facilities, often used in combination:
1. Infiltration Basins
Infiltration basins connect gutters to cisterns that temporarily store rainwater and allow it to percolate into the soil through holes in their sides and bottom. These cisterns, made of materials like concrete, polypropylene, or polyvinyl chloride, are surrounded by crushed stone to facilitate percolation. Sometimes, a permeable sheet surrounds the crushed stone for enhanced effectiveness.
Eligibility for municipal subsidies may depend on specific conditions, such as the diameter of the infiltration trench.
2. Infiltration Trench
Infiltration trenches, connected to rain gutters, are horizontally embedded pipes with holes to allow rainwater infiltration. Enhanced by connecting to infiltration troughs, these trenches are also surrounded by crushed stone and sometimes covered with permeable sheeting. Vertical arrangements, known as stick filters, are also used to allow deeper soil penetration.
3. Infiltration Gutters
Infiltration gutters are designed with fine holes for rainwater percolation. Surrounded by crushed stone and occasionally permeable sheets, porous concrete gutters are used for their reduced clogging risk.
4. Permeable Pavement
Unlike regular asphalt pavement, permeable pavement allows rainwater to seep through. Its composition includes increased coarse aggregate and varied particle sizes to create gaps for water permeation. Drainage pavement is sometimes combined with regular asphalt to balance permeability with strength.
Inspecting Rainwater Infiltration Facilities
Regular maintenance is essential for these facilities to remain effective. High-pressure washers are used to clear sediment, leaves, and debris, preventing filter clogging. Weeds must also be managed to ensure unobstructed water flow. The performance of channels, trenches, and ditches can deteriorate if clogged with debris like fallen leaves or mud.
In permeable pavement, obstacles like discarded cigarettes or gum need removal, often requiring specific tools. Post-washing, the pavement is brushed to eliminate residual dirt.