The Vital Role of Infiltration in Groundwater Sustainability
Rainwater infiltration is extremely important to the supply of groundwater, which according to the U.S. Geological Survey, is considered one of America’s most important natural resources.
Half of the drinking water in the U.S. comes from groundwater, with the balance coming from lakes and rivers. It is vital to agriculture and other industries, as well as essential for ensuring the health of rivers, streams, wetlands and other water bodies.
Urban sprawl has resulted in a decline of rainwater infiltration and decreased groundwater levels, as noted by the United States Environmental Protection Agency. This is largely due to the proliferation of impervious surfaces such as concrete and asphalt, which prevent rainwater from seeping into the ground and recharging the groundwater aquifers.
To mitigate the impacts of reduced rainwater infiltration, it’s important to explore sustainable methods that can help maintain groundwater levels. One such method that proves vital for ensuring future water availability is soil infiltration.
Permeable pavers installed over porous soils are designed to allow for rainwater infiltration, reducing runoff and flooding into nearby storm drains, eliminating the risk of carrying pollutants back into the environment. Most soils, even clay, allow for some infiltration.
Soils with high porosity, such as sand, can have a higher infiltration rate than the actual rate of rainfall. For example, if it is raining at a rate of 2″ (51 mm) per hour, and the soil has an infiltration rate of 4.5″ (114 mm) per hour, the soil will absorb water before it can run off. Even poor soil with a low infiltration rate will work. For example, a soil with 0.25″ (6 mm) per hour of infiltration will have complete infiltration after about four hours per inch of rainfall.
Rainwater Infiltration Revolutionizing Community Design
The Iowa Green Streets Project serves as a catalyst to revitalize the local economy in West Union, attract and support local businesses and stimulate further investment to the historic downtown. The complete renovation of six blocks in West Union replaced aging water, storm and sanitary sewer infrastructure. The project also showcases innovative sustainable design strategies as a model for other communities, including permeable pavement roadways using Unilock Eco-Optiloc™, pedestrian crosswalk treatments with Eco-Priora™, rain gardens, energy efficient lighting, and a district-wide geothermal heating and cooling system.
Prior to design and construction, a cost analysis was completed for the permeable unit paving system. The analysis compared the cumulative cost of permeable unit paving versus that of a traditional bituminous asphalt surface. Analysis showed a payback period of approximately 15 years. Conservatively, the entire system is projected to save over $104 million in operation costs within the next 50 years.
Incorporating sustainable methods like permeable pavers can have a significant impact on rainwater infiltration and groundwater recharge. To learn more about the many benefits of permeable pavers, speak to a local Unilock representative.