It’s happened to all of us. You step outside of Rand just to be met with a deluge of rain. Only worse are the rivers that seem to form on Vanderbilt’s campus. Living in a city with the yearly rainfall being just under 50 inches, the water flows endlessly; its presence is harmful, and not just to your shoes.
The sidewalks and parking lots on Vanderbilt’s campus are made of an impermeable concrete, which is exactly what it sounds like. Water can’t seep in, so it has nowhere to go but in little rivulets. This runoff can find its way into streams, intro rivers and eventually into our ocean. While the water travels over the land, it collects other waste, pesticides and pollutants, all of which are then deposited into our ocean.
So how can we solve this problem? Make it stop raining? Or we could implement permeable interlocking concrete pavers. You’ve probably seen these your entire life, unaware of the benefits they provide you.
These permeable pavers decrease the runoff that pollutes our oceans by trapping the fallen rain water in the cracks between each brick. Underneath is often an open graded, or loose, rock mixture. The water easily flows through this and seeps into the ground below. This would reduce the rivers that we have grown so used to on Vanderbilt’s campus, but its benefits reach beyond what the eye can see.
When it seeps into the ground, it recharges the groundwater. Groundwater is naturally recharged by rainfall, but Vanderbilt’s impermeable sidewalks have blocked what nature does best. Groundwater is a vital resource. To maintain sustainable groundwater management, we can’t take more than it can recharge. This is hard to do when we’re blocking the thing that recharges it.
The runoff also has an impact on topsoil. Topsoil is nutrient dense and allows many of Vanderbilt’s beautiful trees and flowers to grow. When rainwater washes away that top layer of soil, you lose those nutrients too. The runoff isn’t only on Vanderbilt’s campus though. It can impact the entire surrounding area, carrying precious topsoil to the ocean. With the permeable pavers, the water simply sinks into the ground. They also prevent the spread of the materials in runoff. The spaces between the bricks trap the suspended soil and pollutants, keeping our rivers free of the harmful chemicals.
Additionally, the permeable pavers provide gaps in the sidewalk, rather than a long strip of concrete. Cities often experience something called the heat island effect. The pavement surface traps heat; it can be 50-90°F hotter than the air. Urban areas have a lot of pavement, which translates to a lot of trapped heat. When you create cracks and breaks in the pavement, the heat island effect is lessened.
Although replacing all of Vanderbilt’s impermeable surfaces seems costly, the financial benefits outweigh the initial price. The permeable stones would reduce the cost of retention basins, curbs, gutters and other water collection installations. The actual installation is a lower cost solution because it involves no underground construction. The bricks also last 20 to 40 years, which is an equal life expectancy to concrete. The bricks are highly sought after for both their architectural look and their benefits.
The benefit of torrential downpours in Nashville? Wet hair and wet shoes. However, we could seek a higher benefit; permeable pavers would allow us to look on the bright side on cloudy days.
