Unlike its cousin grey infrastructure, green infrastructure has a lot of potential for tying human habitation and the natural world together vis-à-vis stormwater management.
Definitions
“Green infrastructure is an approach to water management that protects, restores, or mimics the natural water cycle,” American Rivers says. “Green infrastructure is effective, economical, and enhances community safety and quality of life.”
For example, the site continues, “It means planting trees and restoring wetlands, rather than building a costly new water treatment plant. It means choosing water efficiency instead of building a new water supply dam. It means restoring floodplains instead of building taller levees.”
The goal of green infrastructure, in essence, is to replace a stormwater harvesting or management system composed of manmade materials with one that uses living biomass to accomplish the same ends. Any time you can use a plant, soil, mulch, or another living system instead of concrete, metal, or PVC, that’s a win.
There are exceptions, of course. If you’re building a stormwater pond to collect runoff and slowly drain it in a sustainable way, you’ll likely need a liner to ensure it functions well. That’s normal and we will discuss it further below. The point is to replace inorganic materials with organic ones wherever you can. This allows us to make use of the natural systems that have managed rain for billions of years, which is better for our water cycle and the environment.
Green Stormwater Management Strategies
“When stormwater is absorbed into soil, it is filtered and ultimately replenishes aquifers or flows into streams and rivers,” the EPA says. Plus, soil is an excellent filtration medium. When water soaks through, the soil and plant roots pull out chemicals, contaminants, and potentially harmful microbes. They neutralize them or trap them in soil, where they can’t hurt people and wildlife.
By the time stormwater reaches the water table (anywhere from dozens to hundreds of feet below), it’s usually clean as a whistle. Aquifers then serve our reservoirs and wells in the form of fresh, potable drinking water.
As such, systems that use soil, plants, and mulch are excellent ways to help manage stormwater on any property, from a large rural one to smaller urban homes and businesses.
Both require different strategies, of course, given that they’re working with different stormwater factors. Large properties already have widespread plant coverage, presumably, but those plants may not allow water to filter through the soil. Lawns with thick thatch, for instance, are particularly resistant to moisture absorption. They often act similarly to pavement in that water will run straight across them. Owners must aerate lawns to keep them healthy and loosen soil if they hope to manage stormwater that way. Using a dethatching tool is also recommended.
A better approach is to use native plants. These species are adapted to your area, so they already know how to manage with the amount of water that comes down, on average, in that area. They are adept at dealing with too much water in rainy years and too little in drought years. Since weather swings are increasingly the norm throughout the world, native plants are an excellent green infrastructure solution.
In urban settings, the goal is to put in as many plants as possible, then funnel stormwater toward them using angles and slopes. Bioswales are an excellent way to do this, diverting natural runoff areas into collection areas or garden beds, where it can later evaporate or soak into the soil. They work in a variety of locations, such as:
- Rain gardens
- Rooftop gardens and green roofs
- Roadside planter beds
- Small parks and greenways
- Bioswales
As with more rural properties, the best bet for urban green infrastructure is to use native plants. These are much less susceptible to die-off during heavy rain or drought years. Plus, they require less fertilization, pesticide application, pruning, and overall management. If you’re looking for a low-impact stormwater management solution, this is an excellent way to go. You can even use native plants atop roofs, where they grow in soilless media that allow water to filter down to the absorbent layer beneath. By harvesting the water in this way, you can then “water” your rooftop down the road rather than using moisture drawn from a waterway or aquifer.
Native plants can also help wrap a pond, reservoir, swale, or other stormwater harvesting system into the environment. They provide food and shelter for animals, who will improve the area by performing services humans can’t replicate. This includes:
- Releasing waste products that act as fertilizer for native plants
- Eating insects to reduce your pesticide use
- Trampling the area, which some species need in order to reproduce
- Improving soil in the area, which allows it to soak up water more effectively
- Creating a healthy ecosystem that will bring more local plants and animals to the area
We can’t stress enough that this isn’t only a solution for rural areas. Indeed, many urban areas are using stormwater harvesting techniques to great effect these days. These can exist quite happily, with thriving wildlife communities, in the middle of cities or suburbs, near shopping malls and apartment complexes. It’s important not to relegate the idea of stormwater harvesting to areas with large swaths of land, since this can work on a small, urban scale just as well.
Next question: how is green infrastructure different from the ways we did things before?
How Is This Different from Grey Infrastructure?
Wait, grey infrastructure? Is that a thing?
Yes, it’s a thing. Named in contrast to the newer idea of “green” or living infrastructure, grey infrastructure uses impermeable materials to manage stormwater. The EPA defines it as “traditional stormwater infrastructure in the built environment such as gutters, drains, pipes, and retention basins.”
Conservation International adds that “Gray infrastructure refers to structures such as dams, seawalls, roads, pipes or water treatment plants.” That’s not to say these approaches are useless, because they’re not. They do help keep stormwater out of public areas to reduce disease and pollution. However, they don’t allow runoff to soak into the ground.
Moreover, grey infrastructure is often old and under-serviced, making it unsuited to manage the needs of growing urban populations. As the EPA explains, “during heavy storms, the large amount of rain overloads aging combined sewers, causing the dirty stormwater to overflow into rivers and streams before it can be treated.”
Think of the LA River, for instance. While it is an excellent backdrop for cinematic strip racing, it’s not so great at gathering water in an ecologically friendly manner. Instead, stormwater pours into it and races down to the coast, carrying every pollutant and disease it picks up along the way, with nary a plant in sight to help absorb it. Plus, its ability to collect stormwater and release it slowly is limited at best, so it all rushes through at once. That only increases its ability to pick up and carry away harmful microbes and trash.
Conservation International posits that a mix of green and grey infrastructure is the healthiest one for the planet. For instance, our gutters and sewers probably aren’t going anywhere any time soon. Same for downspouts, which we need to keep roofs structurally sound.
However, any time we can use natural systems to manage stormwater, we should. “By catching the stormwater for reuse or by allowing it to filter into the ground naturally,” adds the EPA, “green infrastructure helps keep excess stormwater out of sewer drains, keeps polluted water out of our rivers, helps restore the natural water cycle, and helps create healthier urban environments and recharges our groundwater sources.”
If you don’t have such systems in place yet, don’t fret. More solutions come online every year, meaning this is the best time in history to work with eco-conscious companies (like BTL Liners!) that want to help you perfect stormwater management on your land.
To that end, let’s take a look at some of the best stormwater harvesting techniques for small and large properties.
