We Love an Open System

Written By Sophia Shinpaugh

Out of sight, out of mind. With any form of waste on this planet this is our programmed mindset. Trash, we throw “away” and forget about it, but there is no magical place of “away” it still ends up somewhere on this planet of ours. We have the same mindset about stormwater. It flows from our roads and walkways to a hole in the ground covered by a grate. Out of sight and out of mind. Water is a precious and finite resource and most of us don’t even know where our drinking water comes from. As humans we know we need water to survive, as well as, bathe, clean, cook, and if you’re fortunate you use water for relaxing in your hot tub.

Well, water has to come from somewhere and has to end up somewhere. I will be talking about stormwater runoff and drainage and the more sustainable options to deal with water.

Important terms to keep in mind throughout this post:

Stormwater: Water that has been in contact with a surface on the ground (surface water)

Runoff: The excess water that has not been absorbed by the ground and flows with gravity to either a drain in the ground, a body of water, or that muddy puddle in your grass.

Grading/drainage: Changing the land’s surface to direct water to where you want it to go

Pervious vs. Impervious: Pervious = water infiltrates and gets absorbed. Impervious = Any surface where water doesn’t absorb and the water runoffs instead

Closed System: When stormwater runoff gets transported underground to a series of pipes. Closed meaning we can’t see it once it has gone into the drain

Open System: Uses open and pervious surfaces to collect the stormwater water


Now I want to go through some examples. Some can be brought into your home design, while some are better fitted for the urban landscape.

Let us start with my favorite, rain gardens.

Rain Gardens

A common application of rain gardens is in place of those roadside drains. The stormwater gets directed to these beautiful beds full of plants inset into the ground to allow the water to drain into the bed and then infiltrate into the ground.

A rain garden has two key functions that make it an aesthetic and efficient option. One, it reduces the amount of runoff. Two, they help filter out pollutants and provide habitat and food for insects and other wildlife (EPA, 2024). These rain gardens are planted with grasses and perennials that can withstand infrequent and large amounts of water.

This type of open system does involve a lot of thought, planning, and design to ensure it is working as efficiently as possible. Careful calculations using an areas 50 to 100 year flood plan to see how much water this system will need to hold in case of an event such as a flood.

An open system as seen above is a great, natural way to filter out surface pollutants, such as car oil and other debris. This water as it percolates through the soil goes through an extra filter process with the pea gravel that helps collect even more of those pollutants. As the water continues to flow through the system there is a perforated pipe to carry away the excess water and the newly filtered water will end up in the groundwater system.

Thinking back to a closed system, all that polluted water goes straight into the stormwater pipes underground. These open systems, like the rain garden, adds that extra step of infiltration that is completely natural, while also benefiting the environment by creating biodiversity. This is especially important in an urban setting (aka, concrete jungle).

As a landscape designer, these open systems are a catalyst for creative designs that are aesthetically pleasing and educational by drawing the eye of the passerby to this remarkable system. By creating something someone wants to look at while demonstrating its purpose is why I enjoy these types of systems. It is all about creating awareness for a large problem with a beautiful solution. The rain garden at Edinburgh Gardens is a gorgeous example of taking a utility system and making it beautiful.

Bioswales

Similar to rain gardens there are also bioswales. The main difference between the two is that rain gardens are designed to capture stormwater while bioswales are designed to slow stormwater runoff down through a curving or linear path (Pittsburgh Water, 2021). A bioswale, to say it simply, is a ditch. Bio, meaning it is planted with grasses and perennials, and swale, meaning ditch. So, a bioswale is a vegetative ditch (ESF, n.d.).

A bioswale is seen in large parking lots, any area where there is a large area of an impervious surface. There are four functions for how bioswales manage stormwater.

  1. Collection

  2. Conveyance

  3. Filtration

  4. Infiltration

These four traits reduce the volume of peak runoff as well as treating stormwater quality (ESF, n.d.).

Green Roofs

I feel like everyone romanticizes the idea of green roofs. They are beautiful, complex, and you don’t see them often. When done right, green roofs are a very sustainable system for the environment and the building that they are on.

Green roofs can help regulate a building’s internal temperature, reduce stormwater runoff, and mitigate the urban heat island effect (Professional Practice, n.d.). The heat island effect is when a metropolitan area experiences higher temperatures than the neighboring rural areas due to the lack of vegetation and tree canopy (Aircaretoday, 2024). Green roofs have extreme benefits to the urban landscape. They provide economic benefits by increasing the longevity of a building’s roof life as well as providing opportunities for urban food production and biodiversity (Professional Practice, n.d.).

A University of Michigan study showed that a 21,000 square feet $464,000 green roof will save $200,000 over its lifetime. “Nearly two-thirds of these savings would come from reduced energy needs for the building with the green roof.” With Energy savings of about 15-25% for a 2-3 story building (EPA, 2008).

Needless to say, green roofs are power houses of sustainable practices. There are a couple of different types of green roofs that I want to go over. Extensive and Intensive green roofs are the two main types.

Extensive green roofs are naturally self-sustaining and evolving. It is also the most cost effective type of green roof. Extensive green roofs only partially restore the environmental footprint of a structure, but it is said to be the most efficient and most natural (Green Roof Types, 2021).

Intensive roofs are more for a functional purpose for people to use as well. This green roof type has less limitations on plant selection and design opportunities (Green Roof Types, 2021). Intensive green roofs are essentially green/open spaces for a building, on the building. Because, this type of green roof is more of a hangout space than a stormwater collection roof, it has less environmental benefits and strongly depends on plant selection.

There is also a combination of the two, called semi-intensive. In the end the main difference between these different types is how they are constructed and what the plant material is. These types are also categorized by cost, amount of maintenance, weight and height.

Detention and Retention Ponds

Ever see those big empty ponds behind buildings or around parking lots? Those are detention ponds. Both detention and retention ponds capture and slowly release water, however, one permanently holds water while the other does not. Retention ponds permanently hold water, commonly used when groundwater is close to the surface (Detention vs retention basin, n.d.).

Both serve the same purpose, but retention ponds can help remove more pollutants and are more aesthetically pleasing given that it looks like your typical pond. The pond’s natural processes work to remove pollutants, these ponds should be surrounded by natural vegetation, especially retention ponds to improve bank stability and aesthetics (Stormwater basins, n.d.).

Maintenance is important, mainly making sure the drainage orifice doesn’t get clogged or blocked.

Permeable Pavers

I want to talk about one more sustainable solution to stormwater runoff. Permeable pavers are a great option if there is limited space for planting beds. Permeable pavers allow for walkable/parkable space while still allowing water to infiltrate.

Permeable pavers may be more expensive than an asphalt driveway, it is a great way to make your home more sustainable. It can even be as simple as a small backyard patio using these pavers. They can also be used in an urban setting as well. If a space only allows tree grates over trees as the streets vegetation, incorporating these pavers provideds that extra drainage and that walkable area.

Permeable pavement can be defined as a porous urban surface composed of open pore pavers, concrete, or asphalt with an underlying stone reservoir (Upper Midwest Water Science Center, 2019). The cracks between the pavers collects the runoff and stores it in that underlying reservoir. This allows the water to slowly infiltrate into the soil below the reservoir or discharge via drain tile (Upper Midwest Water Science Center, 2019). The benefits of permeable paving is similar to all of these other open systems, it allows water to drain, filter, and eventually end up in the soil or groundwater while reducing the volume of stormwater runoff.


Each system I talked about today have environmental and economic benefits, as well as, the well-being of us, the people, and wildlife. These are beautiful ways to deal with a not so beautiful issue. Adding a rain garden or permeable pavers are a great way to be more sustainably conscious on a small scale, however, these systems will have a much bigger impact in large scale urban settings by removing more pollutants from our water and naturally cleaning our inevitable stormwater runoff.


References

Aircaretoday. (2024, July 26). Urban heat islands: Causes, effects, and Mitigation Strategies. AirCare Today. https://aircaretoday.org/urban-heat-islands-causes-effects-and-mitigation-strategies/?gad_source=1&gclid=Cj0KCQiAgJa6BhCOARIsAMiL7V9iCZbrQib1YrtMeO2yoxWa4U5giAOKb0GzABrIWu_JfYDUgObBixcaAjmFEALw_wcB

Bioswales. (n.d.). https://www.esf.edu/ere/endreny/GICalculator/BioswaleIntro.html

Detention vs retention basin. Detention vs Retention Basin | Manheim Township, PA - Official Website. (n.d.). https://www.manheimtownship.org/1173/Detention-vs-Retention-Basin#:~:text=A%20detention%20basin%2Fpond%20temporarily,designed%20to%20permanently%20hold%20water.

EPA. (2024, August). Soak Up the Rain: Rain Gardens. https://www.epa.gov/soakuptherain/soak-rain-rain-gardens#:~:text=Planted%20with%20grasses%20and%20flowering,song%20birds%20and%20other%20wildlife.

Evaluating the potential benefits of permeable pavement on the quantity and quality of stormwater runoff. Evaluating the potential benefits of permeable pavement on the quantity and quality of stormwater runoff | U.S. Geological Survey. (n.d.). https://www.usgs.gov/centers/upper-midwest-water-science-center/science/evaluating-potential-benefits-permeable-pavement#overview

Green roof types. Green Roof Technology. (2021, November 13). https://greenrooftechnology.com/green-roof-finder/green-roof-types/

Professional practice. Green Infrastructure: Green Roofs and Walls. (n.d.). https://www.asla.org/contentdetail.aspx?id=43536

Stormwater basins: How detention and retention ponds work. (n.d.). https://info.wesslerengineering.com/blog/stormwater-basins-detention-retention-ponds

Stormwater tip: How are Bioswales and Rain Gardens Different?. Stormwater Tip: How are bioswales and rain gardens different? | Pittsburgh Water & Sewer Authority. (2021, June 29). https://www.pgh2o.com/news-events/news/newsletter/2021-06-29-stormwater-tip-how-are-bioswales-and-rain-gardens-different#:~:text=Residents%20can%20create%20simple%20rain,rainwater%20in%20a%20bowl%20shape.

U.S Environmental Protection Agency. 2008. “Green Roofs.” In: Reducing Urban Heat Islands: Compendium of Strategies. Draft. https://www.epa.gov/heat-islands/heat-island-compendium.


Sophia Shinpaugh
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