I’m really excited about a bioswale project that my studio is currently working on. So excited in fact, that I had to write a blog about it. We are only in the preliminary phase for it, and hopefully things will progress in the coming weeks. If you don’t know what a bioswale is, don’t worry. I will explain it after the break, so read on. I’ll also give you more details and show you some images. Hope you enjoy!
So a few months ago, we started working on a bioswale concept for a small town in New Jersey. The site is almost exactly in the middle of its downtown. It’s not a huge site only measuring about 6’ wide and around 78’ long, plus it is sandwiched between a parking lot and a roadway. However, it’s located in an ideal spot to do something like a bioswale.
What is a Bioswale?
The first question you may have is, what is a bioswale? There’s a long and short answer. I’m going to give you the answer in between those two. A bioswale is a way to manage rainwater and other precipitation (aka stormwater) in a more ecological and environmentally sensitive way.
The first question you may have is, what is a bioswale? There’s a long and short answer. I’m going to give you the answer in between those two. A bioswale is a way to manage rainwater and other precipitation (aka stormwater) in a more ecological and environmentally sensitive way.
This definition isn’t self-evident; because you might not know how stormwater is typically managed, so let me give you the background.
Context
When rain falls on a surface like a parking lot nearly all of it (around 98%) will “runoff” into a storm drain. If you compare that with a lawn, far less will runoff a grassy area. Also, when rain flows across a parking lot, it picks up all of the grime, oil and dirt on the surface of parking lot…and parking lots, roads and highways are particularly filthy. After that, all of the rainwater (that is now full of all of the mess that was on the parking lot) goes into a storm drain and is then directed to the nearest river, creek, estuary or stream.
Context
When rain falls on a surface like a parking lot nearly all of it (around 98%) will “runoff” into a storm drain. If you compare that with a lawn, far less will runoff a grassy area. Also, when rain flows across a parking lot, it picks up all of the grime, oil and dirt on the surface of parking lot…and parking lots, roads and highways are particularly filthy. After that, all of the rainwater (that is now full of all of the mess that was on the parking lot) goes into a storm drain and is then directed to the nearest river, creek, estuary or stream.
This is where problems really start. First, all of the extra water into a natural tributary can cause flooding, erosion of property, and damage to bridges & houses. And all of that muck is a huge source of ecological pollution that can kill wildlife, destroy ecosystems and make your favorite beach or lake a not-so-awesome place to go.
However, bioswales can reverse most of that. A bioswale has lots and lots of plants. Instead of the rain going directly into the drain, it will first go through the bioswale. All of the plants act as filters to remove the contaminants from the water. So, by the time the runoff gets to the drain, it is a thousand times cleaner than if it had just gone into the drain straight from the parking lot. Also, bioswales can slow down, and even store some of the rainwater. This slowing down or storage is referred to as “detention” – meaning, the water is not held onsite indefinitely but is released back into the environment through more natural ways.
Detention is a good thing. When it rains, all of the rainwater starts running into storm drains at the same time…and thereby is outflowing into the local river all at the same time. It’s this sudden and amplified presence of water in a river that actually causes water to break dams and overpower flood protections downstream. If we had more bioswales holding more water as well as cleaning it, we would have much healthier aquatic ecosystems as well as more effective control of stormwater. This control would give us cleaner beaches and rivers and greatly reduce flooding in many places.
Other Reasons for Excitement
So, the opportunity to design a bioswale is exciting because they are eco-heroes, and who doesn’t want more eco-heroes in their life? The other reasons for excitement is that this project can turn a fairly nondescript part of a downtown into a centerpiece that helps make it a more desirable place to go. This is usually referred to as placemaking, that is, designing and making places that people love and feel enriched when they go to them. I’ve always felt that placemaking should also use design to express a sense of self-value as well as a value for the people that use them. Or said differently, I think places need to be visually stunning as well as extremely usable and practical.
Back to the Bioswale
So the vision for the bioswale is to be an ecological wonder, a spectacular spot to visit and a great addition to the downtown area. That’s a big order for a narrow strip of dirt, but the preliminary design is moving in that direction. Below is a sneak peek at the current design. When you compare it to the existing conditions, it’s a huge improvement. Right now, the strip is planted with a few evergreen shrubs that are not overly interesting or ecologically beneficial. Our design will use native perennials and grasses in the bioswale. If everything goes well this week, we will start to select specific plants for the bioswale next week.
Detention is a good thing. When it rains, all of the rainwater starts running into storm drains at the same time…and thereby is outflowing into the local river all at the same time. It’s this sudden and amplified presence of water in a river that actually causes water to break dams and overpower flood protections downstream. If we had more bioswales holding more water as well as cleaning it, we would have much healthier aquatic ecosystems as well as more effective control of stormwater. This control would give us cleaner beaches and rivers and greatly reduce flooding in many places.
Other Reasons for Excitement
So, the opportunity to design a bioswale is exciting because they are eco-heroes, and who doesn’t want more eco-heroes in their life? The other reasons for excitement is that this project can turn a fairly nondescript part of a downtown into a centerpiece that helps make it a more desirable place to go. This is usually referred to as placemaking, that is, designing and making places that people love and feel enriched when they go to them. I’ve always felt that placemaking should also use design to express a sense of self-value as well as a value for the people that use them. Or said differently, I think places need to be visually stunning as well as extremely usable and practical.
Back to the Bioswale
So the vision for the bioswale is to be an ecological wonder, a spectacular spot to visit and a great addition to the downtown area. That’s a big order for a narrow strip of dirt, but the preliminary design is moving in that direction. Below is a sneak peek at the current design. When you compare it to the existing conditions, it’s a huge improvement. Right now, the strip is planted with a few evergreen shrubs that are not overly interesting or ecologically beneficial. Our design will use native perennials and grasses in the bioswale. If everything goes well this week, we will start to select specific plants for the bioswale next week.
The bioswale will dip down in the middle to allow water to flow through it. Because of this, we will need to add a bridge where a path is now. I’m hoping to use very durable and sustainable wood to make the bridge. We also want to add benches in three locations (right now, there are no benches in the area). The benches and the bridge would need to match, and a beautiful wood will express a value for nature and people.
Underground
The average onlooker will likely never see the true power of this bioswale, because it will be underground. We are proposing to use a series of stormwater cells to detain as much water as possible. A single cell can hold just under 32 gallons of stormwater.
Underground
The average onlooker will likely never see the true power of this bioswale, because it will be underground. We are proposing to use a series of stormwater cells to detain as much water as possible. A single cell can hold just under 32 gallons of stormwater.
If we max out the number of cells for the strip, we will have the ability to capture around 12,000 gallons of water. That number may be a bit abstract, so I’m hoping the graphic below helps. During an average rainstorm where 1inch of rain falls, an entire section of the parking lot sandwiching the bioswale can be treated before it flows into the storm drain. That will make a huge difference, because less polluted runoff would be emptying into the local river. It’s kind of amazing that this little piece of dirt holds such opportunity.
Above is short video (around 30 seconds) that diagrams the different layers of the bioswale. The underground cells will go in first. They are then wrapped in geotextiles. After that, we will need to add an overflow pipe just in case the entire system gets overcharged with water. Then, we have the grading to allow the water to run through the plants. We’ll need the bridge and benches installed and finally, we’ll add the plants as the last piece.
I’m even proposing we repaint the parking spots so that the bioswale can get more attention. All together, I hope we get to complete the design and can get it installed this year. As more updates come, I’ll try to write blogs about them.
I’m even proposing we repaint the parking spots so that the bioswale can get more attention. All together, I hope we get to complete the design and can get it installed this year. As more updates come, I’ll try to write blogs about them.
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