Last year the Tulsa City-County Library System received two grants to install green stormwater management systems.  We have recieved a presentation from the Library showing the sites, design elements, and final products for both installations and will be posting them here.  Go by and check these out yourself!

The first is at the Judy Z. Kishner Library, located in a Sperry, OK. The library was completed in 2008 and lies in a two acre lot adjacent to the Osage Trail. Nearly the entire town, along with areas to the north, is prone to flooding. The contours and elevations of the library property did not allow positive drainage off the site and were a mosquito haven.

Since draining the water was not an option for this property, the idea of a rain garden took shape.To fund this project, the Library applied for a grant from the Amercina Recovery and Reinvestment ‘Project Green Reserve’ administred by the Oklahoma Water Resources Board. Due to the innovative nature of this problem resolution, the project was fully funded with the Green Reserve Grant Funds.

During construction, the existing surface depression was excavated further and the soil amended.  New vegetation, selected to enjoy the wet conditions, was planted. The finished result is an amenity for the library and the nearby trail as well as a stormwater management feature.

Heifer International - Wetlands

We're back to Heifer International in Little Rock - there was so much to write about! Besides rainwater use on-site, rainwater is also collected and treated through a variety of LID systems. One are the wetlands shown in the previous post. In practice, rainwater falls on the roof, which has been finished as something closer to a swimming pool than your typical roof.

Rainwater is channeled into downspouts, which have been designed as a functional architectural feature. The kids thought these would be great slides during the rain!

The downspouts become horizontal channels closer to the ground. Rainwater flows over the side of the channel, which function like a weir, into the stabilized forebay of a raingarden. You can see the channel as well as reeds in the raingarden to the right.

A surface drain at the end of the raingarden allows stormwater to flow into the wetlands at the site. The wetlands surround the main office building, giving it a castle and moat feeling. But most of all it's lovely, with ducks, turtles and fish enjoying this site, which was previously a contaminated industrial facility.

Below is a design schematic for the wetlands, similar to many, many we've seen in LID and stormwater guidance manuals. But not as often do we have the opportunity to see them in place, in practice. If you happen to be in Little Rock, look behind the Clinton Library for this green gem!

What's Up With Rats?

It seems each time I talk about raingardens, someone has to ask about vermin. You know, squirrels without the cute fuzzy tails: rats and mice. The question is usually, "Do raingardens bring in vermin?". My standard answer is, "No". But after hearing it so many times, I decided to get some additional advice on the topic.

I talked with both a horticulturist and a biologist about this question. On my list were Jay Ross, Horticulture Curator at the Tulsa Zoo, and Stephanie Rainwater, a biologist at URS. Jay and Stephanie both noted that any garden with dense vegetation can provide a nesting area for all types of critters, from songbirds to cats to, you know. The key to what critters you attract is what food supply is nearby. If you have insects, you should get birds that eat insects, and so on.

In the public arena, a community might consider whether the garden is located near areas of animal feeding (advised or not), such as a duck pond or petting zoo. Likewise the residential homeowner should consider whether they leave dog, cat, or bird food where other animals can access it. In my own yard, I've found the compost heap to be a problem.

But are there features that make raingardens uniquely less prone to being used by vermin than other landscaping? The answer is yes. Raingardens are designed to flood - every time it rains. There aren't a lot of critters that will put up with being flooded on a regular basis - they'll pick somewhere else to nest.

So, what does all this mean? Raingardens should be less likely to house these unwanted guests than other types of gardens and landscaping, a fact that should encourage others to bring stormwater controls into their landscaping.

Kill Before You Till

Is this a familiar sight? Bermuda grass is the bane of this gardener. Typically, directions for development of raingardens in native soil are to check permeability, clear the site, till in compost, and plant. But digging up sod in Illinois is different than removing the grass in Oklahoma.

Our primary grass seems to be Bermuda and it is invasive! Bermuda spreads not only by seeds but also by runners above and below ground. It can overtake over a foot of garden in a growing season. So, simply taking off the top layer of sod won't do. You have to kill it.

But how? I checked with the County Extension Office office for some direction. And their advice confirmed my anecdotal experience: Bermuda is tough stuff. You can try thermal sterilization of soil - putting down black plastic and allowing the sun's heat to kill everthing off. This kills the surface plants but doesn't address the deeper roots, which can be six inches or more below the surface. This also kills plants by depriving them of sunlight, but Bermuda can stay dormant under the soil for an extended period of time. I've also tried herbicides, which seem to work for a while, but Bermuda always seems to come back.

Bermuda, it seems, must be killed and killed again. They say up to 6 or 7 sprayings over time are necessary to really eradicate Bermuda from a proposed plot. And that takes planning ahead, about a growing season ahead, of when you want to plant.

And because it continues to spread from the outside, placing a good quality edge to 6 inches beneath the soil (not extending above the ground) will help minimize root intrusion. Surface runners take a hands-on approach. After all that, you should have a garden that is much easier to maintain. But it takes some time and planning (and a bit of grass-killer).

Traveling LID: Florida

As you may have guessed, I have to make note of LID applications wherever we travel. We took a family vacation to Sanibel and encountered these raingardens in a small county park northeast of Ft. Myers. We went to watch manatees, which we didn't see, but we found multiple raingardens!

Much of Florida is condusive to bioretention, a fancy word for raingardens, because of its sandy soils and high infiltration rates. As you can see in these photos, the surrounding landscape has been graded to form a depression. This is where rainwater collects. Plants within the depression have been selected that can withstand periods of standing water, or inundation. And the water is allowed to infiltrate, or seep into, the soil.

Some of the things I liked about this park were the number and variety of raingardens present - in the parking lot, at the entrance, and scattered throughout. They also provided educational signs, which I don't have photos of. I also liked that they made use of a range of vegetation, from trees that look like they've been there forever (and they may well have) to bushes and groundcover. Its not obviously a stormwater treatment system but fits attractively into the overall landscape. Kudos!