Rain Gardens, Bio Swales, Natural storm water solutions…

Landscape Architecture for Landscape Architects Forums SUSTAINABILITY & DESIGN Rain Gardens, Bio Swales, Natural storm water solutions…

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    Anastasia Harrison

    What are you doing to make a difference in the world of landscape that brings about change? How are you managing your details, plans and architecture to best benefit sustainable projects? Has anyone finished a green roof and had a happy client?

    Tanya Olson

    Maintenance plan, maintenance plan, maintenance plan!

    I have worked on two projects that illustrate the difference – one was a creek restoration with a 5-year maintenance plan with oversight by the landscape architect. It was a very successful project with almost no invasive exotics.

    The other project was a parkinglot stormwater wetland system. There was no long-term maintenance plan. The plants did fantastic, and the function was spectacular (better than the mitigated wetlands at the same site), but the maintenance staff didn’t understand what we were trying to do (turnover at the location eliminated consistant maintenance messages, techniques and intents) and they mowed the whole thing, including willows and alders.

    Maintenance along the edges also appears to be paramount – “tidy edges” (see writing and projects by Joan Nassauer) seem to really help communities buy into what can sometimes look ‘too wild’ for the delicate sensibilites of masses.

    Roland Beinert

    Was the maintainance plan just part of the specs?

    Colm Dooley

    I’ve just finished a 50 sq ms grass roof in my own house and I’m a happy client does that count? : )
    well not happy with one of the outlets but that s my own fault, lesson learnt, i’m hoping it will inspire others. green roofs and rain gardens are the way of the future in Ireland hopefully

    Rob Halpern

    Perhaps a happy client and “make a difference in the world” are not the same thing:

    Tanya Olson

    I believe it was actually a separate contract. Maintenance within the specs has never really seemed to work unless the landscape contractor is also contracted to do long term maintenance – its a communication gap I think.

    Tanya Olson

    The way of the future with one foot in the past…part of your cultural heritage…

    Colm Dooley

    Hi Tanya,

    “One foot in the past” It’s an interesting and informed comment.
    While it may be true that our older generations have one foot in the past, It would not be accurate to assume this of the younger generations in our country. With the peace process in action now for almost 16 years our country has come to a time where younger people wouldn’t understand or wouldn’t feel the need to have “one foot in the past” to identify with their cultural heritage.
    As a nation we are proud of our history but we don’t wear it as a badge. We have been mentally unshackled from our own cultural heritage in this sense, whereby we don’t feel the need to harp on about the past. This doesn’t mean we are not informed or don’t appreciate our heritage it just means we are not letting it hold us back, life is too short for that kind of craic. Enough politics now as this is a landscape forum, I just taught you might appreciate the political views regarding the majority of young Eire. Bring on the Ireland of rain gardens and grass roofs!!!!

    All the best

    Colm O Dubhlaigh

    Trace One

    Ripped out irrigation systems along highway, replaced with no-water requirement erosion control planting, with no intention of putting irrigation back after work is done.. Slowly, bit by bit, I am going to rip out all irrigated highway landscapes and replace with no-water..

    does a negative action count towards the positive?


    Tanya, did you have a wetland ecologist involved with your stormwater wetland project? I am in Seattle and pursuing 2 certificate programs here, one in LID and the other in Wetland Science and Management. One thing that has been emphasized is that when designing wetland mitigation or even stormwater wetland systems, it is important to design within the larger landscape context to relate wetland functions from your wetland to adjacent or nearby systems. Sometimes that means designing a wetland with similar functions, sometimes it means adding other functions or habitat conditions that are no nearby. Has anyone had experience with this?

    Ryan Sand

    Im interested in the 50sq m grass roof you have? You should post a picture, I dig home done projects. How can we lead others to do things we dont do ourselves?

    Tanya Olson

    We did have an ecologist working on the mitigated wetlands with us, but not on the stormwater wetlands. My emphasis was in ecology for my master’s in landscape architecture – mostly worked on wetlands as I was in the middle of the prairie pothole region – so I knew a thing or two about wetlands.

    The project was very interesting – a farm field that had been worked for a number of years and was adjacent to a creek system with possible underground connectivity. We also had drainage from off-site in pipe going through the site that we wanted to daylight. It was a very degraded site. We had two types of ‘wetland’ – parking lot stormwater and mitigation wetlands.

    We had no constrictions on the stormwater wetlands and very specific design parameters for the mitigated wetlands – use existing seed bank, use existing soil profiles, and we could not add plants. The type of native wetland in the area has almost no connectivity to other systems. They are mostly ephemeral soggy spots, for lack of a better term, that have been badly degraded almost across the board. I don’t think I have ever actually seen one in an undisturbed state! We did connect these to the daylighted drainage, but only after the drainage had passed through thousands of feet of overland flow. They then drained to a different creek system than the one directly adjacent to the site. It turns out they did not function well – they infiltrated – which was surprising as they were lined with in-situ heavy clay soils.

    The parking lot stormwater wetlands were much more forgiving for some reason. They were probably too deep with sides that were too steep – but they worked! They worked really really well and the plants did great (we did plant them). We connected vegetatively to the adjacent creek system but not hydrologically.

    I’ve worked on a number of restorations and mitigations and I would say that nearly ALL of them are as you describe – adding functions here and there, connecting to systems that maybe weren’t connected before, etc. I think of it as trying to kick-start processes that have been stalled for a while…..and sometimes you are trying to replace multiple processes. I’m not too much of a purist in dealing with severly degraded sites!

    Tanya Olson

    What I mean by ‘purist’ is trying to get everything back to a pristine condition….


    That does sound like a great project. Do you have any photographs or drawings you are able to share?

    This past summer I was volunteering with an environmental non-profit organization, DC Greenworks, and had the opportunity to help design and retrofit an existing swale that eventually sheet-flowed off site, to a bioswale and raingarden. We did the installation with the help of 20 local high school students as part of the Mayor’s Green Summer Job Corps. It was a great project but physically straining from using primarily shovels and pickaxes to do all the grading.

    The existing berm and swale were sloped downhill, north of the arched walkway in the plan. At the end of the swale, the berm stopped and water sheet flowed down the remaining slope, causing erosion issues on the hill. At this location we cut back into the slope and leveled off then base of which would be the raingarden capturing and infiltrating this runoff. The cut material from the slope was relocated to the other side of the raingarden to form the new berm, which connected to the existing berm and enclosed the garden.

    The extents of the existing swale were defined using a post and chain fence and then let to naturally grow from lawn to meadow. The meadow condition will help slow the water and pretreat it before entering the raingarden.

    Tanya Olson

    There are photos of the projects in my folio here on land8lounge. Let me know if I have to ‘friend’ you to look at them – I don’t think you have to. All of the construction details are with the firm I was working for during this project….I don’t have any pics of the mitigated wetlands though, only the stormwater wetlands.

    Your project is interesting. I was surprised to see the swale in the middle of a slope. How is that working? You would think it would destabilize the downhill berm, but if it works it certainly gives an answer to trying to infiltrate water in a limited area. I would NOT like to hand grade an area that size! What a lot of work! If you can, make sure to document the work over time. I’ve really learned a lot from observing my projects over time.

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