05.22.11Kelly Duke

Of Bio-Swales and Single Malt Scotch

Griffith Park LA Zoo Bioswale 005 (Large)This bio-swale at Los Angeles' Griffith Park captures water from both the street and the parking lot and holds it is a series of terraced sections where it percolates through the tree and shrub roots.

Anyone who likes a “wee dram” of single malt will have likely heard of the role that water plays in its creation.  Water is used in single malt production to germinate the barley and start the malting process.  Water is used to wash the malted barley and carry the fermentable sugars as “wort” into the fermenting tuns wherein begins the mysterious journey that transforms a marginal barley beer into what the Scots call “Uisge breatha” or “The Water of Life”.

Many things influence the taste of a given single malt and one is the quality and characteristics of the water used in its production.  What makes water an important part of the formula is the unique combination of chemical characteristics have been imparted to the water on its journey from cloud to still.  Water may pick up mineral salts from the stream beds and aquifer it passes through.  For the single malts of from Islay (pronounced eye-lah), it is often the phenols it acquires as it travels through vast hectars of deep rich peat before it makes its way into the washback.

So what has this to do with issues of water management?

Only that soil and vegetation will influence water quality.  Healthy soil and plant life can be used to filter and enhance water as it makes its way through the hydrologic cycle.  Water landing on roofs or pavement will pick up everything that resides on those surfaces, good or evil, and carry it along to stream, pond, lake, or ocean.  Fortunately there are things we can do to improve storm or nuisance water outflow so as to provide a long-term benefit to our environment.

Bio-swales are a good place to start.  Properly designed these features can provide a low cost means to temporarily impound water so that plants and beneficial soil microorganism can variously filter, absorb, or neutralize some of the  more common pollutants we would otherwise flush into our dwindling water resources.

But a bio-swale is more than a planted ditch.  A good bio-swale is an engineered system designed to detain or slow water flow long enough to allow plants and microbes to have their way with it.  A good bio-swale is constructed with layers of different soil textures designed to promote specific actions:  A surface layer of gravel or cobble slows water velocity and spreads the flow across greater surface area.  A deeper layer of sandy loam allows reasonable percolation rates and good air exchange that supports a filtering network of roots and root hairs.  A drainage course of sand or gravel encased sub-drainage system collects the filtrate and sends the scrubbed outflow to the storm drain and to stream, pond, or ocean beyond.

Bio-swale layout is relatively flexible and can be worked in to virtually any landscape situation.  Effective use is in conjunction with roof drains, parking lots, and roadways where anything from bird droppings and industrial dust to hydrocarbons from spilled fuel and oil can taint run-off and foul streams and ponds.

Bio-swales are making their way in to more landscape designs and, along with Green roofs and Rain Gardens are providing Landscape Architects with new ways of applying old, low-tech solutions to the problems we create in our high-tech civilization.

Whether it is the right solution for your project is certainly something to think about; perhaps over a wee dram.

Kelly Duke

Not many people can say that they have dedicated their life to the landscape industry. Kelly Duke can. His diverse background ranging from maintenance to estimating, to design, along with a passionate commitment to his trade has given Kelly a lifecycle perspective to landscaping. As the leader of the ValleyCrest’s Pre-Construction Services team, he analyzes early conceptual designs to determine whether or not and how they can be built within budget while meeting long-term design and maintenance goals. Many of the projects that come across Kelly’s desk require he examine the cost and savings of baseline water use in comparison to high efficiency alternatives.



  1. Friday, 8:21 Gregory Ray

    I guess you learn something new every day; that is, about single malt scotch. As we design in our communities, bio swales are becoming a major component. Almost every project designed from sports complexes to a residential or commercial development, is talking about how to treat and capture water in our aquifers before it reaches our oceans. It would be interesting to identify the different types for design applications! Low Impact Development (LID) regulations, through our public agencies, are driving the need to figure out how to capture and clean water. This is a great solution that can be a pleasing aesthetic solution!!

  2. Sunday, 7:05 Richard Restuccia

    I enjoyed this article. Bio-swales are becoming asked about by customers more and more. I recently had a neighbor put in a pool and they had to add a bio-swale to the project to capture water run off from the pool.

  3. Friday, 5:38 Frank D. Gorman P.E.

    I’ve been known to have a wee dram time and time again but I digress. Bio-swales certainly add to cleaning up the environment. Most new developments require a W.Q.M.P -Water Quality Management Programs. The relationship between the site design Civil Engineer, the Architect and the Landscape Architect is very important to insure a well designed project, but don’t forget just as important is a long term maintenance program. Now one more for the road.

  4. Tuesday, 8:31 Kelly Duke

    I will follow this post up with some information and photos of a parkway bioswale being completed on the east side of Pasadena. Along with drip irrigation and drought tolerant planting, the street all drains to the gutter which feeds in to a linear bioswale that parallels the roadway. Look for more of these decidedly urban yet low-tech installations designed to both clean and moderate flow of storm water in an increasingly paved environment. KFD

  5. [...] your used soapy water so it’s perfectly harmless to your landscape, much like the bio-swales Kelly mentioned. How cool is that?) You may not be saving much money by harvesting but you won’t be spending any [...]

  6. Tuesday, 6:35 Kelly Duke

    Back at the time when my father and I were “engineering” our primative gray water system laundry detergent contained large quantities of phosphorus. This would not have been a wise project for us to undertake had we lived in an active watershed area as the phosphorus would have been picked up in any run-off and contributed to algae blooms in any water bodies it may have landed in. Increased knowledge of these types of interaction eventually led to the re-forulation of most cleaning products specifically to reduce phosphorus and other ingredients that might have unintended consequences in the watershed. You can’t fix everything overnight and environmental stewardship is less of an end product than it is a process of incremental “little victories” made variously through education and / or enlightened self-interest.

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