Meditative Remediation: A project to demonstrate the thoughtful use of water

Late Show: Sonoma CA 2009

We often forget that water is a precious resource that has limited supply, as we are surrounded by water, lush landscapes, verdant rolling vineyards and reside in an abundant agricultural state with fresh luscious produce at our fingertips. This garden is intended to demonstrate the possibilities for conserving water by recycling wastewater from a single-family home or a winery facility and using it for irrigation in the vineyards and gardens. We also recycle and reuse wine industry byproducts.

Our installation is intended to illustrate a simple system for using plants to decontaminate wastewater which can then be put to use for landscape irrigation. Gray water, such as water from a bathroom sink or shower or from a washing machine, needs simple bio filtration. Black water, such as water from a kitchen sink or from toilets, needs preliminary fermentation and settling processes such as are accomplished in a septic tank. (The actual processes are simulated in this installation, as real phytoremediation requires more than the three days of this garden show.)

The toilet, pipes and showerhead simulate the home or winery toilets and sink, which would be the wastewater sources for a real phytoremediation garden. In actuality, the wastewater is not going to be circulated into the remediation ponds here. The black water from the toilets would, in an actual setup, pass through a septic tank before flowing into the tanks such as we see in this garden. Here, sixteen grape tanks demonstrate a constructed wetland as the gray water treatment, and as the black water final treatment. The wastewater is hidden under gravel with cattails and other facultative wet plants coming up out of it. The plants roots oxygenate the wastewater wetland, extract nutrients (see below) and foster the growth of beneficial microorganisms.

The clarified wastewater from these tanks cascades into a shallow pond surrounded by a native wetland habitat. Here the wastewater is further bio-filtered, aerated, and decontaminated by ultraviolet exposure. Specifically, plants growing in the wetland absorb nutrients, thus reducing the nutrient supply for bacteria and other germs, which are further eliminated by the ultraviolet radiation from the sun. The water coming out of this pond is now suitable for irrigating the surrounding landscape.

Exposed tubes allow visitors to visualize the circulation of the water through the various steps of the process, finally going over the edge of the tanks into the ground. In our demonstration garden, they go into a layer of grape pomace, top-dressed with roasted grape seeds. In our demonstration garden, there is no actual inflow or discharge, so we use solar-powered pumps, re-circulating the water between the pond and the three tanks adjacent to it, to suggest the linear phytoremediation process.

We intended to use native plants specific to the fresh water wetlands of Napa County. The boundary between Sonoma and Napa counties cuts through the wetland West of our current location. With the help of the California Native Plant Link Exchange we identified 66 plants that make up this community, and have used 13 of them in this garden to represent locally appropriate native plants.

Plant list :
Alisma plantago-aquatica
Baccharis salicifolia (syn B.viminea)
Eleocharis macrostachya
Grindela st angustifolia
Juncus effusa var.brunneus
Juncus xiphoides
Lemna minor L.
Mimulus guttatus
Mimulus cardinalis
Scirpus actus var.occindentale

Resources:
Buck Eye Nursery
Calfora Native Plant Exhange
Corn Flower Farm , Elk Grove, CA 916.689.1015
Upper Napa Valley Disposal Services
Flora Grubb Gardens

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