Outline in progress

Rain Gardens Presentation: Outline (Proposed/Rough)

I. What and Why:

Why?

Reasons we can all relate to:

1) Street flooding. (Image )

2) Subsidence. (Image)

When you take water out of our spongy river delta soils

               a) organic matter oxidize and shrinks

               b) the particles of that soil collapse onto one another.

               - In the three years before Katrina, most parts of the city sank 8 mm. per year. Some parts – those that received the worst flooding – sank at annual rate of 28.8 mm per year. (http://earthobservatory.nasa.gov/IOTD/view.php?id=6623)

               - Not only do the buildings sink; the pipes sink and crack. This in turn creates more drainage problems and more flooding.

3) Water pollution:

               a)old cities (including New Orleans) have combined sewer systems. When stormwater dumps into them, they can overflow and send raw sewage into nearby bodies of water. This puts us in danger of violating the Clean Water Act.

               b) by slowing the flow of water, rain gardens allow pollutants to settle out. (source: LA. DEQ)

Sum: Rain gardens are part of overall strategy to “think outside the pipe”. Important in New Orleans – we average 64 inches of rain a year.

Other reasons:

4) They’re nice. (Image of Magellan Street Garden)

5) Make use of a resource (rainwater) that is otherwise wasted.

6) Chance to explore native plants that tolerate flooding AND drought.

6) One part of the garden you won’t have to pay a utility company to water.

What Is a Rain Garden?

1. Dr. Bill Schuster, EPA: “Basically a shallow bowl …. (that) accumulates stormwater runoff” and acts as a sort of sponge.

2. Louisiana DEQ: “A shallow depression designed to catch rain from impervious surfaces such as roofs, streets, patios and driveways.”

-        Can be elaborate: e.g LSU Hammond’s rain garden (photo),

which drains a paved surface by means of an underground pipe and collects water in a subsurface tank.

-        Can be raised, e.g. Tulane University’s Rain Garden exhibit in New Orleans Botanical Garden (2 images).

This has a solar-powered pump that drives rainwater from a retention pond to planters y means of a system of tubing.

-        Can also be very simple: (Image-Groundwork NOLA’s vacant lot garden at N. Prieur and Caffin)

A low-lying area excavated in a vacant lot that was already flooding. Now the rain garden captures significant rainwater, drains the rest of the water, and looks kind of nice.

3. Our definition (review with group): a simple, low-maintenance garden designed to capture rainwater and allow it to sink gradually into the soil, planted with natives that can tolerate flooding as well as drought.

II. Design

Gary’s powerpoint showing his lot, orientation to sun, calculations of water capture.  (Can't upload, sorry.)

III. What to plant

Plant Selections (from Terry) 

IV. How to build it (need graphics)

Emphasize solutions for city-dwellers, do-it-yourselfers, affordable. 

Biggest problem is digging - clay is heavy. 

Use excavated soil, esp. clayey soil, from depression to build up retaining wall/berm on lower/street side of garden. 

Minimum ten feet from foundation, per LA DEQ. 

Depth should be 3-6 inches. Increase retention capacity by building in lower layers of coarse material (construction debris, gravel, sand) into which water can perc. 

Planters as possible solution to water collection at base of downspouts. 

Contractors: EcoUrban LLC has most experience. 

Guidance: Groundwork NOLA will advise homeowners for a fee.  Bayou Rebirth, other organizations may also offer homeowner guidance, will check. 

V. Maintenance and cost

Rosalie
- Proper plant selection biggest key to making it low-maintenance

- Will S&WB give you  a break on your water bill if you install a rain garden? I have asked for a good contact at SWB and will forward if I get. 

VI. Conclusions
a) Summary of ongoing city and federal efforts to promote rain gardens: S&WB funding for education, City of N.O. 6.2 million - 35 year master water plan
b) handout: map and addresses of rain gardens you can visit
c) handout: GNO soils map with key to soil types.