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Overview

Overview. Background & Basics Design Constraints Plant Species Design Process Rain Garden Overview Cost Analysis Maintenance Issues Summary. What is a Rain Garden?. A planted depression that allows rainwater runoff to be absorbed Intended to prevent flooding and filter the runoff

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Overview

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  1. Overview • Background & Basics • Design Constraints • Plant Species • Design Process • Rain Garden Overview • Cost Analysis • Maintenance Issues • Summary

  2. What is a Rain Garden? • A planted depression that allows rainwater runoff to be absorbed • Intended to prevent flooding and filter the runoff • Makes an otherwise dreary spot more aesthetically pleasing

  3. Functions • Diverts runoff from impervious paved surfaces or roofs • Helps to remove pollutants • Replenishes groundwater

  4. How does it work? • Water enters rain garden through spout or drain system • Ponding occurs in rain garden lasting 1 to 2 days • Water seeps into the soil over time using the vegetation as natural filtration

  5. Benefits • Absorbs up to 30% more rainwater runoff than grass • Helps clean runoff of pollutants • Prevents flooding • Provides a habitat for wildlife, such as butterflies and birds

  6. Rain Garden Location • Linden Hall provides optimum location for rain garden • Easily accessible runoff from roof • Relatively low traffic area • Help to increase aesthetics in area • Alcove allows for more controlled environment

  7. Design Constraints • For safety reasons, the volume of the garden should not be able to conceal a person • Along adjacent sidewalk expect crushing snow so use plants that are able to bounce back in the spring • Lawn mower operators must be able to mow the remaining lawn with a 72 inch lawn mower without ever backing up • Plants have to be chosen from a predetermined list

  8. Rain Garden Vegetation • Six plant types suitable for rain garden • Swamp Azelea (Rhododendron viscosum) • Disco Belle Hibiscus (Hibiscus moscheutos) • Cardinalis Flower (Lobelia cardinalis) • Ruby Spice Summer Sweet (Clethra alnifolia) • Sweetfern (Comptonia peregrina) • Little Henry Sweet Spire (Itea virginica) • Chosen for their hardiness and aesthetic aspects

  9. Rain Garden Vegetation • Swamp Azelea(Rhododendron viscosum) • Mature height: 2 – 8 ft • Prefers saturated soils • Highly visible white flowers • Disco Belle Hibiscus (Hibiscus moscheutos) • Mature height: 6.6 ft • Shrub-like herbaceous perennial • White or pink flowers with crimson centers

  10. Rain Garden Vegetation • Ruby Spice Summer Sweet (Clethraalnifolia) • Mature height: 5 – 8 ft • Long flowering and growing period • Yellow fragrant foliage • Cardinalis Flower (Lobelia cardinalis) • Mature height: 2 -3 ft • Shade tolerant • Cardinal red flowers

  11. Rain Garden Vegetation • Sweetfern(Comptoniaperegrina) • Mature height: 2 ft • Good in coarse and medium textured soils • Green leaf blades • Little Henry Sweet Spire (Iteavirginica) • Mature height: 3 – 5 ft • Native to NJ soils • Yellow spiral leaves

  12. Rain Garden Design • Rain gardens are design using several parameters • Amount of Precipitation • Imperviousness of Runoff area • Average depth of water in rain garden • First, need to determine runoff depth • Curve Number (CN) is 98.

  13. Rain Garden Design • Next, determine Runoff area for rain garden • Roughly 1500 ft2 • Area x Runoff Depth = Runoff Volume • Runoff volume is the amount of water the rain garden can hold • Finally, get needed surface area of rain garden Runoff Area

  14. Rain Garden Design • The assumptions made for design: • Precipitation = 1 inch • Asphaltic Roof • Average depth of rain garden = 4 inches • Final Design Results • Runoff Area = 1500 ft2 • Runoff Volume = 104.42 ft3 • Rain Garden Surface Area = 313 ft2

  15. Design for Linden Hall • Oval shaped • Will have sloping sides • Average depth is 4 inches • Accessible for maintenance

  16. A Closer Look Little Henry Sweetspire Swamp Azalea Ruby Spice Summer Sweet Disco Belle Hibiscus Cardinalis Flower Sweetfern

  17. Cost Analysis • Labor being done by various student organizations • Mulch & Vegetation pricing based on rough estimates • Miscellaneous Expenses covers construction materials (i.e. piping, liners)

  18. Maintenance • Pull weeds, especially during the 1st year • Water 3 times a week until established, and also during dry spells • Re-mulch (shredded hardwood won’t float away) • Cut back and trim as needed

  19. What about mosquitoes? • Mosquitoes need at least 7 days in standing water to hatch • A rain garden is not a pond, and will usually dry out within a day or two

  20. Summary • Rain gardens help to reduce pollution and divert runoff • Linden Hall is an optimum location for a rain garden • Majority of design and plant selection is finished • Require little maintenance • Overall, a rain garden is a low-cost, aesthetically pleasing option for any university

  21. Thank you for your time. • Any questions?

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