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 (Clethra alnifolia)
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 (Comptonia peregrina)
Mature height: 2 ft
Good in coarse and medium
textured soils
Green leaf blades
Little Henry Sweet Spire (Itea virginica)
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 = 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)
Pricing Information
Construction Element
Unit Cost ($/sq.ft.)
Total Cost ($)
Vegetation
3.00
950.00
Mulch
0.30
95.00
Misc. Expenses
1.00
317.00
Total
Although, this may seem expensive some of this cost can be mitigated with the help of available resources (i.e. facilities, grants, etc.)

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?