Rain Gardens and bioswales are some of our most effective tools in implementing sustainable water practices. In the presentation, Barrett will discuss how rain gardens and bioswales protect, restore, and mimic the natural water cycle. Additionally, Tom will explain how rain gardens and bioswales can help develop a natural solution for water efficiency, and relieve storm water management issues. Rain Gardens and bioswales create natural filters through which our rainwater can flow. We are in essence helping to remove the contaminants, while reducing the speed and volume in which the water runs to the storm drains. By choosing to create a rain garden or other environmentally responsible landscape solution, we can reduce the contaminants that collect in the sewer systems, and make a significant improvement for a cleaner and healthier environment.

1. Constructing
Rain Gardens
& Bioswales
By Tom Barrett
Green Water Infrastructure, Inc.
www.ThinkGWI.com
Tom.Barrett@ThinkGWI.com Follow us on Twitter @TomBarrett_GWI

2. The GREEN
Economy

3. How Much Rain Falls in Chicago?
January
-
1.86" Image of Rain Falling
February
-
1.58"
March
-
2.59"
April
-
3.28"
May
-
3.75"
June
-
4.08"
July
-
3.39"
August
-
3.38"
September
-
2.91"
October
- 2.65"
November
-
2.09"
December
-
1.88"
Total
33.44"

4. How Much Water Falls in Chicago?
2,500 sq. ft. Roof
January
-
,727 gallons
2 Image of Rain Falling
February
-
,540
2
March
-
,130
4
April
- 5,735
May
-
,268
5
June
-
5,657
July
-
,470
5
August
-
,200
7
September
-
,096
5
October
-
,223
4
November
-
4,691
December
- 3,787
Total
6,525
5

5. How Much Water Falls in Chicago?
3 Acre Commercial Property
January
-
42,560 gallons
1 Image of Rain Falling
February
-
32,784
1
March
-
15,876
2
April
- 299,783
May
-
75,344
2
June
-
295,710
July
-
85,934
2
August
-
76,358
3
September
-
66,383
2
October
-
20,764
2
November
-
245,203
December
- 197,954
Total
2,954,654

6. How Much Water Falls in Chicago?
City Block
(660’ x 660’ – 10 acres)
January
-
75,195 gallons
4
February
-
42,610
4
March
-
19,581
7
April
- 999,267
May
-
17,805
9
June
-
985,690
July
-
53,105
9
August
-
,254,515
1
September
-
87,936
8
October
-
35,873
7
November
-
817,335
December
- 659,842
Total
9,848,756

7. LOW IMPACT SITE DEVELOPMENT

8. Stormwater Mitigation
Stormwater Mitigation
Stormwater Mitigation
Stormwater Mitigation
Stormwater Mitigation

11. Image of Rain Falling

12. PESTICIDE ISSUES
ATRAZINE, NITROGEN, PHOSPHOROUS

15. Peak Flow
(1 Acre Site)
Grass Field Roof
1 Year Storm 1.4 cfs 4.3 cfs
2 Year Storm 2.1 cfs 5.4 cfs
10 Year Storm 4.3 cfs 8.0 cfs
25 Year Storm 5.7 cfs 9.5 cfs
100 Year Storm 8.0 cfs 12.0 cfs
cfs – cubic feet per second

16. Peak Flow
(1 Acre Site)
Grass Field Roof
1 Year Storm 10.5 gps 32.2 gps
2 Year Storm 15.7 gps 40.4 gps
10 Year Storm 32.2 gps 59.8 gps
25 Year Storm 42.6 gps 71.1 gps
100 Year Storm 59.8 gps 89.8 gps
gps – gallons per second

17. Peak Flow
(1 Acre Site)
Grass Field Roof
1 Year Storm 630 gpm 1,932 gpm
2 Year Storm 942 gpm 2,424 gpm
10 Year Storm 1,932 gpm 3,588 gpm
25 Year Storm 2,556 gpm 4,266 gpm
100 Year Storm 3,588 gpm 5,388 gpm
gpm – gallons per minute

18. Peak Flow
(2,500 sq. ft. Roof)
Grass Field Roof
1 Year Storm 0.08 cfs 0.25 cfs
2 Year Storm 0.12 cfs 0.31 cfs
10 Year Storm 0.25 cfs 0.46 cfs
25 Year Storm 0.33 cfs 0.55 cfs
100 Year Storm 0.46 cfs 0.69 cfs
cfs – cubic feet per second

19. Peak Flow
(2,500 sq. ft. Roof)
Grass Field Roof
1 Year Storm 0.60 gps 1.85 gps
2 Year Storm 0.90 gps 2.32 gps
10 Year Storm 1.85 gps 3.43 gps
25 Year Storm 2.44 gps 4.08 gps
100 Year Storm 3.43 gps 5.15 gps
gps – gallons per second

20. Peak Flow
(2,500 ft. sq. Roof)
Grass Field Roof
1 Year Storm 36 gpm 111 gpm
2 Year Storm 54 gpm 139 gpm
10 Year Storm 111 gpm 206 gpm
25 Year Storm 147 gpm 245 gpm
100 Year Storm 206 gpm 309 gpm
gpm – gallons per minute

21. Change in Peak Runoff Flow Before and after Development
300%
225%
150%
75%
0%
1 Year Storm Year Storm Year Storm Year Storm Year Storm
2 10 25 100
Stormwater Effects of Urbanization

22. PLANTING TREES

23. Stormwater Mitigation
– Collection runoff near the
source
– Slow it down
– Soak it in
– Filter it
– Apply it to the landscape
– Create habitats

24. Rain Garden
A Low Spot
Catches Stomwater
Deep Rooted Plants

25. SIMPLE RAIN GARDEN

26. Bioswales
Engineered Soils
Underdrain

27. Location
Rain gardens are
Plant Choices often located at the
end of a roof or
Choose plants based drain spout.
on the need for light
and soil type.
Depth Size Soil
A Rain Garden usually A tpical mix is 65%
A typical Rain Garden
five to ten percent sand, 15% top soil,
is between four to
of the impervious 25% organic matter.
eight inches deep.
surface area.
RAIN GARDENS

28. RAIN GARDEN

29. RAIN GARDEN

30. BIOSWALES
BURNSVILLE, MINNESOTA

31. NATIVE VEGETATION
WWW.EPA.GOV/GREENACRES/ WWW.FOR-WILD.ORG

32. Street Edges
& Medians

33. Parking Lot
Edges

34. Parking Lot
Islands

35. Driveway
Edge

36. Downspout

37. NEIGHBORHOODS

38. Criteria
Meet Stormwater Utility Clearance
Regulations
Soil Investigation
Detention Volume
Percolation Test
Fix Drainage Issue
Fix Erosion Issue

39. Criteria
Near the Rainwater Distributed Evenly
Source Across the Site
Avoid “End-of Pipe” Small Tributary Areas
because of (usually 1 acre or less)
Sedimentation Issues
Typically 10’ to 20’
from Buildings

40. Soil
Investigation
•Soil Profile to Five Feet
•Soil Compaction Level
•Depth to Groundwater and
Bedrock

41. Percolation
Test
•Soil Infiltration Rate
•Key Design Parameter
•Percolates water in 24
Hours

42. Sizing
Determine Design Native vs. Engineered
Goals Soil Assessment
Calculate Runoff
Volume
Determine Allowable
Depth
Calculate Surface
Area

43. Sizing
Runoff
Volume =
Precipitation x
Drainage Area x Runoff
Coefficient
RV=Pr x D(area) x C(un

44. Depth
Based Upon
Infiltration Rate
Infiltration in One Day
Avoid Misquotes
Maximum Depth 18”
for Safety

45. Surface Area
Area of Rain Garden
(ft2) = Runoff Capture
Volume (ft3) / Average
Depth (ft)
A=V/D(average)

46. Engineered Soils
Bioretention
Space Available
Volume of Stormwater
Drain Faster
(the garden can be
deeper and not as
wide)

47. Plants -
Bottom
Palm Sedge
Soft Rush
Tussock Sedge
Marsh Milkweed
Blue Flag Iris
Joe-Pye Weed

48. Plants -
Sides
Purple Coneflower
Showy Goldenrod
Smooth Phlox

49. Plants -
Edges
Butterfly Milkweed
Little Bluestem
Aromatic Aster

50. Inlets

51. Outlets

52. Curb Cut &
Filter Strip
Controls Sedimentation

53. Splash
Blocks
Prevents Erosion and Gullies

71. FUNCTIONAL LANDSCAPES

72. Green • Water • Infrastructure
Green • Water • Infrastructure
Green • Water • Infrastructure
Green • Water • Infrastructure
Green • Water • Infrastructure

73. Thank You