The document outlines the construction and design of rain gardens and bioswales as a method for stormwater mitigation in St. Louis, providing data on average rainfall, water runoff calculations for various property sizes, and recommended plant choices. It emphasizes the importance of native vegetation and engineered soils to enhance water absorption and filtration. Additionally, it includes guidelines for site selection, design parameters, and maintenance practices to improve urban stormwater management.

1. Constructing Rain Gardens & BioswalesBy Tom Barrett Green Water Infrastructure, Inc.www.ThinkGWI.comTom.Barrett@ThinkGWI.com@TomBarrett_GWIFollow us on Twitter @TomBarrett_GWI

2. The GREENEconomy

3. How Much Rain Falls in St. Louis?January - 1.83"February - 1.85"March- 2.88"April- 3.58"May- 4.10"June- 4.72"July - 3.56"August - 3.51"September - 3.17" October - 2.96"November - 2.35"December - 1.85"Total36.36"Image of Rain Falling

4. How Much Water Falls in St. Louis?2,500 sq. ft. RoofJanuary - 2,852 gallonsFebruary - 2,883March- 4,488April- 5,579May- 6,390June- 7,356July - 5,548August - 5,470September- 4,940 October - 4,613November - 3,662December - 2,883Total 56,664Image of Rain Falling

5. How Much Water Falls in St. Louis?3 Acre Commercial PropertyJanuary - 149,075 gallonsFebruary - 150,705March- 234,611April- 291,634May- 333,994June- 384,501July - 290,005August - 285,932September - 258,235 October - 241,128November - 191,436December - 150,705Total 2,961,961Image of Rain Falling

6. How Much Water Falls in St. Louis?City Block (5 acres)January - 248,459 gallonsFebruary - 251,176March- 391,018April- 486,057May- 556,657June- 640,834July - 483,341August - 476,553September - 430,391 October - 401,879November - 319,061December - 251,176Total 4,936,602

7. Low Impact Site Development

8. Stormwater MitigationStormwater MitigationStormwater MitigationStormwater MitigationStormwater Mitigation

11. Image of Rain Falling

12. Pesticide IssuesAtrazine, Nitrogen, Phosphorous

13. Peak Flow(1 Acre Site)cfs – cubic feet per second

14. Peak Flow(1 Acre Site)gps – gallons per second

15. Peak Flow(1 Acre Site)gpm – gallons per minute

16. Peak Flow(2,500 sq. ft. Roof)cfs – cubic feet per second

17. Peak Flow(2,500 sq. ft. Roof)gps – gallons per second

18. Peak Flow(2,500 ft. sq. Roof)gpm – gallons per minute

19. Stormwater Effects of Urbanization

20. Planting Trees

21. Stormwater MitigationCollection runoff near the sourceSlow it downSoak it inFilter it Apply it to the landscapeCreate habitats

22. Rain GardenA Low SpotCatches StormwaterDeep Rooted Plants

23. Simple Rain garden

24. BioswalesEngineered SoilsUnderdrain

25. Rain GardensLocationRain gardens are often located at the end of a roof or drain spout.Plant ChoicesChoose plants based on the need for light and soil type.DepthA typical Rain Garden is between four to eight inches deep.SizeA Rain Garden usually five to ten percent of the impervious surface area.SoilA tpical mix is 65% sand, 15% top soil, 25% organic matter.

26. Rain Garden

27. Rain Garden

28. BioswalesBurnsville, Minnesota

29. Native Vegetationwww.epa.gov/greenacres/ www.for-wild.org

30. Street Edges & Medians

31. Street Median

32. Parking Lot Edges

33. Parking Lot Islands

34. Driveway Edge

35. Downspout

36. Neighborhoods

37. Meet Stormwater RegulationsDetention VolumeFix Drainage IssueFix Erosion IssueUtility ClearanceSoil InvestigationPercolation TestCriteria

38. Criteria Near the Rainwater SourceAvoid “End-of Pipe” because of Sedimentation IssuesTypically 10’ to 20’ from BuildingsDistributed Evenly Across the SiteSmall Tributary Areas (usually 1 acre or less)

39. Soil Investigation Soil Profile to Five Feet

40. Soil Compaction Level

41. Depth to Groundwater and BedrockPercolation Test Soil Infiltration Rate

42. Key Design Parameter

43. Percolates water in 24 HoursSizing Determine Design GoalsCalculate Runoff VolumeDetermine Allowable DepthCalculate Surface AreaNative vs. Engineered Soil Assessment

44. SizingRunoff Volume = Precipitation x Drainage Area x Runoff CoefficientRV=Pr x D(area) x C(un

45. DepthBased Upon Infiltration RateInfiltration in One DayAvoid MisquotesMaximum Depth 18” for Safety

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

47. Engineered SoilsBioretentionSpace AvailableVolume of StormwaterDrain Faster(the garden can be deeper and not as wide)

48. Plants - BottomPalm SedgeSoft RushTussock SedgeMarsh Milkweed Blue Flag IrisJoe-Pye Weed

49. Plants - SidesPurple ConeflowerShowy GoldenrodSmooth Phlox

50. Plants - EdgesButterfly MilkweedLittle BluestemAromatic Aster

51. Inlets

52. Outlets

53. Curb Cut & Filter StripControls Sedimentation

54. Splash BlocksPrevents Erosion and Gullies

60. Functional Landscapes

62. Thank You