BUILDING YOUR RAIN GARDEN

1. BUILDING YOUR RAIN GARDEN

2. Garden Location Observe your yard during a rainfall event • Where does water flow from? • Where does water travel or collect?

4. “Pinch Point”

6. Garden Location Place your garden between runoff source and destination We want to intercept water before it reaches surface waters or low spots!

7. Garden Location SITING GUIDELINES: • >10 feet from house foundation or wellhead • > 25 ft from septic system drain field • Away from utility lines • In full to partial sun if possible

8. Garden Location

9. Garden Timing • Add garden after other construction is finished • Planting best done between November and April

10. Soil Evaluation

11. Soils and Drainage • Signs of an impermeable soil • Ponding water • Wetland soils – grey with areas of brown color • Water remains after two days of no rainfall Design as a Backyard Wetland!

12. Wetland Soils

13. Wetland Soils

15. Backyard Wetland What is it? • An area where the soil is saturated or covered with water for 2-3 weeks during the growing season • Located in spots where water collects much faster than it drains.

16. Backyard Wetland • Install in an area where there is a naturally occurring wet spot or drainage way. • Can be as simple as installing wetland plants in the wet area

17. Backyard Wetland

18. Backyard Wetland

20. Sizing your Rain Garden How much runoff is coming from impervious areas?

21. Sizing Rain Gardens • Roof Area • Driveway Area • Total Impermeable Drainage Area • Depth  Dimensions • Ponding depth 6” – Divide Impermeable area by 20 • Ponding Depth 3” – Divide impermeable area by 10 • Use chart: Sizing Your Rain Garden

22. Sizing Chart

23. Sizing Example EXAMPLE: A house is 60 feet by 60 feet. Based on owner estimation: • 25% of the roof area is draining to the downspout. • The driveway area draining to the rain garden is 500 square feet. For a desired 6 inch ponding depth, what size should the rain garden be?

24. Sizing Example • Roof area: 60 X 60 = 3600 sq. ft. • ¼ of the flow to downspouts: (3600 sq.ft) X 25% = 900 sq.ft • Roof area plus driveway: 900 + 500 = 1400 sq. ft • Divide square footage by 20: 1400/20 = 70 sq. ft. ANSWER: The water garden should be at least 70 square feet. A 5 x 14 or 7 x 10 foot garden design would be sufficient

25. Rain Gardens can be Small

26. Size is flexible • Depth of 3 – 8 inches • Larger for clay soils, smaller for sandy ones • Work with the area you have!

30. Rain Garden Construction

31. Rain Garden Construction Potential Site

32. Before digging, lay out the area Define the boundary by using string or spray paint

33. Digging Your Rain Garden Dig garden 4-6 inches, with a slight depression in the center

34. Digging Your Rain Garden • On sloped sites: • Use dug out soil to create a berm along one side of garden • This will serve to retain water during a storm

35. Planting and Mulching Cover the berm with grass or mulch to prevent erosion Berm

36. Planting and Mulching

37. Planting and Mulching Mulch with 2-3 inches of hardwood mulch

38. Avoid Pine Straw and Lighter Mulches – They Will Float!

39. Mulching • Removes Pollutants • Maintains Soil Moisture • Prevents Erosion