3/26/2011. David Dods URS Corp., Overland Park, KS. Year 5. Photos: David Dods

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1 David Dods URS Corp., Overland Park, KS Photos: David Dods Year 5 1

2 Lessons: With some care and help from us, Mother Nature has an amazing ability to restore degraded lands and waters. It All Begins with Regional Planning and Site Design Rain Gardens Shallow gardens with plants that tolerate periodic saturation Dry out in a day or two Restore hydrologic function to the landscape Habitat Attractive Landscaping Planting Beds - Two Approaches Native Soil Rain Garden Engineered Soil + Underdrain Bioretention Photo: Barr Engineering; Illustration: Dan Shaw Illustrations: Dan Shaw, Waterdrop Innovations; Barr Engineering 2

3 Rain Garden Examples: Common Applications Downspout Driveway Photos: David Dods, URS Corp. Park & Landscape Features (Filtering runoff to protect park lake) Photo: Rusty Schmidt, Waterdrop Innovations Design by BNIM Architects 3

4 Parking Lot Edge Parking Lot Island Photo: David Dods, URS Photo: David Dods Driveway Runoff Street Edges Photo: David Dods Photo: Rusty Schmidt, Waterdrop Innovations 4

5 Design & Photo by BNIM Architects Rain Garden Design Water Plants Soil 1. Define Project Goals 2. Site Analysis 3. Sizing 4. Garden Bed Preparation 5. Inlets & Outlets 6. Mulch, Edging, & Finishing Touches 7. Care & Maintenance 8. Plants Define Project Goals What is the purpose of the rain garden? Remove specific pollutants Provide detention & volume control Groundwater recharge Design depends upon the goals 5

6 Locations Catch Runoff Near the Source Avoid End of Pipe or Bottom of the Hill Evenly Spread Across the Site Small Drainage Areas ~ 1 acre or less Catch Water Before it Picks Up Lots of Speed Above-Ground Obstructions: Trees, Power Lines, Structures, Walking Paths, etc. Below-Grade Utilities: Call in a Utility Check Where does the water come from? Where does it flow? Photos: Barr Engineering (L), Portland Stormwater Manual (R) Utilities Uphill of Buildings on Slopes Soil Types & Compaction Depth to Groundwater and Bedrock Behind Structural Retaining Walls if Not Designed for Water Note asphalt layers Photo: David Dods Photo: Barr Engineering 6

7 Percolation Test Time how fast the water goes down How many inches soak away in hrs Runoff Volume = Precip x Drainage Area x Runoff Coeff. Illustration: Marjorie Vigoren, City of Plymouth, MN Photo: Barr Engineering Land Use & Runoff Coefficients (Small Storm Hydrology Method) Runoff Coefficients Vary by Land Use and Storm Event Size Building, w/ Flat Roof Turf Parking Lot Depth Length x Width Volume Rv = (for 1.4 in. storm event) 7

8 When to Use Engineered Soils (Bioretention) If not enough area is available for a rain garden, bioretention can use less space Engineered soils drain faster, so the garden can be deeper and not as wide Meet specific pollutant filtration goal Garden Excavation Keep Equipment Out of Garden to Avoid Compaction Max Depth ~ 18 (typ) Photos: 1) Kevin Slates, URS, 2) Barr Engineering Bed Shape: Flat-Bottomed Bowl Garden Bed Preparation Using Native Soils Dig out basic bed shape Rip & Break up compacted soils Till in 3 4 inches compost Rake out to final shape Illustrations: Dan Shaw, Waterdrop Innovations Source: The Blue Thumb Guide to Raingardens, by Schmidt, Shaw, & Dods Photograph: Carla Dods 8

9 Re-test Infiltration Before Planting Photo provided by: Rusty Schmidt Photograph: Carla Dods Planting Mulch Use Coarse, Double- Shredded Hardwood Pinebark Nuggets & Cedar Chips Float Photographs: Carla Dods and David Dods Photos: David Dods 9

10 On-Line vs. Off-Line Designs Off-Line Design On-Line Off-Line Off-Line Reduces Erosion Problems Photographs courtesy of Barr Engineering Garden Full System Overflow Curb Cut, Grass Filter Strip, & Splash Pad Depress Sod below curb Photo: David Dods, URS Photo: Barr Engineering 10

11 Curb Cut and Sediment Forebay Temporary Bypass During Plant Establishment Sandbags to Divert Flow Photo: Barr Engineering Photo: Barr Engineering Outlets: Make sure overflows from large storms have a controlled discharge point Finishing Touches Borders and Edging: Make the Garden Look Deliberate Photo: Rusty Schmidt Manhole with a riser Photographs: Carla Dods; Rusty Schmidt 11

12 Maintenance: Typical Landscaping Requirements Weed: 4-5x 1 st yr, 3x 2 nd yr, then 2x/yr Prune & Mulch: Annually Clean sand & debris at inlet: 2x/yr Results of a Successful Garden: Infiltration Improves Each Year (silty clay soils) Lawn: 3 /Day Raingarden: 3 / Hour Photo: Barr Engineering Photo: David Dods Reference: The Blue Thumb Guide to Raingardens Written for upper Midwest, but principles and many of the plants are appropriate for Texas too Rusty Schmidt, Washington Conservation District, Stillwater, MN Dan Shaw, Waterdrop Innovations Kurt Leuthold and Fred Rozumalski, Barr Engineering, Minneapolis, MN Marjorie Vigoren, City of Plymouth, MN Jim Schuessler, BNIM Architects, Kansas City, MO Carla Dods Available from Terrace Horticultural Books 12

13 Questions?