Designing Rainwater Harvesting into Landscaping Systems. Chris Maxwell-Gaines, P.E.

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1 Designing Rainwater Harvesting into Landscaping Systems Chris Maxwell-Gaines, P.E.

2 Integrated water conservation solutions Rainwater, Graywater, Drainage, Irrigation Design / Build Residential / Commercial

3 Why Rainwater Harvesting? Why now?

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5 Flooding

6 Effect of Impervious Cover Residential Developments

7 Effect of Impervious Cover Suburban / Light Commercial Developments

8 Effect of Impervious Cover Urban Developments

9 Urbanization: Before and After

10 TIME Run-off Hydrograph Conventional Developed condition QUANTITY Maximum water shed capacity Pre-Developed or LID Condition

11 Erosion

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13 Largest irrigated crop in US?

14 Turf Grass!!

15 Source: Austin Water website

16 210 MGD 110 MGD Source: Austin Water website

17 Progression of Indoor Fixture Efficiency Indoor Water Conservation Standards

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19 Rainwater Harvesting Intention Accomplishes both stormwater management & water conservation goals within the landscaping system Passive and Active methods Difficulty arises when attempting to seamlessly integrate these practices into landscaping system

20 Passive vs. Active

21 Rain Gardens / Bioretention Ponds

22 Benefits of Rain Gardens Reduces stormwater runoff volume Recharges groundwater resources Filters out pollutants Reduces flooding issues in our communities Creates habitats for wildlife Reduce demand for potable water for landscapes (and the energy required for centralized water Enhances beauty of yards and communities

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25 Rain Gardens

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33 Ecosystem Change, Arizona

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36 Design Considerations 1. Appropriate location down slope from the surfaces/areas that will drain into it 2. Size of rain garden calculated based on water quantities, slope, and soil conditions 3. Plant selection to maximize evapotranspiration as well as aesthetics

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38 Rain Garden Sizing Soil type Slope Area / impervious cover to abate Amount of rainfall to process (Intensity)

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43 Area

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46 Rainfall Intensity

47 Rain Garden Plants Able to withstand brief periods of standing water Yet be able to tolerate extended periods of dryness Best plants are Natives!

48 Deep root natives

49 Rain Garden Plants American Beautyberry Yaupon Holly Bamboo Muhly Big Muhly Cherokee Sedge Cherry Sage Chile Pequin Copper Canyon Daisy Dwarf Yaupon Fall Aster Flame Acanthus Lantana Mexican Bush Sage Mexican Honeysuckle Mexican Oregano Obedient Plant Pine Muhly Red Yucca Rock Rose Turk s Cap Twistleaf Yucca Blue Grama Coreopsis Deer Muhly Engelmann Daisy Frogfruit Gulf Coast Muhly Gulf Coast Penstemon Horseherb Hymenoxys Inland Sea Oats Lawn Sedge Liriope Meadow Sedge Mealy Blue Sage Mistflower Pigeonberry River Fern Spiderwort Texas Betony Texas Sedge Tropical Sage Winecup

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51 Raised Medians Should Go Away

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53 RiverEast Center in Portland,

54 Missouri Botanical Garden

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60 Porous / Pervious Pavement Used for both water quality and detention purposes Typical flowrates of 3 to 8 gallons/sf/min Many variations

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66 Active Rainwater Harvesting

67 The Psychology of Rainwater Harvesting

68 Stage 1: Buckets and more

69 Stage 2: Rain barrels

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71 Stage 3: Multiples

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73 Stage 4: Dress it up

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76 Stage 5: Do it right

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78 Rainwater Math 1 inch of rain on a 1,000 sq ft collection area will yield 623 gallons in of rain X roof sq ft X gal/sq ft

79 Rainwater Uses Outdoor water use Irrigation of landscaping and lawns Other outdoor uses Indoor, non-potable water use Toilets, urinals, & clothes washing machines Potable water supply Filtration and disinfection required

80 System Sizing & Efficiency Three considerations: Collection surface size Storage volume size Expected demand Three main methods Design for Optimization Design for Space Design for Budget

81 Design for Optimization Use water budgets to identify optimal cistern size

82 The Importance of Storage Volume

83 The Importance of Storage Volume

84 Design for Space

85 Design for Budget Most frequent limit for systems intended for irrigation only Systems can be expanded at a later time

86 Dry Rainwater Systems

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90 Dry Rainwater Systems Pipes drain completely Easy system to install and maintain Tank must be located close to collection surface

91 Wet Rainwater Systems

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95 Wet Rainwater Systems Water remains in collection pipes Gutter must be above tank inlet Allows any location of storage tank Greater collection efficiency

96 Imagine a P-Trap

97 Rainwater System Components Metal Asphalt Shingles Clay/Concrete Slate

98 Rainwater System Components Gutter or inlet screening Your first line of defense

99 Inlet Filtration is VITAL

100 Inlet Filtration is NOT First Flush Inlet filters keep large debris out First flush from the roof carries a higher concentration of pollutants Inlet filtration + First flush = Best Practice

101 Rainwater System Components First flush diverter Diverts the initial wash of the roof

102 Adequate First Flush Amount??

103 Adequate First Flush Amount?? TWDB suggests >10 gallons / 1,000 sf Depends on the research you read Ultimately depends on use of rainwater, roof type, and locational issues

104 Rainwater System Components Tank inlet filter and screen

105 Rainwater System Components Pump system Pump sized for demand Different type of systems: Hose bibb only Connected to irrigation On-demand Don t have to settle for onsite water pressure

106 Rainwater System Components Backup water supply Auto-fill mechanism Manual fill Auto-switch Remember, Air gap or RPZ

107 Metal cisterns

108 Polyethylene cisterns

109 Fiberglass cisterns

110 Corrugated metal cisterns

111 Pioneer Water Tanks

112 Rainwater Tank Cladding

113 Pillow Tanks

114 Underground tank systems

115 In Conclusion Why not combine both practices Active + Passive Water Harvesting

116 Hyde Park, Austin Project Rain Garden + Rainwater Collection

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121 Thank you very much!! If you would like a copy of my presentation today, please me at: chris@watercache.com