Rainwater Harvesting in Atlanta - City of Atlanta, Watershed ...

Rainwater Harvesting in Atlanta From Rain to Resource: Rainwater Harvesting for Drought Planning and Stormwater Management

Rainwater Harvesting in Atlanta “It is my goal for Atlanta to become one of the top tier sustainable cities in the nation.” -- Mayor Kasim Reed

Rainwater Harvesting in Atlanta COA’s Multi-Pronged Approach to Rainwater Harvesting •Adopted Potable Rainwater Harvesting Ordinance •Promote rainwater harvesting in COA service area •Enacted Post-Development Stormwater Management Ordinance requiring green infrastructure

Rainwater Harvesting in Atlanta Potable Rainwater Harvesting Ordinance •Allows single-family residential customers to install and use potable rainwater harvesting systems •The only metropolitan area that allows potable rainwater harvesting -Section 1300, www.municode.com (Atlanta)

An above-ground storage tank.

Rainwater Harvesting in Atlanta Potable Rainwater Harvesting Ordinance •Customers must maintain a City water account – no “off-grid” allowed. •Customers must have a working, backflow prevention device. •Customers are billed once per year based on size of storage tank. Discounted billing rates apply if captured rainwater is also used outdoors. A below-ground storage tank.

Rainwater Harvesting in Atlanta Potable Rainwater Fee Table Storage Size (gallons)

Rounded 75 gallon Increment

Fee per 75 gallon Increment

Annual Fee POTABLE*

Annual Fee DUAL **

325 430 550 600 700 1000 1200 1250 1400 1500 1700 2500 2650 3400 5100

4 6 7 8 9 13 16 17 19 20 23 33 35 45 68

$9.74 $9.74 $9.74 $9.74 $9.74 $9.74 $9.74 $9.74 $9.74 $9.74 $9.74 $9.74 $9.74 $9.74 $9.74

$38.96 $58.44 $68.18 $77.92 $87.66 $126.62 $155.84 $165.58 $185.06 $194.80 $224.02 $321.42 $340.90 $438.30 $662.32

$27.27 $40.91 $47.73 $54.54 $61.36 $88.63 $109.10 $115.91 $129.54 $136.36 $156.81 $224.95 $238.63 $306.81 $463.62

* RW system is 100% for potable use ** the Dual RW system is used for irrigation as well as potable use

Rainwater Harvesting in Atlanta Outreach to Community: Rainwater Harvesting Summit, August 2012 The City of Atlanta teamed with stakeholders including the following organizations to promote rainwater harvesting:

Rainwater Harvesting in Atlanta Commercial Applications: Grand Hyatt, Buckhead •The Grand Hyatt, Buckhead installed a 30,000-gallon system to capture rainwater from a 32,000 s.f. surface area and condensate from various points in the hotel •The 438-room hotel uses this captured water in its cooling tower Two of the Grand Hyatt’s eight cisterns and a rainwater collection pipe. (www.grandatlanta.hyatt.com)

Rainwater Harvesting in Atlanta Institutional Uses: Georgia Tech •1.4 million gallon cistern the largest on a U.S. college campus •2.25 million gallons (total) of rainwater/condensate collected in 19 campus cisterns •College reduced water use 31 percent from 2001-2012 Clough Commons Building features a roof garden and rainwater/condensate collection systems. Harvested water is used to flush toilets and for irrigation. (www.gatech.edu)

Rainwater Harvesting in Atlanta Post-Development Stormwater Ordinance •Stormwater runoff volume generated by first 1.0 inch of rainfall to be retained on-site •Requires green infrastructure BMPs that intercept, evapotranspire, infiltrate, or capture/reuse stormwater •Rainwater harvesting a good fit for many sites; pairs well with rain gardens for overflow management

The Original Rainwater Pillow and connection devices. (www.rainwaterpillow.com)

Rainwater Harvesting in Atlanta Post-Development Stormwater Ordinance •Applies to new commercial and residential developments •For redevelopment – ordinance applies to new work site provided impacted area does not exceed 35% of previously developed area. If impacted area larger than 35%, ordinance applies to the entire development. •Ordinance effective February 13, 2013. •www.atlantawatershed.org/greeninfrastructure

Rainwater harvesting tank at Southface. Captured water is used to flush toilets and for irrigation. (www.southface.org)

Rainwater Harvesting in Atlanta For information about Rainwater Harvesting, contact: Jennifer Carlile Environmental Program Manager Department of Watershed Management, City of Atlanta 404-546-1265 [email protected]

For information about the Post-Development Stormwater Management Ordinance, contact: Cory Rayburn, CPESC Environmental Program Manager Department of Watershed Management, City of Atlanta 404-546-1334 [email protected] www.atlantawatershed.org/greeninfrastructure/

Rainwater Supply ‐ Stormwater Mitigation • • • •

Design Considerations Supply Potential Stormwater Mitigation Impact Financial Effect Bob Drew Ecovie Environmental LLC www.ECOVIERAIN.com 404‐824‐0318

Rain

•Quantity •Frequency •Rooftops •Hard Surfaces

Evaporation •Cooling Towers •Gardens, Open Area

Stormwater •Floods •Erosion •To the Ocean

Municipal Water Your Land and Property  Wells

Black Water

Gray Water Groundwater

•Showers •Laundry •Condensate

Rain

Municipal Water

•Quality •Frequency •Rooftops •Hard Surfaces

Evaporation

Less  Evaporation

•Cooling Towers •Gardens and Open Area

•Irrigation •Toilet Flushing •Cooling Towers •Laundry •Potable Uses

Stormwater

Water  Quality

•Floods •Erosion

Black Water

Your Property and Land Less  Demand

Less Floods

More Fresh  Water

Gray Water Groundwater Recharge

Recycling – Reuse •Irrigation •Non‐Potable Use

Atlanta Rainfall Typical Rainwater Collection Calculator

*No Wet or Dry Season = Constant Supply and Constant Stormwater

Rainwater Collection Potential Typical Rainwater Collection Calculator 0.623 x Square  Footage

Roof Square Footage Collection Efficiency Average Monthly Rainfall

= Gallons Rain  Hitting Surface  per 1” of  Rainfall * Overestimates Supply Potential due to no accounting for overflow * Shows Sizing for Collecting First 1” of Rain

Accounting for Overflow 2,000 Sq. Feet 1” Rainfall 1060 Gallons

• • • • •

Size of Tank Usage Rate Rainfall Pattern Overflow Storm Water Reduction

50% Full

660 Gal. Overflow

1000 gal Tank

• Use Daily Rainfall to Estimate True Water Supply 6

Rainwater Collection Potential •Day by Day Rainfall for Specific Years (e.g. 2005, 2007, 2009, 2010, 2011) •Daily Outdoor and Indoor Water Demand and Pattern of Usage •E.G. March to October irrigation every 3 days when no rain •E.G. Laundry Days and Flushes per person per day

•Capture Square Footage, Efficiency (90%)

Rainfall Capture Efficiency Roof Square Footage

Overflow Tank Size Usage

Rainwater Collection Potential Case Study – Small 1,000 Gallon Garden System Details: •Water from 2,000 sq ft Roof used for  outdoor watering •1,000 gallon tank with Pump and Filter •Hose watering •Automatic Irrigation

Results: •21,000 Gallons Supplied •Sufficient to be Only Supply in Watering Ban

Rainwater Collection Potential EXAMPLE 

50,000 Square Foot  Building In City of Atlanta

Process Water 18,000 GPD Cooling Tower  Make Up Per Schedule    AVG 11 k GPD

Irrigation          2 Acres    March‐Oct.

Toilet Flushing 350 Apartments 4,000 GPD

• • • • • •

How Big to Collect 1” Tank Sizing How Much Water Supply Stormwater Mitigated Treatment Required ROI, Payback

Tank Sizing 50,000 x 0.623 = 31,150 Gallons Available to Capture 1” of Rain One Design Method – Have This Amount Available in 7 Days or Less

Process Water Results

Summary: •Assume Approx. $2/Gallon Capital  Cost •Water + Sewer Rate $0.029/Gallon •ROI >35% (may exceed 60%) •Payback