the water-energy nexus: sustainable community source ...€¦ · © 2006 nega drop rainharvesting...

© 2006 Nega Drop Rainharvesting 2007 Latornell Conference

The WaterThe Water--Energy Nexus: Energy Nexus: Sustainable Community Source Protection Sustainable Community Source Protection

Through Through RainharvestingRainharvestingKevin Mercer

President

Nega-Drop Rainharvesting


The path to clean watersheds begins in your own backyard, where rain falls –

at the lot level.


Essential Elements of Low Impact Development

LID re-establishes/protects a watershed’s ecosystem hydrology

• Flow - Interception• Timing - Detention• Treatment - Bio-infiltration


The Coffman List of LID Practices

• Bioretention / Rain Gardens• Strategic Grading • Site Finger Printing• Resource Conservation • Flatter Wider Swales • Flatter Slopes• Long Flow Paths• Tree / Shrub Depression • Turf Depression• Landscape Island Storage • Rooftop Detention

/Retention • Roof Leader

Disconnection• Parking Lot / Street Storage • Smaller Culverts, Pipes & Inlets

• Alternative Surfaces• Reduce Impervious Surface• Surface Roughness Technology • Rain Barrels / Cisterns /

Water Re-Use• Catch Basins / Seepage Pits• Sidewalk Storage• Vegetative Swales, Buffers &

Strips • Infiltration Swales & Trenches• Eliminate Curb and Gutter• Shoulder Vegetation • Maximize Sheet flow • Maintain Drainage Patterns• Reforestation• Pollution Prevention

““Creative Techniques to Treat,Use, Store, Retain, Detain and RechCreative Techniques to Treat,Use, Store, Retain, Detain and Rechargearge””

© 2006 Nega Drop Rainharvesting 2007 Latornell Conference Natural City ConferenceMay 30, 2006

Conventional Approach: Billion Dollar Storage Facilities Conventional Approach: Billion Dollar Storage Facilities

Conventional End of Pipe Stormwater Ponds

BUT…this is what we usually get when decision makers think of t t


Instead of This


Rainharvesting

City of Toronto

Proud Advocate of Source Protection, Climate Change Adaptation and Community-based Integration

Everywhere…


RainHarvesting: The Energy -Water Nexus


The Water Energy Nexus

• Achieves– First order treatment train source protection

for lot level stormwater runoff• Achieves

– Provides a community-based watershed protection and restoration framework through LEED

• Achieves– Silo Busting to tie together water and energy

efficiency


The Energy -Water Nexus

• Low Impact Development’s goal of zero runoff parallels the objectives of energy efficiency.

• Rainwater Harvesting bridges the water and energy efficiency nexus by linking LEED objectives for both new and existing developments.

• Encourage LEED-oriented rewards to coalesce.


Toronto’s Sewer System By the Numbers

• The number of buildings in Toronto’s combined sewer system core represents almost 40% of the city’s total number of buildings (City Planning Division, 2006).

• The potential of RWH captured from the total roof surface area in Toronto is 106 thousand Ml - 40% of this capture is 42 thousand Ml.

• If 42 thousand Ml represents the capture potential for the old core of the city, and if 80% of old core buildings are connected to the combined sewer system, then hypothetically, 33 thousand Ml of stormwater could be diverted from the combined sewer system and waste water treatment.

• These 33 thousand Ml of stormwater represent almost an eighth of the 258 thousand Ml of wastewater that is treated at Ashbridges (Toronto Water, 2005 Annual Report).


Sample City Energy UseMisclleaneou

s10%

Buildings12%

Wastewater Treatment

23%Water

Pumping33%

Streetlights22%

Misclleaneous

Buildings

WastewaterTreatmentWater Pumping

Streetlights


Reusing Stormwater

• Seventy percent of all water tapped for human use goes to agriculture, mostly for irrigation;

• industry accounts for 22%, and • domestic use (household, drinking and

sanitation) accounts for 8%.


Why Reuse Stormwater?

• Toronto’s annual electricity budget to pump potable water and sewerage is the #1 energy demand > TTC, Streetlights, and buildings.

• Wet weather management costs are estimated to total an estimated $3 billion in the next 25 years.


Water and Sewer Energy ConsumptionCity of Toronto

• Total electricity consumption 363 million kWh for potable water provision - over $31 million

• The total kWh for wastewater treatment at the Ashbridges treatment plant was 114 million kWh

(Toronto Water 2005 Annual Report)


The Savings Potential

• The full potential of RWH could provide an estimated annual energy cost savings of $7 million for Toronto Water.

• Utilizing 106 thousand Ml of rainwater to replace an equivalent amount of potable water could conserve 71 million kWh.


GhG Reductions

• Total potable water provision conservation potential of RwH = 71 million KWh » a CO2e reduction of 0.0238 Mt.

• Total wastewater treatment conservation potential of RwH = 14 million kWh » a CO2e reduction of 0.0048 Mt.

• Total CO2e reduction capacity of RWH in Toronto~ 0.028 Mt of CO2e annually.

This estimate is based on the CO2e coefficient provided by the Toronto Atmospheric Fund.


Successfully Integrating RainBarrel Programs into Your Municipal

Stormwater Management• Utilize CBSM to integrate residential

comprehension of their role in stormwater• Purchase the “best” not the lowest

common denominator product to represent change.

• Illustrate the benefits through economic instruments – stormwater utilities / source protection plans


How Much Water Can You Collect

• 900 litres of water can be collected per cm of rainfall from a 100 sq. m. roof area

• 9 litres/cm of rain/sq. m. roof @ 80% collection efficiency harvests 7 litres/cm of rain/ sq.m. of roof.


Cistern Capacity

• Typical heavy weather (or a continuous rain over a few days) can unleash 3 inches of rain.

• 1200 ft2 (roof area)x (3”/12”) x 7.48gal/ ft2 x 0.80 = catchment runoff (gal)

• 1200 ft2 x 0.25 ft x 7.48gal/ ft2 x 0.80 = 1,795 gallons


Water Demand Per Person

• One person needs daily an average 128 litres of water. Conservation can usually reduce this to 100 litres.

• Using rainwater in household applications of toilet flushing and laundry, another 30 litres can be saved.


Average Annual Family Consumption

• The average North American household utilizes roughly 54,750 gallons (3 persons @ 50 gal/person/day X 365 days).


Rainfall As a Resource

• The amount of stormwater that runs off a roof in a typical year could be used to flush a standard 6 litre (2.5g) toilet 12,000 times.


Maximum volumes of rainwater / year (litres)AnnualRainfall Roof area (m2)(mm) 100 150** 200 250 300 400 500150 10080 15120 20160 25200 30250 40320 50400200 13250 21120 26500 35200 42240 53000 70390250 18080 27120 36160 45200 54250 72320 90390300 22080 33120 44160 55200 66230 88310 110400400 30080 45120 60160 75190 90230 120300 150400500 38080 57120 76150 95240 114200 152300 190500600 46080 69110 92150 115200 138200 184300 230400800 (817)62080 93110 124200 155200 186200 248300 310400 Toronto1000 78070 117100 156100 195200 234100 312300 3904001200 94070 141100 188100 235200 282100 377300 470400

Source: David A Cunliff: Guidance on the use of rainwater tanks.


System Design

• The standard RwH system components:– roof capture membrane and drainage structure, – first flush discharge or filtre system, – in or above ground or in building cistern sized to

capture 100% of annual flow, – Pump(s) – potable water top up supply, – overflow discharge, and – purple pipe distribution and system identification

markers

© 2006 Nega Drop Rainharvesting 2007 Latornell Conference Source: fbr international

Residential Rainwater System


Average Cost of Residential RWH• Estimates for an in-ground system

providing plumbed water to non-potable demands (toilet flushing, irrigation and clothes washing) averages $6,000.


Illustration 3: Rainwater Harvesting, an example for a commercial area

Source: fbr international

Industrial Rainwater System


Average Cost of Commercial RWH

• Estimates for an in-ground system providing plumbed water to non-potable demands (toilet flushing, irrigation and clothes washing) averages $50,000.

• $2.50 per foot of piping, $20,000 for pumps and filtres, $10,000+ for cistern (depending on material), and the remainder in planning and approvals.


• UNESCO and the World Water Council rank rain water as the most secure source of water for the 21st century

• Physical-chemical and hygienic testing (Germany & Australia) prove that the quality of the water from state-of-the-technology installations is suitable for toilet flushing, clothes washing, garden irrigation and for cleaning purposes.

Is Rainwater Safe?


Capacity Building The Missing Link

• Canada has a limited appreciation of the business case for rainharvesting.

• No national, provincial or non-governmental association exists to support rain harvesting.

• TRCA researching water quality at Metro Label and Minto condo sites.

• Toronto Atmospheric Fund business case research conducted in 2006.

• Guelph University research supported by CMHC. • Private sector developers leading – SAS Headquarters,

Minto, Rodeo Homes.


Conclusions

• Rain water harvesting (in scalable applications ranging from simple lot level storm capture to full re-use) is an essential element of every municipal source protection plan.

• RWH provides a great framework upon which to establish a supportive relationship with property owners.

• RWH provides water and energy conservation for community-wide sustainability.

• There is a significant need for capacity and association to support of the rainharvestingbusiness case.


Resources• Fbr international – the German national rain

harvesting agency – www.fbrinternational.de• Texas Water Development Board-

http://www.twdb.state.tx.us/home/index.asp• American Rainwater Catchment Systems

Association – http://www.arcsa-usa.org/index.html• International Rainharvesting Alliance,

http://www.irha-h2o.org/• RiverSides – www.riversides.orgThe RiverSafe

Rainbarrel• The International Rainwater Partnership -

http://www.rainwaterpartnership.org/


Thank Youfor

Your Interest

For more information on Water-Energy Nexus Partnership

416 [email protected]


If rainbarrels are so good, then why do they have to be so useless and ugly?


The Useless – 55 gallon food barrel.


The Really Ugly – 214 litre/60 gal. Detergent Container

City of Toronto Downspout Disconnection Program


Rock Creek National Visitors’Centre, Washington, DC

Nine Mile Run RainBarrel Initiative, Pittsburgh, PA

The RiverSafe RainBarrel – 500 litres/132 gal.


Good RainBarrel Characteristics• Sized to accommodate seasonal flows from

standard roof areas• Scalable• Ease of Installation and Maintenance• Mosquito (vector) proof• Multi-media filtre systems• Child proof (enclosed)• Freeze-thaw proof • Post installation social marketing (i.e., 5 Things

You Can Do For Your River)


RainBarrels Are Big

But they should be Bigger…


Example: one 60-gallon barrel would provide runoff storage from a rooftop area of approximately 215 square feet for a 0.5 inch (0.042 ft.) of rainfall.60 gallons = 215 ft.2 x0.042 ft. x 0.90 x 7.5 gallons/ft.3

Rain barrel capture is determined by calculating roof top water yield for any given rainfall, using the following general equation.

V = A2 x R x 0.90 x 7.5 gals./ ft.3 where:V = Volume of Runoff

A2 = Squared Area of Roof

R = Rainfall Quantity

7.5 = conversion factor (gallons per cubic foot)

.90 = a variable determined by first flush disposal if necessary


Total Storm Depth and Number of Times RainBarrel Will Overflow

Sq. Ft. Roof Area Draining to an Individual Downspout

600 550 500 450 400 350

1.0 inch storm (exceeded 7.0 times/ year)Full Cistern

374 343 312 281 249 218 Volume of Rain From the Roof in Gallons

0.7 inch storm (exceeded 14 times /year)RiverSafe RainBarrel

163 150 136 122 109 95

0.5 inch storm (exceeded 24 times / year)Average RainBarrel

51 47 42 38 34 30

CDM Inc. NMRRI


Essential Design Elements• One piece – child/animal proof

construction• Vector (mosquito) resistant• Freeze-thaw proof • Media filtre system• First flush or dual filtre system• Easy maintenance• After-market education and support


Lot Level Social Marketing 5 Things You Can Do For Your River

• Stop Runoff – disconnect downspouts and install rainbarrels• Conserve Water-reuse your rain and utilize efficient

appliances/plumbing• Go Toxic Free – pollution prevention in all things, indoors and

out• Naturalize – re-establish urban canopy, permeate, and use

native species• Get Involved – engage your community decision makers in

promoting knowledge and application of LID


The Homeowners’ Guide To Rainfall• www.torontorainguide.org• Provides on-line capacity knowledge and

support• Encourages scalable lot level actions• Builds a long-term public-private

partnership with BMP owners

the water-energy nexus: sustainable community source ...€¦ · © 2006 nega drop rainharvesting...

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