RAINWATER

HARVESTINGRETURN ON INVESTMENT

BENJAMIN SOJKARAINWATER MANAGEMENT

SOLUTIONS

Benefits of rainwater

harvesting1 inch of rain on a 1,000 ft2 roof yields 620

gallons of collected rainwater

• Decreases use of municipal water --- worldwide

consumption is growing at double the population

growth rate

• Reduces reliance on energy-intensive, aging water

infrastructure

• Decreases stormwater runoff, which is a major source

of pollution

Why Reduce Stormwater

Runoff

• Urban infrastructure increases the imperviousness of

the environment and pollutes and concentrates

stormwater. DC is 43% impervious.

• In cities, like Washington, DC, with combined sewers

the stormwater can overburden the combined sewers

and sewage treatment capacity. About two billion

gallons per year overflows to the Anacostia and

Potomac rivers.

• Combined sewer overflow events result in cities being

sued by the EPA for violations of the clean water act.

What DC is Doing to Avoid

Violating the Clean Water Act

• DC Clean Rivers Project is in the process of digging

large tunnels to be used to divert the CSOs from the

receiving waterways and retain that water to be treated

by Blue Plains WWTP.

• Cost of DC tunnels - $2.6 Billion

• Cleveland - $3 Billion

• Kansas City - $2.48 Billion

• New stormwater regulations aimed at making DC

“spongier” to reduce the amount of stormwater

entering the combined sewers.

Changes to DC Stormwater

Regulations

• New construction over 5000 sq. ft. must retain first 1.2”

of rainfall (90% of storm events).

• Major renovations must retain first .8” (80% of events)

• Retained water must be disposed of on site. Infiltrate,

fixture flushing, cooling tower, evaporate, etc…

• At least 50% of required detention must be done on

site. Remainder can be purchased as credits.

• Credits can be purchased from DDOE for $3.50 per

gallon per year or in the private marketplace.

Rainwater harvesting for

Stormwater Management•Sizing guidelines and

regulations per DDOE

•Stormwater can be detained

and reused on site

•New emphasis is on runoff

reduction

•Works best as part of a

treatment chain 0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20

Per

cen

t of

dem

an

d m

et b

y r

ain

wate

r

Tank size ( thousands of gallons)

Where to Capture Rainwater

Best Practice• Rooftops – The best and cleanest water comes off the roof.

Handle with Care•Green Roofs and Planted Areas – Water from green roofs is

often high in dissolved solids from the growing media.

• Not good for toilet flushing

• May work for irrigation or cooling tower makeup

•Parking Lots – Often contains oils and dissolved salt.

• Salt is difficult to remove and detrimental to plants

Possible Uses of Rainwater

•HVAC cooling systems

•Commercial laundries

•Water closets and urinals

•Irrigation

•Pool and pond Filling

•Other non-potable uses (fire suppression; floor and vehicle

washing)

Rainwater Harvesting and LEED

11 Possible Points

• Reduce or eliminate pollution from stormwater runoff

• Limit disruption and pollution of natural water flows by

managing stormwater runoff

• Limit or eliminate the use of potable water for landscape

irrigation

• Use only captured rain or recycled site water for site irrigation

• Reduce potable water use for building sewage conveyance by

50%

• Reduce water use for building by 20%

• Maximize water efficiency within building to reduce the

burden on municipal water supply & wastewater systems

No matter how big the job is, the concepts are

the same

You just have to choose the

right tools

Size Matters!Larger Tanks – Usually below grade

•Tend to utilize the captured rainwater more efficiently

•Rainwater Harvesting – Want the tank full

•Stormwater Management – Want the tank empty

• Control systems can help manage tank capacity

Smaller Tanks – Architectural Feature•Tend to be much cheaper

•Can reduce the cost of the rainwater system

•Some clients want them above grade to show off system

4 Steps for Rainwater Harvesting

•Self-cleaning filters

•Smoothing inlet

•Floating filter intake

•Multifunction overflow

Storage tank

Grade

Putting it all together1

2

34

Two Ways to Build a Rainwater System

A La Carte Skid System

A group of parts

and pieces are

sourced and

assembled on site

usually following a

project specific

scenario.

The system is pre-

designed and pre-

packaged with

minimal on-site

construction.

Some Considerations for A La Carte Systems

• Increased possibility that the installing

contractor might not assemble the components

in the order that the designer intended.

• Liability concerning installation must be clearly

defined and understood between all parties.

• Some of the equipment may be delicate and, if

poorly understood, may be damaged and or

broken during installation. This will fall on the

contractor.

Skid System On-Site Hook Up

Inlet from

Cistern

To End

Use

Filter

blow-

down

Domestic

Water

supply

line

SYSTEM CONTROLLER

Urban farm

Charlottesville Public Works

Charlottesville Area Transit

Jefferson Houston Elementary

School – Skid System

Jefferson Houston Elementary

School – Skid System

Home Depot

Boeing – Crystal City, VA

Boeing – Crystal City

Boeing – Crystal City

No Pre-Filter

Kellum High School, Virginia

Beach

701 2nd Street, Washington, DC

450 Unit Apartment

ICC Bethesda

High Security Office Building

Oscar Smith Middle School

A two-tiered approach

Two “clean” tanks are

used for indoor use –

toilets and urinals

The other two tanks are

used for irrigation

Manassas Park Elementary

61,500 sf of additional roof area (12,000

pre-k; 49,500 upper elementary)

Estimated project budget $33 million

Manassass Park Elementary School

Effect of system Eighty-two percent of the precipitation that falls on the roof is used in the

building or for irrigation (1.1 million gallons). Any additional runoff is routed

to the constructed wetland for infiltration or evaporation or in extreme

events, detention and release. The initial estimates used in sizing the

system were based on monthly rainfall data. This difference in time interval

is why the signs and other early estimates predict an annual water savings

of 1.3 million gallons.

The school uses about 356,000 gallons of water per year; the neighboring

school (Cougar Elementary) uses 2.2 million gallons of water per year.

LEED Gold certified

Numerous awards including

K-12 Project of the Year, Mid-Atlantic Construction magazine

Platinum Design Award and People's Choice Award, 2009 Virginia

School Board Association

Exhibition of School Architecture; 1st place in the 2007 Go Green

Competition, USGBC James River Chapter

AIA/COTE Top Ten Green Projects

Manassas Park Elementary

School- Education component

Western Virginia Regional Jail Regional partnership between the counties of Franklin,

Montgomery, Roanoke and the city of Salem

264,000 sq. ft. with a rated capacity for 605 inmates

Seeking LEED certification

Includes a siphonic roof drainage system

Payback analysis Total system cost = $258,000

3.9 million gallons of water saved

Current water rate $3 per 1,000 gallons

Annual savings from water = $11,675

Total payback time = 22 years

But does that really include everything?

Payback analysis Offsetting capital costs – the rainwater harvesting

system has the same water quality benefits for storm

water as a bioretention area that would cost about

$240,000 plus take up space on the site

Increasing water rates – if water rates increase 4% per

year, in twenty years, the water savings will have more

than doubled ($24,599 per year)

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

0 10 20 30 40 50

Sys

tem

re

turn

on

in

ve

stm

en

t ($

)

Years

Payback with no offsetting costs

and no increase in water rates

Payback with offsetting costs and

increase in water rates

Benjamin Sojka

Rainwater Management Solutions

bsojka@rainwatermanagement.com

434-531-0381 -direct

The Joyce Agency

3933 Avion Park Court, Suite B102B

Chantilly, VA 20151

www.thejoyceagency.com

1-800-291-9298

Experience Matters!

• All Souls Church – Washington, DC

• Car Barn Training Facility – Washington, DC

• Wounded Warriors Dorm Facility – Bethesda Naval

Hospital, MD

• PH2SO Apartments – Washington, DC

• Patterson House Apartments – Washington, DC

• 800 New Jersey Avenue – Washington, DC

• 880 New Jersey Avenue – Washington, DC

• Park Chelsea Apartments – Washington, DC

• 2001 Clarendon Apartments – Arlington, VA

• 9th Street Office Building – Richmond, VA

• Fairfax Public Safety Building – Farifax, VA

Experience Matters!

• I.C.C. Government Security Complex – Bethesda, MD

• St. Elizabeth’s Rehab and Renovations (2) –

Washington, DC

• H.D. Woodson High School – Washington, DC

• Brookland Middle School – Washington, DC

• University of the District of Columbia Greenhouse –

Washington, DC

• Anacostia High School – Washington, DC

• Arlington Mills Community Center – Arlington, VA

• Kempsville High School – Virginia Beach, VA

• Gunston 9 Secure Facility – Lorton, VA

Experience Matters!

• Mathias Research Center (Smithsonian) – St. Mary’s

County, MD

• Monument View Center (Boeing) – Crystal City, VA

• 82 Eye Street – Washington, DC

• Caffie Building – Arlington, VA

• Manassas Elementary School – Manassas, VA

• University of Maryland Knight Hall – College Park,

MD

• Hillen Street Fire Station – Baltimore, MD

• National Business Park – Baltimore, MD

Experience Matters!

Rainwater Management Solutions

• Over Ten years of rainwater harvesting experience

each

• Have made many of the mistakes and have learned

from them

• Have the financial backing and resources to stand

behind their systems