Rainwater Harvesting:

Transcription

1 Rainwater Harvesting: Using and Reducing the Water that Goes to Waste. By Steve Williams 2012 An Answer to Urban Water Quantity and Quality Problems

2 Urban Ecosystem Analysis The City of Atlanta Tree loss in the Atlanta metro area from 1974 to 1996 resulted in a 33% increase in stormwater runoff (from each 2-year peak storm event). This translates into an estimated 591 million cubic feet of water or 4,420,987,013 gallons. Costs to build engineered systems to intercept this runoff would cost $1.18 billion ($2/cubic ft. of storage) in 2001 dollars. Data from the American Forests study Urban Ecosystem Analysis, Atlanta, GA

3 The total stormwater retention capacity of our urban forest cover in 1996 was worth about $2.36 billion, down from 1974's value of $3.54 billion. This translates to $85.9 million per year.

4 Water Runoff from Development

5 Development in Atlanta, GA and surrounding counties contribute to a yearly loss of groundwater infiltration ranging from 57 to 133 billion gallons from

6 If managed on site, some of this rainwater which could support annual household needs of 1.5 to 3.6 million people, can be captured in cisterns (reservoirs). The rest can be allowed to filter through the soil to recharge aquifers and increase underground flows to replenish rivers, streams and estuaries. American Rivers, Natural Resources Defense Council and Smart Growth America Report: Paving Our Way to Water Shortages: How Sprawl Aggravates the Effects of Draught August 28, 2002

7 Where is the Water Going?

8 TRADITIONAL SOLUTIONS Retention Ponds

9 TRADITIONAL SOLUTIONS Side Walks Sewers

10 TRADITIONAL SOLUTIONS Streets to Sewers

11 THE EFFECTS STREET FLOODING

12 THE EFFECTS EROSION and LOSS of TOP SOIL

13 THE EFFECTS CREEKS OVERFLOWING

14 THE EFFECTS of OUR CURRENT WATERSHED MANAGEMENT

15 CISTERNS A rain harvesting technique that can store water for shortages, reduce stormwater and replace potable water uses with nonpotable water.

16 REASONS FOR USING CISTERNS TO COLLECT RAINWATER Treated water is an expensive resource. Rainwater is a healthier alternative to potable water for plants. By diverting rainwater during heavy rains, cisterns can store it for use during draught, this will also reduce stormwater run off. Technology is readily available and relatively inexpensive. Rainwater collection is insurance for your plants. Less than 50% of American household water usage requires the purification of drinking water such as toilets, laundry and outdoor use. Commercial and industrial uses provide use everyday.

17 THE COMPONENTS

18 THE COMPONENTS Roof Washer First Flush Calming Inlet Floating Filter Pump Overflow Controllers & Level Indicators

19 THE COMPONENTS Roof Washer First Flush Calming Inlet Floating Filter Pump Overflow Controllers & Level Indicators

20 THE COMPONENTS Roof Washer First Flush Calming Inlet Floating Filter Pump Overflow Controllers & Level Indicators

21 THE COMPONENTS Roof Washer First Flush Calming Inlet Floating Filter Pump Overflow Controllers & Level Indicators

22 THE COMPONENTS Roof Washer First Flush Calming Inlet Floating Filter Pump Overflow Controllers & Level Indicators

23 THE COMPONENTS Roof Washer First Flush Calming Inlet Floating Filter Pump Overflow Controllers & Level Indicators

24 THE COMPONENTS Roof Washer First Flush Calming Inlet Floating Filter Pump Overflow Controllers & Level Indicators

25 THE COMPONENTS Roof Washer First Flush Calming Inlet Floating Filter Pump Overflow Controllers

26 STORMWATER MANAGEMENT How can this practice reduce the effects of out of control Stormwater?

27 PEAK FLOW By sizing the tank based on the roof area peak events can be stored to reduce the run off

28 TMDL REDUCTION First Flush The first flush is used to capture the first 2-5% of the water on the roof that holds the contaminants.

29 NORTH CAROLINA STORMWATER Technical Guidance: Stormwater Treatment Credit for Rainwater Harvesting Systems Revised September 22, 2008 Overview: It is the policy of the NC Division of Water Quality to enable and encourage the use of rooftop rainwater harvesting systems (cisterns) to reduce stormwater runoff pollution from an individual site.

30 NORTH CAROLINA STORMWATER PEAK REDUCTION Collecting and storing rooftop runoff, and providing a consistent, dedicated, and reliable end use, will reduce the volume of runoff and enable the reduction in size of other required stormwater treatment systems on the site. TMDL REDUCTION In watersheds requiring nutrient removal from stormwater, dedicated uses of the collected rainwater or proper treatment/infiltration can reduce stormwater nutrient removal requirements. This policy establishes the credit that will be allowed in the NC Division of Water Quality (DWQ) permitting programs that consider impervious built upon areas (BUA) and that rely on calculations of runoff volume and peak flow for sizing stormwater Best Management Practices (BMPs). Stormwater Treatment Credit for Rainwater Harvesting Systems Revised September 22, 2008

31 NORTH CAROLINA STORMWATER In order to receive credit, the following criteria must be met: The cistern must be sized to treat the design rainfall (ex. 1, 1.5, 1-yr 24-hr storm) from the roof area directed to the water harvesting system. All stormwater collected must have a dedicated, year-round. A water balance calculation must be used to establish the dedicated use volumes and rates. The overflow shall discharge flows in excess of the design volume BMP flow for the 10-yr rainfall event. It shall not discharge directly to impervious surfaces. If a first flush diverter is used, the bypassed water must discharge to a properly designed BMP

32 GEORGIA STORMWATER There are possibly 45 stormwater utilities in Georgia, I found 14 and 8 responded. Athens Covington Decatur Duluth Gwinnett Henry County Rockdale County Roswell Rain Barrels Cisterns Reduction BMP s Ga Stormwater Manual 3%, 5%, 10%, 85% Set Amount of Years Reapply Total Credit No Credit Site Verification Photo Verification

33 NEW RAINWATER STORMWATER GUIDELINES Guidance Manual for Rainwater Harvesting as a Stormwater Best Management Practice A Report of the State of the Practice and Recommended Guidance by the EWRI Rainwater Harvesting Technical Committee The goal of this report is to advance rainwater harvesting (RWH) as an urban stormwater management best management practice (BMP) by providing guidance to local governments seeking to implement RWH as part of their stormwater programs. Specifically, the report describes RWH positive and negative impacts on the urban water budget, Local, state, and federal policies affecting RWH, Methods and tools for design, Ways to administrate, maintain, and finance programs, Approaches to provide public education and outreach to developers and maintenance staff.

34 OTHER RAINWATER GUIDELINES Other guidelines that are available or in the process of being finalized IAPMO-International Association of Plumbing and Mechanical Officials IgCC-International Green Construction Code ARCSA-American Rainwater Catchment Systems Association Georgia Rainwater Harvesting Guidelines

35 RESOURCES Georgia Stormwater Management Manual: Volume 1: Atlanta Regional Commission Wikipedia ARCSA: American Rainwater Catchment Systems Association Construction Resources is Britain's first ecological builders' merchant, and a center for ecological building. Urban Ecosystem Analysis, Atlanta Metro Area, Calculating the Value of Nature, AMERICAN FORESTS P.O. Box 2000 Washington DC American Rivers, Natural Resources Defense Council and Smart Growth America, Report Rainwater Harvesting for Drylands Vol. I&II Brad Lancaster Jones, M. P. and Hunt, W. F. Rainwater Harvesting: Guidance for Homeowners. N.C. Cooperative Extension publication AG Raleigh: N.C. State University NCSU BAE Stormwater Engineering Group Rainwater Harvesting at North Carolina State University The Texas Manual on Rainwater Harvesting (2005, 3rd Ed.), Texas Water Development Board. Austin, Texas Georgia Rainwater Harvesting Guide American Society of Civil Engineers and Environmental & Water Resource Institute - Dr. Steven Burian U of Utah and Dwane Jones NCSU

36 Steve Williams