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Grey Water and Drip Irrigation

VIEWS: 15 PAGES: 35

									Bay Friendly Landscaping and
   Gardening Conference

   Gray Water Workshop
            Sherri Osaka, Owner
       Sustainable Landscape Designs
      www.sustainable-landscape.com

                29-Feb-08
Water shortages
Western States
• Colorado River provides
    water to 30 million people
    in seven states
•   Has been in a drought for
    the past eight years
•   Arizona – 40% increase
    in population between
    1990 and 2000
•   Nevada – 66% increase
    in population same time
    frame
Water shortages
Western States
• Lakes Mead, Powell
 may dry up by
 2021, study says
  – Several states would lose key
    water sources, scientists warn
  – Study by San Diego’s Scripps
    Institute of Oceanography        100-foot bathtub ring around Lake Mead,
                                     NY Times magazine, Oct. 2007
Water shortages
Northern California
• The most optimistic climate models …
 suggest that 30 to 70 percent of the
 [Sierra Nevada] snowpack will disappear.
 “There’s a two-thirds chance there will be
 a disaster, and that’s in the best scenario.”
 Steven Chu, Nobel laureate and director
 of the Lawrence Berkeley National
 Laboratory
Water shortages
Georgia
• Gov. Sonny Perdue declared a
  state of emergency Saturday
  for the northern third of the
  state of Georgia and asked
  President Bush to declare it a
  major disaster area. Oct. 2007

• Lake Lanier, a 38,000-acre
  reservoir that supplies more
  than 3 million residents with
  water, is less than three
  months from depletion.
                                   Lake Lanier reservoir
Reusing “gray water” is one
         solution
          What is gray water?
• Water from sinks,          • No water from kitchens
  showers, and laundry tub       sinks (food particles)
                             •   No water from toilets
                                 (black water)
                             •   No water from laundry if
                                 used to clean diapers
                             •   No water containing any
                                 harmful chemicals,
                                 including bleach
 Where can you use gray water in
         the landscape?
• On fruit trees   • Not on
• On ornamental      vegetables
 perennials,       • Not on
 shrubs,             seasonally
 groundcovers,       planted annuals
 and lawns
     Is Gray Water Irrigation safe?

 • Study* of eight households in Los Angeles in
     1992 and checked monthly showed no harmful
     organisms in soil
 •   Still questions on how gray water affects soil
     microbiology
     – Constructed wetlands good solution




*City of Los Angeles, Office of Water Reclamation (CLA,OWR). 1992. “Gray water
Pilot Project: Mid-Course Report”. Los Angeles, CA.
         Gray Water Irrigation
• Advantages
  – Reduces amount of water purchased by using it twice
  – Reduces maintenance for septic systems
  – Reduces load on municipal sewer and waste water
    treatment systems (credits for multi-unit residential,
    commercial and industrial use)
  – Keeps (expensive) landscapes alive during drought –
    mature landscapes valued at $20/ sq. ft.
• Disadvantages
  – Not for plants that like acidity – unless pH is balanced
  – Need to be careful what you put down the drain—no
    chlorine, no boron, etc.
  – More expensive than typical irrigation system
    Water Use in Typical Bay Area Home
    Water use in dry summers about twice that of wet winter months


• Water use in CCFs
    (one hundred cubic
    feet)                    40
•   One CCF = about          35
    750 gallons              30
•   Family of four can       25                                             Average
    produce about 13         20
    CCFs per two month
    water billing period     15
•   Just about the water     10
    required for “typical”   5
    Bay Area landscape       0
•   Estimate of 40                Dec-   Feb-   Apr-   Jun-   Aug-   Oct-
    gallons of gray water         Feb    Apr    Jun    Aug    Oct    Dec
    produced per day
    per person
Gray Water Permitting Comparison

• California
   – Requires permit - ~$500 depending on municipality
   – Patterned after septic systems
   – California Plumbing Code (CPC) Appendix G
• Arizona – updated Jan. 1, 2007
   – Three tiers
   – Type 1 no longer requires permit for less than 400
     gallons/ day – follow 13 Best Management Practices
     (BMPs)
   – $1,200 tax credit for grey water systems
Preparation and Installation of
    Gray Water Systems
       Retrofitting for Gray Water
          Step 1: Separate black and gray water




Drawing from: Gray Water Use in the Landscape by Robert Kourik.
                New House or Construction
“The ideal
way to
plumb the
house is
with
greywater
and
blackwater
totally
separate,…
and the
greywater
lines joined
to the toilet
plumbing
outside the
house.


Drawing from: Oasis Designs, www.oasisdesign.net, quote from Builder’s Greywater
Guide by Art Ludwig
Major Types of Systems and Costs

• Branched drain – may be permitted

• Subsurface drip – can be permitted
Branched Drain
                                     Not specified in California Plumbing
                                     Code




Drawings from: Branched Drain Greywater Systems by Art Ludwig
Branched Drain
• Description
  – No pumps
  – Can be filtered or not
  – Best for fruit trees and fruiting vines (grapes, kiwis)
• Advantages
  – Least expensive
  – Low maintenance, low-tech (but high value system)
• Disadvantages
  – Must be careful that pipes slope a minimum of 2% or
    ¼” per foot
  – Site must slope downhill from house: greater than
    8% best, 2-4% good, less than 2% - forget it
  – Not good for small plants or lawns
Subsurface Drip Gray Water System

• Filtered – sand or constructed wetlands
• Pumped
• Subsurface drip delivery

• See ReWater, Inc. for available system
Components Subsurface Drip Gray Water
              System




       Surge tank, pump, and filter
              Source: ReWater, Inc.
Subsurface Drip

• Valves
• Specially designed
 emitters won’t clog




                       ReWater, Inc. Cone drip emitters
Irrigation Controller
• Twenty-one stations
• Automatic filter
    backwash
•   Fresh water
    supplementation
    (when out of town)   ReWater’s Complete Control irrigation
                         controller
Subsurface Drip Gray Water System
• Description
  – Pumped and filtered
• Advantages
  –   Most flexible
  –   Good for most types of vegetation
  –   Similar to modern irrigation systems
  –   Good for most topographies
  –   Good for multi-unit and commercial sites
• Disadvantages
  – Most expensive
  – Most complicated
Lawn Irrigation Installation




                            Lawn five years after installation


Photos from ReWater, Inc.
Palo Alto Site




Picture from ReWater, Inc.
Sunnyvale Home – Installed 2006
 Sand filter from ReWater




                                           Surge tank in vault

                                           Surge tank in vault




                        Lawn with subsurface drip tubing from Netafim,
                        installed by Cal EarthCare Landscaping,
                        plumbing by Hal Branges
Example of Commercial Subsurface
Drip
• Laundromat with 60
    washers, some 100
    gallons in Chula Vista
•   750 gallon surge tank
•   15,000 sq. ft. of
    landscaping area
•   Surge tank and filter
    installed under parking lot
•   Received a credit from
    sewer district
•   Payback estimated in 3½       Manhole cover on surge tank under
    years                         parking space – photo from ReWater,
                                  Inc.
 Gray Water Charette
  Hands on design to get you
started on your gray water path
Gray Water Requirements Listed in
California Plumbing Code Appendix G
•   Requires a permit (in California)
•   Scaled plot plan
•   Log of soil percolation (or refer to table)
•   Water must never surface
•   Pipes laid 8 inches below surface
•   Water must stay 5 feet away from groundwater and
    ocean water
•   Pipes, tanks, and filters must be marked as gray water

See California Plumbing Code Appendix G for more
  information
Gray Water Charette
• Given:                                  • 40 gallons of water per person per
   –   Number of people/ bedrooms             day
   –   Slope                                   – 25 gpd for washing
   –   Location of gray water sources          – 15 gpd for laundry
   –   Type of soil – infiltration rate   • Branched drain best for slopes 4%
• Determine:                                  and greater
   – Amount of water available            •   Tank/ wetland gravity fed so best
   – Type of system: branched drain,          located near sources of gray water
     subsurface, sand or constructed      •   Emitters spaced 12-24”
     wetland filter
   – Where to locate surge tanks,
                                          •   Coarse sand 20 sq. ft. for 100 gpd
     filters if any                       •   Find sand – 25 sf for 100 gpd
   – Amount of landscape that can be      •   Sandy loam – 40 sf for 100 gpd
     watered                              •   Sandy clay – 60 sf for 100 gpd
   – Types of plants that can be          •   Clay w/ sand – 90 sf for 100 gpd
     watered
                                          •   Clay – 120 sf for 100 gpd
Gray water charettes - scenarios
• Scenario 1                  • Scenario 3
   – Four people
                                 -   5 people
   – Clay soil
   – Lawn, fruit trees, and      -   Clay soil
     ornamentals                 -   Grape vines, fruit trees
   – Less than 2% slope          -   > 8 % slope
• Scenario 2                     -   “Want clean water”
   –   2 people
   –   Clay soil              - Scenario 4
   –   Fruit trees               - 4 people
   –   > 8% slope                - Clay soil
   –   “Cost is an issue”
                                 - California native and
                                   drought tolerant plants
                                 - Less than 2% slope
Additional Information
Subsurface Drip-Type Gray Water
Costs
• ~$3,000 for surge tank and filter from ReWater, Inc.
• ~$2,000 for sophisticated controller
• Subsurface drip – more efficient than standard drip
    system since below grade
•   Extra labor for trenching and installing equipment,
    especially on lawns
•   Especially appealing for new construction, more
    complicated for remodels
•   Multi-unit residential, commercial & industrial sites can
    get credit for reducing sewer use
Prepare for Gray Water
“Stub out” plumbing
“Any construction you do should at least have stub-out plumbing or
dual waste plumbing for a future gray water system; plumbing black
and gray water separate until just past the point of a future gray water
diversion. No law says where you have to join gray water and black
water lines, outside the house is fine.”
Builder’s Greywater Guide by Art Ludwig
References & Additional Information

• Complete gray water system: Rewater, Inc. www.rewater.com
• 1997 California gray water standards (Appendix G):
    www.owue.water.ca.gov/docs/Revised_Graywater_Standards.pdf
•   City of Malibu:
    www.ci.malibu.ca.us/index.cfm?fuseaction=detailgroup&navid=274&cid=29
    49
•   Gray water in Arizona http://www.ci.tucson.az.us/water/docs/adeqtwwq.pdf
•   Demonstration gray water system in Arizona
    http://cals.arizona.edu/AZWATER/arroyo/071rain.html
•   Create an Oasis with Greywater, Builder’s Greywater Guide, and Branched
    Drain Greywater Systems by Art Ludwig
•   Greywater Guerrillas, authors of Dam Nation, www.greywaterguerrillas.com
•   Installing “stubouts” for future greywater systems:
    http://oasisdesign.net/greywater/stubout.htm

								
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