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GRAYWATER CURRICULUMGRAYWATER CURRICULUMGRAYWATER CURRICULUM

Graywater Distribution to the Landscape

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Class 5 Objectives

1. Laundry to landscape distribution

2. Branched drain distribution

3. Unfiltered pumped system distribution

4. Filtered pumped system distribution

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Laundry to Landscape Systems

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Laundry to Landscape Distribution

Laundry to landscape distribution

Step 1: Piping to irrigation field

Step 2: Calculate and dig mulch basins, build mulch shields

Step 3: Trench to mulch basins

Step 4: Lay tubing

Step 5: Test and tune system

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Step 1: Piping to Irrigation Field

You may have to pipe around decks, patios, etc.

You may need to bypass hardscape

Options: go under it, go around it, remove it, cut a strip of it, cut across the driveway and patch in

Maintain a downwards slope

Paint exposed PVC pipe to protect from UV

Caulk holes at building exit points

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Step 2: Mulch Basins

Refer to Class 3 and Table 1602.10, for information on sizing the irrigation area

Plan for mature plant size

Type of Soil Minimum sqftof irrigation area per 100

gallons of graywater/day

Max absorptioncapacity

(gallon/sqft/day)

Coarse sand or gravel

20 5.0

Fine Sand 25 4.0

Sandy Loam 40 2.5

Sandy Clay 60 1.7

Clay w/ considerable sand or gravel

90 1.1

Clay w/small amounts of sandor gravel

120 0.8

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Step 2: Mulch Shields

The purpose of a mulch shield is to provide graywaterwater outlet pipes with protection from soil and plant roots

• Can use small valve boxes or inverted plant containers

• Graywater discharge 2 in. under mulch shield for code compliance

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Step 3: Trench to mulch basins

• Dig a trench, about 4 inches deep, from the PVC pipe to the first mulch basin

• Continue the trench to all the basins, taking the most direct route possible while avoiding sharp turns

• If possible, maintain a slight downward slope or at least a level gradient

• If the system has dips and rises, it will be more difficult to get even distribution of water

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Step 3: Slope

Protect your washing machine's pump:• Flat yard- no more than 50 ft.

• Don't pump more than 2' above the rim of the machine

• With friction loss every 50' flat = 1.5' rise

• Downhill slope - no rule on distance

• Uphill slope - not recommended!• Use a swing check valve to prevent back flow into

the machine

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Step 4: Lay Tubing

• Roll HDPE tubing out in the trench to mulch basins

• Stake tubing so that it stays in place

• At each irrigation point, cut the tubing and insert a 1 inch x ½ inch barbed tee into the tubing

• Attach short section of ½ inch poly tubing and insert into mulch shield

• Maintain 1 inch open end at some point in the system

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Step 5: Test and Tune System

• Test system for leaks and operation before burying pipes and tubing

• Tune flows in the system

• Take photos before burying tubing to include in O&M manual

• Bury tubing

• Caulk holes inside and out

• Post signs

• Post O&M Manual

Adjust angle of tees

Adjust ball valves

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Branched Drain Systems

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Branched Drain Distribution

Branched drain system landscape distribution

Step 1: Branched Drain design and mulch basins

Step 2: Piping to irrigation field

Step 3: Install double ells

Step 4: Document, check and tune

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Step 1: Branched Drain Design

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Step 1: Branched Drain Design

• Irrigate larger plants (trees, shrubs, perennials)

• Pipe size will depend on indoor plumbing (typically 1.5 or 2 inch)

• Pipe size can be reduced at double ells

• Each split divides flow in half if level

• To ensure an even split have a 2' straight section of pipe before splitter

• If pipe enters splitter at an angle the water won't divide evenly

• Plan your branched drain system so the pipes will always have a 2% slope

• Consider obstructions (pipes, roots, etc.) that can make the installation more challenging

• Mulch basin procedure is the same as for laundry to landscape

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Step 1: Single or Multiple Zones

• A 3-way diverter Valve can be used to create two graywater "zones”

• Zones irrigate different areas of the yard

Pros and cons of multiple zones

• Allows aerobic conditions to return to soil

• Available graywater fits more closely to irrigation needs

• Must remember to manually switch zones

• Controllers and automatic valves for unpressurized water are expensive

• Systems that filter and pressurize the water can use standard irrigation solenoid valves for multiple zones

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Activity 1: Branched Drain System Design

• The yard is flat

• Sketch how you could split up the graywater and pipe between the plants

• Try and be accurate with the turning options (90, 45, 60, 22 degree bends), and list the ABS drainage fittings you used

• Use the least amount of materials possible

• Complete only the outside portionof the system.

Pear Tree

Orange Tree

Apple Tree

Raspberry Patch

Shower

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Step 2: Piping to Irrigation Field

A downward slope in all parts of the system is needed to keep the water moving!

• Install pipes at 2% grade downhill or ¼ inch per foot

• Maintain flow and help solids move through pipe

• Level pipes at flow splitter required

• More slope when flow is downhill is okay

Positive slope = Ideal Excessive slope = Not ideal

Negative slope = Not acceptableNo slope = Not ideal

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Step 3: Install Double Ells

Double ells are also called flow splitters

• Each split divides flow in half

• Flow Splitters must be level

• Pack soil under pipe, then stake or bury points along line to keep grade

• Check that all Double Ells are level across the split

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Step 3: Install Double Ells

Double Ells are multifunctional as cleanoutsCreate an access point by putting a container around the double ell so it will be accessible for maintenance

1” PVC threaded plug• Threaded plug• Install cleanouts before burying

Drilled double-ells cleanout• Drill hole• Thread 1” plastic cap

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Activity 2: Plant Placement and Flow Distribution

What fraction of the flow exits at each outlet?

What kind of plants would you use at

each outlet?

WaterIn

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Step 4: Document, Check and Tune

• Final Inspection for Permit

• Check for leaks

• Take a picture before burying pipes to include in O&M manual

• Label pipes every 5 feet “CAUTION: NONPOTABLE GRAY WATER, DO NOT DRINK”

• Best case scenario: pipes are bedded in sand with metal detectable tape over line

• Bury pipes

• Caulk holes

• Post signs

• Post O&M manual

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Step 4: O&M Manual

Required info:• Diagram(s) of the system and location of components

• Instructions on operating the system

• Details on start-up, shut-down, and deactivation

• Applicable testing, inspection and maintenance

• Contact info of installer/designer and component manufacturer

• Directions that the O&M manual needs to remain with the building for the life of the structure

Other helpful info:• What kinds of soaps to use

• A picture of the tubing before it is buried

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Unfiltered Pumped Systems

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Unfiltered Pumped Systems Distribution

• Distribution system similar to laundry to landscape system

• ¾ to 1 inch poly tube (depending on pump size)

• Branches of ½ inch to mulch basins

• Check valve on discharge line to prevent flow back to the pump

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Graywater Pump – Operation

• Dirty water submersible pumps designed to pump solids up to 1 ½ inches or more in size

• Little to no filtration required before the pump, except a hair catch filter

• Graywater capable, submersible, vortex pump, with inline float switch

• Float switch controls operation of the pump

• Pump automatically switches on as soon as approximately 5 gallons of graywater has collected in the basin

• Settings can be adjusted by altering the mounting point of the automatic float switch

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Graywater Pump - Size

A ¾ HP 660 Watt dirty water pump will provide more than enough power for most residential graywater applications

• Length of pipe/distance traveled

• Pipe size

• Head loss & friction loss

• Flow rates

• Friction loss table or calculator:

• http://www.performancepropumps.com/PDF_Files/FrictionLossChart.pdf

• Fitting components (# elbows, # couplings, etc)

• Approximate size of solids

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Graywater Pump – Electricity

• Pump needs an electrical outlet

• New construction should have a dedicated circuit

• Retrofit systems will need to check total amperage load on circuit and verify the addition of a pump will not overload the circuit

• A dedicated 15 amp circuit may need to be installed in a retrofit if circuit will be overloaded

• Electricity use depends on model, approximately 0.6% of average home power consumption

• A 660 Watt pump, in a typical 4-person household will run for ½ hour per day

• Actual use is 450 Watts during operation = total daily power usage is 0.25 kilowatt hours

• At 11 cents per kilowatt hour (2007 USA average) = 2.8 cents per day = $6.70 per year (60.8 kWh)

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Unfiltered Pumped Systems Maintenance

Pump life span

• Pump will need replacement, most come with 2 year warranty, typically last between 5-15 years

Irrigation side of system

• Adjustment as needed and if plants change

• Add/replace mulch in mulch basins

Clean tank

• Systems that require cleaning of filters tend to fail quickly since people forget to clean them!

• See user's guide for additional maintenance instructions on tank system requirements and cleaning schedule

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Filtered Pumped Systems

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Filtered Pumped Systems Distribution

• High amounts of suspended solids (i.e. dissolved detergents, dirt) and bacteria in unfiltered graywater quickly clog traditional filters and small orifices such as drip emitters

• Filtration removes larger suspended solids present in graywater to facilitate distribution through drip tubing with an irrigation controller

• Greater irrigation efficiency

• No mulch basins

• Irrigation of smaller plants and turf

• Several types of filtered systems• Manually cleaned filters

• Self cleaning filters

• Drip tubing specifically designed for graywater• Can be tied into the potable water supply to provide irrigation when

graywater is unavailable

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Filtered Pumped Systems Distribution

• CPC 1602.3 specifies that potable connections be protected by an air gap , reduced-pressure principle backflow preventer, or other physical device that prevents backflow

• Reduced pressure principle backflow• Two independent check valves, plumbed in series, with a pressure

monitored chamber between

• Chamber maintained at lower pressure than the water supply pressure

• Reduced pressure is guaranteed by a differential pressure relief valve, which automatically relieves excess pressure in the chamber by discharging

• Four test cocks are installed to allow an inspector to verify proper operation of the valve with a differential pressure meter

• Typically require annual inspection and certification

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Manually Cleaned Filters

• Require monthly or weekly filter cleaning

• Very high maintenance

• High rate of failure due to filter clogging

Aqua2use Image: Leigh Jarrard

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Self Cleaning Filters

• Self cleaning filters reduce system maintenance by automating filter cleaning process

• Water is back flushed through the filter to remove debris

• Either timed or controlled by sensors

• Mesh / screen filtration

• IrriGray

• WaterSprout

• Sand filtration

• ReWater

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Self Cleaning Filtered Pumped Systems Example: IrriGray

• Pressure sensors identify pressure differentials and activate filter cleaning

• Filter handle rotates 90 degrees to activate alternate water supply

• Backwash water flows the opposite direction through the filter at 40 PSI or more

• Grime and debris is flushed back into the pumping basin or to sewer/septic

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Self Cleaning Filtered Pumped Systems Example: WaterSprout

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Self Cleaning Filtered Pumped Systems Example: ReWater

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Graywater Drip Tubing

Graywater is not compatible with traditional drip tubing

• Even when filtered graywater contains suspended and dissolved detergents that can build up and eventually clog the emitter

• Standard drip tubing may release graywater slower than it is generated, causing a large volume of graywater to be wasted via overflow into either the sewer or septic system

• Various drip technologies have been developed specifically for graywater

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Graywater Drip Tubing Examples

Netafim Bioline

• Pressure compensating (7 – 58 PSI)

• Self flushing

• 0.4, 0.6 or 0.9 GPH

• Can be used sub-surface

IrriGray

• Low filtration requirements (400 micron / 40 mesh)

• 2.0 GPH

• Operating pressure 2 – 45 PSI

ReWater

• Proprietary drip emitter system available since 1990

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Graywater Drip Tubing

• Total dripperline length shouldn’t exceed 450 feet per zone

• Quantity of water required to pressurize lines would exceed the volume of water typically produced

• Potential height differential dependent on pump

• ¾ hp dirty water submersible pump sufficient for 20 feet

• Graywater drip tubing subject to low head/emitter drainage

• Non return valves can be used

• Use swing check valves as spring check valves provide too much flow resistance

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Graywater Drip Irrigation Fields

Table 1602.11 prescribes the minimum number of drip emitters to be used for a subsurface irrigation field and the maximum discharge per emitter each day

Type of Soil Maximum emitter

discharge (gpd)

Minimum # of emitters per gallon of estimated

graywater discharge per day (gpd)

Sand 1.8 5.0

Sandy loam 1.4 4.0

Loam 1.2 2.5

Clay loam 0.9 1.7

Silty clay 0.6 1.1

Clay 0.5 0.841

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Graywater Supply Lines and Drip Tubing

• Either a ¾ inch or 1 inch supply line is used, depending on pump discharge rate

• Larger pipe requires more graywater to be produced before the lines become pressurized

• 1 inch pipe holds twice the volume of water as ¾ inch pipe

• Maximum lateral dripperline length is dependent on inlet pressure

• Can be doubled if the dripperline is connected to the supply line at both ends of the dripperline

• Spacing between dripperlinesdetermined by soil type

• Closer for sandy soils, further apart for clay soils

• Refer to manufacturers specs

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Graywater Drip TubingExample: IrriGray

IrriGray specs for lateral dripperline layout

Inlet pressure

(psi)

Nominal Flow (gph)

Maximum lateral line

length (feet)

3 0.7 52

6 0.8 56

15 1.4 56

30 1.9 59

Soil type Seperation(feet)

Gravel and sand 1.8

Sandy loam 1.8

Loam 2.4

Clay loam 2.7

Light clay 3.0

Medium to heavy clay

4.5

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Graywater Irrigation Controllers

• Filtered pumped systems typically controlled with an irrigation controller

• Controllers exist that manage water from a variety of alternate sources (potable, graywater, rainwater, AC condensate)

• The IrriGray smart controller is one example

• Managed by Android tablet with proprietary electronics interface

• Each landscape zone defined by zone-specific details

• The controller automatically calculates correct volume of water required for each day, in each month of the year

• Performance data (amount of water used, type of water, zone number / name, cleaning events, maintenance events) sent to an internet server which proactively monitors all installations

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Homework

Review handouts:

• Installation overview

• Client interview and site assessment

• Graywater operations and maintenance manual