EVAPOTRANSPIRATION BED

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EVAPOTRANSPIRATION BED

• Bruce Lesikar
• Associate Professor
• Texas Cooperative Extension

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Evapotranspiration Bed System
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Evapotranspiration Bed
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Evapotranspiration Bed-Materials

• Two beds for alternate loading
• Lined beds in permeable soils
• 20 mil plastic
• Concrete
• Gunite
• Clay with conductivity of 10-7 cm/sec
• Unlined beds in clay soils
• Bottom depth at least 12 below tank outlet
• Wicks between trenches for water removal

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Evapotranspiration Bed- Materials / Trench

• Trench for water storage
• Rock 3/4 to 2 diameter
• Chipped tires 2 diameter
• Gravel-less pipe
• Leaching chambers
• Other materials, does not dissolve

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Evapotranspiration Bed- Materials

• Perforated Rigid pipe
• 3 to 4 in diameter
• Drain holes for wastewater to exit pipe
• Distribution at top of media
• Geotextile fabric covering media

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Evapotranspiration Bed- Materials/ Fill

• Back fill with Class II soil

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Evapotranspiration Bed- Depth of Installation

• 18 minimum depth
• 36 maximum depth

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Evapotranspiration Bed- Treatment Method

• Pipe distributes wastewater to trench.
• Pores in media stores wastewater until
  percolation into the soil.
• Geotextile fabric keeps soil out of media trench
  of gravel-less pipe.
• Leaching chamber is not covered with fabric
• Unlined Soil provides treatment of some
  wastewater.
• Lined All water removed by evapotranspiration.

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Evapotranspiration Bed- Pretreatment Required

• Septic Tank

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Evapotranspiration Bed- Separation Distances

• Restrictive Horizons
• Groundwater Lined system

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Evapotranspiration Bed- System Sizing
Requirements/ General Description

• Evaporative surface is the top surface of beds.

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Evapotranspiration Bed-System Sizing
Requirements/ Surface Area Required

• Based on evapotranspiration rate.
• Area Daily Wastewater Flow / Loading Rate
• A 1.6Q / Ret

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Evapotranspiration Bed-Determine Configuration
of Beds

• Evaluate site dimensions.
• Evaluate required setback distances.
• Evaluate slope of site.
• Select be dimensions which fit site.