CONVENTIONAL ONLOT SEWAGE SYSTEMS

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CONVENTIONALON-LOT SEWAGE SYSTEMS

• by
• Albert Jarrett,
• Professor of Biological Engineering
• Penn State University

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Conventional

• In Chapter 73 (Conventional).
• In-Ground Systems
• Beds.
• Trenches.
• Subsurface Sand Filters.
• Elevated Sand Mounds
• Individual Residential Spray Irrigation System

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Alternate Experimental

• There are two additional categories
• Alternate Systems.
• Started as an Experimental System.
• Was tested and approved for use.
• Listed in the Alternate Systems Guidance.
• Experimental Systems.
• Proposed systems.
• Being tested.

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Pennsylvania Protocol

• You have either
• A Conventional system its in Chapter 73.
• An Alternate system its in the alternate
  guidance.
• An Experimental system being tested.

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Septic Tank (Settling)
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Dose Tank
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Soil Absorption Systems
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In-Ground Systems
Subsurface Sand Filter
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Surface/Near-Surface Systems
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Above Ground Systems
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How Do You Decide???

• Based on your soil characteristics
• Depth to Limiting Zone.
• How much suitable soil is available to treat your
  waste water?
• Percolation (Perc) Rate.
• How rapidly can your wastewater enter (and move
  through) the soil?

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Depth to Limiting Zone

• Limiting Zone is
• Water
• Depth to Water Table.
• Depth to Seasonal High Water Table (Mottling).
• Slowly Permeable Zones
• Depth to Bedrock
• Depth to Clay or Fragipan
• Zone of Poor Water/Soil Contact
• Depth to zone of fractured rock, gravel, loose
  rock fragments.

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Perc Rate

• Run Perc Test
• Put water in hole and monitor its infiltration.
• Have Soil Scientist evaluate the soil.

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Conventional Beds Trenches

• Soil Conditions
• Limiting Zone ? 72 inches.
• Perc. Rate 6 to 90 min/in.

12 to 24 inch backfill
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Elevated Sand Mound

• Soil Conditions
• Limiting Zone ? 60 inches ? 20 inches.
• Perc. Rate 3 to 120 min/in.

Top Berm
12 in aggregate
SAND
? 60 inches ? 20 inches
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Individual Residential Spray Irrigation System
(IRSIS)

• Soil Conditions
• Bedrock Limiting Zone gt 16 inches.
• Water Table Limiting Zone gt 10 inches.

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IRSIS Overall System(side view)

• Four Major Components

Treatment Tank
Chlorine Disinfection
Spray Area
Filtration
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IRSIS Spray Area
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Subsurface Sand Filter

• Soil Conditions
• Limiting Zone ? 72 inches.
• Perc. Rate (above 36 inches) ? 90 min/in.
• Perc. Rate (36 to 60 inches) ? 3 to 90 min/in.

12 to 24 inch backfill
12 in aggregate
SAND
Slow
Slow
? 12 inches
? 72 inches
? 60 inches