Transcript SEPTIC SYSTEMS

Household Wastewater Systems
Typical Waste Water System
Well
Renovated Wastewater
Minimum Lot Size for
Wastewater Disposal Systems
Disposal System
Type
Water Supply Source
Private Well Public Supply
Aerobic w/ sprinklers
¾ acre
½ acre
ET/Absorption Trench
1 acre
1 acre
Subsurface (fast perc.)
¾ acre
½ acre
Subsurface (slow perc.)
1 acre
1 acre
2 ½ acres
2 ½ acres
Lagoon
Wastewater System Components
• Water-tight sewer lines
• Septic tank
• Disposal system
– Subsurface drain field
• Absorption trenches
• Infiltration chambers
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ET/Absorption trenches
Aerobic system with sprinkler
Total retention lagoons
Pre-approved alternative disposal systems
Screen vent pipe opening to prevent
blockage by birds, squirrels, etc.
Household Plumbing
Sewer and Vent System
•Sewer lines in the house
collect waste water for
conveyance to the septic
tank
•Roof vents and the traps
under sinks, tubs, showers,
toilets and wall/floor drains
prevent sewer gas from
entering the house.
Main Sewer Pipe
Septic Tank
• All household wastewater systems will have a
septic tank
• Microbial action digests solid wastes
• Liquids flow through tank to disposal area
• Tank size
– 1000 gallon liquid capacity (4-BR house or less)
– Add 250 gallons per additional bedroom
Typical Septic Tank Installation
Two-Chamber Tank
Baffles
House
Foundation
Effluent Disposal Area Options
• Absorption field
– Absorption trenches
– Infiltration chambers
– ET/Absorption trenches
• Lagoons
• Aerobic systems
• Authorized alternative systems
Subsurface Absorption Field Approval
• Percolation Test
– 3 test holes in drainage area perc at a rate of
60 min/inch of water or faster
• Soil Profile Description
– 3 test holes without any of the following:
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(1) impervious material (bedrock, clay pan)
(2) water saturated soil (discoloration)
(3) loamy coarse sand or coarser soil, or
(4) sandy clay or finer soil
Cross-Section of Subsurface Absorption Trench
8-ft minimum distance to
center of next trench
Perforated Pipe
150’ MAX.
Lateral lines following the slope contour
150’ max. length
Aerobic Systems
• Used to treat septic tank effluent where
subsurface disposal is not possible
• Bubbling air through effluent supports
aerobic bacteria for further digestion
• Exposure to oxygen kills most pathogens
• Chlorination allows surface land application
of wastewater through sprinklers
Onsite Aerobic Treatment System
Onsite aerobic treatment systems treat septic tank
effluent further by aerobic digestion, chlorination to
kill pathogens, and surface application through a
spray head sprinkler system.
(Septic Tank)
EFFLUENT FROM
SEPTIC TANK
WASTEWATER
TO CHLORINATOR
& SPRINKLERS
DIFFUSER
Typical Aeration Chamber of Aerobic Treatment System
Pump Chamber and
Surface Application System
Access Hatch
Pump
Pump Control &
Alarm Floats
Spray Heads
Regular green stripes in a dry
lawn are the lateral lines
Household Water Use
• Typical Usage: 50-100 gallons/person-day
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Clothes washer:
30-50 gallons/load
Dishwasher:
7-15 gallons/load
Garbage Disposal: 4 - 6 gallons/day
Shower/Bathtub: 25-60 gallons/use
Ordinary toilet:
1.6 - 5 gallons/flush
Water softener: 50-100 gallons/regeneration
Septic System Additives
Biological
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Bacteria
Yeast
Enzymes
Combination
Chemical
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Acids
Bases
Organic Solvents
Flocculants
Biological Additives
• Will not eliminate need for tank pumping
• 20% of sludge is inorganic (indigestible)
• Billions of bacteria live in septic tanks-a few million more have little effect
• If natural bacteria have been killed,
added bacteria will die also
• Normal population is restored in 30-60
hours even if 99.99% has been killed
Waste Water System Failures
Common Causes
• Hydraulic overloading (too much water)
• Solids migration to drain field
– Failure to pump tank on schedule
– Baffle failure
• Root intrusion into sewer lines
• Traffic damage to drain field
• Garbage disposal overuse
Reducing Hydraulic Loading
• Equipment Adjustments
– Low flow toilets (1.6 gpf and 0.6 gpf)
– Water-saving showerheads
– Front-loading washing machines
• Lifestyle Adjustments
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Shower vs. bath
Distribute laundry loads throughout week
Distribute bathing morning & evening
Full loads only for washer & dishwasher
If you don’t maintain your on-site wastewater system, it
will demand your attention when it is most inconvenient.