Onsite Waste Disposal

September 25, 2013

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Historical sewage treatment◦ Washed away and diluted by rain and surface water

◦ Early human habitations were often built near rivers or oceans for conveyance and sewage disposal

As population densities increased sewer collection and conveyance systems were developed. ◦ First sanitation system was found southeast of Iran,

used in palaces in Crete, Greece (3,000 years old & still works)

◦ As populations rose, systems became more complex

Rome had complex sewer networks between 46BC-400AD2

Human Waste Disposal

Most cities in early times had no sewers and relied on nearby rivers or occasional rain to wash away sewage. In some cities, waste water simply ran down the streets.

The growth of cities quickly caused polluted streets and became a constant source of disease. Even as recently as the late 1800’s street sewerage systems and individual cesspits were common.

Rain often caused the cesspits to overflow leaving the pavements awash with foul sewage and caused water-borne diseases such as cholera and typhoid.

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Human Waste Disposal

Vinaigrette ◦Containing aromatic herbs (sage, cinnamon,

lavender, mint and rosemary) and mixed with alcohol and acetic acid to create a pleasant perfume

◦Protection from foul odors ◦ It was believed at the time that they could protect

one from cholera◦Used by both men and women, suspended from

chatelaines, placed in pockets, hung from long chains, bracelets or finger rings.

◦Often designed in the shape of a rectangular box, and often made from multicolored gold or silver

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Add for 2013:

Because of the Industrial Revolution, populations in European and North American cities grew rapidly

Often led to crowding and increasing concerns about public health

Many cities developed municipal sanitation programs and constructed extensive sewer systems to help control outbreaks of disease in the late 19th and early 20th centuries

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Human Waste Disposal

Initially these systems discharged sewage directly to surface water, without treatment

Water pollution became a concern so cities added sewage treatment

Rural American families and many in towns and small cities:◦ Outhouses were common until about 50 years ago

◦ Then, septic systems became common and added:

Convenience

Public health

Environmental protection

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Human Waste Disposal

Ag Research facilityNiger, August, 2007

About a third of all Indiana homes use septic systems

Septic systems remove pathogens from wastewater ◦ Shigella

◦ Giardia

◦ Escherichia coli (E. coli)

Most (~ 85%) of these systems are conventional septic-absorption fields

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Who Uses Septic/Onsite Systems?

Typical Systems

◦ Wastewater is drained in a septic tank

◦ Grease and oils rise to the top

◦ Solids settle to the bottom where they decompose

The clarified effluent is channeled to an absorption field.

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Septic Systems (Onsite systems)

Septic Tank

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Sewagefrom Home

Vent

Sludge Layer

Liquid Layer

Scum Layer

Tank care: septic tanks should be pumped every 3-5 years

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Conventional Onsite Dispersal System

Soil Absorption Field

SepticTank

Distribution box

Soils effectively treat effluent through the following processes

◦ Chemical

◦ Physical

◦ Biological

The best soil for an absorption field is a deep, well-drained soil

Oxygenated soil is necessary for waste degradation

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Indiana Soils & Septic Systems

Soil texture and structure affects the speed that water moves through soil

Problems for absorption fields:◦ High water tables◦ Dense or impermeable subsoil (transmit water too slow)◦ Sandy soils (transmit water too fast)

Prime Ag land (land that is good for crop production) usually does not make a good septic absorption field.

58% of Indiana is considered prime Ag land, second only to Illinois at 59%. (IA=52%, OH & KS=45%)

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Indiana Soils & Septic Systems

Soil A is well drained (oxygen rich) and suitable for a conventional trench septic system.

Soil C is poorly drained (oxygen deprived) and saturated with water most of the time.

Soil B is saturated briefly during the year. Soils B and C are unsuitable for

conventional trench septic systems.13

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This map shows the percent of land that is estimated as unsuitable for conventional onsite (septic) systems, unless the site or the system is modified.

Prior to 1977◦ No septic system regulations in Indiana

(construction or placement)◦ Construction practices varied widely

Current Standards◦ Wastewater must not:

Contaminate groundwater Contaminate surface water Interfere with household plumbing

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Septic System Regulations

Conserve water to avoid overloading your septic system

Toilets◦ 1992 US Energy Policy and Conservation

Act requires 1.6 gallon/flush “ultra low-flow toilets”

◦ 2007: US government is now promoting 1.3 gal/flush toilets

Do not use caustic drain openers for a clogged drain (use boiling water or a drain snake to open clogs)

More to follow…

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Onsite System Care

CleanersUse commercial bathroom cleaners and laundry

detergents in moderation. Use a mild detergent or baking soda when possible.

Do not flush anything other than human wastes and septic safe toilet paper (no diapers, medications, etc…. Your septic system is not a trash can)

Do not use a garbage disposal (compost instead)

More to follow…

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Onsite System Care

Avoid dumping grease or fats down your kitchen drain

Keep latex paint, varnishes, thinners, waste oil, photographic solutions, pesticides, or other hazardous chemicals out of your septic system

Do not use septic tank additives, commercial septic tank cleanser, yeast, sugar, etc. ◦ These products are not necessary and some may

be harmful to your septic system

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Onsite System Care

Water from roof drains, basement drainage sump pumps, hot tubs, and swimming pools should not enter the septic system

According to Indiana state regulations:◦ Water softener backwash must be treated as

sewage◦ Water wasted from reverse osmosis water

treatment must also be treated as sewage.

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Water Conservation

Treatment and percolation of wastewater depends on presence of 24” of undisturbed, uncompacted, unsaturated soil below the trench

Never allow anything heavier than a riding lawnmower on soil absorption area.Heavy vehicles on the drain field before, during, or

after construction and when the soil is saturated can damage soil’s ability to absorb wastewater

Compaction drives frost deep into the soil and prevents effective treatment in winter

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No soil compaction

Water conservation Effluent filters Lower high water tables with perimeter

drains Use elevated systems (e.g., sand mounds) Shallow trenches Use shallow drip irrigation (requires pre-treat) Connect to existing central sewer system Alternative sewer and cluster systems

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Overcoming Septic Limitations

Mound system Effluent filters Constructed subsurface wetlands Recirculation media filters Aeration treatment units Drip irrigation Cluster systems

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Practical Alternatives for Indiana

Mound System

Benefits Costs

Allows use of septic systems in areas with poor soils, shallow bedrock, or high water tables

Operates in all climates

• More space needed• Limited use on slopes• Requires pump maintenance • Higher installation cost than

conventional absorption fields (~ $10,000)

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Effluent Filter

In Flow

Septic Tank

Out Flow

Sludge

Riser

Effluent Filter

Effluent Filters

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Protects disposal field from solids overflow

Requires routine maintenance Additional cost for installation

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Question: Why is routine maintenance especially important to people with an effluent filter?

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Effluent Filters

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Constructed Subsurface Wetlands

SepticTank

Soil Absorption Field

PumpChamber

ConstructedWetland

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Constructed Subsurface Wetlands

18” Deep

HomeSepticTank

Cleanouts

ConstructedWetland

Level AdjustSump

DisposalField

Constructed Wetland Treatment

Benefits Costs

• Works for both large, continuous flows and for individual residences

Relatively large land area required, 150 sq ft/bedroom

Requires regular maintenance and monitoring

Affected, but only slightly, by seasons

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Media Filter Treatment

SepticTank

Soil Absorption Field

RecirculationTank

(recirculating)

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2” sand around 1/2” plywood box

2 feetsand

From tank

1” of 1/4” gravel

3/4”-1”gravel(5” deep, mound

over pipe)

4” PVC pipe underdrain

3/8” peagravel

(3” deep)

Drain pipe to recirculation

tank or absorption field

1” dia. pressurized pipe 2’ apart with 1/8” holes 2’ o.c.

orifice shield

Manifold

2” of 3/4-1” gravel

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Sand, Gravel, Peat

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Why Use a Media Filter?

Benefits Costs

Limited area needed for the absorption field (about 30 ft2 per bedroom)

Can replace a failed conventional absorption field when there is not enough room for a new one

Can be used with high groundwater, shallow bedrock, poor soils, or other site restrictions

Will keep N out of groundwater

These systems are more expensive, so they are generally used only when necessary and centralized treatment unavailable or too expensive

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Aeration Treatment Units

Benefits Costs

Often used to renovate failing systems in other states

Effective when ATU is placed before a septic tank or an effluent filter is used after ATU to keep solids out of absorption field in case of malfunction (overflow must go to the soil absorption area)

Relatively inexpensive to install

Electricity and alarm required (relatively costly to power aerator)

Professional maintenance required every 3-6 months

Widely fluctuating flows can cause problems.

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Aeration Treatment Units (ATU)

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Frequent application of small quantities of wastewater just below soil surface with applicators along distribution line (less than 1 gal/hr per ft of pipe)

Drip systems have been used in agriculture for 30 years

Drip Irrigation

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Benefits Benefits

Easy to design and install

Wastewater is slowly and uniformly distributed over the entire absorption area

More water moves laterally through capillary action, reducing deep percolation so the wastewater is placed in biologically active soil

Only 12” deep so helps overcome limitations of seasonal high water tables & slow permeability

Water and nutrients can be reused by vegetation

Reduces nitrogen percolation to groundwater

Can be used on very steep slopes (with pressure compensators)

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Drip Irr., Benefits

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98% of soil biological activity is in top 16” of soil.

Drip Irrigation, Costs

Costs Costs

More expensive (pipe with drip emitter is 50-60 cents/ft)

Potential plugging problems. Higher operational cost Maintenance needed 3-4 times/year Septic tank effluent must be treated and filtered

before drip disposal

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Cluster System◦ Collective household sewage treatment and

disposal◦ Collaboration between multiple neighboring

homes◦ Requires a large soil absorption area for

treatment Typically used in areas with poor soil

conditions or where home lots are too small for replacement systems.

The central disposal site must be carefully selected to handle the large flow

Cluster Systems

Cluster Systems

Benefits Costs

Cheaper than large diameter sewers, central treatment and discharge systems

More costly than individual septic systems to install (but cost/family generally much less)

No Indiana cost-share A mechanism must be set up

to manage and collect costs (installation and continuing maintenance)

Rural families and regulators are not familiar with it

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Primary treatment◦ Separates large solids from the waste stream,

using metal grates and a grit tank ◦ The waste stream goes to the primary

sedimentation tank where about half the suspended, organic solids settle out

Secondary treatment ◦ A trickling filter bed, aeration tank, or sewage

lagoon ◦ Biologically degrades dissolved organic

compounds

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Municipal Sewage Treatment

Tertiary treatment ◦ Removes plant nutrients (especially nitrates and

phosphates)

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Municipal Sewage Treatment

Primary treatment Secondary

treatmentTertiary treatment

Primary sedimentation tank

sand gravel Organic solids

trickling filter bed, aeration tank, or sewage lagoon

biological degradation of the dissolved organic compounds

removes plant nutrients, especially nitrates and phosphates