Water Quality and Septic Systems in Indiana

	Jane Frankenberger, Ph.D.
	Department of Agricultural and Biological Engineering
	Purdue University

Water quality concerns

	81% of Indiana’s streams do not meet water quality standards for recreation
	208 streams and lakes are on the 303(d) list, which means they do not meet water quality standards

Water quality concerns

	One example: In White County, E. coli  has threatened a $40 million/year recreation industry
	Bacteria, including E. coli, are the most common contaminant found in drinking water

Water quality concerns

	Most E. coli are not harmful; they serve as an indicator of harmful pathogens that cause hepatitis, typhoid, gastroenteritis, etc.
	One E.coli  known as 0157:H7 produces a toxin that can cause hemorrhaging and death

Wastewater concerns

	Untreated wastewater is one source of E. coli  in streams
	1/3 of Indiana’s population or about 1,842,000 people (1999 population estimates) not connected to sewer systems

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How much waste?

	110,000,000 gallons wastewater per day
	4,000,000,000,000,000 E.coli per day
	3,520 lb nitrate per day
	Many other potential contaminants

Are septic systems treating the waste adequately?

	Some function well
	Some could function well but are at too high a density
	Some systems have failed
	Some were never installed -- septic tanks discharge to tile or town drain

Outline of presentation

	Water quality concerns when a system is functioning well
	Density issues
	Failure issues
	Septic non-system issues

Potential contaminants from septic systems

	Pathogens: Bacteria, Viruses, Parasites
	Oxygen-demanding substances (BOD, COD)
	Nutrients: Nitrate, Phosphorus
	Organic compounds (solvents, cleaners, gasoline, etc.)

Contaminants in septic systems: Pathogens

	A family of 4 produces enough E.coli each day to contaminate 1 million gallons
	Bacteria can survive weeks or months
		E. coli   3-4 months
		Salmonella 44 days
		Shigella 24 days

Contaminants in septic systems: Pathogens

	Mostly trapped in biomat and soil, but not necessarily inactivated
	Can move tens of feet through soil

Contaminants in septic systems: Pathogens

	Viruses probably move more easily than bacteria
	Recent study: Viruses moved within 11 hours from toilet through septic tank and drainfield and into environment
	Excreted at 1,000,000 per gram
	Typical virus survival: 67 days

Contaminants in septic systems: Pathogens

	Parasites (protozoa) such as Cryptosporidium and Giardia usually filtered by soil in less than 10 feet
	Bacteria still used as indicator, but may be replaced in the future

Fate of contaminants in septic systems: Phosphorus

On-site wastewater treatment

Contaminants in septic systems: Nitrogen

	Most nitrogen in wastewater in the form of organic nitrogen and ammonia (NH3)
	Changed to nitrate (NO3) under aerobic conditions. NO3 moves easily to ground water
	Can denitrify (change to N2 gas) under anaerobic conditions if organic carbon present

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The new ground water standard for nitrate

	Defines ground water management zone as
		Any drinking water well
		Property boundary
		300 feet
	Requires nitrate concentration of 10 mg/l or less at the edge of the ground water management zone

ISDH proposed rule to meet ground water standards

	Soils with restricting layer (fragipan, dense till) generally protect ground water
	In soils without restricting layer, effluent discharged must be below 10 mg/l at the point of discharge.
	(Significantly stricter than ground water standard)

"What spacing is needed to..."

	What spacing is needed to keep nitrate concentration below 10 mg/l, assuming no pre-treatment or denitrification?

Assumptions about the effluent: Volume (V_e) and N_e

	Volume (Ve): At 150 gallons per bedroom, a 3-bedroom house uses 450 gal/day.
	Nitrate Concentration (Ne): 50 mg/l

Assumptions about ground water recharge (V_r and N_r)

	Recharge varies around the state. Estimates of 1 inch, 3 inches, 10 inches, and 14 inches.
	Nitrate concentration of precipitation in Indiana averages 1 mg/l.
	Some nitrate from other sources such as lawn fertilization
	Nr probably around 2 mg/l.

Area needed to keep long-term nitrate concentrations below 10 mg/l

	If recharge is 3 in/year: 10 acres
	If recharge is 10 in/year: 3 acres
	If recharge is 14 in/year: 2.1 acres

This method is conservative

	Assumes that nitrate is diluted only by precipitation falling on the property.
	Ground water is actually flowing.

Comparison to other studies

Outline of presentation

	Water quality concerns when a system is functioning well
	Density issues
	Failure issues
	Septic non-system issues

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Incomplete system

	Older homes built before regulations requiring proper septic system (early 1950’s)
	Some homes in small communities (survey by RCAP)
	Some homes on large lots where soil absorption field could be built but has not

Incomplete system

	Septic tank usually connected to tile drain or town drain
	Functions well for household but disastrous for water quality

How many
“septic non-systems”?

	In Farm*A*Syst assessments in 2000, many had no absorption field
	Some illegal discharges identified through monitoring
	Housing age may give clues

Housing survey can help define septic system needs

	Clinton County had survey done that included “windshield survey” of all housing structures in county
	Median age of housing 1947
	Ages and condition by town

Failed systems

	Seepage backing up into plumbing
	Effluent seeping to or ponding on surface
	Effluent contaminating ground or surface water

Causes of failure

	High water table
	Undersized
	Reached end of design life
	Unsuitable soil

Many soils are not suitable for conventional systems

	High water table
	Slope too great
	Permeability too high
	Impermeable layer too shallow

Soil limitations (NRCS)

	Flooding: Frequent or Occasional
	Depth to bedrock     <40 inches
	Depth to cemented pan or layer<40 in
	Ponding likely
	Depth to high water table <4 ft
	Low permeability (24-60" depth) <0.6 in/hr
	High permeability (24-60"  depth) >6.0 in/hr
	Slope >15%

Severe limitations by county
% of area with “severe limitations” according to NRCS criteria.

Soil suitability - Online maps using “Internet Map Server”

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Information available

	Six counties (Wayne, Owen, Tippecanoe, Marion, LaPorte, Scott)
	Soil Limitations: Slight, Moderate, or Severe
	Roads (identifiable by name)

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What we can do

	Plan for sustainable onsite wastewater management when new houses are built
		Density must be low enough to protect ground water quality
		Permits could be for a limited time
		Maintenance and replacement plans must be developed

What we can do

	Consider community maintenance
		Many people don’t want responsibility
		Easier to pay $20/month for sewer than $5000 every 20 years for septic system
		Wastewater district can be responsible for design, inspection, operation, maintenance

What we can do - failed and incomplete systems

	Some are able to pay and should be encouraged to be responsible
	Low or no-interest loans
	Grants for communities
	“Septic Systems for Humanity”?

What we can do

	Emphasize ground and surface water protection in important areas
		Wellhead protection areas
		Watersheds for recreation areas

Wellhead protection

	All Indiana communities that use ground water are required to develop wellhead protection plan by March 2002
	They will identify potential contaminants and develop management plan

Watershed management

	Water quality projects focusing on various watersheds throughout the state
	Potential allies in protecting water quality

Conclusions

	Pathogens, including bacteria and particularly viruses, have been shown to move into ground water
	Nitrate can easily move to ground water
	Solvents and petroleum products, including some additives, can be a severe contaminant in some cases

Conclusions

	Surface water is contaminated by pathogens from septic systems more often than ground water

For more information

	Jane Frankenberger
	frankenb@purdue.edu
	765-494-1194