Household Wastewater SystemsHousehold Wastewater SystemsMike KizerMike Kizer

OSU Extension Biosystems & Agricultural EngineeringOSU Extension Biosystems & Agricultural Engineering

Typical Waste Water SystemTypical Waste Water System

Well

Renovated Wastewater

Wastewater System RegulationWastewater System Regulation

• Regulatory agency in Oklahoma is: Regulatory agency in Oklahoma is: Department of Environmental Quality (DEQ) Department of Environmental Quality (DEQ) 707 N. Robinson, OKC (Tel: 405-702-6100)707 N. Robinson, OKC (Tel: 405-702-6100)

• DEQ field offices in many countiesDEQ field offices in many counties Check local listing under: Check local listing under: Oklahoma – State of –Oklahoma – State of –

• Regulations are outlined in Title 252 of Regulations are outlined in Title 252 of Oklahoma Administrative Code, Ch. 641Oklahoma Administrative Code, Ch. 641

• DEQ wastewater system website: DEQ wastewater system website: http://www.deq.state.ok.us/ECLSnew/septic.htmhttp://www.deq.state.ok.us/ECLSnew/septic.htm

Minimum Lot Size for Minimum Lot Size for Wastewater Disposal SystemsWastewater Disposal Systems

Disposal System Disposal System TypeType

Water Supply SourceWater Supply Source

Private WellPrivate Well Public SupplyPublic Supply

Aerobic w/ sprinklersAerobic w/ sprinklers ¾ acre¾ acre ½ acre½ acre

ET/Absorption TrenchET/Absorption Trench 1 acre1 acre 1 acre1 acre

Subsurface (fast perc.)Subsurface (fast perc.) ¾ acre¾ acre ½ acre½ acre

Subsurface (slow perc.)Subsurface (slow perc.) 1 acre1 acre 1 acre1 acre

LagoonLagoon 2 ½ acres2 ½ acres 2 ½ acres2 ½ acres

Wastewater System Separation DistancesWastewater System Separation Distances(distance in feet)(distance in feet)

TanksTanks

(septic, pump, (septic, pump, aeration)aeration)

Perforated Perforated Pipe or Pipe or

ChamberChamber

Solid PipeSolid Pipe LagoonLagoon Sprinkler Sprinkler HeadHead

Spray Spray HeadHead

Private WellPrivate Well 50 / 10050 / 100 50 / 10050 / 100 50 / 10050 / 100 50 / 10050 / 100 50 / 10050 / 100 1515

Public WellPublic Well 300300 300300 5050 300300 300300 1515

BuildingsBuildings 55 55 NANA 5050 NANA NANA

Other StructureOther Structure NANA 1010 NANA NANA NANA NANA

Water LineWater Line 55 1515 1010 1515 1515 NANA

Property LineProperty Line 55 55 55 1010 55 55

Stream/LakeStream/Lake 1515 1515 NANA 1515 1515 1515

DrainsDrains 1515 1515 NANA 1515 NANA 1515

Wastewater System ComponentsWastewater System Components• Water-tight sewer linesWater-tight sewer lines• Septic tankSeptic tank• Disposal systemDisposal system

– Subsurface drain fieldSubsurface drain field• Absorption trenchesAbsorption trenches• Infiltration chambersInfiltration chambers

– ET/Absorption trenchesET/Absorption trenches– Aerobic system with sprinklerAerobic system with sprinkler– Total retention lagoonsTotal retention lagoons– Pre-approved alternative disposal systemsPre-approved alternative disposal systems

Household Plumbing Household Plumbing Sewer and Vent SystemSewer and Vent System

•Sewer lines in the house Sewer lines in the house collect waste water for collect waste water for conveyance to the septic conveyance to the septic tanktank

•Roof vents and the traps Roof vents and the traps under sinks, tubs, showers, under sinks, tubs, showers, toilets and wall/floor drains toilets and wall/floor drains prevent sewer gas from prevent sewer gas from entering the house.entering the house.

Screen vent pipe opening to prevent blockage by birds, squirrels, etc.

Main Sewer Pipe

Septic TankSeptic Tank

• All household wastewater systems will have a All household wastewater systems will have a septic tankseptic tank

• Microbial action digests solid wastesMicrobial action digests solid wastes

• Liquids flow through tank to disposal areaLiquids flow through tank to disposal area

• Tank sizeTank size– 1000 gallon liquid capacity (4-BR house or less)1000 gallon liquid capacity (4-BR house or less)– Add 250 gallons per additional bedroomAdd 250 gallons per additional bedroom

House Foundation

Typical Septic Tank InstallationTypical Septic Tank InstallationTwo-Chamber TankTwo-Chamber Tank

Baffles

Wastewater Piping MaterialsWastewater Piping Materials

• Water-tight Sewer Conveyance LinesWater-tight Sewer Conveyance Lines– Cast ironCast iron– PVC (Sch. 40 is preferred weight)PVC (Sch. 40 is preferred weight)– Transite (asbestos-cement)Transite (asbestos-cement)– Orangeburg (paper-tar product: old houses)Orangeburg (paper-tar product: old houses)

• Drain Field LinesDrain Field Lines– Perforated PVCPerforated PVC– Polyethylene infiltration chambersPolyethylene infiltration chambers– Clay tile (old houses)Clay tile (old houses)

Effluent Disposal Area OptionsEffluent Disposal Area Options

• Absorption fieldAbsorption field– Absorption trenchesAbsorption trenches– Infiltration chambersInfiltration chambers– ET/Absorption trenchesET/Absorption trenches

• LagoonsLagoons

• Aerobic systemsAerobic systems

• Authorized alternative systemsAuthorized alternative systems

Subsurface Absorption Field ApprovalSubsurface Absorption Field Approval

• Percolation TestPercolation Test– 3 test holes in drainage area perc at a rate of 3 test holes in drainage area perc at a rate of

60 min/inch of water or faster 60 min/inch of water or faster

• Soil Profile DescriptionSoil Profile Description– 3 test holes without any of the following:3 test holes without any of the following:

• (1) impervious material (bedrock, clay pan)(1) impervious material (bedrock, clay pan)

• (2) water saturated soil (discoloration)(2) water saturated soil (discoloration)

• (3) loamy coarse sand or coarser soil, or (3) loamy coarse sand or coarser soil, or

• (4) sandy clay or finer soil(4) sandy clay or finer soil

The size and type of waste water disposal system The size and type of waste water disposal system is very dependent on the soil at the building site. is very dependent on the soil at the building site. Even before a percolation test or soil profile Even before a percolation test or soil profile evaluation you can get an idea of site suitability evaluation you can get an idea of site suitability from the county soil survey.from the county soil survey.

Cross-Section of Subsurface Absorption TrenchCross-Section of Subsurface Absorption Trench

Perforated Pipe8-ft minimum distance 8-ft minimum distance to center of next to center of next trenchtrench

150’ MAX.

Lateral lines following the slope contour

150’ max. length

Infiltration ChambersInfiltration Chambers• Polyethylene infiltration Polyethylene infiltration chamber has 100% open chamber has 100% open volume vs. 50% for gravel-volume vs. 50% for gravel-filled absorption trenchfilled absorption trench

• Corrugated design gives Corrugated design gives strength to support ground strength to support ground traffic over its 2-ft widthtraffic over its 2-ft width

• Chamber cost per unit Chamber cost per unit length is approximately length is approximately equal to unit cost of equal to unit cost of perforated PVC pipe, plus perforated PVC pipe, plus gravel and installationgravel and installation

ET/Absorption Trench SystemET/Absorption Trench System

• Used when soil percolation rate is too slow Used when soil percolation rate is too slow for ordinary subsurface absorption trenchesfor ordinary subsurface absorption trenches

• Uses evapotranspiration (ET) of grasses plus Uses evapotranspiration (ET) of grasses plus soil absorption to dispose wastewatersoil absorption to dispose wastewater

• Plant a mix of cool and warm season grasses Plant a mix of cool and warm season grasses for year-round ETfor year-round ET

Cross-Section of ET/Absorption TrenchCross-Section of ET/Absorption Trench

Cool-Warm Season Grass Mixture

Perforated Pipe

LagoonsLagoons

• Used when soil percolation rate is too Used when soil percolation rate is too slow for soil absorption systemsslow for soil absorption systems

• Require 2 ½ acre minimum lot sizeRequire 2 ½ acre minimum lot size

• Fencing required around the lagoonFencing required around the lagoon

• Size based on house size, and rainfall and Size based on house size, and rainfall and evaporation of geographic zoneevaporation of geographic zone

• Must retain all wastewater (no overflow)Must retain all wastewater (no overflow)

3

1

Typical Lagoon InstallationTypical Lagoon Installation

5 ft max.

7 ft7 ft

4 ft4 ft

Concrete PadConcrete Pad

1 ft min.1 ft min.

- 2.5 acre minimum lot size required2.5 acre minimum lot size required

- 4-ft high fence required4-ft high fence required

- lagoon size based on house size and local rainfalllagoon size based on house size and local rainfall

Location & Lagoon SizeLocation & Lagoon Size

The required size of The required size of total retention waste total retention waste water lagoons (because water lagoons (because of their annual of their annual hydraulic balance) hydraulic balance) makes them less makes them less desirable the farther desirable the farther east you build in east you build in Oklahoma.Oklahoma.

Aerobic SystemsAerobic Systems

• Used to treat septic tank effluent where Used to treat septic tank effluent where subsurface disposal is not possiblesubsurface disposal is not possible

• Bubbling air through effluent supports Bubbling air through effluent supports aerobic bacteria for further digestionaerobic bacteria for further digestion

• Exposure to oxygen kills most pathogensExposure to oxygen kills most pathogens

• Chlorination allows surface land application Chlorination allows surface land application of wastewater through sprinklersof wastewater through sprinklers

(Septic Tank)(Septic Tank)

Onsite Aerobic Treatment SystemOnsite Aerobic Treatment System

Onsite aerobic treatment systems treat septic tank Onsite aerobic treatment systems treat septic tank effluent further by aerobic digestion, chlorination to effluent further by aerobic digestion, chlorination to kill pathogens, and surface application through a kill pathogens, and surface application through a spray head sprinkler system.spray head sprinkler system.

Typical Aeration Chamber of Aerobic Treatment SystemTypical Aeration Chamber of Aerobic Treatment System

DIFFUSER

EFFLUENT FROM SEPTIC

TANK

WASTEWATER TO CHLORINATOR & SPRINKLERS

Stack-Feed Contact Stack-Feed Contact Tablet ChlorinatorTablet Chlorinator

Chlorine Chlorine Tablet Feed Tablet Feed TubesTubes

Ca(OCl)2 Tablets

Effluent Inlet

Effluent Outlet

Pump Chamber and Pump Chamber and Surface Application SystemSurface Application System

PumpPump

Pump Control & Pump Control & Alarm FloatsAlarm Floats

Access HatchAccess Hatch

Spray HeadsSpray Heads

Finding Waste Water System Components

• Waste water components are normally downhill Waste water components are normally downhill from the house (gravity flow)from the house (gravity flow)

• Septic tank can be no less than 5 feet, and is Septic tank can be no less than 5 feet, and is normally no more than 50 feet from house normally no more than 50 feet from house

• Two-way sanitary sewer clean-outs located:Two-way sanitary sewer clean-outs located:– Within 5 feet of the houseWithin 5 feet of the house– Within 5 feet of every bend greater than 45Within 5 feet of every bend greater than 45ºº– Every 100 feet of straight sewer lineEvery 100 feet of straight sewer line

• Grass over septic tank may be Grass over septic tank may be brownbrown in summer in summer

• Grass over drain field will be Grass over drain field will be greenergreener in summer in summer

Clean-outs on main sewer lineClean-outs on main sewer line

Locating Waste Water System ComponentsLocating Waste Water System Components

Sewer system roof ventsSewer system roof vents

4-inch roof vent on main sewer line

2 2 1/21/2-inch roof vent on branch line-inch roof vent on branch line

Locating Waste Water System ComponentsLocating Waste Water System Components

Largest roof vent on main sewer lineLargest roof vent on main sewer line

Clean-outs on main sewer line exiting houseClean-outs on main sewer line exiting house

Locating Waste Water System ComponentsLocating Waste Water System Components

Regular green stripes in a dry Regular green stripes in a dry lawn are the lateral lineslawn are the lateral lines

Household Water UseHousehold Water Use

• Typical Usage: 50-100 gallons/person-dayTypical Usage: 50-100 gallons/person-day– Clothes washer:Clothes washer: 30-50 gallons/load 30-50 gallons/load– Dishwasher:Dishwasher: 7-15 gallons/load 7-15 gallons/load– Garbage Disposal:Garbage Disposal: 4 - 6 gallons/day 4 - 6 gallons/day– Shower/Bathtub:Shower/Bathtub: 25-60 gallons/use 25-60 gallons/use– Ordinary toilet:Ordinary toilet: 1.6 - 5 gallons/flush 1.6 - 5 gallons/flush– Water softener:Water softener: 50-100 gallons/regeneration50-100 gallons/regeneration

Septic System AdditivesSeptic System Additives

BiologicalBiological• BacteriaBacteria• YeastYeast• EnzymesEnzymes• CombinationCombination

ChemicalChemical• AcidsAcids• BasesBases• Organic SolventsOrganic Solvents• FlocculantsFlocculants

Biological AdditivesBiological Additives

• Will not eliminate need for tank pumpingWill not eliminate need for tank pumping• 20% of sludge is inorganic (indigestible)20% of sludge is inorganic (indigestible)• Billions of bacteria live in septic tanks--Billions of bacteria live in septic tanks--

a few million more have little effect a few million more have little effect• If natural bacteria have been killed, If natural bacteria have been killed,

added bacteria will die alsoadded bacteria will die also• Normal population is restored in 30-60 Normal population is restored in 30-60

hours even if 99.99% has been killedhours even if 99.99% has been killed

Maximum Safe Levels of CleanersMaximum Safe Levels of Cleaners(Single dose in 1000-gallon septic tank)(Single dose in 1000-gallon septic tank)

• Bleach (5.25% Cl): Bleach (5.25% Cl): 1.3 gallons1.3 gallons

• Cleansers/Disinfectants:Cleansers/Disinfectants: 2.5 2.5 gallonsgallons

• Drain Cleaners:Drain Cleaners: 0.65 0.65 ouncesounces

Chemical AdditivesChemical Additives

Strong Acids and BasesStrong Acids and Bases

• Disrupt normal tank biological activityDisrupt normal tank biological activity

• Harm soil structure in drain fieldHarm soil structure in drain field

Organic SolventsOrganic Solvents

• Clean thin layers of sewer line build-upClean thin layers of sewer line build-up

• Contaminate ground waterContaminate ground water

Annual Cost of AdditivesAnnual Cost of AdditivesAmherst, MA Retailers Study - Amherst, MA Retailers Study -

19891989(using manufacturer’s recommended rates)(using manufacturer’s recommended rates)

• Biological (11):Biological (11): $19.75/yr$19.75/yr

• Solvents (3):Solvents (3): $78.00/yr$78.00/yr

• Acid/Base (8):Acid/Base (8): $13.48/yr$13.48/yr

Annualized Pumping CostAnnualized Pumping Cost(USPHS Pumping Frequency Estimate)(USPHS Pumping Frequency Estimate)

$150 Pumping Cost for 1000-gal tank$150 Pumping Cost for 1000-gal tank

Family Size Pumping Freq. Annual Cost

22 20 yrs20 yrs $ 7.50/yr$ 7.50/yr

33 12 yrs12 yrs $12.50/yr$12.50/yr

44 8 yrs8 yrs $18.75/yr$18.75/yr

55 6 yrs6 yrs $25.00/yr$25.00/yr

66 4 yrs4 yrs $37.50/yr$37.50/yr

Septic System AdditivesSeptic System AdditivesConclusionsConclusions

• Biological additives are harmless but of little useBiological additives are harmless but of little use• Chemical additives can damage septic system Chemical additives can damage septic system

and contaminate ground waterand contaminate ground water• Don’t use if active ingredients are unspecifiedDon’t use if active ingredients are unspecified• Annualized cost of additives is about the same as Annualized cost of additives is about the same as

for tank pumping on recommended schedulefor tank pumping on recommended schedule• ““These products make a lot of money for the These products make a lot of money for the

people that sell them.”people that sell them.”

Waste Water System FailuresWaste Water System FailuresCommon CausesCommon Causes

• Hydraulic overloading (too much water)Hydraulic overloading (too much water)

• Solids migration to drain fieldSolids migration to drain field– Failure to pump tank on scheduleFailure to pump tank on schedule– Baffle failureBaffle failure

• Root intrusion into sewer linesRoot intrusion into sewer lines

• Traffic damage to drain fieldTraffic damage to drain field

• Garbage disposal overuseGarbage disposal overuse

Reducing Hydraulic LoadingReducing Hydraulic Loading

• Equipment AdjustmentsEquipment Adjustments– Low flow toilets (1.6 gpf and 0.6 gpf)Low flow toilets (1.6 gpf and 0.6 gpf)– Water-saving showerheadsWater-saving showerheads– Front-loading washing machinesFront-loading washing machines

• Lifestyle AdjustmentsLifestyle Adjustments– Shower vs. bathShower vs. bath– Distribute laundry loads throughout weekDistribute laundry loads throughout week– Distribute bathing morning & eveningDistribute bathing morning & evening– Full loads only for washer & dishwasherFull loads only for washer & dishwasher

Root DamageRoot Damage• Plant no trees or shrubs near sewer linesPlant no trees or shrubs near sewer lines

• Copper sulfate to kill tree/shrub rootsCopper sulfate to kill tree/shrub roots– Treatment is not toxic to plantsTreatment is not toxic to plants– Once intruding roots are killed, absorption endsOnce intruding roots are killed, absorption ends– Add ½ cup of crystals to distribution box or to Add ½ cup of crystals to distribution box or to

cleanout downstream from septic tankcleanout downstream from septic tank– If added through toilet, 2 pounds of crystals are If added through toilet, 2 pounds of crystals are

needed (not harmful to tank bacteria)needed (not harmful to tank bacteria)

• See See OSU CR-6428OSU CR-6428 for more information for more information

Traffic DamageTraffic Damage

• No vehicle parking over drain fieldNo vehicle parking over drain field

• No vehicle traffic except lawn mowersNo vehicle traffic except lawn mowers

• No traffic at all if ground is saturatedNo traffic at all if ground is saturated

Solids & Drain FieldsSolids & Drain Fields

• Solids must be retained in septic tankSolids must be retained in septic tank

• Baffles should be inspected when tank is Baffles should be inspected when tank is inspected or pumpedinspected or pumped

• Use of additives that “liquefy” sludge and Use of additives that “liquefy” sludge and scum can lead drain field failurescum can lead drain field failure

• Septic tanks: like fuses in electrical wiring Septic tanks: like fuses in electrical wiring (failure in controlled location; cheap to fix)(failure in controlled location; cheap to fix)

Garbage DisposalsGarbage Disposals

• Add to hydraulic load (running water)Add to hydraulic load (running water)

• Add to solids (more frequent pumping)Add to solids (more frequent pumping)

• Poorer digestion environment Poorer digestion environment – (Carbon:Nitrogen ratio is more unfavorable)(Carbon:Nitrogen ratio is more unfavorable)

Water Softeners & Septic SystemsWater Softeners & Septic Systems

• Salt does not affect septic tank functioningSalt does not affect septic tank functioning

• Added hydraulic load (regeneration water)Added hydraulic load (regeneration water)– Use water meter or sensor controlled Use water meter or sensor controlled

regeneration rather than time clock aloneregeneration rather than time clock alone

• Added sodium can affect marginal drain Added sodium can affect marginal drain fields (dispersal of clays slows perc rate)fields (dispersal of clays slows perc rate)– Use potassium chloride (KCl) salt if a problemUse potassium chloride (KCl) salt if a problem

On-Site Wastewater System ResourcesOn-Site Wastewater System Resources

MWPS-24MWPS-24 Home*A*Syst Home*A*Syst OK DEQ Ch. 641 OK DEQ Ch. 641Onsite Domestic SewageOnsite Domestic Sewage Worksheet #3Worksheet #3 www.deq.state.ok.us www.deq.state.ok.usDisposal HandbookDisposal Handbook

If you don’t maintain your on-site wastewater system, it If you don’t maintain your on-site wastewater system, it will demand your attention when it is most inconvenient.will demand your attention when it is most inconvenient.