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Understanding Septic Systems: Questions and Answers Understanding Septic Systems Common misconceptions Typical septic system questions Educational resources Common Misconceptions Disposal of wastewater is the primary concern Centralized sewers are better than septic systems Maintenance is not required Out of sight--Out of mind Typical septic system questions Typical septic system questions What is a septic system? Why use a septic system? How does a septic system work? Where are septic systems used and how big are they? How do I know where the septic system is located? Do I need to do anything to my septic system? When is sewer coming? Am I on a septic system? What is that smell? Why are there stripes in my yard? Why can’t I plumb my Downspouts Water softener backwash A/C condensate… into my tank Why can’t I drive/build on my system? Why do I have to pump my tank? How often do I have to pump my tank? Why is that red light blinking? What is a septic system? treatment and disposal of On-site wastewater Composition of Domestic Wastewater Toilet Laundary Bathing Kitchen Garb. Grind. Misc. What is a septic system? 4 common components (Conventional) Source Septic Tank Drainfield Soil beneath the drainfield Types of Septic Systems Conventional or gravity systems Standard design Modifications Pump systems Advanced treatment/dispersal “Conventional” System Components Source Well Tank Drainfield Purification in Soil Groundwater Pump to gravity Source Pump Tank Drainfield Septic Tank Soil with effluent screen Advanced pretreatment Septic Tank Pump with effluent Tank To drainfield screen Why use a septic system? Safely treat and dispose of sewage Protect your family’s health Protect public health in the community Keep the environment clean Help keep housing affordable How does a septic system work? What takes place in the septic tank? Solids separation • Heavy solids sink • Lighter solids float Some pollutant reduction Typical Septic tank LIDS RISERS INLET TEE SCUM OUTLET TEE W/ EFFLUENT CLEAR LAYER SCREEN SLUDGE How does a septic system work? What happens in the drain field and in the soil? Major source of treatment Filtering action NH4 converted to NO3 Adsorption by soil Must be aerobic for maximum treatment Fecal coliform in the soil and drainfield 1’ < 200 cfu 4,000,000 cfu 1,900,000 cfu 1’ < 200 cfu < 200 cfu 600 cfu Fecal coliform in the soil and drainfield 1,900,000 CFU Fecal coliform in the soil and drainfield 1’ < 200 CFU 1’ N Cycle in Septic Systems Immobilization Nitrification and Sorption Denitrification ? Aerobic zone Well Aerobic soil Groundwater Where are septic systems used? Where can a septic system be used? Only in areas were the soil and site is suitable for system installation The soil must be able to accept AND treat the effluent No breakouts Reasonable treatment before reaching groundwater What kinds of soils are best suited for septic systems? or Why doesn’t my land perc? Thick, gently sloping, well drained, deep soils are best It should be neither too sandy or clayey and have “good” structure. Avoid excessively steep or rocky areas, sticky clays, or restrictive layers Soil should be a uniform brown, yellow, or red ... it should not be gray or contain gray spots within 24” of the surface. Wetness Conditions Evaluated using soil colors mottles and matrix Common (2-20%) gray mottles are assumed to indicate the seasonal high water table Trench bottom is set to be 12” (18” in sands) above the seasonal high water table Photo: Too rocky? Photo: Enough soil? Topography Photo: Typical Mountain Soil/Site Landscape position Being at the base of a slope results in more surface and subsurface water on the lot. Head Slope Being located in a head slope results in water flow coming in from 3 sides. How is a site evaluated for a septic system? Have a county environmental health specialist conduct an investigation--Costs vary for this service Contact Cooperative Extension for Investigate Before You Invest Site Evaluation Drainage and topography Well locations Distance to water bodies Property boundaries Other How large is a typical system? Size varies according to Soil conditions House size (occupants or # of bedrooms) There must be enough area for a repair area as well as the present system. Distances to streams, lakes, wells, etc. are also considered. Generally dictated by regulation Where is my system located? How to locate a septic system Check the original permit information Look for plumbing vent on roof Look under the house to determine where sewer lines exit Tank is often 5-10’ away from house near where sewer lines exit How to locate a septic system Look for regular green stripes in the lawn, these are the drain lines How to locate a septic system Use a tile probe or thin rod to locate lines, septic tank, and D-box check for utility lines first! Do I need to do anything to it? What maintenance is needed? What maintenance is needed? Know where all components of your system are located Install a watertight riser over septic tank To facilitate maintenance Water conserving toilets Conserve water--50 gal. per day per person. What maintenance is needed? Only put domestic waste into system Don’t use it as a trash can • Cigarette butts • Kitty litter • Hygiene products Restrict garbage disposal use Restrict dumping grease/cooking oil down drain What maintenance is needed? Pump the tank regularly When should I pump the septic tank? Variesaccording to use and size of tank Rough estimate: every 3 to 5 years How do I know when to pump the septic tank? Pump when solids are 25 to 33 % of the tank volume Checking solids SCUM LAYER CLEAR LAYER SLUDGE LAYER What is that thing in the outlet of the tank? It is clogging up my pipes! Effluent screens Inspect and clean regularly Servicing Effluent Screens Homeowner can perform this themselves or contract out ALWAYS wear gloves If tank is pumped, clean the screen! Effluent Screen Cleaning Wash off directly into the septic tank Should be done at the inlet end of the tank to prevent solids bypass Bypass protection on some models Are there any additives that are necessary? NO! Some may be harmful Research has shown little effect for sludge reduction May not be cost effective Additives How should the drainfield be maintained? Start at the source: Conserve water Check for and fix leaks promptly How do I maintain the drainfield? Maintain vegetation over the drainfield Gutters and downspouts Redirect roof runoff away from system Proper grading Divert surface water away from system No vehicular traffic Keep cars and equipment off the drainfield Do not build in drainfield or repair area A septic tank should not to be used as a foundation. What is that smell? Around the septic tank Check for pipe breakage Unsealed riser lid or inspection port Look in the drainfield for breakouts What is that smell? From roof stack Abnormal development of tank biology If only during still air or temperature inversion • Extend roof stack to above the ridge • Install activated carbon filter on the stack(s) What is that smell? In the house Drift from the roof stack? Dry plumbing trap? Recognizing and Identifying Problems Determining the Cause of the Problem Abuse of system Construction history Age of system Are there similar problems in area or with installer? Maintenance history Causes of problems Obvious vs. Obscure Red flags: Inside of the House Leaky fixtures Slow drains Garbage grinder Red flags: Outside of the House Guttersand down spouts Driveway and patio Landscaping Uneven vegetation Construction Failure due to water flow Driving on the system should be avoided Landscaping and Lot Problems Surface drainage Properly maintained swale Poorly maintained drainage swale Damaged tile drainage Where’s the system? Where’s the water table? Mother Nature’s influence Downed tree Is there a problem? After a 1/4” rain Where’s the system Drainfield and Tank Area Surfacing effluent Wet spots Areas of standing water Growth patterns in vegetation Location Pattern Odor Bull's-eye pattern Striping with problem Seep on slope Wet slope with repair Standing water? Odor from swamp? Or from straight pipe? What to look for Construction Recent additions Out buildings New cable for TV, phone, electric, etc. New water line, gas line, etc. Cut into line Compaction Nearby system by same contractor Cable Lawn mower Maintenance History When was the tank last pumped How often pumped Remember the tank pumper can be your septic system’s best friend The Pumper What about sewer? Sewer plant Sewer vs septic systems Sewers are generally more costly to build and maintain Septic systems are appropriate in rural areas Sewers are appropriate in urban areas Where can I go for more information? County Cooperative Extension County Health Department Educational Resources Educational Resources on Septic Systems Extension publications Programs Demonstration and training sites Extension Publications Septic System Owners Guide Investigate Before You Invest Septic System and Their Maintenance Management of Single Family and Small Community Wastewater Treatment and Disposal Systems Home*A*Syst Choices for Communities: Wastewater Management Options for Rural Areas Extension Programs Video Slide sets PSA Septic system models On-site Wastewater Demonstration and Training Sites Vernon James Research and Extension Center, NCSU, Plymouth Lake Wheeler, NCSU, Raleigh Guilford County CES, Greensboro Brunswick County CES, Bolivia Septic System Information on the Web http://plymouth.ces.state.nc.us/septic/ index.html http://onslow.ces.state.nc.us/staff/ drashash/enved/sepsites.html http://ces.soil.ncsu.edu/soilscience/ programs/index.htm Septic systems can be a permanent solution to wastewater management if homeowners understand and maintain their systems.
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