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Septic System Inspection & Testing

• Baffles, Septic Tank septic tank baffles defects and inspection suggestions
• Books on Septic Systems to Buy Online, our list of recommended books on septic system maintenance, design, and alternative designs available at Amazon.com - Septic System Education Materials
• Buyer's Guide Home Buyer's Guide to Septic Systems Inspection & Testing - What to Do, Step by Step.
• Cesspools Home Buyer's or Owner's Advice
• Cesspool Age Estimates help evaluate cesspool condition and need for repair or replacement
• Cesspool Safety Warnings include dangers of cave-in and fatality
• Clearances & Distances from septic system components to other site features, property boundaries, waterways, etc.
• Design Guide for Septic Systems complete list of detailed "how to" articles
• Don't Pump Before Testing Septic Systems: warnings for home buyers about septic tank pumping
• Drain Noises: may indicate defective or clogged plumbing: how to diagnose and cure drain sounds
• Drainfield Inspection Procedure Septic Leach Fields - how to inspect and diagnose septic drainfield failures
• Drainfield Layout: septic drainfield or leaching bed shape and placement considerations
• Drainfield Layout: septic drainfield or leaching bed shape and placement considerations
• Drainfield Location: how to find the septic drain field or leaching bed
• Drywells Home Buyer's or Owner's Advice
• Dye Amounts, Water Volume: how much septic dye and how much water to use to perform a septic dye test
• Dye Tests: how to perform a Septic Loading and Dye Test - the complete procedure for septic loading & dye testing, a septic function test
• Failure Causes - Septic Systems Basic Septic Inspection Procedures: for septic tanks, septic drainfields, cesspools, drywells, distribution piping
• Failure Causes - Drainfields: how to inspect septic leach fields & what causes septic field failure
• Failure Spots - Where septic system trouble is likely to show up regardless of septic dye testing
• Filter Clogging signs of clogging septic filters at septic tanks or drywells
• Floating up Tanks - Septic tanks or oil tanks float up out of the ground if empty and exposed to rising ground water or flooding
• Inspecting & Testing Septic Systems: Online Septic Book, Inspection, Test, Diagnosis, Repair, & Maintenance: Our Online Septic Book: Septic Testing, Loading & Dye Tests, Septic Tank Pumping, Clearances, details of onsite waste disposal system inspection, testing, repair procedures.
• Inspection & Testing of Septic Systems complete list of detailed "how to" articles
• Inspecting Onsite Waste Disposal Systems Online Septic Class, Explaining Septic System Operation to Clients; Visual Inspection, Testing, Invasive Inspection , Evaluation, Reporting; Future Trends, Legislation
• Life Expectancy of Septic Systems and septic system components
• Maintenance & Repair of Septic Systems complete list of detailed "how to" article
• Media Filter Septic Systemstypes of alternative septic systems using sand, peat, textile, foam cube or other filter media, single pass vs. recirculating media filters, how to identify them.
• Sewer Gas Odors diagnosing, finding, and curing septic tank and sewer line smells
• Sewer Gas - Methane and other septic system gas explosion or asphyxiation hazards such as hydrogen sulfide
• Wet Weather or Cold Weather Septic Odors or Sewage Odor Diagnosis & Repair Guide diagnosing and eliminating cold weather sewer gas odors
• Septic Site Inspection Procedure - Simple OutsideVisual Site Inspection Gives Key Information About Septic System Condition
• Septic Sludge & Scum Levels in Septic Tanks - Measuring the Level of Accumulated Solids, Sludge and Floating Scum in Treatment Tanks
• Septic Tank Depth - how deep will we find or install a septic tank
• Septic Tank Inspection Procedure - How to Inspect Septic Tanks and evaluate the septic tank condition, baffles, sludge levels, damage, evidence of septic failure, etc.
• Septic Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location
• Septic Tank Pumping Articles - list of tank pumping and tank repair articles
• Septic Tank Size: septic tank size and capacity vs. usage determine the required septic tank size, calculate size of an existing septic tank
• Septic Tanks, Concrete defects and inspection suggestions for concrete septic tanks
• Septic Tanks, Fiberglass or Plastic defects and inspection suggestions for fiberglass or plastic septic tanks
• Septic Tanks, Steel defects and inspection suggestions for steel septic tanks
• Septic Tanks, Home Made defects and inspection suggestions for home made or site built septic tanks
• Sewage Contaminants which may be released from sewage spills from residential septic systems and wastewater disposal systems
• Soil Percolation Tests Perc Tests or Deep Hole Test for Soil Absorption Rate Testing
• Spotting Breakouts - Spotting Dyed Septic Effluent Breakout Outside - Where Septic Dye is Likely to Show Up During a Septic Dye
• Toilet Emergencies: how to stop a toilet from overflowing

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Inspecting, Testing, & Maintaining Residential Septic Systems - An Online Septic System Textbook

NOTE: The master copy of the following article is maintained as a separate web document www.inspect-ny.com/septtext.htm

Septic system inspection procedures, defects in onsite waste disposal systems, septic tank problems, septic drainfield problems, checklists of system components and things to ask. Septic system maintenance and pumping schedules. © 2008-1978 Daniel Friedman, All Rights Reserved. Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted. No warranties are expressed or implied. Use of this information in books or pamphlets for sale is reserved to the author. Some technical review by industry experts has been completed-reviewers are listed at "References." New York State Home Inspection License # 16000005303

Introduction to Septic Systems - Inspection, Testing, Maintenance

What is a Septic System

A "septic system," also referred to as a private, on-site waste disposal system, receives waste water and solids from a Building's plumbing facilities (bathrooms, kitchens, shower, laundry), treats, and then disposes of the effluent from this waste, by permitting it to absorb into soils at the property. "Treatment" is accomplished by bacterial action in the "septic" or "treatment" tank and it is mostly accomplished by bacteria in the soil around and below the effluent absorption system, or "drain field." This bacterial action is needed to reduce the level of pathogens in the effluent discharges from the waste system into the soil. The principal components of a private on-site waste disposal system usually include the following:

• piping connecting the Building to the treatment tank
• a septic or treatment tank which retains solid waste
• piping connecting and conducting clarified effluent from the treatment tank to a distribution box
• a distribution box connecting the effluent line from the tank to the absorption system or "drain field"
• an absorption system which permits effluent to drain to soils below
• a bio-mat or bio-mass of pathogen-digesting bacteria which forms in soil below the absorption system.

Many variations on this general scheme are used, depending on local climate, soil conditions, available space, economy, and available materials. Special equipment and systems may be designed for problem or difficult sites such as rocky or wet ground, permafrost, or wet tropical marshlands. Readers who are unfamiliar with what a private septic system is and the types of systems installed should review articles and sketches of septic system components found at The Septic System Information Website

Types of treatment tanks, adsorption systems, pumps, and other special equipment are discussed in some further detail in this text, and are listed in the septic system inspection checklist data. For a more detailed introduction you may want to read our Lockwood article "What is a Septic System" and then return here to continue by using your browser's "BACK" button.

Safety Warnings for Septic System Inspectors

Providing inspection and diagnosis of on-site waste disposal systems is an extremely valuable public service which helps protect people from expensive unanticipated septic system repair costs and helps protect public health by assuring sanitary disposal of sewage and gray water waste from Buildings. More importantly though, such inspections may detect and warn about serious safety hazards at some properties. The strong warnings issued below intend to reduce septic system safety hazards for inspectors and property owners/occupants, but it is not the author's intention to dissuade inspectors from providing this valuable service.

Danger lurks at cesspools, open covers, tanks or tank covers in poor condition, and from high levels of methane gas. These risk collapse, falling, asphyxiation, and other potentially fatal hazards as well as risks of unsanitary conditions.

Septic and Cesspool Inspection Safety:

• Collapse Hazards: Septic system inspectors face personal risks of health and safety including possible fatal system collapse or asphyxiation. Old steel tanks, thin, rusting steel or rotting home-made wood tank covers, site-built tanks and cesspools, and recently-pumped cesspools are at particular risk of collapse. Falling into a septic tank or cesspool is likely to lead to rapid asphyxiation from methane and in cases of collapse, there is risk of becoming buried. The author has consulted in cases involving such fatalities (homeowner fell into a site-built cesspool), and at one site inspection, walking near an overgrown area the author himself stepped through a rusting steel septic tank top, surviving only by throwing himself into a nearby clump of brambles! Beware of
  • flimsy, rusted, old-steel, home-made, or missing septic tank/drywell/cesspool covers
  • abandoned systems which may not have been filled-in
  • collapsed, or collapsing septic tanks or cesspools
  • possible presence of multiple components at a property, abandoned or in-use
• Entering or Looking into Tanks: No person, except those licensed, equipped, and trained, should ever enter a septic tank. Special equipment is needed. Tank inspection (or service) should not be performed alone. Even leaning over to look into a (recently pumped) tank has been reported to cause asphyxiation.
• Unsanitary conditions: Be alert for unsanitary conditions such as surface effluent or sewage backups into Buildings, events which risk serious viral and bacterial hazards and which indoors, may require professional cleaning.
• Issue appropriate warnings: Septic system inspectors (and service personnel) must recognize and respond properly unsafe conditions at a site, including issuing appropriate warnings and in some cases, marking off unsafe areas where, for example, there is visual evidence of a risk of collapse hazard.
• Avoid damaging septic system components or the Building: Improper septic testing procedures, such as flooding a dosing-system, can damage the system. Also, remember to check for leaks into or under the Building being tested when running water into the Building fixtures and drains. Don't leave water running unattended - at risk of flooding the Building.
• Don't do anything dangerous: Inspectors should omit and report the omission of any planned inspection procedure which in the inspector's judgement is unsafe or unsanitary.

Septic Inspector Qualifications/Licensing

If you perform septic inspections you are obligated to do so with proper information, training, procedures, and in some communities a license is required. Some states (e.g. CA, CT, NJ, MA) have specific certification requirements for inspectors of septic systems, as well as specific regulations regarding the performance of the inspection itself. Be sure to obtain information pertinent to your own state, usually from the state health department or state department of environmental protection. For example, Massachusetts septic inspectors will want to look at the links and the Title 5 regulations at our page on the Massachusetts Septic Testing Law. Other links to septic system installation and inspection regulatory agencies are at our "Local, State, U.S. Federal Government, & International Agencies & Resources for Septic Systems Wastewater Treatment" page.

Septic System Warnings to Home Owners and Home Buyers

Septic system concerns for a Building owner start with safety. Here are some red flags:

• Signs of collapse-possible fatal hazards: include depressions or "soil subsidence" anywhere on or around the property. Any suspect area should be roped-off and absolutely no one should walk over or even close to such a spot until it has been investigated by a professional.
• Old or abandoned systems: such as site-built cesspools or drywells were often made with a thin steel or wood cover which with age can collapse. If the history of the site or visual observation suggests that there are or were old systems at the property, professional investigation is warranted. Improper "abandonment" (failing to fill-in a pit) can lead to sudden collapses. Signs that there may be old systems at a property might come from anecdotal evidence (ask a neighbor, ask the local septic installing or service companies), or visual evidence such as seeing abandoned waste pipes at basement or crawl space walls or floors. Don't assume that an old house which is now connected to the public sewer didn't previously have an on-site waste disposal system.
• Septic service by untrained workers: such as aerating, agitating, or pumping out an old site-built cesspool, can lead to sudden system collapse. Prevent access over or near any such systems.
• Unsanitary conditions such as discharge of sewage effluent to the yard surface, to a nearby well or stream, or previous septic backups into a Building deserve professional attention. Indoors special cleaning may be needed to remove bacteria or other pathogens.
• Septic testing by inexpert "inspectors" who may not follow an adequate procedure increases the risk of a costly surprise.
• Uninformed homeowners may not notice a danger or malfunction.Homeowners should review the safety warnings listed above. The information here is general in nature. Since conditions and requirements vary widely at individual sites, the you should obtain qualified expert advice pertaining to the specific system about which you have questions, and should not rely on this general text for costly diagnostic/repair/replacement decisions. In other words, I'll try to give you some helpful information. In exchange, don't expect me to pay for your new septic system.

The next chapter proceeds with inspection of the septic system components.

How Does Each Septic System Component Fail? - What to Look For During a Septic Inspection

This chapter discusses detailed "how to" steps instructing the investigator in how to inspect specific septic components for signs of failure. The following section will discuss types and causes of septic failure and will provide criteria that define "failure."

Before digging up your septic tank or calling a septic pumper, if you think the septic system is failed because of drain blockage or drains backing up into the Building, you should to see "Diagnosing Clogged Drains: Is it a blocked drain or the septic system? - A First Step for Homeowners". If you link to that text, please return here using your browser's "BACK" button.

Inspecting Outside Waste Piping

Outside waste piping conducts sewage (black water and gray water) from the Building to the treatment tank or "septic tank," and from the treatment tank to the distribution box. These lines should be of solid, non-perforated material and need to be protected from mechanical damage (such as by vehicles). Piping extending from the distribution box into drain fields is normally perforated, though solid lines might be used if effluent is being processed by more specialized devices such as seepage pits, galleys, or a sand-bed system.

House to tank

This line may become blocked by waste, damaged by collapse of a section, or invaded by roots. Detection of these conditions is fairly easy by routing a snake or power snake from the Building drain to the septic tank. An experienced power snake operator can often tell by "feel" that a drain line is collapsed, partially collapsed, or invaded by roots. While you may make a temporary "repair" of such a condition by drain-cleaning, if the line is broken or root-invaded, you should expect to have to excavate and replace it soon.

Tank to Distribution Box

The same failures can occur on this line as from house to tank.

Drain field piping

In a conventional "drain field" of perforated pipes buried in gravel-filled trenches, a drain line may be invaded by tree roots. This is why experts advise keeping tree and shrub plantings away from drain fields. Vehicle traffic can also collapse this or any outdoor waste piping, which is why experts advise against ever driving over a drainfield or over any other septic system components.

Inspecting Septic Tank Condition

The purpose of the treatment tank or "septic tank" is to contain solid waste and to permit the beginning of bacterial action to process sewage into a combination of clarified effluent, settled sludge, or floating scum in the tank. An intact, un-damaged septic tank is normally always filled with these materials.

Only by pumping and visual inspection can actual tank capacity and condition be completely determined. Probing in the area of a tank, without excavation, is not recommended as the probe may damage a steel or fiberglass tank.

Steel septic tanks

Concrete septic tanks

Other types of tanks and home-made onsite systems are described below at Septic Tank Type, Capacity, Material Details

Inspecting the Condition of Septic Tank Baffles

Baffles in a septic tank are provided to keep solids and floating scum and grease inside the tank. Baffles are provided at both the inlet to the tank (from the Building) and the outlet from the tank (to the absorption system).

Broken baffles or high sludge levels can cause solids to flow out of the tank and into the absorption system. The result is reduced absorption into surrounding soil and eventual failure of the system. Floating scum thickness and settled solids thickness can be measured through access ports into the tank or cesspool. Finding solids at or covering the outlets or damaged baffles should result in report of a very questionable adsorption system and possible major repair cost.

If baffles are lost or damaged (rusted off on a steel tank or broken off on a concrete tank), they can be repaired or replaced. For example at a steel tank the contractor may simply insert a plastic piping "Tee" into the tank inlet or outlet to create a new baffle system.

However, depending on how long the tank was used without good baffles, the volume of solids and grease that moved from the tank to the absorption system will have begun clogging soils there and will have reduced the future life expectancy of the absorption system.

Baffle damage and repair, or even a complete tank replacement when the absorption system has been left alone always lead the author to warn the Building owner that the future life of the absorption system may be in doubt and that additional expense will be involved.

Inspecting the Level of Accumulated Solids, Sludge and Floating Scum in Treatment Tanks

Solids entering a septic tank are intended to remain there until pumped out during tank service. A large portion of solids settle to the bottom of the tank as sludge. Grease and floating scum remain at the top of the sewage in the tank. Baffles (discussed above) help keep solids, scum, and grease in the tank. Bacterial action in the tank make a modest reduction in the solids volume and begin the processing of sewage pathogens, a step later completed by soil bacteria in the absorption fields.

Net free area: If the sludge level becomes too high or the floating scum layer too thick, in addition to risking passage of solids out of the tank (damaging the absorption system), the remaining "net free area" of liquid in the tank is reduced. When the net free area becomes too small, there is insufficient time for waste entering the tank to settle out as bottom sludge or top floating scum. That is, for an in-use septic tank with a small net free area, the frequent entry of solid and liquid waste will keep the tank debris agitated, thus forcing floating debris into the absorption system where the life of that component will be reduced (due to soil clogging).

The importance of keeping an adequate net free area in a septic tank is the reason that tanks need to be pumped at regular intervals. Building owners who never pump a tank until it is clogged have already damaged the absorption system.

See the Massachusetts Title 5 Septic Inspection procedure discussed below for details about determining the level of floating and settled scum and sludge in the tank.

Inspecting the Septic System Distribution Box

The distribution box (more than one may be in use) connects a single effluent line from the septic tank to a network of absorption system components such as drainfield leach lines or to a network of seepage pits or galleys.

In good system design the outlet openings from the distribution box to each drainfield line can be adjusted to regulate the flow among the various absorption lines. If a distribution box becomes tipped (or clogged) effluent may be routed to only a portion of the absorption system, thus overloading it and leading to a "breakout" of effluent at the surface or to clogging and system backup. An examination of the box interior may show flood lines in the box if the drain field has been clogged or saturated in the past even if at the time of inspection the box is not flooded. If the fields have been flooded you should be pessimistic about the remaining life of the absorption system. If the box is tipped and/or effluent has not been uniformly distributed among the drainfield lines (assuming they are of equal length and in equally good soils), only a simple adjustment of the outflow may be needed. Round plugs with eccentric openings may be present or can be inserted in the D-box outlet openings to regulate flow among the individual absorption lines.

Liquid level in the adsorption system

The absorption system or "drain field" has two jobs. First, it disposes of liquid effluent by permitting it to seep into the soil below. Second, a "bio-mat" of bacteria which forms in the soil below the drainage field processes pathogens in the septic effluent to make the effluent sufficiently sanitary as to avoid contaminating nearby ground water. This distinction between successful "disposal" and successful "treatment" is important to avoid groundwater contamination but has not been addressed by regulation in every municipality. Municipalities which require a minimum distance between the bottom of the drain field trenches (or equivalent component) and the top of the seasonal high ground water table have recognized the importance of a working bio-mat and the need to provide adequate dry soil for it to function.

Even in a well-designed drainage field, eventually the soil surrounding the drainfield device (perforated pipe in gravel trench or other seepage system) becomes clogged with grease and debris. Examining an excavated cross-section of a failed drainfield will often display a black or gray band of sludge and grease of about 1" thickness at the inside perimeter of the gravel trench. When this layer of soil becomes sufficiently clogged the passage of effluent into the soil below is slowed and eventually blocked, leading to the need for replacement. Keeping a tank pumped so as to reduce the passage of debris and grease into a drain field will extend its life.

This is the most expensive problem to correct. Look for septic effluent seepage to ground surface in area of equipment or downhill from such equipment. Look for (illegal) drain field line extensions to nearby streams, storm drains, or adjoining properties where the temptation to "fix" a failing system by sending the effluent to an improper destination overwhelmed a previous owner or repair company. In some areas inspectors use septic loading and dye test. Seepage may be due to overloaded tank, failed absorption system, or blocked/broken piping (may be less costly).

An excavator or septic contractor will often explore one or more drain lines (or similar components) by excavating a portion of it to look for evidence of flooding or soil clogging. We've used a simple probe at the end and along a leach bed to check for flooding of that component. (Be careful not to break or collapse old piping.)

Types, Causes, and Failure Criteria for Septic Systems: Defining "Failed" Onsite Wastewater Treatment or Disposal

This chapter discusses types of septic system failure lists causes of each type of septic component failure, and lists the septic component failure criteria or in other words what conditions are defined as "failure"?. The detailed "how to" steps instructing how to inspect specific septic components for signs of failure are discussed in the text above.

In simplest terms, there are two visible disposal failures:

• Toilets or other fixtures back up into the house - but first see "Diagnosing Clogged Drains and Septic Backups then return here using your browser's "BACK" button.
• Effluent or sewage appears at the surface of the yard, or the neighbor's yard!

Septic odors may also indicate a system failure or an imminent failure. But such odors may also be produced by defects in the plumbing vent system or other site conditions. Beware, sewer gas contains methane and is explosive if it reaches a dangerous concentration inside a Building.

Typical causes range from things that are easy and cheap to repair, to a need for complete system replacement:

• Clogged pipes
• Broken pipes
• Damaged tank
• Tipped distribution box
• Clogged/broken soil absorption piping
• Clogged absorption soils (grease & solids)
• Saturated soil absorption area

However there can also be treatment failures. Effluent may not back up or appear on the surface, but if insufficiently treated effluent reaches a private well or any stream or waterway, the environment is being contaminated -- an unacceptable condition. Historically many people have just worried about disposal. As the quality of drinking water deteriorates in many areas and as population grows in many previously thinly-populated areas, proper treatment has become the real concern for everyone's health.

For example, if there is not sufficient soil between the bottom of the soil absorption system trenches and the local groundwater, the local environment is being contaminated.

Other causes of onsite wastewater disposal system failure:

• Driving over the absorption system, leach field, drainfield
• Paving over the absorption system
• Flooding the absorption system with surface or roof runoff, or rocky, poorly-drained or under-sized sites may simply lack capacity
• Improper original construction , especially on rocky, poorly-drained sites (pipes settle, for example)
• Tipped or flooded distribution boxes, resulting in uneven loading of soil absorption system lines
• Use of septic tank or drain field additives which claim to extend system life can generate so much activity in the tank that solids are held in suspension and forced into the soil absorption system! Do not add any treatments, chemicals, yeast, or other treats to a septic system. In general these treatments don't work, may ruin the system, and are illegal in many localities. There is no magic bullet to repair a bad SAS.
• Rusting steel tank covers can cause death! Rusted covers can collapse. I have reports of children and adults who have died from this hazard, as recently as December 1997. In 2000 I consulted in a fatality involving an adult falling into a cesspool. At a Building inspection I myself stepped through a hidden, rusted-through steel septic tank cover. Falling into a septic tank, drywell, or cesspool is quickly fatal, either from being buried by falling soils and debris, or by asphyxiation. Septic gases are highly toxic and can kill in just minutes of exposure. Even leaning over an empty (just pumped) tank has led to collapse and fatality of a septic pumper.
• Concrete tank lids: can be damaged by vehicle traffic; heavy duty covers are available.
• Steel tank baffles: rust out and fall off, permitting solids to enter the soil absorption system
• Steel tank bottoms rust out permitting effluent to leak into soils around the tank, possibly giving a large void in tank at time of testing, thus subverting a loading or dye test;
• Concrete tanks can crack or sections may separate causing leaks with the same effects as just stated
• Concrete tank baffles: may erode from chemicals, detergents, poor concrete mix, water flowing over top of baffles, or may be broken by improper pumping procedures
• Houses clustered around a lake: often will have a marginal system as properties were crowded together, built as part-time summer-camps, were built without code supervision, and often were built using amateur, marginal home-made systems.
• Age: eventually even a well-maintained SAS will clog and have to be replaced.

Onsite Waste Disposal System Failure Criteria

Massachusetts Title 5 lists specific failure criteria and serves as a good model for septic inspections anywhere.

• Backup anywhere in the system
• Discharge of effluent to the surface, stream, etc. regardless of whether or not septic dye is observed
• Static effluent level above outlet in the D-box
• System has to be pumped more than 4x/year
• Metal septic tanks (municipality dependent; note that in special site conditions small metal tanks may be the "only" solution and may be approved by local officials. An owner/buyer must be informed of the implications of such installations.)
• Soil Absorption System (or cesspool, etc) is at a depth exposing it to the maximum groundwater level

Cesspool failures (MA)

• less than 6inches of freeboard
• less than 1/2 day's storage
• within100 ft. of a pond or dug well (surface water supply)
• within50 ft. of a private well (modern sanitary well)
• between50 and 100 ft from a private well if well fails bacteria test
• inMA, within Zone 1 of a public well
• BOHevaluation is required if within 50ft of any surface water

Soil Absorption System Failures (leach fields, drain fields, seepage pits)

• Breakout of effluent observed (& I consider odors as well)
• BOH evaluation in MA if within 100 ft of surface water supply
• within Zone 1 of a public well
• within 50ft of a private well
• between 50ft and 100ft of a private well if well fails bacteria test.

Levels of Septic System Inspection and Testing

LEVEL-0 Septic Inspections - Basic Visual, Loading & Dye Test

This level of inspection is typically provided during a "home inspection" for real estate transactions.

1. VISUAL ONLY: Basic visual inspection and reporting of information (Performed by home inspector or other expert) (Some municipalities require this test be performed only by specifically licensed septic contractors or engineers.)
2. VISUAL PLUS LOADING DYE TEST - Visual + Dye test and system loading. Warning: using an inadequate amount of tracer dye or an insufficient volume of water for this test will make it meaningless. Therefore ordering a "stand-alone" septic loading and dye test of a system should be expected to cost considerably more than such a test which can be performed overlapped in time with other Building inspection services. Beware of quick, minimal tests which place only a small volume of liquid into the system (perhaps 50 gallons over 10 or 15 minutes).

   The minimum quantities of water and septic dye needed are discussed in a separate chapter at Septic Loading and Dye Test Procedure Details - a chapter of this text "Inspecting, Testing, & Maintaining Residential Septic Systems".

   ADDITIONAL LEVELS OF INSPECTION for real estate transactions and for problem diagnosis and bidding prior to actual repair work.

3. LEVEL 1 = Level 0 + Open accessible covers & inspect equipment. May include loading and dye test, often does not. May include requiring tank pump out and inspection. (Performed by home inspector or other expert) (Some municipalities require this test be performed only by specifically licensed septic contractors or engineers.) This is the Pennsylvania PSMA definition for level-1. More detail is at Level 1.
4. LEVEL 2 = Level 1 + Locate, excavate if needed, open, inspect tank and distribution boxes, pump and inspect tank, baffles, distribution boxes; determine system capacity, scum thickness, baffle condition, etc. (Performed by septic pumping contractor or other expert.) (Some municipalities require this test be performed only by specifically licensed septic contractors or engineers.) More detail is at Level 2.
5. LEVEL 3 = Level 2 + additional site excavation, test openings in leaching area, other test holes, soil percolation testing, other engineering work. (Performed by septic pumping contractor, engineer, or other expert.) (Some municipalities require this test be performed only by specifically licensed septic contractors or engineers.) More detail is at Level 3.

Absorption System Design & Maintenance Soil Perc Tests & Septic Drain Field Design & Maintenance

Soil Percolation Requirements and Soil Depth Requirements for Septic Absorption Systems / Septic System Drainfields

What is a septic system soil percolation test?

In specifying the size and type of absorption field (leach field, seepage pits, galleys, other) a septic engineer or health department official will require that a soil percolation test or "perc" test be performed. You may hear it described as a "deep hole test." The first time I participated in this procedure I found myself smiling with surprise at how low-tech the procedure actually was (in New York State.) After identifying the most-likely location on the lot for placement of a septic drainfield, the excavator used a backhoe to dig a rough hole about 5 ft. deep. Happily no groundwater immediately filled in the hole (which would have been bad news). Perhaps this is why builders try to have this test done in July which is the period of most-dry weather and lowest groundwater table levels. After digging this rough hole, the septic engineer poured a 5-gallon (joint compound) bucket of water into the hole. In some cases a few buckets might be dumped therein. After that sophisticated move, the observers simply watched the rate at which the water disappeared. a one-inch drop in water level in this hole in three minutes was considered very good. If the water was found still in the hole at no drop in level the next morning, this was considered seriously bad and probably requiring some soil exchange or other special design measures.

What are the soil perc and other soil requirements for septic systems?

I like the Massachusetts Title 5 Septic Inspection criteria for defining a (at least possibly) functional drainfield, as the text explains the role of the biomass below the absorption bed, sets soil depth requirements, and recognizes the importance of keeping the bottom of the working biomass area in well drained soil sufficiently above the seasonal high water table.

Here is an example of soil requirements for a functional drainfield. This version is particularly clearly written and is for residents of Ohio but the principles apply anywhere. "In Ohio, soil absorption systems can be used in areas where the percolation rate of the soil is between 3 and 60 minutes per inch (soil permeability between 1 and 20 inches per hour). At least 4 feet of suitable soil is required under the soil absorption system to provide adequate treatment of the septic tank effluent. To accommodate the construction of the system and provide adequate soil cover to grade, a minimum of 5 1/2 to 6 1/2 feet of suitable soil is needed above the limiting layer. A limiting layer may be bedrock, an impervious soil layer (hardpan, fragipan) or a seasonally high water table (gray soil or mottles). The soil absorption system must be at least 8 feet from any drain line on the lot, 50 feet from a water supply, and 10 feet from the property line, right-of-ways and the house. Septic systems cannot be placed on the flood plain and are limited to areas with less than a 15 percent slope." http://ohioline.osu.edu/aex-fact/0743.html Ohio State University Fact Sheet "Septic Tank - Soil Absorption Systems"

How large does the absorption field need to be?

The size of the absorption field needed (in square feet of area, presumably also unencumbered by trees, driveways, Buildings, etc.) can range considerably depending on the soil percolation rate. A lot with a good percolation rate or "perc" of perhaps one inch of percolation in three minutes might require about 4500 square feet for a typical three bedroom home. If the same home were built where there was a poor a soil percolation rate of an hour per inch, 9000 square feet or more might be required for the absorption area.

Drainfield size and location also have to take into account local zoning - setback requirements from property borders, setbacks from streams, wetlands, wells, water supply lines, and other encumbrances.

Drainfield trench/line specifications

In the most common design of drainfield, perforated pipes are buried in gravel-filled trenches to form the drainfield. Pipes are placed across the slope line of sloped property (so that all of the effluent doesn't simply rush down to and leak out at the end of the drain line pipe). While some experts describe the bottom of these trenches as "level" in practice they are dug to slope slightly, perhaps 1/8" per foot or less. A typical trench is 18 to 30 inches in depth, and 8 to 12 inches wide. The trenches are dug about 6 feet apart which allows, in good design, space for a set of replacement trenches to be placed between the original ones when the first set fails. The maximum length of a trench is typically about 150 feet but I've found installations that were three times that length.

Where lot space does not permit drainfield trenches such as I've just described, a septic engineer may specify that seepage pits or galleys are to be installed. These fit in a smaller space since a single pit may be 6' to 8' in diameter. But the depth to which effluent is being delivered (4' or more) means that the sewage effluent is unlikely to be fully treated by a biomass. These systems may successfully "dispose" of effluent but they are probably not adequately "treating" it.

What destroys or shortens the life of drainfields?

It's easy to ruin or shorten the life of a drainfield:

• install a drainfield in wet weather (which compacts the soil)
• drive over the drainfield or build a parking lot over it (compacts soil, breaks pipes)
• plant trees on the septic absorption field (roots enter pipes)
• put a swimming pool in the middle of a drainfield - yes I've seen people do this!
• forget to pump out the septic tank regularly (solids/grease are discharged into the fields, clogging the soil)
• direct roof runoff or surface runoff across the drainfield or into the septic tank (flooding the system)
• install the drainfield in an area of high seasonal water tables (flooding the system)
• use the septic system to dispose of illegal oils, chemicals, fats, greases - one system in New York near the Taconic State Parkway was connected to house in which was operated an illegal drug manufacturing operation. So much contaminant was flushed down house drains that the workers contaminated their own well and poisoned themselves

Septic System, On-site Waste Disposal Inspection, Maintenance, Testing, Repair, Design: References

1. "EPA Design Manual: Onsite Wastewater Treatment and Disposal Systems," R. Otis et al, EPA 625/1-80-012. GPO Bookstore, 26 Federal Plaza, Room 110, New York NY 10278 212-264-3825.
2. "Septic Systems," T. & A. Ferrero, Tri State ASHI Seminar, November 6-7 1993, and attachments listed below.
3. "Septic Tank Pumping," Paul D. Robillard, Kelli S. Martin, Penn State College of Agriculture, Cooperative Extension, Agricultural Engineering Fact Sheet SW-161, Agricultural Engineering Department, 246 Agricultural Engineering Building, University Park PA 16802 814-865-7685 814-863-1031 FAX.
4. "Preventing Septic System Failures," Paul D. Robillard, Kelli S. Martin, PennState College of Agriculture, Cooperative Extension, Agricultural Engineering Fact Sheet SW-162.
5. "Mound Systems for Wastewater Treatment," Paul D. Robillard, Kelli S. Martin, Penn State College of Agriculture, Cooperative Extension, Agricultural Engineering Fact Sheet SW-164
6. "Septic Tank Soil Absorption Systems," Paul D. Robillard, Kelli S. Martin, Penn State College of Agriculture, Cooperative Extension, Agricultural Engineering Fact Sheet SW-165
7. "The Soil Media and Percolation Test," Paul D. Robillard, Kelli S. Martin, Penn State College of Agriculture, Cooperative Extension, Agricultural Engineering Fact Sheet SW-163
8. "Level 1 Septic System Inspections During Real Estate Transactions," Paul D. Robillard, Kelli S. Martin, Penn State College of Agriculture, Cooperative Extension, Agricultural Engineering Fact Sheet SW-166
9. "Take Care of Your Septic Tank," Washington State Septic Tank Pumpers Association, (WSSTPA) (Les Eldredge, President, 206-334-8263); Courtesy of Bob Kelwitz, 10/93. Items 3-9 provided courtesy of Jules Falcone.
10. "Cottage Country, Environmental Manual for Cottages," 6th Ed., 1989, ISBN 0-7729-5085-7, Environment Ontario, 135 Clari Ave. West, Suite 100, Toronto Ontario M4V 1P5
11. Septic Tank Maintenance," Circular 1343/January 1990, and "Why Do Septic Systems Fail?," K. Manci & J.A. Moore, Extension Circular 1340/January 1990, Oregon State University Extension Service, and "Know your Septic System," a homebuyer's guide to on-site septic systems, Washington Association of Realtors, Govt. Affairs Dept, PO Box 719, Olympia WA 98507 206-943-3100, provided by Len Sherr, Bend OR
12. One and Two Family Dwelling Code, Section P-2506, Septic Tank Design and Construction.
13. "The Septic Tank Home Wastewater Treatment and Disposal System," Southern Rockingham Regional Planning District Commission, 19 Main St., Salem NH 03079 603-893-5766
14. "Septic Tank News & Views," Stanley Carraway, Florida ASHI Seminar, October 9-10, 1993 available from FLASHI Chapter, includes some USDA tables and charts on design, loading, and references the New (1992) Chapter 10D-6, Florida Administrative Code, Standards for Onsite Sewage Disposal Systems.
15. Pennsylvania Septic Management Association, RD 3 Box 3231, Moscow, PA 18444
16. HUD Handbook 4910.1 (Well Clearances)
17. "Private Sewage Disposal, Some Suggestions," RES-I-TEC, 145D Grassy Plains St., Bethel CT 06801 1989
18. "A Homeowner's Manual for Septic Systems," Robert Berg, Wastewater Facilities Management Element Bureau of Construction and Connection Permits, State of New Jersey Department of Environmental Protection, Division of Water Resources, January 1990, 609-984-4429, courtesy of Lewis Home Inspections
19. "What Remodelers Should Know About Septic Systems,", Russ Lanoie, Journal of Light Construction [New England Builder], July, 1988, p. 31-36, RR#2, PO Box 146, Richmond VT 05477
20. "Water Conservation and Wastewater Disposal," R. Siegrist et al., 1978, ASAE Pub. 5-77:121-136
21. "Soil Infiltration Capacities as affected by septic tank effluent application strategies. In: Proceedings of the 3rd national Symposium on Individual and Small Community Sewage Treatment." ASAE Pub. 1-82 pp. 72-74. ASAE PO Box 410, St.Joseph MI 49085
22. "Aerobic on-site systems studied in New Mexico," Asbury R. and Hendrickson C., 1982, Journal of Environmental Health, 45:86-87
23. "Soil Clogging: Mechanisms and Control," R. Otis, Proceedings of the 4th National Symposium on Individual and Small Community Sewage Treatment, ASAE Pub. 07-85 pp. 238-250, ASAE, 2590 Niles Rd., St. Joseph MI 49085-9659
24. "Residential Graywater Management in California," A. Ingham, 1980. California State Water Resources Control Board, PO Box 100, Sacramento CA 95081
25. "On-site disposal of small wastewater flows," R. Otis, 1977, Department of Civil and Environmental Engineering, University of Wisconsin, Madison.
26. NAHB Library, several resources listed, contact NAHB, 15th and M Streets NW, Washington, DC 20003 202-822-0203. "Pumped septics - improved waste-water systems distribute effluent from septic tanks over a wide area, preventing contamination of drinking water," Noele Stuart, Popular Science, My 1989, p. 84; "Septic tank effluent pump systems: an alternative to conventional sewers and grinder pump systems," Small Flows, October 1991, p 4. Courtesy of Heather Groves, NAHB Library and Information Center. 800-368-5242 Ext 204 (CD ROM search service, fees involved, for GTHBA members and NHBA members)
27. "Septic Tank/Water Softener, potential effects of water softener use on septic tank soil absorption on-site wastewater systems; the effect of home water softener waste regeneration brines on individual aerobic wastewater treatment plants," Water Quality Research Council, Water Quality Association, 477 E. Butterfield Road, Lombard IL 60148
28. "Design Handbook, Grinder Pumps, Low Pressure Sewer Systems," Environment One Corporation, 2773 Balltown Road PO Box 773, Schenectady NY 12301 518-346-6161 (Richard C. Grace, Sales Mgr.)
29. "What you should know before buying a home served by a septic system," State of Connecticut, Department of Health Services, 150 Washington St., Hartford CT 06106, via Allspect, Westhaven CT and Butterly's Building Inspection Service, CT.
30. "Soil infiltration capacities as affected by septic tank effluent application strategies," D.L. Hagett, et al, 1982, In: Proceedings of the 3rd National Symposium on Individual and Small Community Sewage Treatment." ASAE Pub. 1-82, pp. 72-84. ASAE, PO Box 410, St Joseph MI 49085, current address: ASAE, 2950 Niles Rd., St Joseph MI 49805-9659, courtesy of Bob Stead, ASHI.
31. "Aerobic on-site systems studied in New Mexico," R. Asbury and C. Hendrickson, Journal of Environmental Health 45: 86-87,
32. "Soil clogging: mechanisms and control," R. Otis, 1985, in National Symposium on Individual and Small Community Sewage Treatment." ASAE Pub. 1-82, pp. 238-250.
33. "Residential Greywater Management in California," California State Water Resources Control Board, PO Box 100, Sacramento CA 95801
34. "EPA Design Manual: Onsite Wastewater Treatment and Disposal Systems," R. Otis, et al., No. EPA-625/1-80-012 (or later edition if avail.)
35. "On-site disposal of small wastewater flows," R. Otis, Dept. of Civil and Environmental Engineering, University of Wisconsin, Madison WI

36. Private communication and "Private Sewage Disposal System," septic
        checklist developed for ITA, Inspection Training Associates, Kevin
        O'Malley, 1016 S. Tremont Street, Oceanside CA  92054, 800/323-9235
       Private communication, K. Oberg to DJ Friedman,  12/15/93, 12/16/93, 7/22/94
       Private communication, J. Appleby to DJ Friedman, 9/16/93, Venice FL
       Private communication, D. Barnett to DJ Friedman, 9/15/93, Evansville IN
       Private communication, N. Becker to DJ Friedman, 9/15/93
       Private communication, E. Fitzgerald to DJ Friedman, 9/94, Adoption of New
    Jersey environmental protection law addressing septic system operation and
    maintenance, Subchapter 12, documented in New Jersey Register, 8/21/89, Cite 21
    NJR 2635. Requires annual inspection beginning in 4th year after construction,
    describes acceptability criteria, inspection steps, conditions of failure.
       Private communication, T. Moore to DJ Friedman, 1/15/94, "Private  Septic 
          System Evaluation," Goshen NY, 914-294-3398
       Private communication, S. Vermilye to DJ Friedman, 1/15/94, and 
          sample checklist, 914-255-8888.
       Private communication, D. Surette to DJ Friedman, 5/6/94
       Private communication, R. Klewitz to DJ Friedman, 10/1/93
       Private communication, L. Scherr to DJ Friedman, 10/1/93, 
          Cascade Home Inspection, Bend OR
       Private communication, G. Reid to DJ Friedman, 12/6/93
       Private communication, G. Carroll to DJ Friedman, 11/29/93, 
          Action Inspection Service, Cincinnati, OH
       Private communication, R. Johnson to DJ Friedman, 11/5/93, 
          The Home Specialist, Inc., Roswell GA
       Private communication, E. Rawlins to DJ Friedman, 10/7/93, Boca Raton FL,
    and "You and Your Septic Tank, a guide to the proper operation and maintenance
    of a septic tank system," Department of Natural Resource Protection, 500 E.
    Broward Blvd, Suite 104, Fort Lauderdale FL 33394 305-765-5181, 
       Broward County, FL, January 1993
       Private communication, R. and B. Williams to DJ Friedman, 
          11/20/93, Williams Home Inspection Co, Hollis NH
       Private communication, A. Carson and R. Dunlop to DJ Friedman, 2/6/92,  11/10/93
       Private communication, L. Cerro to DJ Friedman, 8/22/93
       Private communication, R. Passaro to DJ Friedman, 9/15/93, 10/15/93,
    Res-I-Tec Corp., Bethel CT; also see Passaro's "Private Sewage Disposal, Some
    Suggestions," NY Metro ASHI Seminar, October 1993 (cc on hand)
       Private communication, J. Falcone to DJ Friedman, 10/15/93
       Private communication, C. Greenberg to DJ Friedman, 9/9/93
       Private communication, V. Faggella to DJ Friedman, 9/14/93, 9/24/93, Yorktown Heights, NY
       Private communication, R. Stead to DJ Friedman, 9/20/93, Charlton MA
       Private communication, T. Lewis to DJ Friedman, 9/20/93, 
          Lewis Home Inspection, Lawrenceville NJ
       Private communication, G. Guarino to T. Lewis, 12/12/91, Septic system
    failure and inspection limitations, Township of Hopewell, Department of Health,
    201 Washington Crossing, Pennington Rd., Titusville NJ  08560
       Private communication, C. Eldredge to J. Falcone,  3/27/91, Septic
    Certification and Testing Information from the Pennsylvania Septage Management
    Association, Curt Eldredge, General Manager, Wastewater Management, Inc., West
    Chester PA  19380  215-436-4045.
    

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• For general septic repair advice, contact your local health department, or experienced septic engineer or contractor in your area.
• Besides Septic Tanks, other types of tanks such as buried and aboveground oil storage tanks present similar environmental and hazard issues.

More Information About Septic Systems - Onsite Waste Disposal Design, Maintenance, Repair

• The Septic System Information Website home page for this topic
• Septic Systems Inspection, Testing, & Maintenance- online textbook. Detailed how to inspect, maintain, repair information
• Septic System Inspection Methods and Procedures, - online illustrated class for Building and septic inspectors
• Septic Tank Pumping Guide: When, Why, How to pump the septic tank

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