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SEPTIC SYSTEM INSPECT DIAGNOSE REPAIR
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SEPTIC DRAINFIELD FAILURE DIAGNOSIS
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SEPTIC FAILURE SIGNS
SEPTIC INSPECTION & TEST GUIDE
SEPTIC LIFE EXPECTANCY
SEPTIC SUPPLIES & PARTS
SEPTIC SYSTEM DESIGN ALTERNATIVES
SEPTIC SYSTEM DESIGN BASICS
SEPTIC SYSTEMS, HOME BUYERS GUIDE to
SEPTIC SYSTEM SAFETY WARNINGS
SEPTIC TREATMENTS & CHEMICALS
SEWAGE BACKUP PREVENTION
SEWAGE EJECTOR / GRINDER PUMPS
SEWER GAS ODORS
SEWER LINE REPLACEMENT
SINKHOLES, WARNING SIGNS
SOAKAWAY BED FAILURE DIAGNOSIS
SULPHUR & SEWER GAS SMELL SOURCES
TOILETS, INSPECT, INSTALL, REPAIR
TRAPS on PLUMBING FIXTURES
TREATMENTS & CHEMICALS, SEPTIC
VIDEO GUIDES: Septic Videos
WATER CONSERVATION MEASURES
WATER SOFTENERS & CONDITIONERS
WATER SUPPLY & DRAIN PIPING
WATER, WELLS, WATER TANKS: TESTING GUIDE
WASHING MACHINES & SEPTIC SYSTEMS
WASTEWATER TREATMENT BASICS
WINTERIZE A BUILDING
How to abandon a septic tank, cesspool, drywell:
This document outlines basic procedures for finding and safely abandoning unused septic systems and cesspools, and provides some safety suggestions for septic system inspectors, septic system inspections, septic pumping contractors, and home owners.
When a septic tank, drywell, or cesspool is no longer to be used, either because a building is connected to a municipal sewer or because the old tank is being left in place and a new septic installed elsewhere, there are very important safety steps that should be taken.
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Septic tanks, cesspools, and drywells present serious hazards including septic cave-in's or collapses, methane gas explosion hazards, and asphyxiation hazards. Simple precautions which we describe here can help avoid a dangerous septic, cesspool, or drywell hazard.
In addition to having been consulted in fatalities involving humans, we have learned that falling into septic tanks and cesspools is a risk for animals as well. Readers should also see specific warnings about cesspools
Watch out: for unsafe septic tanks and cesspools or drywells and for systems that were not properly abandoned. In 2008 Mark Cramer shared a report from an owner that that their horse fell into a septic tank and died tragically before it could be rescued.
The collapsing septic tank was not in the location which the owners thought it would be found, and clearly it had an unsafe cover. We were consulted in a Long Island death of an adult who fell into and was buried in a collapsing cesspool. And in 2012 we were contacted for comment involving the death of two boys who fell into and perished in an "abandoned" septic tank or cesspool that lacked a safe cover.
It is important to properly abandon un-used septic tanks, cesspools, or drywells. If an old septic tank, cesspool, or drywell is simply "left alone" there may be very serious cave-in or fall-in safety hazards.
Septic tank, drywell, or cesspool abandonment or tank closure may involve complete tank removal, tank crushing (steel septic tanks), or most common with site-built tanks/cesspools/drywells, and with concrete tanks, the cover is opened and the tank is filled-in with rubble and soil. Details of septic tank, cesspool, drywell abandonment procedures are discussed in this article.
Septic Tank Abandonment Choices
When a septic tank is no longer going to be used, various factors determine what will happen to the old tank:
To avoid the risk of a collapsing septic tank, cesspool, or drywell which is no longer used, it is important to find and properly close out such facilities at any property, residential or commercial. In the photo at the top of this page, the truck "found" an abandoned septic tank by driving over it.
Properly abandoning a septic tank, drywell, or cesspool which is no longer in use involves at least the following steps:
Example State Requirements for Septic Tank Abandonment
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Frequently Asked Questions (FAQs)
Question: is it ok to fill a concrete septic tank with sand?
Can you fill a concrete septic tank in with sand? We are preparing to hook up to city sewer and need to know what the best cost-effective way to handle our septic tank will be. - 8/13/2012
Cassandra, the tank gets pumped, cleaned, and filled - sand should be acceptable to your local building department.
Question: can I convert an old septic tank into a pond?
I've got an old septic tank in the garden of the house I'm buying. Is it possible to turn it into a pond? I was wondering if I could line it with butyl liner on a cushion of sand (to be more hygienic) - Victoria 9/25/2012
Is it possible to turn an old septic tank into a pond? I was wondering whether I could line it with butyl liner on a cushion of sand. - Victoria
While the conversion you describe is technically feasible, it seems a bit deep, unsanitary, and cost-unbalanced an idea to me. To reduce the sanitation hazard you'd need to
Question: how do I abandon a septic tank that remains under the slab of an existing building addition
I have a client with a problem I can't fix YET ! She thinks that a remodel to her living room years ago was built on an abandoned septic. We have relocated all plumbing and waste lines in the area to start with . The air still feels bad , the close hanging the closet get mold on them in a short time and she is sick all the time. If there is a septic under the slab what is keeping it from just drying out and if I jack hammer the slab , how do i remove it all and fill in ? HELP - B.B. 11/15/2012
Your question is a reminder of the suggestion that it would have been best to properly abandon a septic tank before ever building over it. I had to deal with this problem at a building whose prior owner built a screened porch atop an old steel septic tank. Luckily the porch had just a wooden floor built on piers, so it was easy to cut an opening in the floor, find the septic tank opening(s), and inspect, pump, clean, and fill the tank. In my case the tank was a steel one that had a rusted-through bottom, had been out of service for decades, and was not particularly smelly. We filled in the tank with stone, rubble, and clean soil just to make sure that it did not collect water (and produce odors) in the future.
In your case, I'd proceed to locate, inspect, and abandon the under-slab septic tank as follows:
That should be sufficient to stop the odor problem and eliminate future hassles with an old septic tank that smells, collects groundwater, collapses, or is in general a possible hazard.
Question: foul odors from basement after connection to sewer
(Nov 18, 2012) ray tom said:
First Ray we need to know where the old septic tank was located: in a basement would be quite unusual.
Next we need to find the source of basement odors: possibly from a plumbing leak, improper venting, or from a prior sewage backup in that area. See SEPTIC SYSTEM ODORS
Question: when abandoning a septic tank what happens to the drainfields or soakbeds or transpiration pits?
(Mar 26, 2014) Anonymous said:
Leave the septic drainfield or soakbed as-is.
Anon, no one should fill a drainfield with concrete. We're talking about 6" perforated pipes buried in gravel trenches or the equivalent; left alone. Only if there were structures in danger of collapse would a fill-in be appropriate. Then one would use rock and soil, not concrete when abandoning such a system.
Question: is it ok to build a structure atop an abandoned septic tank
(May 7, 2014) Anonymous said:
(Aug 1, 2014) Michele said:
Anon, if the septic tank was emptied, cleaned, drilled with rubble, it's properly abandoned in my opinion. Building over it should be ok. I'd not bear a structure directly on an abandoned septic tank as a structural support.
At our old Poughkeepsie office the prior owner had constructed a wood-framed porch over an old steel septic tank. He left a trap door in the porch floor to permit tank pumping but no actual tank inspection nor repair. We had the tank emptied, cleaned, and filled with stone and concrete rubble. There were no subsequent odor problems. But none of the porch structure was borne on the tank itself nor on nearby piping trenches.
One of the most common complaints readers report about abandoned septic systems is subsequent subsidence or collapse - not only safety worries but serious problems for anything built atop the septic tank.
Question: How to abandon a septic tank in Australia
(May 25, 2014) Michelle said:
Take a look at Massachusetts Title 5 Septic Regulations for requirements in general. But the contractual obligation of the contractor is another matter. You'll need to review with your attorney the contract that you signed for work to be performed to understand the scope of work that was required.
Generally to be sanitary and safe an abandoned septic tank should be emptied of sewage and then filled-in.
(Aug 1, 2014) Anonymous said:
Typically an abandoned septic tank or similar component is emptied, then filled-in to avoid collapse risk before constructing over the site. Check also with your local building department to determine whether or not there are local requirements.
(Aug 1, 2014) Michelle said:
Reply: transpiration pits
I'm not sure what you really mean by transpiration pit. IF you actually had a seepage pit rather than a drainfield, it too needs to be emptied and filled-in. If you refer to an excavated hole into which was put a pre-cast drywell or cesspool or soakpit structure to dispose of effluent then such devices also need to be filled-in to avoid a future collapse hazard. - Mod.
(Aug 1, 2014) Michele said:
Reply: difference between a transpiration pit and a soakbed or soakaway bed
OK Michele, but a "pit" as opposed to a network of perforated pipes draining effluent into the soil is what we call a drywell, seepage pit, or cesspool. Those methods of disposing of sewage effluent are effective for a limited time as "disposal" methods but ineffective as a treatment method.
Details are at CESSPOOLS
If we were abandoning a conventional soakbed or soakaway bed or drainfield, not a drywall, not a seepage pit, nor other underground cavity, there is nothing to fill-in.
Question: building an above-ground pool over an abandoned septic tank
(Nov 1, 2014) Jo said:
Pool collapse, injury, unsanitary conditions come to mind, Jo. Along with some extra costs to access and properly abandon and fill-in the septic tank
Question: sinking and cave-ins in the yard may be due to old septic tank?
(June 7, 2014) Sue said:
Sue we hope you roped off the area for safety pending further investigation or fill-in as needed.
Also see SINKHOLE DETECTION, WARNING SIGNS
Question: what is the proper fill to use when abandoning a septic tank
(Dec 8, 2014) ROGER said:
Roger an abandoned septic tank can be filled with stone rubble or sand. You might use dirt (soil) but I'd watch for future setttlement or compaction problems. Don't toss old tree branches, appliances, or junk into a septic tank to be abandoned as the decay of those items is likeliy to lead to a subsequent collapse.
Question: patio sinking over abandoned septic tank
1/1/2015 Cindi said:
First let's be sure the trouble is due to settlement at the old tank location.
If that's the case then I suspect either poor co paction or poor choice of fill contents. Anotherr possibility is a steel tank rusting out and collapsingg into a void beneath the old tank.
Most likely a large part of the cost you cite was the sewer hookup, so not all of that $ was wasted.
Surely no one built a structure bearing on the old septic tank did they?
In any event if a patio, presumably poured concrete, is settling or tipping towards a building foundation wall I'd expect problems with directing roof spillage or rain or melting snow water against the foundation as well as possible foundation damage from the patio weight against the foundation. The fix may require removing the patio and proper grading and fill compaction before re-building.
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