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Main Forums => The Roundtable => Topic started by: Balog on June 16, 2008, 05:35:18 AM

Title: Interesting comparison of septic systems
Post by: Balog on June 16, 2008, 05:35:18 AM
http://www.engineeredseptic.com/Anaerobicvs.Aerobic.htm

Fairly detailed compare and contrast between aerobic and anaerobic septic systems. Anyone know how fair of a comparison this is? Seems to be shilling a bit, but doesn't mean it's not true.
Title: Re: Interesting comparison of septic systems
Post by: wmenorr67 on June 16, 2008, 05:38:27 AM
Almost deserves to be in Politics based on the headline. laugh
Title: Re: Interesting comparison of septic systems
Post by: Manedwolf on June 16, 2008, 05:40:43 AM
1. Dig hole in backyard.
2. Draw pentagram, etc.
3. Open gateway to Hell.
4. Attach drain line.
5. Cap pit.

grin
Title: Re: Interesting comparison of septic systems
Post by: Balog on June 16, 2008, 05:42:12 AM
I just need a way to teleport it all to the abysmal swamp that is DC. I doubt they'd notice the extra.  shocked smiley
Title: Re: Interesting comparison of septic systems
Post by: cassandra and sara's daddy on June 16, 2008, 05:45:59 AM
in my reallity the slightly more expensive amounts to double the cost.   but they do work and have made unperkable lots viable
Title: Re: Interesting comparison of septic systems
Post by: Hawkmoon on June 16, 2008, 02:14:26 PM
I'll try to remember to ask my boss, but I know for a fact that most underground, anaerobic residential systems go for well beyond 50 years. And it has always been my understanding that the effluent from the septic tank is mostly clear liquid. The leaching fields get clogged only if the tank isn't pumped regularly, which results in the sludge building up to a level high enough that the sludge is discharged into the leaching trenches rather than clear liquid.

I think this web site is "not unbiased."
Title: Re: Interesting comparison of septic systems
Post by: Balog on June 16, 2008, 02:20:47 PM
I'll try to remember to ask my boss, but I know for a fact that most underground, anaerobic residential systems go for well beyond 50 years. And it has always been my understanding that the effluent from the septic tank is mostly clear liquid. The leaching fields get clogged only if the tank isn't pumped regularly, which results in the sludge building up to a level high enough that the sludge is discharged into the leaching trenches rather than clear liquid.

I think this web site is "not unbiased."

Oh, I'm sure it's biased. Doesn't mean the info isn't factual. And then there's the whole "pumped regularly" thing. Gets a bit spendy, I'd imagine. And what if you're in a far backwoods situation where the pumper trucks can't get to you? And of course if you're intending to pass the house on to future generations 50 years isn't that long. What's it cost to totally redo it after that average 50 years has gone by?

I don't have a dog in this fight, mind you. I have no septic system or stake in anyone having anything to do with them. I'm just wondering (for future building plans) if this site contains factual information, as far as it goes.
Title: Re: Interesting comparison of septic systems
Post by: Leatherneck on June 16, 2008, 03:04:10 PM
Quote
Gets a bit spendy, I'd imagine.
Not so much. $300 every three years around here, mandated by the county gov.

The problems with septic systems are when you mix questionably maintained septic systems with shallow wells in too dense an environment.

TC
Title: Re: Interesting comparison of septic systems
Post by: Balog on June 16, 2008, 07:12:44 PM
Hmm, not bad at all. Still leaves the accessability/sustainability question up in the air tho.
Title: Re: Interesting comparison of septic systems
Post by: cassandra and sara's daddy on June 16, 2008, 07:17:13 PM
every 5 years here for pumping. 150 if you dig hole  i set a section of well casing last time  never dig hole again.and proper care makes a drainfield last a long time

we joke though about being able to perk a concrete slab with new systems.
any oldtimers ever use dynamite to cheat the old perk tests?
they were sometimes the worst part of permiting
Title: Re: Interesting comparison of septic systems
Post by: The Annoyed Man on June 17, 2008, 04:16:45 AM
The article is broadly technically correct in what it says, but it omits some things and colors others to sway potential buyers of its particular magical engineering services.

Anerobic gravity systems are simple, work well and will last, as long as they are properly installed and maintained. Maintenance means pumping the septic tank of sludge that accumulates and gets processed at the bottom. How often depends upon how much organic matter loading the tank receives. Your mileage may vary depending .... Leach fields vary in size and design dependant upon soil type and flow from the residence. They should never be used as secondary treatment of sludge. If septic tank allow sludge into the field it gets plugged and is ruined in about six month's time. The bio-mat growth at the holes in the field is a natural bacteria elimination process. It is secondary treatment of effluent bacteria but not of sludge which should already have been removed at the tank.

Aerobic treatment is more rapid, does not produce the odors from hell of anerobic systems and is used very successfully in municipal systems. BUT ...   There's a whole lot more going on, with skilled operators controlling and monitoring a multi step, energy intensive, chemistry complicated process. But it has to be that to work, meaning it is not suitable for single family residences. Small scale "package plants" that can do this usually become economically feasible at around 100 residences.

In my past life I used to approve septic system plans and was routinely approached by entrepeneurs with new miracle systems, anerobic and aerobic both. Some rather comical like a propeller down a septic tank to make them aerobic with a few cranks per day, to engineers with glorious blueprinted bullroar. Their prime motive usually is making a buck, so you have to be a little skeptical of new miracles. That does not mean that there are not new and good ideas, but investigate fully, hold on to your wallet, and see what governing officials have to say.     
Title: Re: Interesting comparison of septic systems
Post by: K Frame on June 17, 2008, 05:02:14 AM
My Father was a civil engineer who designed a LOT of septic systems.

I know he had information on home aerobic systems, and he was borough engineer in a town of about 10,000 people that had its own treatment plant, but he never had reason to design an aerobic system.

He was of the opinion that a properly designed and maintained septic system could last 50 years. Several of the systems that he designed in the early 1970s are still in daily use and showing no indication of failing.

Several that he designed have failed, but the cause has always been the same, idiots not maintaining the system, flushing all sorts of junk down it (one person couldn't understand why her bacon grease couldn't go down the drain), the end result being solids flushing into the field and clogging it.
Title: Re: Interesting comparison of septic systems
Post by: Firethorn on June 17, 2008, 05:47:06 AM
Several that he designed have failed, but the cause has always been the same, idiots not maintaining the system, flushing all sorts of junk down it (one person couldn't understand why her bacon grease couldn't go down the drain), the end result being solids flushing into the field and clogging it.

The site seems to imply that the clogging is permanent, but I have to wonder.  Would a field 'recover' over time if the drainfield is moved elsewhere for 25 years or so?  Would a deep equivalent of a rototiller fix the problem?

My grandparents haven't had a problem in over 40 years, and in asking about it they've only had it pumped a couple times, not even close to once every 3 years.
Title: Re: Interesting comparison of septic systems
Post by: Hawkmoon on June 17, 2008, 05:49:00 AM
I just spoke with the state sanitarian who covers our region of the state. He said two things: First, these aerobic systems require mechanical aeration, and they are not allowed for residential use in my state (which I won't identify). Second, the number in the article referring to conventional systems being only 40 to 65% clean is false. As I thought, the effluent from a properly functioning, conventional (anaerobic) septic tank is clear. There are still "nutrients" in the liquid that are then eaten by aerobic bacteria in the leaching field, but the implication that the tank effluent is full of "stuff" that will gum up the leaching field within a relatively few years is incorrect and misleading.

So I guess I can continue to flush after #2.
Title: Re: Interesting comparison of septic systems
Post by: Balog on June 17, 2008, 05:51:31 AM
I've seen the 50 year number a lot in regards to the expected service life of a septic system. I'm curious; what happens after 50 years? Install a new system, convert to a different type of waste management, or....?
Title: Re: Interesting comparison of septic systems
Post by: K Frame on June 17, 2008, 06:27:02 AM
"The site seems to imply that the clogging is permanent, but I have to wonder.  Would a field 'recover' over time if the drainfield is moved elsewhere for 25 years or so?  Would a deep equivalent of a rototiller fix the problem?"

Generally yes, clogging is, for all intents and purposes, permanent.

If sludge gets into the leach field, it clogs the leaching material (sand, soil, etc.) around the pipes.

Pretty much there's nothing that will dissolve or digest that sludge -- it's what's left when the anerobic bacteria have had their fill.

The only way to fix the field in a situation like that is dig out the leach field and replace it with new leach media or relocate the system entirely.


"I've seen the 50 year number a lot in regards to the expected service life of a septic system. I'm curious; what happens after 50 years?"

The field explodes and scatters poop over a 4 county area.

Actually, after 50 years the field may be perfectly fine and may continue to operate for years to come.

The estimate is, IIRC, a best guess based on average household usage, moderate, but not high-level, system maintenance, and the recognition that in most systems some sludge is going to get through occasionally.

You can design a system that will pretty much prevent any sludge from reaching the leach field using multiple settler boxes and/or strainers, but maintenance on those systems is even more critical and they're a lot more expensive.

The absolute best thing that anyone with a septic system can do is have it pumped REGULARLY to remove sludge. How often you need to have it pumped depends a lot on the size of your collector tank and the number of people in your household. Two people in a home with a 1,500 gallon collector tank may only need to have the tank pumped only once every 5 to 10 years.

Other things you can do to increase the life span of your septic system:

1. Limit the amount of water you put into it every day. You can overwhelm your system and flush sludge into the leach field if you push a lot of water through your system in a short amount of time. Do full loads of laundry and dishes, take short showers, recycle the rinse water from your washing machine (not the wash water), for watering plants, etc.

2. Don't use the garbage disposal. Food waste is, for some reason, very tough on septic systems. There are disposals that have enzyme cartridges that supposedly counteract that, but they're generally quite expensive and Dad was never convinced that they worked worth a damn. Compost your vegetable waste.

3. Use soaps, detergents, tissue, and other products that are specifically marked septic system safe.

4. NEVER pour chemicals such as paint thinner, lye, drain cleaners, oil, etc., down the drain. They can bring the bacterial processes to a complete stop, and then you are truly screwed.

5. Never flush cooking oil or grease down the system. It can clog intakes or, if it gets into the leach field, can permanently clog soil pores, causing system failure.

6. Keep a good layer of grass over the leach field. This will help prevent water logging from surface water.



Title: Re: Interesting comparison of septic systems
Post by: roo_ster on June 17, 2008, 08:09:14 AM
So I guess I can continue to flush after #2.

What other options were you considering?
Title: Re: Interesting comparison of septic systems
Post by: Firethorn on June 17, 2008, 08:57:54 AM
Generally yes, clogging is, for all intents and purposes, permanent.

If sludge gets into the leach field, it clogs the leaching material (sand, soil, etc.) around the pipes.

So even a big rototiller wouldn't work?
Title: Re: Interesting comparison of septic systems
Post by: K Frame on June 17, 2008, 09:14:46 AM
The clogging occurs in the soil OUTSIDE the pipes.

The pipes are buried in soil of specific characteristics. It has to pass water at specified rates, known as the Percolation Rate.

A "Perk Test" is how you tell if the soil on a site is suitable for use in a septic system. Essentially it involves digging a hole anywhere between 20 and 30 inches deep with an auger or post hole digger, presoaking it with water, then after a certain amount of time, filling it and timing how long it takes the water to drop a certain amount.

You do this over a period of time, IIRC normally a minimum of 4 hours, and needs to be done over a fairly large area where the leach field is proposed.

The soil on an area can fail for either draining too slowly or too rapidly. Too slowly and the natural pores in the soil are too small or, if in a heavy clay area, are non-existent. Too fast and the soil is too porous.

That's a LONG way of getting to this point...

If sludge or grease gets into the pipes in the leach field, it flows OUT of the pipes and is caught in the pores in the soil, clogging them.

Once those soil pores are blocked, there is nothing that can be done to open them up again.

In that sense, sewage sludge and grease are, in a lot of ways, a lot like clay.
Title: Re: Interesting comparison of septic systems
Post by: Larry Ashcraft on June 17, 2008, 11:17:55 AM
Everything Mike said is spot on.

I've lived with septic systems for over 50 years.  One thing not mentioned was bleach.  Since a cup of bleach will sanitize 1000 gallons of water, it won't do your septic system much good either.

What we do is drain the washing machine into a flower garden (no edibles) or treeline.  That's controversial, since its against county regulations here, but I do it anyway.

Also, no "anti-bacterial" anything goes down the drain, not even soap.  If we're using large amounts of water in the sink, as in washing vegetables for canning, I bail most of the water out of the sink into a 5 gallon bucket and dump it on the lawn or compost pile.

Also, I buy a "bacterial drain cleaner" by the case from a chemical company I do business with.  About every four weeks I put about one ounce in each drain before we leave for work.  The bacteria digests organic matter in the drain, and also removes smells.  I've never had to use a commercial acid drain cleaner.  This stuff is made to remove smells from drains in institutions.
Title: Re: Interesting comparison of septic systems
Post by: cassandra and sara's daddy on June 17, 2008, 01:02:59 PM
we used to do perk tests with the county inspectors  now we hire a private soil scientist who "certifies" our site and plan.and for what itsworth i've not known a crooked one yet. the old perk tests involved a small square hole at a couple spots on lot where you wanted to locate drain field.if we thought it might not perk we droped a quarter stick of dynamite in hole well before inspector showed up. they all perk then angel

systems get more inventive each year  mine is an old school anerobic deal with a twist. i have the standard tank near house fuild the goes to a second tank 10 feet away with a pump. it gets pumped down the ravine in a sleeved pipe under the creek and back up hill to a third distribution tank where it gravity feeds a drainfield pump was good for 22 years. its a do it yourself replacement.

also a decent drainfield plan has a reserve area where you can excavate and add a couple extra trenches. if system starts to overload.  the new ones usethese sections of "half pipe" and work grat less prone to clog. a good septic guy is a gift. one that you won't appreciate for years.  a mediocre job won't always fail right away  may last a few years then haunt you
Title: Re: Interesting comparison of septic systems
Post by: The Annoyed Man on June 17, 2008, 01:07:25 PM
Wow.  You guys go to a lot of trouble, don't you?  We just have our septic tank pumped when it needs it.  It's lasted 15 years so far and will have to be replaced in the next 2 years or so.
Title: Re: Interesting comparison of septic systems
Post by: Iain on June 17, 2008, 01:15:55 PM
1. Limit the amount of water you put into it every day. You can overwhelm your system and flush sludge into the leach field if you push a lot of water through your system in a short amount of time. Do full loads of laundry and dishes, take short showers, recycle the rinse water from your washing machine (not the wash water), for watering plants, etc.

Are there affordable greywater set-ups out there? Larry mentions that draining his washing machine into his garden is against county regulations - those regs the main barrier?
Title: Re: Interesting comparison of septic systems
Post by: Larry Ashcraft on June 17, 2008, 02:02:58 PM
Iain,

Just goes to show how bright our county health dept is.  We're in the driest part of the arid southwest (12 in. precip per year), and our county does NOT allow the use of gray water, treated or not.

Some counties east of Denver will actually help you pay for a gray water system.
Title: Re: Interesting comparison of septic systems
Post by: Leatherneck on June 17, 2008, 02:10:13 PM
Quote
It's lasted 15 years so far and will have to be replaced in the next 2 years or so.
Paddy, why would a septic tank have to be replaced? The ones here in the East are concrete and last...forever, basically.

I've witnessed quite a few pump-outs of my tanks and others (sick prurient interest I guess) and I've never seen a sludge level even close to the outlet in a pumped system. The scum layer has approached 2 feet thick however, in systems that had been ignored too long.

TC
Title: Re: Interesting comparison of septic systems
Post by: cassandra and sara's daddy on June 17, 2008, 02:16:30 PM
there was a church converted into a house in catlett that had a room addition built over septic tank   what a disaster that was.

bootlegged a replacement septic system in the same area some years back. baffled her neighbor and the county pricks that were trying to condemn the old lady's house   was the most fun i ever had with a septic system
Title: Re: Interesting comparison of septic systems
Post by: Leatherneck on June 17, 2008, 02:58:38 PM
Quote
was the most fun i ever had with a septic system
I think that's more than I need to know, thanks.

My impression is that the whole area around Catlett, Cedar Run, and Nokesville lies pretty close to the surface water table, yes?

TC
Title: Re: Interesting comparison of septic systems
Post by: cassandra and sara's daddy on June 17, 2008, 03:10:06 PM
very close so much so that often there is trouble with water leaking into older tanks. says a guy who parged the inside of a septic tank to stop the ground water overload.  the one that was under the room addition


was another in snowhill that thenew construction up hill changed drainage so that water flow was reversed from drain field to tank. should not happen in a correctly done system
Title: Re: Interesting comparison of septic systems
Post by: Boomhauer on June 17, 2008, 03:43:20 PM
For us, it depends on the septic system. We've had a few problems from the large amount of water usuage...we can't easily reroute the tub, sink, dishwasher, and washing machine discharge for greywater...

We've had to have ours pumped out a few times over the past 20 years...and, we've expanded the leaching field for better drainage...since we did that, we haven't had any problems.

I've seen a couple of septic systems that have never needed to be pumped out...it just depends on the system, sometimes...

And, if you have never opened a septic tank up, pray that you never have to. It's a smell from hell.

Title: Re: Interesting comparison of septic systems
Post by: Hawkmoon on June 17, 2008, 07:35:49 PM
For us, it depends on the septic system. We've had a few problems from the large amount of water usuage...we can't easily reroute the tub, sink, dishwasher, and washing machine discharge for greywater...

We've had to have ours pumped out a few times over the past 20 years...and, we've expanded the leaching field for better drainage...since we did that, we haven't had any problems.

I've seen a couple of septic systems that have never needed to be pumped out...it just depends on the system, sometimes...

And, if you have never opened a septic tank up, pray that you never have to. It's a smell from hell.


If your problem is caused by throwing too much water at the system, the solutiuon would be a larger tank, more so than additional leaching area.
Title: Re: Interesting comparison of septic systems
Post by: K Frame on June 17, 2008, 08:23:18 PM
"I've never seen a sludge level even close to the outlet in a pumped system."

You need to hang around with a civil engineer who does septic work.

I saw some really nasty stuff over the years, including a complete failure of a 1,200 gallon tank system that had been badly abused.

The system revolted and backed up into the house. When we got to looking the leach field was so contaminated with sludge and raw sewage that the waste water was running on the surface. The smell on a hot summer day was absolutely horrific.

The grass over the area was an incredible verdant green and it was growing so fast that you could practically hear it stretching.

The tank had over 1,000 gallons of sludge in it, and it was so compacted on the bottom that it had to be shoveled out - the vac truck couldn't pull it up.

Title: Re: Interesting comparison of septic systems
Post by: Leatherneck on June 18, 2008, 12:05:43 AM
I confess to having lived a sheltered life in that regard then.  I also admit to a visceral dislike of blackwater plumbing work.  I didn't mind doing the new installation of 3" and 4" drainpipes from the river house to the septic tank, but once the poop hits it, I'm outta there.

TC
Title: Re: Interesting comparison of septic systems
Post by: The Annoyed Man on June 18, 2008, 05:19:34 AM
Working on septic systems, once operational, is not only nasty but quite humbling. Anybody who thinks their s**t doesn't stink is quickly dissuaded. But it also is potentially dangerous. Beyond the obvious bacteriological potentials, like nasty bacteria getting into wounds, eyes, mouth, respiratory system, the biggest danger is asphyxiation in a confined space.  This is especially true of large commercial sysytems. Methane and other gases displace oxygen and anyone entering quickly succumbs. It is often the case that the second person presumes the first had a heart attack or something and climbs down in to help and also dies. And then the first emergency services rescuer, although confined space training is much better now. I remember 3 or 4 of these instances [nation-wide] during my twenty years in the field.

Best left to the professionals, for whom I acquired a lot of respect. They truly earn their money, IMO.

Septic tanks usually do not need to be replaced unless they are found to be leaking into groundwater. They are supposed to be water tight, nowadays. However the baffles within them do wear out. Baffles divert water flow downward to keep floaters from going straight across from ingress to egress and out into the field. Depending upon design, these may or may not be replaceable. If not the tank has to be replaced.

I do not believe that a field can be remediated by tilling. Typically the field is dug out and replaced by new media. With the price of the work compared to the price of sand, I don't think it's cost effective to try to re-use the old stuff. But I am speculating and have never seen any research on any thing like this.

Mike is right. A well maintained residential gravity system can last forever if they are properly maintained. Typically though, they will go 15 to 20 are not pumped and the field gets ruined.
Title: Re: Interesting comparison of septic systems
Post by: cassandra and sara's daddy on June 18, 2008, 05:40:51 AM
Quote
was the most fun i ever had with a septic system
I think that's more than I need to know, thanks.

My impression is that the whole area around Catlett, Cedar Run, and Nokesville lies pretty close to the surface water table, yes?

TC

i think you woulda liked it too! old lady was nanny/house keeper for the folks who sold out to developer  as part of land deal she got to keep her house till she dies or chose to leave.  the rich folks in the mcmansions didn't like her lil house. one bottomfeeder got the county to come out after real bad rains when ground was soaked and got the pinhead inspector to condemn her drainfield. and pw county wouldn't give he a permit for new one.we rolled in on a saturday and did a real fast new system and sodded the lawn.  she passed the reinspection. she outlived the prick lawyer next door that started the trouble
Title: Re: Interesting comparison of septic systems
Post by: K Frame on June 18, 2008, 06:26:54 AM
Moderator Mal lives out behind Catlett.

I'm going to have to ask him what kind of system his house has. I've seen no evidence of an elevated sand mound when I've been out to his place in the past.
Title: Re: Interesting comparison of septic systems
Post by: K Frame on June 18, 2008, 06:32:04 AM
Firethorn,

My apologies, you said rotoTILLER, and for some reason I read it as rotoROOTER, as in rooting out the pipes.


No, I don't believe a rototiller will do much of anything at all.

At the very basic level, it would require removing the drain pipes from the field anyway. At that point, since you've got it 3/4 disassembled, why not just go ahead an replace the clogged filter material?

That way you have a fully functional (not partially functional) system.
Title: Re: Interesting comparison of septic systems
Post by: Firethorn on June 18, 2008, 08:00:42 AM
At the very basic level, it would require removing the drain pipes from the field anyway. At that point, since you've got it 3/4 disassembled, why not just go ahead an replace the clogged filter material?

Ah, okay.  I had the feeling that you weren't quite understanding how drastic of an action I was proposing...

I was thinking that the clogging might not actually effect that much soil, and a thourough mixing would break up the clods and such, mix in good soil, restoring drainage.

Rather than having to ship in a good deal of dirt or sand, for example.
Title: Re: Interesting comparison of septic systems
Post by: K Frame on June 19, 2008, 09:58:32 AM
It may, but it's still a tremendous amount of work for the knowledge that no matter how well you mix it the system is not going to be operating at peak efficiency, and that means that additional problems are more likely.