Interesting comparison of septic systems

[Balog]

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.

[wmenorr67]

Almost deserves to be in Politics based on the headline.

[Manedwolf]

1. Dig hole in backyard.
2. Draw pentagram, etc.
3. Open gateway to Hell.
4. Attach drain line.
5. Cap pit.

[Balog]

I just need a way to teleport it all to the abysmal swamp that is DC. I doubt they'd notice the extra. 

[cassandra and sara's daddy]

in my reallity the slightly more expensive amounts to double the cost.   but they do work and have made unperkable lots viable

[Hawkmoon]

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."

[Balog]

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.

[Leatherneck]

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

[Balog]

Hmm, not bad at all. Still leaves the accessability/sustainability question up in the air tho.

[cassandra and sara's daddy]

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

[The Annoyed Man]

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.     

[K Frame]

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.

[Firethorn]

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.

[Hawkmoon]

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.

[Balog]

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....?

[K Frame]

"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.

[roo_ster]

So I guess I can continue to flush after #2.

What other options were you considering?

[Firethorn]

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?

[K Frame]

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.

[Larry Ashcraft]

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.

[cassandra and sara's daddy]

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

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

[The Annoyed Man]

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.

[Iain]

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?

[Larry Ashcraft]

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.

[Leatherneck]

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