how septic systems work?

Im trying to figure out how septic systems work. I moved to PA recently and everybody here has septics, including me. If anyone could help clear my mind, that would be great.
I have a big tank for the liquids, and another smaller tank next to it for the solids...and then like 30 feet away from those tanks is a big sand mound with plastic vent thingees sticking out. I also have a septic pump.
#1, i dont understand how the tanks can distinguish between the solids and the liquids. like how does it know which tank to go into?
#2 , the big sand mound with vents... I dont quite understand the purpose of this. Does any water or other sewage get pumped up towards the sand mound? Or is it just used to vent the system?
any info would be great.
thanks mike
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http://people.howstuffworks.com/sewer2.htm

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mike wrote:

Google is your friend...
http://ohioline.osu.edu/aex-fact/0744.html
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As the sewage pipe leaves the house, it first goes to the solids tank, where the heavy bits sink to the bottom, and the light bits float. There's a pipe from the solids tank that has a baffle that "skims" the surface to keep the light bits in the solids tank. Then, the liquid overflow from the solids tank goes into the liquid tank, where the liquids are kept for a while. In both tanks bacteria are busy trying to break the stuff down.
After going through both tanks and being acted upon by bacteria, the water is routed through a series of perforated pipes in a sand bed ("leach field") where it's distributed into the ground. By the time the water makes it to the leach field it's pretty clean.
Most septic tanks, at least around here, are one big tank with a series of baffles in the middle so the "upstream" half is the solids, and the downstream half is the liquids.
Two tanks with solids separation are required to prevent solids from going out into the leach field and plugging the perforations.
These systems are usually a simple gravity feed (meaning the sewage plumbing in the house is higher than the tank, and the outflow of the tank is higher than the bed).
In your case, obviously some or all of your drain plumbing in the house is _below_ the tank, hence you need the septic pump.
Needing venting on the bed is a little unusual, so it might not be exactly as described above. Might be something needed to ensure that your septic pump doesn't overpressure the bed lines and pop them apart.
Septic tanks need periodic cleanout if they're used more than occasionally. Mostly to remove the solid buildup, and as such, you can often skip cleanout of the liquid tank. If you know when it was last cleaned out, remember to get it done again in 3 years later, and ask them to tell you whether it needs to be done more or less often.
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
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Whoa! Not so fast... In our area, pumps are now required on all new installations. More on that, below.

All of our new systems have such vents, as well. Hardly unusual.

Really? I had one pumped last year that hadn't been pumped for about 15-20 years. It was about half filled with solids and in perfect working order. Mostly, it depends on the composition of the soil, who is using the system, and what they allow to go into it.
Re: Pumps I was told by an experienced installer that the new "pumped" systems (mandated by local government) are guaranteed to fail, as they will ultimately pump solids into the drain field. I guess that's why they also require a designated "back-up" drainfield area to be established, where nothing can be built. Pity the poor sucker who has a smallish lot.
This subject stinks,
Unc
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snipped-for-privacy@msn.com says...

In a traditional septic system, the leach field is lower than the septic tank, meaning the leach pipes are buried well below grade. Great if the soils work well for that.
But in areas with high water tables or soils that don't percolate well, the leach field can be a built-up sand bed *above* grade. These systems require a pump to lift the sewage from the septic tank to the leach field. Very different from a traditional septic system, more expensive, more maintenance, but they can work in small spaces with poor soils.
--
snipped-for-privacy@phred.org is Joshua Putnam
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Yeah, I've got about 10,000 miles on my car since the last oil/filter change, and it's still working fine, too.
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FTR, the contents of the tank were previously unknown, as it was a rental house. I know I got lucky. I was simply illustrating that "2-3 years" is often a "magic" number, perpetuated by people who profit from hauling poop. However, this area (Hood Canal, Olympics, WA) is all glacial till, i.e. a natural drain, so it's not uncommon for folks to wait several trouble-free years between pumpings.
I'll admit, it's not unlike going ten MPH over the speed limit... because everybody else is. Works for me. Think of it as a crap-shoot, so to speak.
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Are you sure they don't mean on systems where the leach field is above the tank (ie: "mound systems"?).
If you're in an area with poor soils almost always needing "mound systems" in order to get sufficient percolation, it might lead you to believe that up-pumps and vents are mandatory everywhere, but in actual fact, it's specific to your local soil conditions.
I find it hard to imagine that codes would insist on septic pumps _unless_ there was a percolation problem. Because a pumped system has a higher likelyhood of failing sooner or later.

The buildup of solids is exclusively dependent on the habits of the homeowner, and has nothing to do with the leach field. It can't - it hasn't gotten to the leach field yet, has it? ;-)
If you have a larger-than-necessary septic tank for your habits, you can go longer than usual. If you use more toilet paper than the average, shorter intervals. Etc.
While it's true that some combinations of septic system/people could go virtually forever without pumping out at all (especially cottage systems - my father's system hasn't been pumped in almost 40 years), most "correctly sized" residential systems with the average family living in it full time will need pumping every 2-5 years.
The issue is that with a new house, you have no idea what the situation is, and often no idea when it was last done. So, you need to figure out some sort of baseline.
Not knowing when it was last done, I had two pumpouts done three years apart, consulted with the pump-out guy, and made an intelligent guess of my own - especially after seeing what it looked like after we forgot and left it 5 years - if it's a hard/dry crust that you have to beat down with a crowbar, you've left it too long :-(
3-4 years seems to be our "sweet spot". The pumpout guy says he has one customer who _has_ to be pumped out every year - slightly undersized system from the beginning, it has 5 people with very long hair living there ;-)
The issue with leaving it too long is that the solids may build up to the point where it'll start going thru the overflow to the second half, and potentially plug the pipe, or fill up the liquids half too. Once that fills up, you start spewing solids into the drainfield. _Big_ trouble.
A properly installed septic system is pretty forgiving.
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
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Quite sure. The affluent must be pumped into the drainfiled, even though most of our county is glacial till. River valleys, on the other hand, don't drain for sh**. Thus, there have been and continue to also be new mound systems installed. It's just another broadly-stroked government solution to a problem which doesn't exist, right here. Life goes on.

Your astonishment is duly noted, and you are correct, as far as I know. But believe it, all new systems are pumped. It doesn't need to make sense. Visualize a guy with a fancy computer, who has never actually touched a septic tank lid, handing down his overly enviornmentally-correct opinions to some yahoo who advises the yahoos who actually decide what laws shall apply, and it should be easy to grasp.
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wrote in message

i think affluent should be pumped into a drainfield too, but don't you mean effluent?

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news:dkdq19

LOL. Sorry, I was just reading an article about the net worth of some of the administration's top advisors (Hey, my spell-checker liked it). But now that you mention it, I'll go with effluent... with some notable exceptions.
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As a person who's lived with them all my life and seen the evolution of the sand-mount system, here's what I know about them:
Waste leaves the house to a large tank. The waste (solids and liquids) enter at one end of the tank where the solids settle to the bottom, floating "stuff" stays at the top, and in the middle is the liquid. Solids break down over time in the bottom of the tank and are reabsorbed eventually. The liquid leaves at the opposite end of the tank, having passed around one or more baffles to keep the floaters and solids from leaving the tank. The second tank accepts the flow from the first tank and contains a pump. Any solids that make it past the first tank will be given a chance to settle out here as well. When the level gets high enough, the pump switches on and pumps the liquid out to the sand mound. There is a distribution box that the liquid is pumped into and splits into multiple pipes that are buried in the sand mound called leach lines. The pipes are perforated to allow the liquid to seep into the sand, which will filter the wastewater. Some of the liquid evaporates, some of it seeps through the sand back into the environment.
You should have the tanks pumped out regularly. Depending on tank size and how much water your household uses: every 2-5 years. The solids have a way of building up in the bottoms of the tanks over time, since they don't really break down fast enough to keep from filling up. The pump should be good for 10 years or so I'm told. There should be an alarm in the system to let you know if the liquid level gets higher than the pump float (indicating that the pump isn't working). I'm not sure what your vents are in the sand bed, but I suspect it may be one or more manholes for access to distribution box(es).
Here's a decent site I found once to describe different systems: http://www.eco-nomic.com/indexsdd.htm#Mound%20Systems Here's one with more info, including a handy link to an estimate of how often to pump your tank: http://www.inspect-ny.com/septbook.htm
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I hate to be picky but you are wrong. I lived in four different houses in PA and none has septic. None of my neighbors did either. Some people in certain areas did, but certainly not all.
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wrote:

rather than the whole state. Obviously not every home in PA uses septic.
Beachcomber
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Someone wiser than me once said "say what you mean and mean what you say" I've found it works well.
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wrote in message

for -LOL!
In my experience, I've never seen any build up in my tank when it is pumped. Prior to the new '3 yr' law requirement I had it done once when I moved in, once 10 yrs later and then, at three yr intervals. The problem which necessitates governments making laws to protect our water and, therefore ourselves, is the inattention to the requirements of maintaining a healthy septic tank. All that said, pumping is a good idea.
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Well he did get me thinking that I've been peeing in the wrong hole all these years.
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Rather than try to explain, there are several websites that show drawings and are excellent. I have been to them. Sorry I can not give the links, use your fav. search engine such as Teoma.com and search for SEPTIC.
Mark
On Thu, 3 Nov 2005 09:55:47 -0500, "mike"

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