Septic drainage field (slow draining)

bcugkMarch 18, 2007


I live in Southwestern Ontario, i replaced my drainage field in 1998, since then i have had the tanks pumped every other year (the installer had indicated that the tanks were quite small 2 x 325 gal tanks for 1600 sq ft home, 2 baths, 2 adults, 2 kids).

Since 2001 each spring the liquid tank overflows, and approx every other year the line from the house to the solids tank plugs.

The tank overflowed yesterday, i pumped the tank down, could the drainfield be partially plugged and if so is there something i can pour directly into the liquid tank thus not hurting the bugs in the solids tank.

The drainage field has 2 100' drains (4" plastic perforated tiles).

Thanks in advance,


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I am not familiar with the system of having a solid tank and liquid tank. Are things in your house separted so that different fixtures go to different tanks?
When the line going to the solids tank plugs up, is the tank full?
As far as the leach lines go...2-100" lines, they sound like enough, but so much depends upon how well it was designed ....soil conditions and all of that stuff. If the soil conditions are bad then the liquid can't drain off because the ground gets saturated. In other words, build a system in a swamp and it will never drain right. When you have a saturated condiiton, no matter what you put into the waste water, it's not going to help much.
Please explain more clearly about this tank situation. I have dealt with many systems over the years and might be able to offer some ideas.

    Bookmark   March 18, 2007 at 4:27PM
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Thanks for your response, the system is a two tank system, the house line enters the first tank (solids tank), the solids settle, scum layer on top and the liquids overflow to the second tank (liquid tank) from there a single 4" line tee's into the two 100' drainage lines.
The tanks were not full when the line from the house plugged, the last time this happened i borrowed and successfully used a power auger all the way to the house (some pretty scary stuff was removed from the line).
The drainage bed was installed professionally in 1998 2' sand, 2' gravel, lines, 2' of gravel, 2' sand and then backfill.
The part that annoys me is that my neighbours don't have any problems and have not had their tanks pumped in recent memory.
My neigbours property (we have approx 2 acres each) is tiled and his tile runs adjacent to my drainage bed.
We are in a clay soil area.

    Bookmark   March 18, 2007 at 6:43PM
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I live in southern Ontario and I have never heard of a system like yours.

The minimum size of an approved pre-cast septic tank is 1000 gallons and it is a dual chamber tank. Secondly, 200 lineal feet of tile field is inadequate for any house.

Thirdly, I have never heard of any contractor being allowed to dig trenches for a septic field over eight feet in depth, as you describe. Two feet of sand plus four feet of gravel plus another two feet of sand plus a foot of backfill add up to nine feet.

You should have at least 400 lineal feet of tile and perhaps as much as 600 feet. It sounds to me as though your current tile field is flooded and cannot disperse the water fast enough to keep up with the needs of your household.

If I were you, I would be going to the town and talking to the people that grant the permits and do the inspections on septic systems. You need to hear it directly from them as to what your home should have for a tank and septic field. Anything less, is just pure speculation.

This is a problem that needs to be addressed quickly or you could have some serious health issues and the town could force you to evacuate your home until the system is brought up to code.

    Bookmark   March 18, 2007 at 7:22PM
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Okay, I understand the system and have had two of that type. In each of mine, the second tank had a pump that pumped to a leach field some distance away.
First, the line with the solids (the line from the house)...if that plugs and the tanks aren't full it means that there is either a low spot in the pipe that collects grease over time and plugs up. Or there can be a break or a separation at a joint that catches paper and stuff until it builds up and plugs. On this problem I would suggest getting a local company to come in with a simple sewer camera that is pushed down the pipe to see what is going on. The picture of what the camera sees shows up on a TV like screen. The price for this runs as low as $150 to the thieves who will try to charge you $1000 or more. Usually the expensive guys have a $20,000 truck mounted system that you don't need. If you are handy at all I would look around at the rental stores to see if you can rent one. The simple ones don't generally go more than 100' so you have to have some idea of the legnth of your pipe. You also have to have some spot where the pipe can be opened to put in the camera.
After you've viewed with the camera, you will know what your problem is and then figure how to correct it. A friend of mine had a similar problem and found out that a truck that he had in the yard for something else had driven over the pipe and flattened it. It was only about 6" deep, which is rare.
Now on your liquid tank...if you are in clay, that is a terrible soil for leaching. I would hope that it was designed by a licensed person. Did the guy actually draw up plans and get a permit? Regardless, I would check the outgoing pipe of the liquid tank. I have seen where enough scum has gotten into the outlet pipe to block it and the tank would eventually fill up and flood and there was nothing wrong with the leach area. As Castoff says, maybe the leaching area is not large enough. I can't tell you that, but can tell you that I've seen systems operate with less leaching area than you have. Here in Vermont when the designer or engineer pulls a permit he has to specify the type of sand and stone to be used and the sand has to come from a sand pit that is certified by State Engineers to meet certain specs. The truck driver delivering each load of sand has to bring with him a certificate from the sand pit. In other words, sand is not just sand when it comes to leach fields.
Anyway, I think your solid plugging can be investigated as I suggested. You should check on the liguid part to see if it is a plugged outlet or a leach field problem. If it's a leach field being overwhelmed, I would see if someone could design something for you that could be added to your present system if they think it's in good condition rather than starting over. There is really no method that I know of to "clean" a leaching area.
Different towns have different rules on these things. You will have to ask around. Quite often you can get a "repair" done without a permit and in other places you need a permit for everything. Some workers can really stretch what they consider a repair. I've never seen a town require that a house be vacated for a bad septic, but I have seen them order the tanks be pumped every few days and that will get very expensive so it is something that has to be dealt with. Good luck and let us know what you find out.

    Bookmark   March 18, 2007 at 10:52PM
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I don't know what's permissible in Vermont nor how old either your system or the OP's system is. Single chamber tanks have been gone from the scene here in Ontario for many, many years because they don't do a good job of keeping solids out of the leach fields.

Our systems use twin-chamber tanks that normally are gravity-fed to the leach field. Leach fields either use a concrete distribution box or a header system made from solid four inch plastic pipe. Some systems are "open" style, meaning that the individual runs just end fifty feet or so away from the header or distribution box. Other systems are "closed", meaning that a footer pipe joins the ends of all the runs together.

Closed systems help distribute effluent to the back side of a blockage in a damaged run, thus increasing the life of the system. If a septic field cannot be accessed by gravity, then a seperate concrete pumping tank is used AFTER the twin chamber tank. The pumping tank is sized to the system so that when it reaches a certain level, it empties out and floods the entire field and not just one or two lines closest to the point of entry.

Just so everyone knows, the bulk of Ontario is made up of clay-based soils. There are certainly areas with sandy soils too but clay predominates. That said, there is no big problem with designing leach fields that work. However, the big issue is that of the seasonal high level water table. The regulation calls for trenches to be no deeper than forty inches ABOVE the water table at it's highest point annually.

If that cannot be achieved due to the existing ground elevation, then a raised filter bed must be constructed to conform to that criteria. Such beds often cost in the neighbourhood of twenty-thousand dollars or more due to the special sand (just like VT) needed.

What the OP has described regarding the two only runs that are nine feet deep makes no sense to me and it flies in the face of the URL's below. All of these are Ontario-based and none of them speak to a system as described by the OP. Some of them are PDF links. I hope that they will cut and paste OK. -

Condemning a home temporarily is an extreme measure but under specific circumstances it can happen. Here in Ontario, a homeowner has a LEGAL obligation to inform the local authorities if his septic system is not working properly. Something is seriously amiss with the OP's system and the ONLY place he can trust are the people at the local municipality who have the final say about tank and leach field design.

After all, they're the ones who issue the mandatory permits, approve the designs and conduct the various inspections in order to obtain the needed clearance. They also have the power to force homeowners to comply and initiate legal action when they don't.

Here is a link that might be useful: Tarion

    Bookmark   March 19, 2007 at 8:06AM
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Sounds like you have systems that are similar to Vermont's. We also have open and closed systems, distribution boxes, etc. The 2 systems with pumps that I described both had leaching areas remote from and higher than the tank and so had to be pumped. In this area if it is all clay soil, I can almost gurantee that a raised leaching area would be they are called "mound systems."
In my dealings (until new State laws were passed 3 or 4 yrs ago) each town or city had its own regulations. The smaller towns did nothing. They left it up to home owners and local contractors to design and build their own systems. In most of these cases they were rural communities and the landowners had many acres...the practice was to just build something big enough and to heck with any fancy design.
The State of VT now has to issue permits for all designs. The trade off for this regulation is that they will now accept "modern" systems that allow systems in soils that would never work before.
When a system is being designed a "perk test:" has to be done on the soil. A hole is dug with a back hoe and the engineer/designer establishes soil conditions at different levels. Then water is poured into the hole and a timing is done to determine how long it takes for the water to leach out.
I can tell you that in the civilized areas here, the clay soild conditions that you describe, especially with seasonal high water, would never pass and would require a built up mound system I must confess that I haven't fooled with systems for about 8 years and don't know the specs on the new systems that are allowed or if the new tanks are 2 chambered. I know that many of the designers are requiring filters on the outgoing side of the tank. Possibly this serves the same purpose as the 2 chamber tank. Once a year, you pull the filter out of the inspection hole on the outgoing side and hose it off.
I hope that the PO finds some solution. It would be too bad to find out that money had been spent on a design that doesn't work. If it only floods on a seasonal basis, then it does sound like a design problem.
If that was the case and it wasn't too terrible, I would investigate anything that might lessen the water flow to the system.....low flow fixtures....toilets, shower heads, etc. I guess I'm trying to think of ways to save someone money, but this system could be beyond that.
I don't know what part of Canada the PO is in. I owned property in rural Quebec in a small towwn. I can tell you that there was no regulation (20 yrs ago) over septic least no regulation that was enforced unless it was a newly constructed building. This town was small enough that the town clerk's office was in the living room of his house and was only open 2 nights per week:-)

    Bookmark   March 19, 2007 at 9:01AM
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FWIW, my 1972 Michigan home has two tanks only a few feet apart. The county refers to them as the "solids" and "liquid" tanks. The liquid tank drains into a subdivision sewer rather than a drain field because the soil is mostly clay. Even new houses require a septic tank between the house and the sewer, though they probably use the twin-chamber tanks.

In my case, the sewer line is uphill from the tank, so there is a pump in the liquid tank. The entire arrangement is maintained by the county. (The county cleans the solids tank at regular intervals at no additional expense to us, though I could easily digress into complaints about my tax bill.)

The sub was conceieved in 1968, but without the sewer. The original developers went bust when the health dept would not allow traditional drain fields in most lots. Several years later, another developer installed the sewer and the sub has since flourished.

Mine is one of the early homes built. It originally had a drain field, but it was later abandoned in favor of the sewer.

Soon after we bought the house in the 90s, the liquids tank would overfill whenever it rained, setting off an alarm mounted outside the house. The county would then come and pump out the liquids.

After several rainy-day return visits, the county replaced the original concrete tank with a new plastic one. That's when we learned about the two tanks and the original drain field. It turned out that groundwater was seeping into the liquids tank from the old field connection. The alarm has not sounded since.

    Bookmark   March 19, 2007 at 10:46AM
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I've never heard of a system like you are describing in Michigan. If the liquid goes into a city sewer system...someplace at the end, the sewage has to be treated. Any city that I've ever seen the solids and liquids go together and are treated together in a treatment plant.
Maybe they've come up with a system that's cheaper to treat the two separately. Around here, the pump trucks have 2 options for dumping. It can get spread on an "approved" (engineer certified field) area or it can be dumped at a city treatment plant. I guess you can imagine that the owners of the pumping service try to buy up land and get it approved because it is much much cheaper...and they charge the customer the full amount. Being in Vermont, the tourist state, you will never see an approved field near a road where a tourist might see human waste being spread on a field:-)
Seriously, I would be curious to know how your area treats the different waste products. It sure is labor intensive to be pumping those solid tanks all the time.

    Bookmark   March 19, 2007 at 11:56AM
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Our sub has neither city sewer nor city water. The original development included a man-made lake which permantly flooded a section of county road, so I'm certain that a great deal of time, planning, and money was expended to get the required approvals, build the dams, put in roads, etc. I can neither explain nor imagine how the development progressed as it did without a better plan for handling sewage, though a handful of houses did get built.

I believe the hybrid septic tank/sewer system was engineered specifically to salvage the sub. The treatment facility is specific to our sub and is limited to handling liquid.

A history of the county describes it this way: "... the surrounding land would not perk. This meant that in order to build homes on the lake, a sewer system needed to be installed. One of the first hybrid water treatment systems which combines a local sewage tank with a gray water treatment facility was then installed."

I don't know how common our two-tank configuration might be. Perhaps it does what the twin-chamber tanks do, but with separate tanks. Neither the county guy nor the backhoe driver acted like it was unusual. The county guy did mention that they installed a larger tank than was required because they were using what they had on hand. Maybe he meant that they don't keep many single-chamber tanks around.

The alarms are intended to catch overflows before sewage can reach the lake. They are mounted on the outside front of each house and include a blinking light that is visible from the street. The label on the front provides a number to call "immediately" if the alarm is sounding. A reset button will silince the alarm for about an hour, but only the county can turn off the light.

I'm sure I've exceeded my allowance for digression and rambling. I mostly just wanted to add that we, too, have a two-tank system, and that we had trouble at one time with ground water causing one of the tanks to overfill.

    Bookmark   March 19, 2007 at 3:35PM
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Thanks for all the replies, i will monitor the situation, if it floods again i will rod the liquid tank outlet.
The contract simply replaced what was there from the original installation in 1959 which was two 100' clay tiles, of which one was cut off and bagged, not sure when this was done but the previous household (original builder) had 3 sons and it obviously worked over the years.

    Bookmark   March 19, 2007 at 5:02PM
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Sounds like your developer had some pull in that town;-) I bought a large rental property in Flordia and found all kinds of things that were unusual. The city was responsible for all of the street lights on my private streets, they were responsible for 100's and 100's of feet of water and sewer pipes...all on private land. The developer was a local guy with lots of contacts and possibly was handing out cash favors. It was certainly nice to be the owner of the property after him. If any problems came up, just call the city. They were responsible for everything on my 8 acre development.

    Bookmark   March 19, 2007 at 5:43PM
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Yep, there must have been some influence there, but I think the local government is also quite happy to have the extra property tax revenue. We are pretty much out in the sticks, so the lake was a big deal when it was developed.

Another odd twist is that the lake is considered to be private and the lake bottom is privately owned (by some of the original developers, no less), but the State still controls it. Our POA spent several years getting approvals to lower the lake about a foot each winter to prevent ice sheer along the shore. If you ever thought it was difficult to get approval for a residential plumbing project, try letting a little water out of a lake sometime!

    Bookmark   March 19, 2007 at 9:33PM
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In our area of SW Mich. when a drywell fails on an older property it is replaced with two drywells and an A-B switch. every year at the 4th of July we switch from one drywall to the other. This allows the drywall to dry out and renew itself for a year.

    Bookmark   March 20, 2007 at 12:45AM
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Ah, those old drywells:-) I owned a mobile home park. ..was having some excavation done and the rear wheel of the back hoe fell into a drywell that we never knew about. We figured it wasn't safe to leave it and figured it wasn't being used. We uncovered it and found it to be about 100' long by 20' wide. Seems that the man who developed the mobile home park also built a small housing development nearby. He used this drywell as an overflow for the individual houses' septic systems. In other words, built poor septic systems and when they were drenched, their pipes allowed overflow to this drywell.
We bulldozed the large drywell and capped off the incoming pipe. People in the housing development never knew why there systems all of a sudden began backing up. All 8 homes in the development had to put in new systems.

    Bookmark   March 20, 2007 at 9:33AM
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Posted by bcugk (My Page) on Mon, Mar 19, 07 at 17:02

Thanks for all the replies, i will monitor the situation, if it floods again i will rod the liquid tank outlet.
The contract simply replaced what was there from the original installation in 1959 which was two 100' clay tiles, of which one was cut off and bagged, not sure when this was done but the previous household (original builder) had 3 sons and it obviously worked over the years.

You asked for opinions so here's my latest ones.

1. You don't know if the old system worked all year around for the original owner with three sons. He may have had the same sort of problems you are having but was too cheap to fix it.

2. You can rod that tile line and tank outlet 'till the cows come home. If the tile is buried below the seasonal high point of the water table, then those runs are flooded with ground water and will not accept any water from your septic tank. When that happens, the waste water has no place to go. It either has to back up inside your home or run out of the lid or vent on the second tank.

If your neighbour sees or smells this, he may call the town in and rightfully so. Raw sewage is a major health hazard. Coliform bacteria can kill people. It's nothing to trifle with.

3. This isn't a problem that is going to magically cure itself or go away on it's own. The main line from your house to the first tank has a problem that needs to be cured. If there was no problem, then it wouldn't be plugging up.

Bottom line. It's your house and you can do whatever you want. If having your sanitary system fail on you every winter doesn't trouble you or your family all that much, then I guess it's no big deal to just live with the inconvenience. It wouldn't be my choice. But if you decide to sell this house, don't think that you can just sell the problem with it.

That was something that could be done years back but not today. If a new owner discovered the problem you described in your first post, then you would be facing a lawsuit for whatever amount it cost to make things right. If that meant a complete new tile field and tank, then they would be coming after you for whatever it cost to put that in and they would win at trial. This is a known deficiency. Sooner or later you will end up correcting it. Doing it this summer allows you to control the costs to a degree. Waiting until you are forced to deal with it means the end of any cost control.

    Bookmark   March 21, 2007 at 6:00PM
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