Leach field failed.....again!

My leach field failed six years after an upgrade. The upgrade was a three foot lateral shift of a horribly inadequate drain field of a single run of 50' of perforated 4" pipe (which worked with two people for twenty years).

Data:

My house was constructed in 1986 on a flat suburban site.
Location is in a river valley in Chenango County. Soil is native and sandy. Nearly zero rocks.
Perc rate was just tested today at 18 minutes per inch in an 18 inch trench.
Effluent flows from the house at a depth of 16 inches from ground surface to the top of 4 inch pipe.
Two adults, one teen (long showers), one tween.
Hard water at 30-35 grains/gal. pH 7.3.
Water softener discharge rate is 14 gal per day using 3 lbs of salt per day on average (water boss 900 regenerating every other day)
1000 gal single chamber concrete septic tank with concrete outlet baffle, no tees or chambers.
the existing failed drain field consists of two 60ft runs of 36" Infiltrator brand vaults. The depth varies from 12 to 24 inches below the surface.
All effluent flowed into the septic tank first (black water and gray water).
The septic tank was not pumped regularly (my bad)--only when it was failing.
We use biodegradeable detergents in the washer. The washer is the old style using 30-40 gallons per load.
The old water softener was malfunctioning over the winter and I found it running the house pump all day on two occasions before it was replaced two months ago.
We have had heavy rains all spring and had a heavy amount of snow. No droughts for three years running.

Which factors contributed to the failure and in what probable proportion?

I have an professional engineer working on this problem now but I want the second opinion of this board.

Thanks!

Hi Mike - Has the failed portion of the leach field been dug up yet? Any clogs or material found in the pipes? I am thinking that with your heavy greywater load and the malfunctioning water softener you got some solids pushed out into the leach field, but that is just speculation. It was sure a challenging spring for any leach field.

On a side note, a Sunday afternoon install of a drywell for the washing machine and water softener would be a big help. The local septic gestapo won't like it, but the leach field sure will.

I was also going to suggest a separate dry well for the washer and softener. Also, does your septic tank have a plastic basket filter at the outlet? I've seen these filters mostly on systems that have a pump tank, but they would also work on your type system as well. You have to rinse off the basket every so many months (your time frame may vary from the 4 month schedule I use). That will help keep the solids out of the drain field. A little more maintenance, but better than a clogged drainfield.

One thing to try is to put in something like Septic Helper. When I moved into our last house the leech field was in sad shape. The soil was full of shale and had a bad perc rate. The water level in the leech field was high enough to discourage any activity there. A few months after I started added the Septic Helper the problem went away never to return. In ten years of living there I pumped out the septic tank twice. Both times took much less time than normal and there was not much build up. Had two adults and a young child at the time.

mikeandgerry wrote:The septic tank was not pumped regularly (my bad)--only when it was failing.

Thanks!

This is your answer. Your septic tank doesn't fail, only the leach field. Tanks should be pumped every 3 years, especially if it is only a 1000 gallon, single chamber. Around here, you can't bury anything smaller than a 1500 gallon two chamber.

If the tank isn't pumped soon enough, solids pass through the tank and into the field clogging it. Post cleaning of the leach field with powe flushing or chemicals is damn difficult and only sometimes sucessful.

My leach system is a sand filter. As added safety, I have a filter on the outlet of my tank that will clog before the solids reach the sand filter. I plan to pump every 5 years as soon I will have an empty nest.

http://zabelstore.stores.yahoo.net/grav ... lters.html

http://www.health.state.ny.us/environme ... rs/septic/

Dig so you can get the lid off the holding tank--get a hose & find your leach outlet--shove the hose in it & let it run--yep it sounds like a blockage in the lead in leach pipe---worth a shot:)-- by the way--the above is not a factor--but a possible solution and yes--before doing this--get the tank pumped---I love it when engineers get involved

Wow. Thanks for the fast responses.

@Fred: a clog was a consideration until I was mowing my yard a few weeks ago and sank down six inches in mucky mush at the far end of the leach field. (and I immediately thought of you and your farm, Fred!) Then it got worse. I pulled the pumpkin lid and you can't even see the outlet there is so much water in the tank--a third of the way up the riser! How we are still flushing without backing up is a mystery. (We are not doing any wash loads or showering though, just limited sink use)

@Steamup: I am certain I created most of my problem by not adhering to any pump out schedule. What miffs me though is the lack of information from the "experts" in the area, that is, septic diggers and pumpers. Some say every year, some say every five years. Then you have people in the neighborhood who have NEVER done it. (My parents never have had it done in 38 years and the current engineer on the job said his dying 90 y/o father has never had it done either!) Go figure! Rest assured, now it will be an every year thing now to satisfy my lack of certainty (at least until we are empty nested).

The drain clearing guy said that he didn't think his power flushing nozzle would work on vaults, just 4 to 6 inch pipes. He didn't think it would travel.

I like the filter on the outlet idea 'cuz if I screw up again and forget, or the septic guy forgets to sent the reminder postcard, it may save me. I will pass that by the engineer.

@wlape3: I think my issues are larger than those that can be solved with additives at this point.

@titleist1: I keep making the suggestion to split the drainage field to the engineer but he says I don't have enough room. This makes no sense to me. If I have enough room for a drainage field that accommodates all waste water, then splitting the field and the waste water should not be a space issue. I told the excavator that if the plan doesn't include a dry well for my washwater and water softener effluent then we will be adding one after he leaves! Apparently this leaked back to the engineer and his answer is to forget the separate drains but to route the saline discharge from the water softener to my footer drainage tiles which run to daylight away from the leach field. Not a bad idea but what's the problem with a separate gray water system!?! The NYS guidelines that steamup posted say it's preferable. We will likely be getting a pump tank so I think the filter basket will be a part of that-- I will make sure of it. (I would prefer a simple gravity system but I have no expertise here so I will probably end up listening to the PE)

@ markviii Yes, the midnight digger may be necessary to dig a leach pit for the graywater if the engineer's design doesn't accommodate the graywater differently than what I have now.

Thank you all for the great advice. Too bad I didn't think to ask earlier. Education is expensive, no doubt.

mikeandgerry wrote:Apparently this leaked back to the engineer and his answer is to forget the separate drains but to route the saline discharge from the water softener to my footer drainage tiles which run to daylight away from the leach field.

Mike, that is how my house is setup. My basement drains, deep sink, and softener all go into a daylight drain. The remaining greywater all goes into the septic. Not ideal, but it seems to handle it fine. I talked to the farmers turned septic installers that installed my system in the late 80's...they said the leach field is in a "bed" of crushed stone and is surrounded by a 8" drainage tile that makes a big loop in the nearby lawn. No wonder it handles the greywater.

You have theory and then there is actual load. Theory is based on worst normal case. In your case, you have an active growing family. You are going to generate lots of solids with plenty of water to flush them with. Older people generally eat less, wash less, etc and have a low load on their systems. Some people just get lucky and get by. Wait until the next poor person gets their system and puts a load on it.

FYI, based on the info you posted, do not be surprised if the engineer states that your entire system is marginal at best but more likely slightly undersized. Your perc rate is ok but not great. You use a little more leach field than what you got. Sandy soil plugs quickly.

If you have the room, a second 500 gallon tank after the 1000 gallon tank would create a larger capacity, two compartment tank system. The filter could go in the outlet of the second tank. I have also seen filters for distribution boxes. I am not a fan of dosing systems if they can be avoided but they are required on some systems to even out the flow to larger leach fields. I don't know if a dosing system is applicable here.

If only the far end of the leach field is wet, was the field installed level?

If you have two runs of chambers, do you have a distribution box? Is the box distributing evenly?

I would avoid pipe with holes for the leach field. I was told by someone that installs them he only uses the open bottom things, whatever they are called, for this very reason.

Pump when the solids are 25%...
Small tank, high flows, no chambers or baffles...
Let solids into the field...
Salt from the water conditioner helps bind the soil...
The basket or filter at the outlet of the tank will stop the solids if you 'forget' to pump...
Leach chambers are better than pipe...
The leach field can never be too big...
I used concrete chambers an went 30% oversize...
Lot size and groundwater prevented me from going bigger...

I used a product called Biofroce - seems to work well at keeping solids down. Forget the Lowes stuff.

steamup wrote:FYI, based on the info you posted, do not be surprised if the engineer states that your entire system is marginal at best but more likely slightly undersized. Your perc rate is ok but not great. You use a little more leach field than what you got. Sandy soil plugs quickly.

If you have the room, a second 500 gallon tank after the 1000 gallon tank would create a larger capacity, two compartment tank system. The filter could go in the outlet of the second tank. I have also seen filters for distribution boxes. I am not a fan of dosing systems if they can be avoided but they are required on some systems to even out the flow to larger leach fields. I don't know if a dosing system is applicable here.

If only the far end of the leach field is wet, was the field installed level?

If you have two runs of chambers, do you have a distribution box? Is the box distributing evenly?

The engineer has made exactly those comments in passing but has reserved his conclusion until he studies his data and formulates a plan. So he says.

The second tank sounds like a good idea to me. The engineer has floated the idea of replacing the tank but I don't see why we have to do that. I think modifying it or adding a second tank as you suggest is ideal. The digger thinks the house breaching is too low in the ground (18" o.c. of 4" pipe, from the surface).

The "lower run" of leach field is wet at the surface the whole length. 0 I say "lower" only because the surface varies over the leach field by one foot from highest to lowest ground cover, the wet end being just 10 or 11 inches below the surface). The D box has not been checked because the tank is full (up-the-riser full) and I avoided the suggested repairs from the local digger/septic guy (he just keeps wanting to pump but I played that game last time and it cost me $750)and the local drain guy and went directly to the engineer. I just don't have any confidence in the local digger or drain guy. They too were not confident.

The local digger/septic guy has a lot of experience but not at diagnosis, only digging. The drain guy didn't believe his power jet would clean the vaults. So I abandoned them and went to the engineer. The engineer was confident that the system had failed and because it was very near the last failed field, it was time to move it. His information on the septic tank is base on information from me. The digger thinks the septic tank can be modified but doesn't like the depth. Both now agree that the load is too heavy for the size of the field considering all factors of load and soil. I agree with that but also think my ignorance and the tank design contributed to early failure. Now I am educated (thanks to this board and others), I think a new leach field is what the doctor will order but I want a new septic tank, or modifications to it, which could be a second smaller tank with filters. The new system will have to have a pumping chamber because of the grade to the leach field. The other issue is the water softener salt. One way or another I will prevent that from going to the septic system.

coaledsweat wrote:I would avoid pipe with holes for the leach field. I was told by someone that installs them he only uses the open bottom things, whatever they are called, for this very reason.

Good advice but I have vaults (the open bottom things). They make the surge capacity of a leach field higher but they don't increase the ability of the soil to perc. They can fill up with "bio mat" just like the pipes but it takes a little longer to clog. The intent is to have no solids go into the leach field to prevent feeding the bacteria that form the bio mat.

From my research, this is my understanding of septic tank functioning, pumping requirements and leach fields.

If a system works properly, that is, it's properly sized to the load and just treating dirty water and human waste, then you really shouldn't have to have it pumped out in a lifetime. (But that is an ideal situation). There is very little ash from human waste which is what becomes the non-degrade-able sludge on the bottom of the tank. The scum that floats on the top is degrading oils and light solids. It's my understanding that the baffle keeps the scum and floating solids out of the leach field but the scum has a purpose, which is to seal the top of the tank water and make the tank an anaerobic system. It keeps air out so that only anaerobic bacteria decompose the wastes (I am not totally sure why, but I think it is merely that if the system were aerobic then your septic tank would have to be vented and thus noticeably stinky). Additions of bacteriostatic chemicals, too much water or solid waste will overload or compromise the ability of the tank to decompose the waste.

Only when the distance between the sludge on the bottom and the scum on the top becomes small, does the tank need to be pumped. At that point there is too little water and bacteria to decompose the solids efficiently. There is a ratio of desired sludge/water/scum thickness (but I can't tell you what they are without research). Because that's too complicated and nasty for the septic guy, or the average homeowner, to measure and figure out, they suggest a time interval for pumping out. It's actually a cop out method because in reality every situation is different and one pumping interval does not fit all septic systems.

As for the leach field, only "clean" water should be going into it, that is, water free of organic solids. The bacteria that do go in to the leach field die because without organic solids as nutrients, they cannot survive. When solids do go in to the leach field, the anaerobic bacteria grow massively over time and form an undesirable "bio mat" (a thick slime) on the walls of the pipes and vaults which eventually seals off the soil from the water and percolation stops, which is called a leach field failure. Methods for repairing this could utilize power jetting, chemical treatment, venting, or replacement of the drain field or a combination of certain methods. It is my believe that the power-jetting and chemical methods work but but with varying degrees of success because the soil perc rate has been compromised by the addition of solids and bacteria. Ventilation and rest may be successful in ridding the system of the bio mat but it may not be acceptable to authorities, the homeowner or neighbors. It may not be practical in colder climates. The soil will remain compromised.

It that all accurate?