Comparing our bog filter designs to a home septic system

[poconojoe]

My daughter has a 36 year old septic at her house. Her high water alarm tripped and we had two different guys come out to take a look.

I'm learning more about these systems and I've always thought there were similarities in how we build our bogs.

However, I'm finding there are some big differences in how I thought these systems were constructed. Mainly the size of the manifold pipes and amount of holes in those pipes.

We thought there was a clog or even a complete blockage but it now seems that it's possible that the float switch might have been the culprit.

There were no clean-out pipes in the original build so we dug out and cut off one of the end caps to see if there was any blockage. We found the interior of the pipe looked clean as new. That was a bit shocking considering it's age. Then we turned the pump on and it flowed out the pipe like a geyser. So, good news....there's no blockage.
We will be adding clean-out pipes for all 6 pipes for future maintenance.

Anyway, I was shocked to see that the distribution pipes were so small. They are only inch and a half pvc. I thought they would be at least 4".
And the other shocker is when the guy explained to me that the holes in the pipes are only a mere 1/4" and are spaced 6 feet apart!

I would have never thought that little amount of holes would be adequate. Again, they're 6 feet apart!

When I built my bog, I spaced the slits an inch and a half apart and I used 2" pvc!
Was that overkill? Maybe, maybe not. The two systems while similar are certainly different.
I wanted to use slits instead of holes fearing the holes would get clogged. Who knew?

It's a very interesting experience.

 

[GBBUDD]

The delivery pipe is only 1 1/2" to the leaching field? The holding tank will have the 4" TO IT and the solids sit in there and settle. then the liquids escape TOWARD THE TOP OF THE HOLDING TANK. then leaches through the smaller pipes.

 

[combatwombat]

A leach field is not dealing with the kind of continuous flow rates that our ponds are. Your average home can't do more than about 1,000 GPH in flow and your septic system would (hopefully) never see that for more than a few moments here or there. You definitely need a lot more open area in a bog manifold to not—pardon the pun—bog down the system.

 

[poconojoe]

A leach field is not dealing with the kind of continuous flow rates that our ponds are. Your average home can't do more than about 1,000 GPH in flow and your septic system would (hopefully) never see that for more than a few moments here or there. You definitely need a lot more open area in a bog manifold to not—pardon the pun—bog down the system.

Makes sense!

 

[poconojoe]

The delivery pipe is only 1 1/2" to the leaching field? The holding tank will have the 4" TO IT and the solids sit in there and settle. then the liquids escape TOWARD THE TOP OF THE HOLDING TANK. then leaches through the smaller pipes.

The house was built around 1986 or 1987.

I learned a lot from this experience.

Sorry for the long post, but maybe my experience will help others....

We had two different guys come out to look at it. The first guy was a rip-off. The second guy spent about an hour explaining the whole thing, showed me a typical sketch and didn't charge her a penny.

Yes, there's a 4" pvc from the house to the first tank where the solids drop off.

The liqiuds then skim off to the second tank.
There's a pump, float switch for the pump and I think a separate float switch for the high water alarm in that second tank.

The pump sends the liquids to the leach field through an 1-1/2" pvc. There's a check valve there before it leaves the tank.

The sand mound (leach field) has all 1-1/2" pvc pipes. The PVC from the pump enters the sand mound in the center and there are three legs off of that center pipe.
So, there's 6 end caps. The end caps had a 1/4" hole drilled in the center of them and there are 1/4" holes located under the pipes every 6 feet.

The sand mound did not have any clean-outs.
I dug and found each of the 6 ends, cut the end caps off and added a 45 elbow and a 2 foot piece of 1-1/2" pvc with a female threaded adapter and a male screw in cap for future access. I was also told to drill a 1/4" hole in the 45 elbow to replace the hole that was in the glued on cap that I cut off.

After cutting off the glued on cap I ran the pump to clear the pipes out. One was clean and had no accumulation. The other 5 had about 8"-10" of sludge that shot out.

I'm confident that the system is clear of any sludge and now she has clean-out pipes for future maintenance.

The magic number for locating the pipes and their end caps was 6 feet. The branches of PVC were 6 feet apart and the 1/4" holes on the underside of the branches are spaced at 6 feet. Once I found one end cap it was only a matter of measuring 6 feet over to the end cap of the next branch. Then I measured in 6 feet increments to find and end cap way on the other end. I think it was 30 feet.

It definately was an experience.
It really wasn't complicated once I knew what to look for, but I am a bit sore from digging!

The first guy came and replaced the float switches. He ended up being not so good. He charge her $375 to come out and replace the float switches. He tried to convince her to have him tear up the whole sand mound and replace all the pipes for 20 grand.
Then when she told him I was going to add the clean-out pipes and I was at Lowe's getting the material, he said oh, no you can't just buy that PVC stuff at Lowe's, it's special pipe. A big BS from him! Schedule 40 pvc is all the same, no matter where you get it.

Hope others learn from my experience!

 

[combatwombat]

That’s pretty lame. “Nice system ya got there. I could dig it up for ya for $20k.”

There are different grades of schedule 40 pvc, but even the lowest grade is more than sufficient for a sand mound sepctic system. You could probably even use schedule 20 and be perfectly fine for generations.

 

[poconojoe]

That’s pretty lame. “Nice system ya got there. I could dig it up for ya for $20k.”

There are different grades of schedule 40 pvc, but even the lowest grade is more than sufficient for a sand mound sepctic system. You could probably even use schedule 20 and be perfectly fine for generations.

That jerk actually left a few fittings and a short piece of PVC. They were the exact same components I bought at Lowe's.

Again, I'm new to septics. I've never owned a home with a septic or a well for that matter. I've always had sewers and central water including my current home. So it's an education for me.

Oh, and the second guy who educated me and didn't charge my daughter a penny said if he had to redo the sand mound he would only charge $8K. Big difference from $20K.

 

[addy1]

Our septic, I found the first tank digging the pond. Found the drain from the first tank to the two tanks in the back field while digging. Found out we had the two tanks in back field during a permit inspection.

We did not have any inspection when we bought the house. Have no clue where the tank was. The opening was two feet under ground. I put a HD bucket over it and a big white rock on the top to mark it.

We did a check when we found the opening nothing but liquid, have not touched it since. 11 years.

I assume the two tanks have leach pipes coming out.

 

[poconojoe]

In our area the leach fields are above ground sand mounds commonly called turkey mounds.
Sometimes they are in people's front yards and it's kind of ugly. They are usually covered with grass.
I think they are above ground due to the rocky nature of northeastern Pennsylvania.

 

[GBBUDD]

Thats exactly why. the perk or draining of water in your soils is poor. your not passing the perk test, probably due to title 5 from mass 30 years ago. so they build on top of the limited soils giving more room for the liquids to drain

 

[Beercan31]

Like Paul Harvey coined the phrase "Now the rest of the story"

A septic system is sized by how many bed rooms in the house (expected load)
A septic system is comprised of multiple components The first component is a contact tank, this is where your effluent is allowed slow down and non-digested fats are allowed separate. Grease and fats go up solids go down, there are bugs and bacteria here to break down the solid waste in this tank, Two "Tee's"are in this tank to prevent grease/oils entering back into the house pipe and 2nd contact tank or pump pit. here bacteria is hard at work. If the company you hire looks at the system they also look closely at the 2nd contact tank if they find a substantial amount of debris in this section the system is being "pushed" and not allowing the solids to settle out. you don't usually see clean-outs on the leaching side of the system because its a clear solid free fluid. I would be VERY concerned if you did find sediments in the section pipes, this would mean the system is being overworked or ground water is infiltrating ahead system and pushing solids out.

As far as the size of the holes in the leach field pipes you have to look at how many time the pumps come on a day, you'd be surprised how little it does and how long the effluent is allowed to settle out. you'd see the pumps are active early morning 5-7am. and then again at or around 5-9pm. (ie showers, cooking, laundry ect).

The bacteria cycle/process is much the same with a septic systems as it is with bio filtration unit, both systems are NOT a closed system, meaning fresh air is allowed contact the fluid. With the pump system you mentioned there might be a vent that looks like a candy cane pvc pipe on the tank, this is so air can enter the system to prevent it from becoming anaerobic, the gasses are vented out through the vent stacks on your roof, that's why you have traps on all drains in your home to prevent the gasses from entering the building.

Hope I filled in some of your questions.

 

[GBBUDD]

A septic system is sized by how many bed rooms in the house (expected load)

A GREAT WRITE UP. About a rather shity subject
I'D also mention the system design is also influenced by the soil type, and as mentioned the existing water table. This is determined by a perk test. This is where they dig a hole that is a certain size . It is then filled with water and they see how long it takes to drain out. The slower the drain the larger the system needs to be.

 

[Beercan31]

A GREAT WRITE UP. About a rather shity subject
I'D also mention the system design is also influenced by the soil type, and as mentioned the existing water table. This is determined by a perk test. This is where they dig a hole that is a certain size . It is then filled with water and they see how long it takes to drain out. The slower the drain the larger the system needs to be.

you are correct. if the leach field does not pass perk they will bring in "select soil" .

 

[Beercan31]

I did go off topic on my post,

Comparing our bog filter designs to a home septic system​

A septic system is not designed to be a constant run system (explained previously)

both system rely on bacteria to convert solid/harmful waste into a non harmful by product.

A bog/wet lands filter is designed for a constant flow. too little the bacteria die, too fast and bacteria does not have the time to do its job and you blow out your waste products into the pond or clog you filter field.

both systems rely on a "dwell" time to do its work.

I know when I was working with a sewage authority if the plant was pushed to hard ... water infiltration from ground water and broken pipe it would push the active bacteria out of the digester. not a good thing to happen. the only way to reactivate the digester is to put shovel fulls of soil in it.

off topic: a sewage treatment plant is a HUGE bog filter. except at the end of the process effluent is treated with chlorine (kill all remaining bugs) before it ran threw a de chlorination chamber where it was then treated with a small amount of ammonia (neutralize any remaining chlorine) and dumped into a F-1 trout producing stream.

all 3 systems have a "sweet spot" where they like to work at.

I think it was @addy1 that did an exultant write up on bog/wet lands sizing. I'm a guy... size matters and so does flow rate.

 

[GBBUDD]

both system rely on bacteria to convert solid/harmful waste into a non harmful by product.

The bog is definitely a take off from sewer treatment plants but more the middle to end of the process where after the solids are broken down the trash removed, after it is treated, aerated the areas that have the land often have football field sized settling , polishing ponds / sheet flow through the wetland plants. no one is better at removing some chemicals and minerals than plants. That's where we come in