New septic and leach line: Infiltrators vs pipe /poly tank vs concrete?

[beowulf]

We are in preliminary planning stages for building a second home on our 90 acres for daughter and SIL. Now getting estimates for construction, grading, well, new electrical, water storage (fire dist requirements) and septic-leach field.

Re the septic and leach field there are a couple of decisions to make:
1) poly vs concrete for tank
2) pipe and gravel vs infiltrators for leach line.

I have researched a bit about the pros and cons for tank types and leach field options, but always like to get advice here - usually the best source.

Pertinent to the issues:

-when I replaced our home's septic a few years ago I went with a 1500 gallon poly tank which was the strongest they had (called a Bruiser tank) and the installer was impressed with it vs concrete. It was a tank that they promote as being one that is strong enough that you can back fill even before you fill the tank with liquid, which I was told you could not do with regular poly tanks.
-I replaced a concrete tank that was very old and had cracked (it was never driven over but was really old and sort of an upright concrete culvert system).
-there will be no chance of upheaval or drive-overs given where the tank will be situated.
-there is access to the site so a concrete tank could be dropped in.
The home site is in an area where there is a slope about 20-30 feet on 3 sides beyond the home site pad - so, I guess adequate drainage overall.

Anyway, I am leaning toward a poly tank and infiltrators, but willing to listen and reevaluate all options.

 

[grsthegreat]

I had our concrete tank replaced with a poly tank 3 years ago. I had a contractor I do electrical work for , who installs lots of septic tanks, do the work. i replaced my 2 section tank because the middle joint was leaking. The tank was not even half filling. Was told this happens alot and that they are now making concrete vault tanks that are solid bottom and full height sides, with a separate top. No joints except for lid. This is instead of the split in half junker i had.

I then asked about poly tanks. The ones they have up here in n idaho are amazing in their toughness. He said the only bad thing that he can say about the poly tanks.....they last forever.... cut down on his future work. Funny thing was, the poly tank cost more than the concrete. I have an account at septic supply house as i regularly purchase floats, controllers, etc.

No problem backfilling this monster 1,000 gal tank. And i would not hesitate driving over it...mind you not with a semi. Its in an area that has occasionally needed me to drive my tractor over, but its usually just my kawasaki mule or my lawn mower.

My leach field is now 24 years old. Was made of those domed covers over a 4 inch percolation pipe. Never had any issues there. We sit on decomposed granite. After a rain, puddles of water disappear within 30 minutes. No clay to destroy my leach field.

 

[herm0016]

poly and infiltrators. when we bought our current house, the septic did not pass and we put in all new. poly 1500 gal. tank, and 400 feet of infiltrators. our soil is all clay. Lucky the engineer got the county to approve a 4 ft depth for the infiltrators, so i don't worry about driving over them with a tractor. its the only thing i see used around here with bad soil.

 

[grsthegreat]

poly and infiltrators. when we bought our current house, the septic did not pass and we put in all new. poly 1500 gal. tank, and 400 feet of infiltrators. our soil is all clay. Lucky the engineer got the county to approve a 4 ft depth for the infiltrators, so i don't worry about driving over them with a tractor. its the only thing i see used around here with bad soil.

I dont remember how deep mine were, but they were down there quite a ways.

 

[3Ts]

I have the plastic tank with the arched infiltrators. It's what was installed about 7 years ago and is trouble free. The tank is one that can be backfilled without filling it because at the time it was installed, the well had not been put in. I have driven over the infiltrators with an 8,000# tractor without any problems and supposedly it will handle 26,000#. The tank is out of the way, so is only driven over with a ZTR mower.

I had a concrete tank and pipe leach field in the previous house and had to replace the entire leach field when it got plugged up. (I suspect it was not installed properly the 1st time.) I was always nervous about any vehicle (including mowers) over the tank and leach field. I've had less problems with the plastic tank and arches than the concrete with pipe.

The plastic tank was delivered by one person in the back of a pickup truck. He just rolled the tank off the pickup and it was lowered into the hole with straps and the forks on a tractor.

The infiltrators are in a 3' deep trench.

 

[RalphVa]

No metal tank. Had a metal one in Baton Rouge parish rust out and fell in. Replaced with concrete. There, they require a small air pump called a "modad" be installed with the tank.

Never done leach fields. No comment.

Ralph

 

[oosik]

I would recommend the poly tank and infiltrators. Properly constructed and installed poly tank will outlast innumerable concrete tanks. Many local Health Depts will give a reduction in required drain area if infiltrators are used.

My original system lasted 34 years. Tank failure. My new system - poly septic tank > poly pump tank > 2" perf leach lines. This new system should last as long as I will ever need.

The only down side to a poly tank. If your area experiences seasonal high ground water - it may be necessary to strap side weights - concrete weight blocks - on the side of the tank to keep it from floating. This would only be a problem when the tank had routine pumping for maintenance.

 

[4570Man]

I’d rather use the infiltrators because they only require about 1/3 the amount but I’ve never had a site approved to use them so I’ve always used the gravel/pipe system. Locally a concrete tank is about $200 cheaper so I use those. The biggest advantage to poly is they can be set with small equipment and set immediately without waiting for a truck and having to drive the truck to the hole. The downside is due to the light weight they will float away and must be 100 percent filled immediately after setting. Also poly tanks aren’t allowed for a pump tank.

 

[grsthegreat]

I’d rather use the infiltrators because they only require about 1/3 the amount but I’ve never had a site approved to use them so I’ve always used the gravel/pipe system. Locally a concrete tank is about $200 cheaper so I use those. The biggest advantage to poly is they can be set with small equipment and set immediately without waiting for a truck and having to drive the truck to the hole. The downside is due to the light weight they will float away and must be 100 percent filled immediately after setting. Also poly tanks aren’t allowed for a pump tank.

We use poly tanks for pump tanks here in idaho. Dont fill them prior to burial. But we dont have high water level.

 

[4570Man]

We use poly tanks for pump tanks here in idaho. Dont fill them prior to burial. But we dont have high water level.

A pump tank only runs about 1/4 full under normal conditions. The septic inspector won’t allow it here. I doubt you’d have any trouble once it’s buried and settled but they’ll sure float out when they’re left uncovered for inspection.

 

[grsthegreat]

A pump tank only runs about 1/4 full under normal conditions. The septic inspector won’t allow it here. I doubt you’d have any trouble once it’s buried and settled but they’ll sure float out when they’re left uncovered for inspection.

you must have higher water tables where you live. I saw a concrete swimming pool lift out of the ground when it was emptied to be acid washed back in California... a site to behold.

 

[oosik]

High water tables is no problem here. My concern - sufficient cover over basaltic bedrock to allow a drain field. That's why I have a pump tank. Pressure drain field is some 275 feet away from pump tank.

 

[grsthegreat]

I hate pump tanks for 1 reason. Sooner or later that pump will fail. Usually at the most inopportune time. The guy i did alot of work for hooking up the pump systems, and believe me when you get into time dose septic systems the electronics start to get complicated, knew that i ONLY worked on new systems. If the unit failed that was in use many years.... dont call me. Aint enough money in the world.

 

[GSVette]

Poly tank hands down-more durable, easier to handle-big benefit if doing install yourself.

My recently permitted and installed system has 2 poly tanks (1500 and 1000 gallon dual baffle)-easy to handle off of trailer with my backhoe boom.

Have 5 100’ laterals using low profile infiltrators-in my region, gravel and pipe isn’t even allowed anymore since infiltrators are considered more reliable and thought to do a better job of distributing the effluent in the drain field.

 

[mikester]

The only down side to a poly tank. If your area experiences seasonal high ground water - it may be necessary to strap side weights - concrete weight blocks - on the side of the tank to keep it from floating. This would only be a problem when the tank had routine pumping for maintenance.

I have no experience using the poly tanks WRT longevity but have heard NOT to use them if you have high groundwater issues. I have no issues with concrete and would use it again especially if its cheaper and easier to install.

 

[herm0016]

Poly tank hands down-more durable, easier to handle-big benefit if doing install yourself.

My recently permitted and installed system has 2 poly tanks (1500 and 1000 gallon dual baffle)-easy to handle off of trailer with my backhoe boom.

Have 5 100’ laterals using low profile infiltrators-in my region, gravel and pipe isn’t even allowed anymore since infiltrators are considered more reliable and thought to do a better job of distributing the effluent in the drain field.View attachment 666783View attachment 666784View attachment 666785

holy heck, are you running a hotel?

 

[GSVette]

holy heck, are you running a hotel?

Permitted for a 5 bedroom house plus shop and barn with full bathrooms.

 

[beowulf]

My thanks to everyone for taking the time to respond. This has been very helpful. I made contact today with a septic system installer and he recommended that I first have the system 'engineered'. I did not do that when I put in a new leach line many, many years ago, but I am totally willing to do that now. I pulled up the County requirements re septic systems. There are many very specific requirements that an engineer of such a system could more easily address so I can (a lot I would likely struggle with) so I can see why having all that 'engineered' makes sense, but it is not required that the system be 'engineered'. I trust the septic installer who made the recommendation so will likely arrange for that. Cost is $2,500 which is a lot but not a lot to get it done right.

Again, my thanks.

 

[LS Tractor Owner]

I went with a poly tank, but two laterals done the conventional way of stone / 4" perforated pvc pipe. For our area, it was the most cost effective method.

 

[4570Man]

There’s no way I’d spend $2500 to have a system “engineered” I’d take that money and overdo it by double if it would make you feel better. Locally the state office provides a sheet of the minimum requirements they deem necessary for the soil conditions and bedrooms.