Drive equipment over septic drainfield?

[skipro3]

My system, a 4 line, Quick4 ISI Chambered leach field, has vents on the end of each line. They are 4 inch lines that poke about a foot above the ground and are capped but not glued. Supposed to be able to take the cap off to view down to the leach field I am told. I pulled one off tonight. Phew! Yup, that's a sewage leach field alright!!

[Richard]

Lemme see if this helps clear some things up...

I talked to the guys today and the septic guy says "flexible pipe" is very common here. He said it would be something like 10" in diamater.

He also said he felt after 10 years (maybe 9) that it's been installed that it "should" be ok to drive over.

Now...let's define drive over....

1. They need to get a backhoe in here to dig up lid on old tank
2. They need to get a gravel truck in here to fill old tank with gravel, then they're going to top it off with 4/6" of concrete on the top (of the inside)
3. Concrete truck needs to get in here to pour footers and pad for floor of room

I've taken a digitial picture that I'll try to post tomorrow at work to try to give some perspective

Unfortunately, I've got a (small) dogwood tree blocking one way in however, that same direction is also on a slope and they said the concrete truck couldn't come in that way with that degree of slope.

They want to take this tree out (that we've specifically built around trying to keep) and then take some 12x12 boards, scab some OSB onto them, maybe 8' long and build some "ramps" that they'll place on the ground to act as a "road", moving the ramps as the vehicle travels down it (build several sections and rotate them)

The septic guys says right now, we don't really know any answers until they "scratch around" some with his machine to find out where the pipes exit my house, where they enter the old tank and where they exit the old tank. Then, we'll know the elevations of what is where and how difficult this might be and where the equipment might need to be placed.

I am NOT too keen on the idea of a concrete truck traipsing through my front yard (although I'm not against redoing my front yard because it does need it) My issue is getting that kind of tonnage and knowing how they can cut through dirt/mud (if damp/wet) with their weight

I'll try to post that picture tomorrow morning

[Richard]

Originally Posted by plowking

the contractor is afraid the old tank will settle if not filed with concrete for support

Exactly

Also, he called mine ...drats...what did he call it... a "rockless" or sandless? maybe a "no fill" system where the pipes were not surrounded by what is essentially, a gravel pit in the trenches.

They dug the trenches and put the flexible pipe in and as best I know, covered them up with dirt.

The guy who did it also dug my well and is well respected around here for doing good work (and nailed me a 100 plus GPM well!)

[Richard]

Actually, instead of the old tank settling, he's afraid that the weight of the addition on the ground, might cause the old tank to cave in and cause the foundation to settle.

(the new foundation will be within probably 3-5 feet of the old tank and it's supposed to be minimum of 10' if I recall)

[plowking]

Originally Posted by Richard

Lemme see if this helps clear some things up...

I talked to the guys today and the septic guy says "flexible pipe" is very common here. He said it would be something like 10" in diamater.

He also said he felt after 10 years (maybe 9) that it's been installed that it "should" be ok to drive over.

Now...let's define drive over....

1. They need to get a backhoe in here to dig up lid on old tank
2. They need to get a gravel truck in here to fill old tank with gravel, then they're going to top it off with 4/6" of concrete on the top (of the inside)
3. Concrete truck needs to get in here to pour footers and pad for floor of room

I've taken a digitial picture that I'll try to post tomorrow at work to try to give some perspective

Unfortunately, I've got a (small) dogwood tree blocking one way in however, that same direction is also on a slope and they said the concrete truck couldn't come in that way with that degree of slope.

They want to take this tree out (that we've specifically built around trying to keep) and then take some 12x12 boards, scab some OSB onto them, maybe 8' long and build some "ramps" that they'll place on the ground to act as a "road", moving the ramps as the vehicle travels down it (build several sections and rotate them)

The septic guys says right now, we don't really know any answers until they "scratch around" some with his machine to find out where the pipes exit my house, where they enter the old tank and where they exit the old tank. Then, we'll know the elevations of what is where and how difficult this might be and where the equipment might need to be placed.

I am NOT too keen on the idea of a concrete truck traipsing through my front yard (although I'm not against redoing my front yard because it does need it) My issue is getting that kind of tonnage and knowing how they can cut through dirt/mud (if damp/wet) with their weight

I'll try to post that picture tomorrow morning

There are portable concrete pumping trucks with booms that can pump from the cement truck with hoses,it will add to cost but keep truck off the lawn. I also have a contractor who found a tank on a project after I had pumped all the existing tanks,this tank was under brand new lawn and landscaping.They called a company who brought a special pumper and filled tank by running hose and pumping some clay,paper combination off the truck to fill tank instead of caving it in. plowking

[CurlyDave]

Richard:

All of this stuff is heavy. And there is a way around most of it, for a price.

The gravel truck does not have to be fully loaded, but this will cost you more in transport fees.

Think about pumping concrete in. More expensive, but you can keep the concrete truck out of the area.

Another way to look at this is: what would a new leach field cost?

Actually, instead of the old tank settling, he's afraid that the weight of the addition on the ground, might cause the old tank to cave in and cause the foundation to settle.

How much would it cost to pour a grade beam that would prevent this problem by properly distributing the weight of the addition? I bet that would end up being less than backfilling the tank with concrete. Just fill it with gravel.

Many times, I have spent more money trying to save something than it would have cost to sacrifice the old one and get a new one.

[TedLaRue]

I just read through this entire thread, and I agree with many of the posts, but I think CurlyDave has a nice summary.

If the ground is dry, I wouldn't worry about a rubber tired hoe crossing the leach field once or twice, but a dumptruck full of gravel or a concrete truck is out of the question. Use the options CurlyDave suggests.

[Richard]

Originally Posted by CurlyDave

How much would it cost to pour a grade beam that would prevent this problem by properly distributing the weight of the addition?

What's a grade beam?

[Richard]

I think I forgot to add... they need to get the truck in here that will put in the NEW septic tank. This new location will be more towards the middle of the field (drain) than the end of the field as the current one is.

Again, I'll try to post some pics when I get to work (who me work at work? )

Also... (is this the beam?)

What if they brought in several truckloads of dirt (preferabley topsoil since I wanted to do that anyway)

Much like the egyptians perhaps, build a "ramp" to and over the drainfield so that the weight of vehicle will be an additional 12/24 inches ABOVE the current level of the grass??

Then, if they use topsoil, I can just box out the yard like I was planning on doing.

Is that a grade beam?

[MarkV]

I believe that Richard’s field is done with what we call “easy lay” here. It has perforated pipe that is surrounded with what looks like the Styrofoam pellets you use to pack fragile items and it is all held together with a wrap of soil fabric. The total package ends up about 10” round. This type of system has the advantage of not requiring gravel backfill and it does not have to be run in a perfectly straight line.

Richard the grade beam Dave is referring to does what a header over a window opening in a wood frame does. From the footing on either side of the the existing tank the concrete people would form a beam of concrete with a bunch of steel that would span the gap in the footing where the existing tank sits. It needs to be engineered but is a very common building practice. Often grade beams are used where native soil does not have the strength to support regular footings. In those situations they drive or pour pilings down to solid ground and then pour grade beams that sit on top of the piles for the building to be built on.

MarkV